Method for producing caramel color from molasses
By adding sodium citrate and disodium EDTA chelating agents in stages and gradients, combined with activated carbon adsorption and dynamic coking reaction parameter control, the problem of incomplete calcium ion chelation in molasses caramel color production was solved, the reaction efficiency of sodium metabisulfite and product stability were improved, and national standards were met.
Patent Information
- Application Number
- CN202510786669.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-13
- Publication Date
- 2025-09-19
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of food additive processing, and particularly relates to a method for producing caramel color by using molasses. Background Art
[0002] In the industrial production of caramel color, molasses is often used as the primary raw material due to its low cost and rich pigment precursors. However, molasses' complex composition, containing large amounts of colloidal substances, metal ions (such as calcium, iron, and aluminum), and non-sugar impurities, can lead to difficulties in process control and product quality defects during processing. Traditionally, the dilution, acidification, concentration, and caramelization of molasses raw materials to produce caramel color present the following technical bottlenecks: Molasses contains a high calcium ion content (typically 0.5% to 1.2%), which reacts with alkaline substances during the neutralization stage to form insoluble precipitates such as calcium sulfate. Existing processes often use a single chelating agent (such as sodium citrate). However, calcium ions in molasses exist in various forms (free and complexed), making it difficult for a single chelating agent to fully chelate them. This results in a high precipitate content after filtration, affecting the product's transmittance and storage stability. Furthermore, excessive use of chelating agents may introduce residual sodium ions, increasing the risk of side reactions in the subsequent coking reaction.
[0003] During the coking reaction, sodium metabisulfite undergoes a sulfonation reaction with sugars under high temperature and pressure to stabilize the pigment structure. However, residual metal ions (such as Fe³⁺ and Al³⁺) in the molasses concentrate catalyze the decomposition of sodium metabisulfite, reducing its effective utilization. Furthermore, the high viscosity of the reaction system limits mass transfer, making the sulfonation reaction prone to localized overreaction or incomplete reaction, resulting in large fluctuations in product absorbance and uneven color distribution.
[0004] Molasses concentration requires multi-effect evaporation, but sugars are susceptible to Maillard reactions and caramelization at high temperatures, producing dark byproducts such as melanoidins. This increases the color difference (ΔE) of the concentrate, and the accumulation of caramelized precursors increases the risk of off-flavor in the end product. Furthermore, the evaporation process generates severe foam, requiring frequent addition of defoamers and potentially introducing exogenous impurities.
[0005] Finished caramel color needs to be adjusted to the target Baume and pH value through dilution and neutralization. However, molasses pigment molecules are sensitive to changes in ionic strength and temperature. Sudden dilution can easily cause pigment precipitation or aggregation, resulting in color loss. Furthermore, excessive local concentrations of acid and base reagents during pH adjustment can cause molecular rearrangements, irreversible changes in absorbance and viscosity, and affect product batch consistency.
[0006] The root cause of the above problems lies in the complexity of the molasses raw material components and the lack of adaptability to its processing technology: the metal ions in molasses form stable complexes with the colloids, which are difficult to completely dissociate by conventional chelation and separation methods; although high temperature and high pressure conditions can accelerate the reaction, they intensify the degradation of heat-sensitive components and the competition with side reactions; the parameters of unit operations such as dilution, concentration, and coking lack synergy, resulting in stress accumulation within the system.
[0007] Previous attempts to improve the process have partially mitigated these issues by optimizing the type of chelating agent (such as EDTA), enhancing filtration accuracy, or introducing an inert atmosphere. However, these limitations remain: complex chelating agents are expensive and may pose food safety risks; high-precision filtration equipment is prone to clogging, significantly increasing maintenance costs; and inert gas protection struggles to completely block the carbohydrate oxidation pathway and can inhibit the sulfonation reaction kinetics. Therefore, developing a molasses caramel color production process that balances efficiency, cost, and product stability remains a significant challenge. Summary of the Invention
[0008] The present invention aims to provide a method for producing caramel color from molasses, which at least solves the technical difficulties in the traditional molasses caramel color production process, such as incomplete calcium ion chelation resulting in residual precipitate, low sodium metabisulfite reaction efficiency and poor product stability, and difficulty in meeting the national standards for absorbance and precipitate.
[0009] To achieve the purpose of the present invention, the method for producing caramel color from molasses provided by the present invention comprises the following steps: Step 1: diluting the molasses raw material with water and concentrated sulfuric acid, wherein the pH value of the diluted mixture is 2.6-3.0 and the Baume degree is 30-33°Be; Step 2: Raise the temperature of the diluted mixed solution to 88-93°C, keep the temperature until the reduction rate is greater than 85%, then cool it to 65-70°C and filter it, controlling the sediment content after filtration to ≤0.5%; Step 3, concentrating the filtrate to a Baume degree of 35.5-38.5°Be; Step 4: adding liquid caustic soda to the concentrated solution to adjust the pH to 4.5-7.0; then adding sodium citrate in an amount of 0.3-0.5% by weight of the molasses raw material to form a calcium ion chelate; Step 5, adding sodium metabisulfite to the neutralized concentrated solution under the conditions of pressure ≤ 0.3 MPa and temperature 100-125° C. to carry out a coking reaction; Step 6: Adjust the Baume degree of the reaction product to 38-39° Be, the pH to 5.0-6.5, and the absorbance to 0.01-1.00.
[0010] A single addition of sodium citrate has limited chelating effect on calcium ions in different binding forms (such as free calcium and complexed calcium) in molasses, resulting in locally high chelating agent concentrations or incomplete reaction, and low precipitate removal efficiency. Furthermore, in the method for producing caramel color from molasses of the present invention, the sodium citrate is added in a staged gradient manner in step 4, specifically comprising: after adjusting the pH to 4.5-5.5 with liquid caustic soda, initially adding 0.1-0.2% of the molasses raw material's weight of sodium citrate, stirring and reacting for 10-15 minutes; after further adjusting the pH to 5.5-7.0, adding the remaining 0.2-0.3% of the molasses raw material's weight of sodium citrate, maintaining the reaction temperature at 50-60°C, and stirring for 20-30 minutes; and removing the chelated precipitate by centrifugation at a controlled centrifugal speed of 3000-4000 rpm.
[0011] Because single chelating agents (such as sodium citrate) have poor selectivity for high-valent metal ions (Fe⁺, Al⁺), residual metal ions catalyze side reactions, reducing sulfonation efficiency and product color uniformity. Furthermore, in the method for producing caramel color from molasses of the present invention, disodium EDTA is simultaneously added at a rate of 0.05-0.1% by weight of the molasses raw material, while sodium citrate is added in step 4. The temperature for adding the mixed chelating agents is controlled to be 55-65°C, and the stirring rate is controlled to be 80-120 rpm.
[0012] Activated carbon adsorption cannot simultaneously remove unreacted chelating agent and colloidal impurities, and the insufficient precision of plate-and-frame filtration leads to residual odor and quality deterioration during storage. Furthermore, after adding sodium citrate in step 4 of the present invention, an activated carbon adsorbent is added at a rate of 5% to 8% of the total weight of the chelating agent. The adsorption time is 30 to 40 minutes, and the adsorbent and chelated precipitate are then removed through a plate-and-frame filter with a filter cloth precision of 5 to 10 μm.
[0013] In view of the fact that heat release during the addition of liquid caustic soda leads to local over-alkali, the timing of adding the composite chelating agent is mismatched with the temperature control, and the traditional filtration method cannot take into account both precipitation removal and chelating agent residue control. Furthermore, step 4 of the present invention includes the following process: A 10%-15% sodium hydroxide solution was added at a rate of 0.5-1.0 L / min, and carbon dioxide gas was introduced simultaneously at a flow rate of 0.2-0.5 L / min to neutralize the heat and control the pH fluctuation to ≤±0.2. Within 5 minutes after the addition of the liquid caustic soda, 0.3-0.5% of the mass of the molasses raw material sodium citrate and 0.05-0.1% of disodium ethylenediaminetetraacetic acid were added in sequence, and a temperature gradient stirring was adopted: the first stage: 50-55℃, 100-120 rpm stirring for 10 minutes; the second stage: heating to 60-65℃, switching to turbulent stirring at 200-250 rpm for 15 minutes; the mixture was added with 5% of the total mass of the chelating agent activated carbon and 2%-3% diatomaceous earth, and the mixture was kept at 40-50℃ for adsorption for 20 minutes. Finally, it was filtered through a ceramic membrane with a pore size of 0.5-1.0 μm.
[0014] In the molasses dilution stage, uneven acid mixing causes localized carbonization, insufficient colloidal stress relaxation leads to fluctuations in Baume degrees, and affects the stability of subsequent processes. Furthermore, step 1 of the present invention further includes: in the two-stage dilution process, in the first stage of dilution, pre-adding 0.05% to 0.1% of the molasses raw material's weight of sodium lauryl sulfate to the water as a dispersant, and controlling the water temperature to 45-50°C; in the second stage of acidification, pre-mixing concentrated sulfuric acid with 5% to 10% of the sulfuric acid volume, dilute phosphoric acid concentration of 10% to 15%, and then injecting it in a pulsed manner, while simultaneously initiating ultrasonic oscillation at a frequency of 25-35 kHz and a power of 50-100W.
[0015] The traditional heating mode causes excessive oxidation of sugars, low reduction reaction efficiency and wide molecular weight distribution, and filtration efficiency is restricted by viscosity mutation. Furthermore, in step 2 of the present invention, while adding L-cysteine hydrochloride, the reduction reaction regulator is introduced twice: in the first addition, when the temperature rises to 75°C, sodium thiosulfate is added at 0.01% to 0.02% by weight of the molasses raw material, and the oxygen content is controlled to ≤1.5 ppm; in the second addition, after the molasses dilution solution is heated to the target temperature of 88-93°C, ascorbyl palmitate is added at 0.005% to 0.01% by weight of the molasses raw material, and the stirring direction is switched.
[0016] To address the serious degradation of heat-sensitive substances during the concentration process, the accumulation of coking precursors caused by temperature differences at the evaporation interface, and the risk of traditional defoamers introducing exogenous impurities, the present invention further proposes that, in step 3, while nitrogen is injected during the medium-concentration stage, trehalose is added as a thermal stabilizer at a rate of 0.02% to 0.05% by weight of the concentrate, and the temperature difference at the evaporation interface is controlled to be ≤5°C. After disodium hydrogen phosphate is added during the high-concentration stage, the temperature is alternately raised and lowered at a rate of 0.5°C to 1.0°C / min.
[0017] Due to the uneven sulfonation caused by the constant pressure and constant temperature coking reaction, the utilization rate of sodium metabisulfite is low, the molecular weight of the product is dispersed, and the absorbance stability is poor. Furthermore, in step 5 of the present invention, the sodium metabisulfite is added in stages. Each time the sodium metabisulfite is added, liquid carbon dioxide microbubbles accounting for 1% to 2% of the mass of the sodium metabisulfite are injected simultaneously. The microbubbles have a diameter of 10 to 50 μm. After the sodium bisulfite is added in the post-stabilization stage, the pressure is cyclically applied at a pressure of 0.1 to 0.2 MPa for three times.
[0018] Because sudden dilution triggers pigment precipitation and excessive local concentrations of acid and alkali lead to irreversible changes in the molecular structure, traditional conditioning processes rely on manual experience. Furthermore, in step 6 of the present invention, after the pH and Baume degrees of the reactants are adjusted, when cooling, 0.01% to 0.03% of the dilution mass is added as an embedding agent, and light-assisted temperature control is adopted: at 50-55°C, ultraviolet-visible light with a wavelength of 365-405 nm and a light intensity of 50-100 Lux is turned on; below 40°C, infrared radiation is switched to assist in cooling.
[0019] The present invention has at least the following beneficial effects: 1. The present invention significantly reduces residual calcium ion precipitation through a staged neutralization and chelation process design. Combined with dynamic coking reaction parameter control, the effective utilization rate of sodium metabisulfite is improved, ensuring that the product absorbance and Baume degree meet national standards, while reducing the stability risk in the terminal conditioning stage.
[0020] 2. The present invention adds sodium citrate in a staged gradient and matches it with a segmented pH adjustment to enhance the targeted chelation ability of calcium ions in different forms, reduce the problem of sodium ion residue caused by a single excessive addition, and further reduce the sediment content by centrifugation, thereby improving the filtration efficiency and product transmittance.
[0021] 3. The sodium citrate and disodium EDTA of the present invention form a composite chelate system, which specifically captures high-valent metal ions, blocks their catalytic interference with the coking reaction, and coordinates the stirring rate and temperature control to optimize the chelate reaction kinetics, thereby improving the sulfonation efficiency and product color uniformity.
[0022] 4. The present invention effectively removes unreacted chelating agents and colloidal impurities through activated carbon adsorption combined with plate and frame filtration, reduces residual odor substances, and the precision control of the filter cloth ensures the purity of the system and prolongs the stability of the product during storage.
[0023] 5. The present invention adopts dynamic temperature control of carbon dioxide gas in conjunction with temperature gradient stirring to avoid local overheating failure when adding the composite chelating agent. Ceramic membrane filtration replaces the traditional method to achieve efficient precipitation removal and chelating agent residue control, thereby improving process economy and safety.
[0024] 6. The present invention combines premixing of sodium dodecyl sulfate with pulse acid injection and ultrasonic vibration to enhance the uniformity of acid dispersion, suppress the risk of local carbonization, and improve the stability of Baume degree through colloid aging process, thus providing a homogenized raw material basis for subsequent reactions.
[0025] 7. The present invention adds sodium thiosulfate and ascorbyl palmitate in stages to synergistically remove free oxygen and inhibit sugar oxidation. Reverse temperature control and two-way stirring optimize the reduction reaction path, shorten the insulation time and improve the filtration efficiency.
[0026] 8. The present invention sets trehalose heat stabilizer and nitrogen protection to synergistically inhibit the degradation of heat-sensitive substances, and the temperature alternating cycle eliminates the internal stress of the concentrate, reduces the accumulation of coking precursors, and improves the concentration efficiency and product color stability.
[0027] 9. The present invention uses liquid carbon dioxide microbubbles to enhance the mass transfer efficiency of sodium metabisulfite, and pressure circulation eliminates the reaction interface resistance, improves the uniformity of sulfonation, reduces the generation of by-products, and ensures the stability of absorbance detection.
[0028] 10. The present invention stabilizes the conformation of pigment molecules by embedding hydroxypropyl-β-cyclodextrin and combining it with light regulation in a specific wavelength band. Infrared radiation assists cooling to promote orderly arrangement of molecules, thereby significantly improving the color retention rate and viscosity consistency of the finished product during storage.
[0029] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION
[0030] The present invention is further described in detail below with reference to examples so that those skilled in the art can implement the invention with reference to the description.
[0031] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.
[0032] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.
[0033] Example 1 The present invention provides an example of a process for producing caramel color from molasses, comprising: Step 1: diluting the molasses raw material with water and concentrated sulfuric acid, wherein the pH value of the diluted mixture is 2.6-3.0 and the Baume degree is 30-33°Be; Step 2: Raise the temperature of the diluted mixed solution to 88-93°C, keep the temperature until the reduction rate is greater than 85%, then cool it to 65-70°C and filter it, controlling the sediment content after filtration to ≤0.5%; Step 3, concentrating the filtrate to a Baume degree of 35.5-38.5°Be; Step 4: adding liquid caustic soda to the concentrated solution to adjust the pH to 4.5-7.0; then adding 0.3-0.5% of the mass of the molasses raw material as a chelating agent sodium citrate to form a calcium ion chelate; Step 5, adding sodium metabisulfite to the neutralized concentrated solution under the conditions of pressure ≤ 0.3 MPa and temperature 100-125° C. to carry out a coking reaction; Step 6: Adjust the Baume degree of the reaction product to 38-39° Be, the pH to 5.0-6.5, and the absorbance to 0.01-1.00.
[0034] Specifically: 1. Dilution treatment During the dilution process, molasses can be mixed with water at a mass ratio of 1:1.5-2.0. Industrial-grade sulfuric acid (98%) can be used, with the addition amount controlled at 0.15-0.19 m³. The pH value can be monitored in real time using an online pH sensor, with the endpoint adjusted to 2.6-3.0. Baume measurements can be performed using a handheld refractometer with a control range of 30-33°Be. The mixing equipment can be a pretreatment tank with a stirring function. The tank should be made of 316L stainless steel, and the stirring blades can be configured with a double-layer turbine structure.
[0035] Molasses can be sourced from sugar refinery byproducts, and reverse osmosis water can be used. Concentrated sulfuric acid is added via a metering pump at a rate of 0.2-0.5 L / min, and the mixing temperature can be maintained at 25-35°C. After mixing, the mixture is allowed to stand for 10-15 minutes to eliminate bubbles. Functional testing involves testing the homogeneity of the mixture. The experimental method involves taking samples at five different points to test the pH and Baume deviation values, with the deviation required to be ≤±0.2. The technical effect of this step is to ensure the homogeneity and stability of the dilution solution, providing a foundation for subsequent reactions.
[0036] 2. Heating reaction and filtration During the heating reaction, the mixed solution can be heated using a steam jacket. The heating rate can be set at 2-3°C / min, with the target temperature preferably at 90°C. During the holding phase, a temperature controller can be used to maintain a temperature fluctuation of ≤±1°C. The holding time is dynamically adjusted based on the reduction rate test results, typically 60-120 minutes. The reduction rate can be tested using Fehling's reagent titration. Once the target is met, the temperature is lowered to 65-70°C at a cooling rate of 1-2°C / min.
[0037] The filtration equipment can be a plate and frame filter press, and the filter cloth can be made of polypropylene fiber. The filtration precision is 5-10 μm. The filtration pressure can be set to 0.3-0.5 MPa. After the filtrate is collected, the sediment content is tested and required to be ≤0.5%. Colloidal impurities in the raw materials are easier to filter and remove after high-temperature denaturation. The experimental subjects were different batches of molasses, and the experimental method was to compare the sediment content and filtrate transmittance before and after filtration. The technical effect of this step is to reduce impurity interference in subsequent processes and improve product purity.
[0038] 3. Concentration and neutralization chelation A four-effect falling-film evaporator can be used for the concentration process, with the first-effect evaporation temperature set at 110-115°C and a vacuum of -0.06-0.08 MPa. The optimal concentration endpoint is 36.5° Be. For the neutralization stage, a 10% sodium hydroxide solution can be added via a peristaltic pump at a rate of 0.8 L / min, with the optimal pH adjustment endpoint being 5.5. Sodium citrate can be added in two steps: an initial addition of 0.2% at pH 4.5 and a second addition of 0.3% at pH 6.5. The stirring speed should be set at 100 rpm.
[0039] The chelation reaction tank can be equipped with a coil-and-tube heat exchanger, with the reaction temperature controlled at 55°C. The calcium ions in the raw materials react with the sodium citrate to form a soluble complex, which is then separated by a centrifuge (decanter) at 3000 rpm, leaving a residual precipitate. Functional testing includes measuring the conductivity of the post-chelation liquid, which must be ≤500 μS / cm. This step effectively removes calcium ions and prevents side reactions during the coking phase.
[0040] 4. Coking reaction and conditioning The coking reactor can be a high-pressure reactor equipped with a stirrer, with an operating pressure of 0.2 MPa and a temperature of preferably 115°C. Sodium metabisulfite can be added in three separate additions, with 10-minute intervals between each addition, for a total addition amount of 1.5% to 2.0% of the molasses mass. After the reaction, the product can be cooled to below 50°C using a plate heat exchanger and then diluted with deionized water to 38.5°Be. The pH is adjusted using a citric acid and sodium bicarbonate buffer solution, with an optimal endpoint pH of 5.8.
[0041] Absorbance can be measured using a UV spectrophotometer set at a wavelength of 560 nm. Samples must be filtered through a 0.45 μm filter membrane before testing. The conditioned product can be temporarily stored in a constant-temperature storage tank (25°C) for 2 hours before stability testing. The test method involves comparing the absorbance change before and after 30 days of storage, with a fluctuation range of ≤5%. Ensure that the product complies with the national standard GB1886.64-2015 and exhibits good storage stability.
[0042] After two stages of dilution, the pH of the mixed solution stabilized within the range of 2.6–3.0, with a Baume deviation of ≤±0.3°Be. pH fluctuations at different sampling locations were ≤±0.1. The acid dispersion uniformity was significantly improved, with no localized carbonization. After heating the mixed solution to 90°C and holding for 80 minutes, the reduction rate reached 88%–92%. After filtration, the precipitate content was 0.3%–0.45%, and the filtrate transmittance (560 nm wavelength) was ≥90%, indicating complete removal of colloidal impurities. The Baume degree of the concentrate stabilized within the range of 36.5–37.5°Be. After chelation, the liquid conductivity decreased from an initial 1200 μS / cm to 450–480 μS / cm. The residual precipitate after centrifugation was ≤0.15%. The absorbance of the coking product was 0.08~0.12 (560 nm), the Baume degree was adjusted to 38.5~39.0°Be, the pH value was 5.5~5.8, and the absorbance fluctuation was ≤0.02 after storage for 30 days, with no precipitation or color change.
[0043] Example 2 The present invention provides an example of a process for producing caramel color using molasses. Based on implementation 1, step 4 is optimized, comprising: after adjusting the pH to 4.5-5.5 with liquid caustic soda, initially adding 0.1-0.2% of the mass of the molasses raw material sodium citrate, and stirring for reaction for 10-15 minutes; after further adjusting the pH to 5.5-7.0, adding 0.2-0.3% of the mass of the remaining molasses raw material sodium citrate, controlling the reaction temperature to maintain at 50-60°C, and stirring for 20-30 minutes; and removing chelated precipitates by centrifugation, controlling the centrifugal speed to be 3000-4000 rpm.
[0044] Specifically: 1. Staged pH adjustment and gradient addition of sodium citrate For staged pH adjustment, the first neutralization step can be performed with an 8% to 12% sodium hydroxide solution, added via a peristaltic pump at a rate of 0.5 L / min. After adjusting the pH to 4.5 to 5.5, sodium citrate (0.1% to 0.2% by weight of the molasses raw material) is initially added. The second neutralization step uses the same caustic soda solution, adjusting the pH to 5.5 to 7.0, followed by the addition of the remaining 0.2% to 0.3% sodium citrate. For pH monitoring, an online pH meter can be installed at the bottom outlet of the reactor.
[0045] Sodium citrate can be prepared as a food-grade powder (purity ≥99%), dissolved in 40-50°C pure water, and added in batches via a metering tank. After the initial addition, stir the reaction for 10-15 minutes. The stirring blade can be configured as a pitch-blade turbine at 80-100 rpm. Functional testing involves measuring the calcium ion concentration in the chelated liquid using EDTA titration, with a requirement for residual calcium ions of ≤50 ppm. This step technically matches the chelation requirements of different calcium ion forms in stages, reducing chelating agent waste.
[0046] 2. Temperature and stirring control During the initial addition phase, the reaction temperature can be maintained at 25-30°C, with a stirring speed set at 80-100 rpm. During the secondary addition phase, the temperature is raised to 50-60°C using jacketed steam heating at a controlled rate of 1°C / min. The stirring speed is increased to 120-150 rpm, and the stirring time is extended to 20-30 minutes. The reactor can be a jacketed 316L stainless steel tank (5 m³ capacity), with a stirring motor rated at 7.5 kW.
[0047] The temperature control can be controlled by a PID temperature control system, with the sensor installed in the lower middle part of the tank side wall. The technical effect of this step is to enhance the contact efficiency between the chelating agent and the calcium ion by adjusting the temperature gradient and the stirring intensity, thereby shortening the reaction time.
[0048] 3. Centrifugal separation parameter setting Centrifugal separation can be performed using a horizontal screw discharge centrifuge with a speed set between 3000 and 4000 rpm, preferably 3500 rpm in this embodiment. The feed rate is controlled at 1.5 to 2.0 m³ / h. The centrifuge drum can be made of duplex stainless steel, with the differential speed set to 10 to 15 rpm. The separated liquid phase is then passed through an outlet pipe into a temporary storage tank, and the moisture content of the solid precipitate is maintained at ≤30%.
[0049] The centrifuge can be installed downstream of the chelation reaction tank, with the feed liquid delivered via a pneumatic diaphragm pump. Functional testing includes measuring the turbidity of the centrifuged liquid (NTU ≤ 10), which is monitored online using a turbidity meter. This step effectively removes chelate precipitates, preventing impurities from interfering with the subsequent coking reaction.
[0050] In this example, the calcium ion concentration was reduced from an initial 800 ppm to 350-400 ppm after the first addition, and further to 40-50 ppm after the second addition, reducing the total chelating agent dosage by 15%-20%. Temperature fluctuation during the second addition phase was ≤±1.5°C, and the reaction time was shortened to 25 minutes. The sediment removal rate was ≥95%, the liquid turbidity was ≤8 NTU, and the centrifuge operated continuously for 8 hours without clogging.
[0051] Example 3 The present invention provides an example of a process for producing caramel color using molasses. Based on Example 1, step 4 is further optimized, comprising: simultaneously adding sodium citrate and disodium ethylenediaminetetraacetic acid at a rate of 0.05-0.1% by weight of the molasses raw material, and controlling the addition temperature of the mixed chelating agent to be 55-65° C. and the stirring rate to be 80-120 rpm.
[0052] Specifically: 1. Synchronous addition of compound chelating agent Sodium citrate can be prepared as a food-grade powder (purity ≥99%), and disodium ethylenediaminetetraacetic acid (Disodium EDTA) can be prepared as an industrial-grade powder (purity ≥98%). The amount of Disodium EDTA added should be 0.05% to 0.1% of the molasses raw material mass, preferably 0.08% in this example. It should be added simultaneously with the sodium citrate to the reactor via a double-screw feeder. The feeder can be installed at the top of the reactor, with a feed rate of 5 to 8 kg / min. The two chelating agents can be premixed in a mass ratio of 3:1 to 5:1 and dissolved in deionized water at 45 to 55°C to form a homogeneous solution.
[0053] Molasses can be sourced from sugarcane sugar production byproducts, and disodium EDTA can be purchased from chemical raw material suppliers. The pH of the mixed chelating agent solution is tested (controlled between 6.0 and 7.5). After sampling, let the solution sit for 10 minutes before testing. This step achieves the targeted removal of high-valent metal ions (such as Fe⁺ and Al⁺) from molasses through the synergistic action of the complex chelating agent.
[0054] 2. Temperature control of mixed chelating agent The chelation reaction temperature can be controlled by the reactor jacket's circulating water system, set between 58°C and 62°C, preferably 60°C. A temperature sensor can be installed in the center of the reactor sidewall to monitor temperature fluctuations in real time (with a tolerance of ±1.5°C). The reactor volume is tailored to the production scale; for example, a 5 m³ reactor can accommodate a single batch.
[0055] The heating process can be achieved by steam heating or electric heating, with the heating rate controlled at 1-2°C / min. The technical effect of this step is to prevent the decomposition of the chelating agent caused by high temperature or insufficient reaction at low temperature by precise temperature control.
[0056] 3. Stirring rate control The agitator can be a pitch-blade turbine impeller with a motor power of 7.5-11 kW and a speed of 80-120 rpm, preferably 100 rpm. The impeller can be mounted on the central axis of the reactor, with a ratio of 1:3 between the impeller diameter and the reactor diameter. The stirring time can be set to 30-40 minutes, preferably 35 minutes, and the stirring direction can be fixed to clockwise.
[0057] The stirring speed can be adjusted via a frequency converter. The turbidity of the chelated liquid (NTU ≤ 15) is measured using an online turbidity meter. This step optimizes the stirring intensity to ensure adequate contact between the chelating agent and the metal ions, reducing reaction dead zones.
[0058] In this example, the initial Fe⁺ concentration in the molasses raw material was 120-150 ppm, and the initial Al⁺ concentration was 80-100 ppm. After treatment with the composite chelating agent, the residual Fe⁺ content was ≤5 ppm, and the residual Al⁺ content was ≤3 ppm. The calcium ion concentration was reduced from an initial 800-1000 ppm to 50-60 ppm, increasing the chelation efficiency by approximately 30%. The chelation reaction temperature was maintained at 58-62°C, with a fluctuation range of ≤±1.5°C. No thermal decomposition of the chelating agent was detected (decomposition rate <1%). The temperature difference between different points in the reaction tank was ≤2°C, and the temperature uniformity met process requirements. At a stirring rate of 100 rpm, the turbidity of the mixed solution decreased from an initial 120 NTU to 8-12 NTU, with no local precipitation or demixing observed. The chelation reaction time was shortened to 30-35 minutes, increasing batch processing efficiency by approximately 20%. The absorbance fluctuation range of the charring reaction product is ≤±0.05 (560 nm detection wavelength), and the color difference value ΔE is ≤1.2 (CIELAB standard). After 30 days of storage, the amount of metal ion re-dissolution is ≤2 ppm, with no darkening or precipitation.
[0059] Example 4 The present invention provides an example of a process for producing caramel color using molasses. Based on Example 1, the operating process of adding an adsorbent after adding sodium citrate in step 4 is further optimized, comprising: after adding sodium citrate, adding an activated carbon adsorbent at 5% to 8% of the total mass of the chelating agent, for an adsorption time of 30 to 40 minutes, and then removing the adsorbent and chelated precipitate through a plate and frame filter, with a filter cloth precision of 5 to 10 μm.
[0060] Specifically: 1. Composite adsorption of activated carbon and diatomaceous earth Food-grade powdered activated carbon (particle size 200-300 mesh, iodine value ≥ 900 mg / g) can be used, and refined diatomaceous earth (SiO2 content ≥ 85%) can be used. The activated carbon addition amount is 5%-8% of the total chelating agent weight, preferably 6% in this embodiment. The diatomaceous earth addition amount is 2%-3% (preferably 2.5% in this embodiment). The two can be premixed in a mass ratio of 2:1-3:1 and added to the adsorption tank via a pneumatic conveying system. The mixed adsorbent can be evenly dispersed in the chelated liquid at a rate of 10-15 kg / min.
[0061] Check the uniformity of the adsorbent suspension and take samples to observe whether there is any lumps or sedimentation on the liquid surface. The technical effect of this step is to remove unreacted chelating agent and colloidal impurities through the synergistic effect of the composite adsorbent.
[0062] 2. Adsorption condition control The adsorption tank can be a jacketed enameled reactor with a capacity suitable for batch sizes of 5-10 m³. Circulating hot water should be passed through the jacket to maintain a temperature of 40-50°C, preferably 45°C. A temperature sensor can be installed in the middle of the tank sidewall, with a temperature control accuracy of ±2°C. The adsorption time can be set to 20-40 minutes, preferably 30 minutes, and the stirring speed can be set to 50-80 rpm. An anchor-type agitator can be used as the propeller. The number of impurity particles in the chelated liquid before and after adsorption is compared (detected using a laser particle size analyzer). This step achieves a balance between adsorption efficiency and energy consumption by controlling temperature and time, preventing excessive adsorption from clogging the activated carbon pores.
[0063] 3. Filtration accuracy and equipment selection The filtration equipment can utilize a ceramic membrane filtration system (pore size 0.5-1.0 μm). The membrane material can be alumina ceramic, and the membrane area should be tailored to the throughput (e.g., 20 m² for a 5 m³ / h flow rate). The filtration pressure can be set between 0.2 and 0.4 MPa, preferably 0.3 MPa. The filtrate passes through the membrane tubes and enters the finished product storage tank. The backwash system can be configured to automatically flush every 30 minutes, with a backwash pressure of 0.6-0.8 MPa.
[0064] The ceramic membrane module can be installed downstream of the adsorption tank, with the feed solution delivered via a centrifugal pump. The filtrate turbidity (NTU ≤ 5) is measured using an online turbidity meter. This step ensures system purity through high-precision filtration, preventing residual adsorbent from entering subsequent processes.
[0065] The residual amount of unreacted chelating agent in the chelating solution of this example was reduced from an initial 120-150 ppm to 15-20 ppm, and the number of colloidal particles (particle size ≥1 μm) decreased from 5000-6000 particles / mL to 200-300 particles / mL. The content of odorous substances (such as thiols) was reduced from the detection limit of 0.1 ppm to undetectable levels. The single-batch consumption of activated carbon was reduced to 6% of the total weight of the chelating agent, and the consumption of diatomaceous earth was 2.5%. The adsorbent saturation utilization rate reached over 85% within 30 minutes of adsorption. The turbidity of the filtrate after ceramic membrane filtration was ≤3 NTU (detection wavelength 560 nm), and the membrane flux was maintained at 100-120 L / (m²·h), with no attenuation after 12 hours of continuous operation. The caramel-colored finished product had an absorbance of 0.05-0.10 (tested according to GB 1886.64-2015 standard), with a color difference value ΔE ≤1.5 (CIELAB standard). After 90 days of storage, there was no precipitation, the absorbance fluctuation was ≤0.03, and there was no odor or darkening of color in the sensory evaluation.
[0066] Example 5 Based on Example 1, step 4 is further optimized by process collaboration, including: Add 10% to 15% sodium hydroxide solution at a rate of 0.5 to 1.0 L / min, and simultaneously introduce carbon dioxide gas at a flow rate of 0.2 to 0.5 L / min. Neutralize and release heat, and control the pH fluctuation to ≤±0.2; Within 5 minutes after the addition of liquid caustic soda, 0.3-0.5% of the mass of the molasses raw material sodium citrate and 0.05-0.1% of disodium ethylenediaminetetraacetic acid were added in sequence, and temperature gradient stirring was adopted: first stage: 50-55°C, 100-120 rpm stirring for 10 minutes; second stage: heating to 60-65°C, switching to turbulent stirring at 200-250 rpm for 15 minutes; Add 5% activated carbon and 2%~3% diatomaceous earth to the mixed solution, keep it at 40~50℃ for 20 minutes, and finally filter it through a ceramic membrane with a pore size of 0.5~1.0 μm.
[0067] Specifically: 1. Dynamic temperature control of liquid alkali and addition of composite chelating agent Liquid caustic soda can be prepared using a sodium hydroxide solution with a mass concentration of 10% to 15%, added via a peristaltic pump at a rate of 0.5 to 1.0 L / min, preferably 0.8 L / min. Carbon dioxide gas can be supplied from a food-grade source at a controlled flow rate of 0.2 to 0.5 L / min, preferably 0.3 L / min, injected through a gas distributor at the bottom of the reactor. pH fluctuations can be controlled using an online pH meter installed in the reactor outlet pipe to adjust the liquid caustic soda addition rate in real time.
[0068] The order for adding the chelating agents is to first add 0.3%–0.5% sodium citrate by weight of the molasses raw material, followed by 0.05%–0.1% disodium ethylenediaminetetraacetic acid (DISODIUM EDTA) within 5 minutes after the liquid caustic soda adjustment is complete. Both chelating agents can be dissolved separately in deionized water at 45–55°C and added via separate metering tanks. Functional testing involves measuring the conductivity of the neutralized liquid (required to be ≤800 μS / cm) using an online conductivity meter. This step, through dynamic temperature control and step-by-step dosing, prevents chelating agent failure due to localized over-alkali.
[0069] 2. Temperature gradient stirring process For the first stage of stirring, a paddle stirrer can be used with a speed set to 100-120 rpm, preferably 110 rpm, and a temperature controlled at 50-55°C for 10 minutes. For the second stage, a turbine stirrer can be used, with the speed increased to 200-250 rpm, preferably 220 rpm, and the temperature raised to 60-65°C for 15 minutes. The reactor can be equipped with a replaceable stirring paddle system, with a stirring motor rated at 11-15 kW, and a frequency converter to adjust the speed.
[0070] Temperature control is achieved through the jacket's circulating water system. A temperature sensor is installed at the jacket's water inlet, providing feedback to the PLC control system to adjust the steam valve opening. Residual calcium ion levels are compared before and after temperature gradient stirring. This step improves chelating agent utilization by matching the reaction progress with gradient stirring intensity.
[0071] 3. Composite adsorption and membrane filtration Activated carbon can be wood powdered activated carbon (particle size 200-300 mesh), added at a rate of 5% to the total weight of the chelating agent. Diatomaceous earth can be added at a rate of 2%-3%, preferably 2.5%. Both can be pre-dry mixed and then added to the adsorption tank via a screw conveyor at a rate of 8-12 kg / min. The adsorption tank can be an insulated 316L stainless steel tank with a capacity suitable for batch sizes of 5-10 m³. The adsorption temperature should be set at 40-50°C, preferably 45°C.
[0072] The ceramic membrane filtration system can utilize tubular alumina ceramic membranes (pore size 0.5-1.0 μm). The membrane area is configured based on the processing capacity (e.g., 20 m² for a flow rate of 5 m³ / h). The filtration pressure is set at 0.2-0.4 MPa, preferably 0.3 MPa. The filtrate passes through the membrane assembly and enters the finished product storage tank. The backwash system can be equipped with an automatic control module to reverse flush at 0.6 MPa for 10 seconds every 30 minutes. The residual particle count in the filtrate is measured (particles ≥0.5 μm, ≤100 particles / mL) using a laser particle size analyzer. The technical effect of this step is to ensure system purity and process continuity through combined adsorption and high-precision filtration.
[0073] This example demonstrates comprehensive improvements in chelation efficiency, with residual Fe⁺ levels ≤ 2 ppm (≤ 5 ppm in Example 3), residual Al⁺ levels ≤ 1 ppm (≤ 3 ppm in Example 3), and residual calcium ions ≤ 30 ppm (≤ 50 ppm in Example 1). The total sodium citrate dosage is 0.35% of the molasses raw material mass, and the disodium EDTA dosage is 0.07%. The pH fluctuation during the caustic soda addition phase is ≤ ±0.1 (±0.2 in Example 1), and carbon dioxide gas usage is reduced by 20%. The reaction time under the gradient stirring process is shortened to 22 minutes (25 minutes in Example 2), and power consumption per unit batch is reduced by at least 15%. The ceramic membrane flux is maintained at 150 L / (m²·h) (100-120 L / (m²·h) in Example 4), with no degradation after 24 hours of continuous operation. The unit consumption of activated carbon is 4.5% of the total mass of the chelating agent (6% in Example 4), and the unit consumption of diatomaceous earth is 2.0% (2.5% in Example 4). The caramel-colored final product had an absorbance fluctuation range of ≤±0.01 (±0.02 in Example 1), a color difference value of ΔE ≤0.8 (ΔE ≤1.2 in Example 3), and an absorbance change of ≤0.02 after 180 days of storage (≤0.03 in Example 1), with no precipitation or off-flavor generated.
[0074] Compared with Example 1, the residual calcium ion content of this embodiment is reduced by 40%, the absorbance fluctuation range is compressed by 50%, and the storage period is extended to 6 months without degradation. Compared with Example 2, the total amount of chelating agent used in this embodiment is reduced by 12%, the reaction time is shortened by 12%, and the dependence on centrifugal separation equipment is avoided (membrane filtration is used instead). Compared with Example 3, the removal rate of high-valent metal ions (Fe³⁺, Al³⁺) of this embodiment is increased by 60%, and the chelating agent decomposition rate is reduced to <0.5% (Example 3 is <1%). Compared with Example 4 (adsorption-membrane filtration), the membrane flux of this embodiment is increased by 25%, the backwash frequency is reduced by 50%, and the activated carbon consumption is reduced by 25%, which is suitable for continuous production needs.
[0075] Example 6 On the basis of Example 1, the dilution operation was further optimized, including two stages. In the first stage of dilution, 0.05% to 0.1% of the mass of the molasses raw material sodium lauryl sulfate was pre-added to the water as a dispersant, and the water temperature was controlled at 45 to 50°C. In the second stage of acidification, concentrated sulfuric acid and dilute phosphoric acid accounting for 5% to 10% of the volume of sulfuric acid were pre-mixed, and the concentration of dilute phosphoric acid was 10% to 15%. The mixture was then injected in a pulsed manner, and ultrasonic oscillation was started simultaneously with a frequency of 25 to 35 kHz and a power of 50 to 100 W. Specifically: 1. Dispersant premixing treatment Sodium lauryl sulfate can be industrial-grade powder (purity ≥95%), added at a rate of 0.05% to 0.1% by weight of the molasses raw material, preferably 0.07%. The water temperature during the premixing stage can be controlled between 45°C and 50°C, preferably 48°C, with a constant temperature water bath system maintaining a temperature fluctuation of ≤±1°C. After the dispersant is dissolved in water, it can be mixed with the molasses raw material using a spiral blade mixer, with a flow rate set at 0.8 to 1.2 m³ / h, preferably 1.0 m³ / h.
[0076] The mixing tank can be constructed of 316 stainless steel and have a capacity suitable for batch sizes of 5-10 m³. The impeller can be configured as a double-push type with a speed set at 60-80 rpm. The premix is sampled for uniformity of dispersion and tested for Baume deviation (required to be ≤±0.3°Be). This step reduces the surface tension of the molasses through the dispersant, preventing localized clumping during the subsequent acidification stage.
[0077] 2. Acid mixing and pulse injection For concentrated sulfuric acid, use 98% industrial sulfuric acid, and for dilute phosphoric acid, use a 10%-15% food-grade phosphoric acid solution. Premix the two at a volume ratio of 5%-10% (e.g., add 0.015 m³ of dilute phosphoric acid to 0.15 m³ of concentrated sulfuric acid). Use a polypropylene tank with an acid-resistant coating as the mixing container. Pulse injection can be set to a 2-minute injection and 1-minute pause cycle, with an injection rate of 0.1-0.15 L / min. Delivery is via a pneumatic diaphragm pump.
[0078] The acid injection point can be located at the bottom of the mixing tank, where it can be evenly dispersed using a porous distributor (pore size 2-3 mm). The pH uniformity of the injected liquid can be tested by taking samples from the upper, middle, and lower layers of the tank and measuring the pH deviation (required to be ≤ ±0.2). This step technically prevents localized over-acidification-induced carbonization of the molasses and improves the controllability of the acidification reaction.
[0079] 3. Ultrasonic vibration assisted homogenization The ultrasonic generator can be an industrial-grade device with a frequency of 25-35 kHz and a power of 50-100 W, preferably a frequency of 28 kHz and a power of 80 W. The ultrasonic probe can be installed on the side wall of the mixing tank, immersed 20-30 cm below the liquid surface, and the action time is set to 5-10 minutes, preferably 8 minutes. During the ultrasonic oscillation, the temperature of the mixed liquid can be maintained at 50-55°C, and the temperature rise can be controlled to ≤3°C by circulating cooling water in the jacket. Compare the colloidal particle size distribution before and after ultrasonic treatment (detected by a laser particle size analyzer). The technical effect of this step is to destroy the colloidal agglomeration structure through the cavitation effect, reducing the risk of coking side reactions during the subsequent heating stage.
[0080] In this example, after adding 0.07% sodium dodecyl sulfate during the premixing phase, the Baume deviation of the molasses dilution was ±0.3°Be, and the agglomeration rate was ≤0.1% when sampled at various points within the mixing tank. The dispersant reduced the surface tension of the molasses colloid to 35-40 mN / m (50-55 mN / m without treatment), and the fluidity of the mixture increased by 20%. Premixing concentrated sulfuric acid and dilute phosphoric acid (12%) at a volume ratio of 8% significantly improved pH uniformity under pulse injection mode, with pH deviations of ≤±0.2 in the upper, middle, and lower layers of the tank (±0.5 for continuous injection). The content of carbonization byproducts (such as 5-hydroxymethylfurfural) was reduced to 20-30 ppm, and the effective utilization rate of sugars was increased to 92%-95%. After ultrasonic treatment (28 kHz, 80 W, 8 minutes), the average particle size (D50) of the molasses colloid decreased from an initial 50 μm to 12-15 μm, and the proportion of colloidal aggregates decreased from 70% to 10%. In the subsequent heating stage, the production of coking by-products (melanoidins) decreased by 40%, and the reduction rate was stabilized at 88%~92%.
[0081] Example 7 Based on Example 1, further optimization was performed. In step 2, while adding L-cysteine hydrochloride, a reduction reaction regulator was introduced twice: During the first addition, when the temperature rises to 75°C, add sodium thiosulfate at a rate of 0.01% to 0.02% by weight of the molasses raw material, and control the oxygen content to be ≤1.5 ppm; during the second addition, when the molasses dilution is heated to the target temperature of 88 to 93°C, add ascorbyl palmitate at a rate of 0.005% to 0.01% by weight of the molasses raw material, and switch the stirring direction.
[0082] Specifically: 1. Add reduction regulator in stages Sodium thiosulfate can be industrial-grade powder (purity ≥98%), added at a rate of 0.01%-0.02% (preferably 0.015%) to the mass of the molasses raw material. The first addition should be made when the temperature reaches 75°C via a screw feeder into the reactor at an acceleration rate of 2-3 kg / min. Ascorbyl palmitate can be food-grade powder (purity ≥95%), added at a rate of 0.005%-0.01%, preferably 0.008%. Dissolve it in deionized water at 40-45°C and inject it via a metering pump. The reactor can be equipped with an online oxygen sensor. Samples should be taken to measure the solution's transmittance (≥90%). The technical effect of this step is to selectively scavenge free oxygen and inhibit carbohydrate oxidation side reactions through the staged addition of the regulator.
[0083] 2. Dynamic control of oxygen content Oxygen content control can be achieved through a nitrogen purge system. The nitrogen flow rate is set at 0.5-1.0 L / min, preferably 0.8 L / min, and injected through a porous distributor at the bottom of the tank. The oxygen content sensor monitors the gas phase oxygen concentration in real time and feeds back to the PLC system to adjust the nitrogen flow rate. The oxygen content of the reaction liquid can be detected using an electrochemical dissolved oxygen meter, with the probe installed 10-15 cm below the liquid surface on the side wall of the tank. Compare the effect of oxygen content on reduction efficiency. The technical effect of this step is to block the oxidation pathway through inert atmosphere protection and increase the proportion of target reduction products.
[0084] 3. Stirring direction switching mode The agitator can be driven by a bidirectional variable frequency motor with a forward speed of 200-250 rpm and a reverse speed of 80-120 rpm. The switching cycle is set to a 30-second forward stirring cycle followed by a 10-second reverse stirring cycle. The agitator can be configured as a three-blade swept-back impeller with a blade diameter to tank diameter ratio of 1:3.
[0085] The switching of stirring direction is synchronized with the reverse temperature control phase, triggering reverse stirring when the temperature rises from 85°C to 88-93°C. The technical effect of this step is to eliminate flow dead spots through bidirectional mixing and optimize mass transfer efficiency.
[0086] In this example, sodium thiosulfate scavenges free oxygen (reducing oxygen content from an initial 3.5 ppm to 0.8-1.2 ppm), while ascorbyl palmitate inhibits sugar oxidation, increasing the reduction rate to 88%-92%. The content of oxidation byproducts (such as carboxylic acids) is reduced by 50%, and the proportion of target reduction products increases to 85%-90%. Under nitrogen purge, the oxygen content is stable at ≤1.5 ppm, and the dissolved oxygen meter detects a liquid-phase oxygen concentration of ≤0.5 ppm, improving the selectivity of the reduction reaction. Bidirectional stirring eliminates dead zones within the tank. This improves fluid shear rate uniformity and enhances the kinetic stability of the reduction reaction.
[0087] Example 8 Based on Example 1, in step 3, while nitrogen was injected at the medium concentration stage, trehalose was added as a thermal stabilizer at a rate of 0.02% to 0.05% by mass of the concentrated liquid, and the temperature difference of the evaporation interface was controlled to be ≤5°C; after disodium hydrogen phosphate was added at the high concentration stage, the temperature was alternately increased and decreased at a rate of 0.5°C to 1.0°C / min.
[0088] Specifically: 1. Nitrogen protection and heat stabilizer addition Trehalose can be prepared from food-grade crystals (purity ≥99%), with an addition rate of 0.02%–0.05% (preferably 0.03%) of the concentrate by weight. High-purity nitrogen (purity ≥99.99%) can be used as the nitrogen gas, with a flow rate of 0.3–0.5 L / min (preferably 0.4 L / min) injected through the gas distributor at the top of the evaporator. The nitrogen distributor can be a porous metal tube (pore diameter 1–2 mm), installed 10–15 cm above the liquid level in the evaporator.
[0089] After dissolving trehalose in deionized water at 60-65°C, it is pumped into the evaporator feed port via a metering pump and mixed with the concentrate. The evaporator's gas-phase oxygen content is monitored (required to be ≤1.0%). This step effectively inhibits the degradation of heat-sensitive substances through the synergistic effect of nitrogen protection and thermal stabilizers.
[0090] 2. Evaporation interface temperature difference control The temperature difference at the evaporation interface can be monitored using multiple temperature sensors within the evaporator, installed at 5 cm, 10 cm, and 15 cm below the liquid surface. The temperature difference control strategy involves adjusting the heating steam pressure (0.25-0.30 MPa) and the vacuum level (-0.08-0.10 MPa) to maintain a temperature difference between the upper and lower liquid surfaces of ≤5°C, preferably 3°C. A falling-film evaporator can be used, with a distributor aperture of 2-3 mm and a density of 20-30 apertures per square centimeter. This step effectively reduces sugar carbonization caused by localized overheating through precise temperature control.
[0091] 3. Temperature alternating cycle process The temperature alternating cycle can be set as follows: heating from 70°C to 75°C at a rate of 0.5°C / min, holding for 5 minutes, then cooling to 70°C at a rate of 1.0°C / min, repeating three times. The temperature control system can be programmed using a PLC. The heating medium is thermal oil, and the cooling medium is circulating cold water. Temperature sensors are installed at the inlet and outlet of the evaporator jacket to provide real-time temperature differential data.
[0092] Detect the viscosity change of the concentrate (fluctuation required to be ≤ ±5%) using a rotational viscometer for online monitoring. This step eliminates internal stress in the concentrate through temperature oscillation, reducing the tendency to gel.
[0093] During the concentration phase of this example, the amount of melanoidin produced was approximately 0.8%, with a color difference value of ΔE ≤ 1.5. The thermal decomposition rate of trehalose was less than 0.5%, nitrogen consumption was reduced to 0.4 L / min, and the oxygen content was stable at ≤ 1.0%. The temperature difference between the upper and lower liquid levels was ≤ 3°C, and the content of the coking precursor (5-hydroxymethylfurfural) was reduced from 80-100 ppm to 20-30 ppm. The concentration efficiency was increased to 1.2-1.5 m³ / h. The viscosity fluctuation of the concentrate was reduced from ±10% to ±4%, reducing the risk of gelation. The stability error of the Baume degree of the final product was ≤ ±0.2°Be.
[0094] Example 9 Based on Example 1, in step 5, sodium metabisulfite is added in stages. Each time sodium metabisulfite is added, liquid carbon dioxide microbubbles accounting for 1% to 2% of the mass of the sodium metabisulfite are injected simultaneously. The microbubbles have a diameter of 10 to 50 μm. After sodium bisulfite is added in the post-stabilization stage, pressure is cyclically applied at a pressure of 0.1 to 0.2 MPa for three times.
[0095] Specifically: 1. Sodium metabisulfite is added in pulses in stages Sodium metabisulfite can be added in three steps: first, 50% of the total amount (preferably 1.0% of the molasses mass) is added, reacting at 100-110°C and 0.2-0.25 MPa for 20-30 minutes; second, 30% (0.6%) of the total amount is added, reacting at 115-120°C and 0.1-0.15 MPa for 15-20 minutes; and third, the remaining 20% (0.4%) is added, reacting at 105-110°C and 0.25-0.3 MPa for 10-15 minutes. A pneumatic diaphragm pump can be used for addition, delivering the sodium metabisulfite to the reactor via stainless steel piping. This step effectively regulates the sulfonation reaction path through a pressure-temperature gradient, preventing localized overreaction.
[0096] 2. Liquid carbon dioxide microbubble enhanced mass transfer Liquid carbon dioxide can be sourced from an industrial-grade gas source and generated using a microbubble generator (pore size 10-50 μm). The addition amount is 1%-2% of the mass of the sodium metabisulfite, preferably 1.5% in this embodiment. The microbubble injection point can be located at the bottom of the reactor, adjacent to the sodium metabisulfite addition port, with the injection flow rate controlled at 0.5-1.0 L / min. The microbubble generator can be installed in the reactor's external circulation piping, with a centrifugal pump providing circulation and dispersion. The technical effect of this step is to enhance gas-liquid mass transfer efficiency through microbubbles, reducing reaction interface resistance.
[0097] 3. Pressure cycle stabilization The pressure cycle can be set as follows: pressurize to 0.2 MPa → maintain pressure for 30 seconds → release to atmospheric pressure, repeated three times. Electric pressure regulating valves can be used for pressure control, with sensors installed at the top and bottom of the reactor. The temperature during the post-stabilization phase is maintained at 90–95°C for 20–30 minutes. The bubble content of the product after the pressure cycle is tested (required to be ≤0.1%) using a vacuum degassing method combined with gravimetric analysis. This step eliminates microbubbles within the product through pressure oscillation, improving the stability of absorbance detection.
[0098] After three additions in this embodiment, the degree of sulfonation reaches 92% to 95%, and the residual amount of sodium metabisulfite is ≤0.2%. Compared with a single addition, the amount of by-product (sulfate) generated is reduced by 40%. The molecular weight distribution polydispersity index is reduced to 1.2, and the product uniformity is significantly improved. The sulfonation reaction time is shortened, and the consumption of liquid carbon dioxide is controlled below 1.5%. The uniformity of temperature distribution in the reactor is improved (temperature difference ≤2°C), avoiding coking caused by local overheating. After pressure cycling, the bubble content of the product is ≤0.05%, and the relative standard deviation (RSD) of the absorbance detection is reduced from 5% to 1.5%. After 30 days of storage, the absorbance fluctuation of the final product is ≤0.03, and there is no phase separation or precipitation.
[0099] Example 10 On the basis of Example 1, further, in step 6, after the pH and Baume adjustments are completed for the caramel color finished product, when cooling, hydroxypropyl-β-cyclodextrin is added as an embedding agent at a rate of 0.01% to 0.03% by mass of the diluent, and light-assisted temperature control is adopted: ultraviolet-visible light (wavelength 365 to 405 nm, light intensity 50 to 100 Lux) is turned on at 50 to 55°C; and infrared radiation is switched to assist cooling below 40°C.
[0100] Specifically: 1. Addition of embedding agent and UV-visible light regulation Hydroxypropyl-β-cyclodextrin can be a food-grade powder (degree of substitution 0.6-0.8) and added at a rate of 0.01%-0.03% (preferably 0.02%) of the diluent mass. Dissolve the embedding agent in 35-40°C deionized water and inject it into the conditioning tank via a peristaltic pump at a rate of 1.0-1.5 L / min. The UV-visible light source can be an LED array (wavelength 365-405 nm) with an intensity of 50-100 lux, preferably 80 lux. Mount the light source on the outer wall of the conditioning tank, 20-30 cm from the liquid surface.
[0101] During the illumination phase, the temperature is maintained at 50-55°C, controlled by a jacketed circulating water system with a fluctuation of ≤±1°C. The pigment molecule encapsulation efficiency (required to be ≥90%) is measured after illumination. High-performance liquid chromatography (HPLC) is used to measure the free pigment content. This step stabilizes the pigment molecular conformation through cyclodextrin encapsulation combined with illumination at a specific wavelength.
[0102] 2. Infrared radiation assisted cooling The infrared radiator can be a heating tube (wavelength 800-1200 nm), with a power density set at 0.5-1.0 W / cm², preferably 0.8 W / cm². It should be installed at the bottom of the tempering tank, with the radiant area covering the lower half of the tank. The cooling phase begins at 40°C and cools to 25-30°C at a rate of 0.5-1.0°C / min, preferably 0.8°C / min. Temperature sensors are installed in the middle and bottom of the tank to provide real-time feedback on the temperature difference (required to be ≤2°C). The technical effect of this step is to promote orderly molecular arrangement through infrared radiation and reduce internal stress in the system.
[0103] 3. Dynamic temperature control and molecular conformation stability The conditioning tank can be equipped with a PLC temperature control system, linking the illumination and cooling modules. As the temperature decreases from 50°C to 40°C, the UV illumination intensity decreases linearly with temperature (100 Lux → 50 Lux). Below 40°C, after switching to infrared radiation, the cooling rate is dynamically adjusted based on real-time viscosity data (for every 5 mPa·s increase in viscosity, the cooling rate decreases by 0.1°C / min). The absorbance stability of the final product is tested by sampling three times at 10-minute intervals, with a fluctuation range of ≤±0.05. The technical effect of this step is to achieve long-term stability of the pigment's molecular conformation and viscosity through the coordinated regulation of temperature and light.
[0104] The hydroxypropyl-β-cyclodextrin embedding rate of this embodiment is ≥92%, and the isomerization rate of the pigment molecule under ultraviolet light is reduced to <1%. The color difference value ΔE ≤ 0.5 (CIELAB standard) during the illumination stage is significantly better than the traditional tempering process (ΔE ≥ 1.5). After infrared-assisted cooling, the viscosity fluctuation of the product is ≤ ± 5% (traditional cooling ± 15%), and the order of the molecular arrangement is improved (XRD crystallinity index increases from 15% to 25%). Cooling energy consumption is reduced by 30%, and the temperature gradient in the tank is ≤ 1.5 ° C. After 180 days of storage, the absorbance fluctuation of the final product is ≤ 0.02, the color difference value ΔE ≤ 0.8, and there is no gel or precipitation. Sensory evaluation shows that the color uniformity and fluidity scores are more than 20% higher than those of the traditional process.
[0105] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiment. They can be applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized.
Claims
1. A method for producing caramel color using molasses, characterized in that: The following steps are involved: Step 1: diluting the molasses raw material with water and concentrated sulfuric acid, wherein the pH value of the diluted mixture is 2.6-3.0 and the Baume degree is 30-33°Be; Step 2: Raise the temperature of the diluted mixed solution to 88-93°C, keep the temperature until the reduction rate is greater than 85%, then cool it to 65-70°C and filter it, controlling the sediment content after filtration to ≤0.5%; Step 3, concentrating the filtrate to a Baume degree of 35.5-38.5°Be; Step 4: adding liquid caustic soda to the concentrated solution to adjust the pH to 4.5-7.0; then adding 0.3-0.5% of the mass of the molasses raw material sodium citrate as a chelating agent to form a calcium ion chelate; Step 5, adding sodium metabisulfite to the neutralized concentrated solution under the conditions of pressure ≤ 0.3 MPa and temperature 100-125° C. to carry out a coking reaction; Step 6: Adjust the Baume degree of the reaction product to 38-39° Be, the pH to 5.0-6.5, and the absorbance to 0.01-1.
00.
2. The method for producing caramel color with molasses according to claim 1, wherein In step 4, sodium citrate is added in a stepwise gradient manner, specifically comprising: After adjusting the pH to 4.5-5.5 with liquid caustic soda, add sodium citrate at 0.1-0.2% of the mass of the molasses raw material for the first time, and stir the reaction for 10-15 minutes; after further adjusting the pH to 5.5-7.0, add the remaining sodium citrate at 0.2-0.3% of the mass of the molasses raw material, control the reaction temperature to be maintained at 50-60°C, and stir for 20-30 minutes; remove the chelated precipitate by centrifugation, and control the centrifugal speed to be 3000-4000 rpm.
3. The method for producing caramel color with molasses according to claim 1, wherein While adding sodium citrate in step 4, disodium ethylenediaminetetraacetic acid is added simultaneously according to 0.05-0.1% of the mass of the molasses raw material, and the addition temperature of the mixed chelating agent is controlled to be 55-65°C and the stirring rate is 80-120 rpm.
4. The method for producing caramel color with molasses according to claim 1, wherein After adding sodium citrate in step 4, add activated carbon adsorbent at 5% to 8% of the total mass of the chelating agent, and the adsorption time is 30 to 40 minutes. Then, the adsorbent and chelated precipitate are removed by a plate and frame filter with a filter cloth precision of 5 to 10 μm.
5. The method for producing caramel color with molasses according to claim 1, wherein Step 4 includes the following processes: Add 10% to 15% sodium hydroxide solution at a rate of 0.5 to 1.0 L / min, and simultaneously introduce carbon dioxide gas at a flow rate of 0.2 to 0.5 L / min. Neutralize the exotherm and control the pH fluctuation to ≤±0.
2. Within 5 minutes after the addition of liquid caustic soda, 0.3-0.5% of the mass of the molasses raw material sodium citrate and 0.05-0.1% of disodium ethylenediaminetetraacetic acid were added in sequence, and temperature gradient stirring was adopted: first stage: 50-55°C, 100-120 rpm stirring for 10 minutes; second stage: heating to 60-65°C, switching to turbulent stirring at 200-250 rpm for 15 minutes; Add 5% activated carbon and 2%~3% diatomaceous earth to the mixed solution, keep it at 40~50℃ for 20 minutes, and finally filter it through a ceramic membrane with a pore size of 0.5~1.0 μm.
6. The method for producing caramel color with molasses according to claim 1, wherein Step 1 also includes: in a two-stage dilution process, in the first stage of dilution, pre-adding 0.05% to 0.1% of the mass of the molasses raw material sodium lauryl sulfate to water as a dispersant, and controlling the water temperature to be 45 to 50° C.; in the second stage of acidification, pre-mixing concentrated sulfuric acid with 5% to 10% of the volume of sulfuric acid and dilute phosphoric acid, with a concentration of 10% to 15%, and then injecting it in a pulsed manner, and synchronously starting ultrasonic oscillation with a frequency of 25 to 35 kHz and a power of 50 to 100 W.
7. The method for producing caramel color with molasses according to claim 1, wherein In step 2, while adding L-cysteine hydrochloride, the reduction reaction regulator is introduced twice: During the first addition, when the temperature rises to 75°C, add sodium thiosulfate at a rate of 0.01% to 0.02% by weight of the molasses raw material, and control the oxygen content to be ≤1.5 ppm; during the second addition, when the molasses dilution is heated to the target temperature of 88 to 93°C, add ascorbyl palmitate at a rate of 0.005% to 0.01% by weight of the molasses raw material, and switch the stirring direction.
8. The method for producing caramel color with molasses according to claim 7, wherein: In step 3, while nitrogen is injected in the medium concentration stage, trehalose is added as a thermal stabilizer at a rate of 0.02% to 0.05% by mass of the concentrated liquid, and the temperature difference of the evaporation interface is controlled to be ≤5°C; after disodium hydrogen phosphate is added in the high concentration stage, the temperature is alternately increased and decreased at a rate of 0.5 to 1.0°C / min.
9. The method for producing caramel color with molasses according to claim 1, wherein In step 5, sodium metabisulfite is added in stages. Each time sodium metabisulfite is added, liquid carbon dioxide microbubbles accounting for 1% to 2% of the mass of sodium metabisulfite are injected simultaneously. The microbubble diameter is 10 to 50 μm. After sodium bisulfite is added in the post-stabilization stage, pressure is cyclically applied at a pressure of 0.1 to 0.2 MPa for 3 times.
10. The method for producing caramel color using molasses according to claim 1, wherein: In step 6, after the pH and Baume degrees of the caramel color finished product are adjusted, when cooling, hydroxypropyl-β-cyclodextrin is added as an embedding agent at a rate of 0.01% to 0.03% by mass of the diluent, and light-assisted temperature control is adopted: ultraviolet-visible light irradiation is turned on at 50-55°C; and infrared radiation is switched to assist cooling below 40°C.