Cocoa anti-frosting continuous grinding process and application
By using multidimensional physical field coupling technology, the problems of low efficiency, flavor loss and easy blooming of finished products in traditional cocoa grinding processes have been solved, realizing efficient and stable continuous production of cocoa liquor, and improving production efficiency and product quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YUNNAN AGRICULTURAL UNIVERSITY
- Filing Date
- 2026-04-03
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional cocoa grinding processes are inefficient, result in significant flavor loss, and cause the finished product to easily develop bloom, making continuous production difficult and leading to low production efficiency and unstable product quality.
A stable Form V-type crystal structure is formed by using multi-dimensional physical field coupling technology, including PPoP and phospholipid mixing, ultra-low temperature embrittlement, and continuous grinding with a twin-screw extruder combining pulsed electric field and high-power ultrasound.
It reduces grinding time from hours to minutes, increases production efficiency by two orders of magnitude, and the finished product shows no white bloom on the surface within 120 days, retains good flavor, and is suitable for large-scale industrial production.
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Figure CN122004332A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of food processing technology, specifically to a continuous grinding process and its application for preventing cocoa blooming. Background Technology
[0002] Cocoa liquor is the core ingredient of chocolate, and its quality directly determines the taste, flavor, and storage stability of the final chocolate product. The core of cocoa liquor preparation lies in the grinding process, which aims to grind cocoa kernels rich in oil (about 21%-23%) to a fineness of 15-30 micrometers, so that the cocoa butter released by cell rupture can fully coat the solid particles and form a flowing slurry.
[0003] Traditional cocoa grinding processes primarily employ ball mills or refining machines for intermittent grinding, which suffers from the following technical drawbacks: 1) Extremely low grinding efficiency: Traditional grinding processes require 24-72 hours of prolonged processing to achieve the target fineness. This is mainly because cocoa butter precipitation forms a lubricating film around the particles, and ultrafine particles agglomerate under the influence of oil and van der Waals forces, leading to reverse grinding and severely limiting production efficiency; 2) Significant loss of heat-sensitive components: During prolonged grinding, frictional heat causes the material temperature to rise, resulting in the volatilization of aromatic substances in cocoa butter and protein denaturation, leading to significant flavor loss; 3) Poor storage stability of finished products: Chocolate products commonly experience fat bloom during storage, as cocoa butter transforms from a stable Form V crystal to a more stable Form VI crystal, resulting in grayish-white spots on the surface. This not only severely affects the product's appearance but also leads to a rough texture and degraded quality. This is due to the complexity of traditional processes and the sensitivity of cocoa butter to temperature fluctuations; 4) Existing processes are mostly intermittent operations, making continuous production difficult, resulting in poor batch consistency and failing to meet the demands of efficient industrial production.
[0004] Therefore, a new cocoa processing technology is urgently needed to solve the problems of low efficiency, flavor loss, and blooming in traditional cocoa grinding processes. Providing technical and theoretical support for the cocoa grinding industry will facilitate the construction of new high-standard cocoa processing production lines and promote the development of large-scale chocolate production enterprises. Summary of the Invention
[0005] The purpose of this application is to overcome the shortcomings of the prior art and provide a method for continuous production of highly stable cocoa liquor using multidimensional physical field coupling, so as to solve the technical problems of low efficiency, flavor loss and easy blooming of finished products in traditional cocoa grinding processes.
[0006] This application provides a continuous milling process for preventing cocoa from blooming, the continuous milling process including the following steps: 1. A continuous milling process for preventing cocoa blooming, characterized in that the continuous milling process includes the following steps: S1, PPoP, cocoa butter and phospholipids are mixed in a mass ratio of 5:24:1 and melted and stirred at 50℃-60℃ to obtain anti-frost nucleation premix; S2, after cooling the peeled cocoa kernels to below -50°C, crush them to obtain brittle granules; S3, the brittle particles from step S2 and the anti-frost premix from step S1 are fed into a twin-screw extruder at a mass ratio of 1:(0.15-0.3) to complete the grinding; The twin-screw extruder is equipped with a PEF treatment zone where a pulsed electric field is applied; downstream of the PEF treatment zone, high-power ultrasonic waves are applied.
[0007] Furthermore, the length-to-diameter ratio (L / D) of the screw in the twin-screw extruder in step S3 is 20:1 to 40:1.
[0008] Furthermore, in step S3, the electric field strength of the pulsed electric field is 15-35 kV / cm and the frequency is 200-800 Hz.
[0009] Furthermore, in step S3, the outlet material temperature of the twin-screw extruder is 28-33°C.
[0010] Furthermore, in step S3, the frequency of the high-power ultrasound is 20-40 kHz and the power density is 0.5-1.5 W / cm². 3 .
[0011] Furthermore, in step S2, the diameter d of the embrittled particles is less than 2 mm.
[0012] Furthermore, the phospholipid in step S1 is selected from one or more of dimyristoyl phosphatidylcholine (DMPC) and dipalmitoyl phosphatidylethanolamine (DPPE).
[0013] This application also provides an application of the above-described continuous grinding process in the preparation of chocolate.
[0014] Beneficial effects 1. Extremely high efficiency: Grinding time is reduced from 24-72 hours in traditional processes to minutes (material throughput time 8-15 minutes), production efficiency is increased by two orders of magnitude, and energy consumption is significantly reduced.
[0015] 2. Precise Crystal Form Control: Based on the phospholipid self-assembly nucleation mechanism, phospholipids such as DMPC form micelles in cocoa butter, which interact with POS to serve as nucleation surfaces, directly inducing the formation of Form V-type crystals. Compared with traditional processes that rely on complex temperature gradients to control crystal form, this application achieves precise molecular-level control of crystal form.
[0016] 3. Simplified tempering process: Traditional chocolate production requires a precise tempering profile of 45℃→27℃→32℃, which places extremely high demands on equipment and operations. This application utilizes a phospholipid nucleation mechanism to enable cocoa butter to directly form stable Form V-shaped crystals during cooling, significantly simplifying the traditional tempering process.
[0017] 4. Long-lasting anti-frost effect: Phospholipid micelle template-guided crystal growth forms a more stable crystal network structure. After cyclic storage experiments at 20 / 30℃, chocolate prepared using the method described in this application showed no surface white bloom within 120 days, demonstrating an anti-frost performance improvement of over 80% compared to traditional processes.
[0018] 5. Quality Improvement: Low-temperature environment (maximum temperature <60℃ throughout the process) and rapid processing (minutes) maximize the preservation of the original aroma of cocoa; PEF treatment promotes the release of flavor substances within cells, resulting in a richer and fuller flavor in the product.
[0019] 6. Continuous production: This application uses a twin-screw extruder as the core reactor to achieve continuous production from raw materials to slurry, overcoming the batch variation problem of traditional intermittent processes. It has a high degree of automation and is suitable for large-scale industrial production.
[0020] 7. High process integration: The process integrates multiple steps such as anti-frost nucleation matrix preparation, ultra-low temperature pretreatment, PEF cell disruption, ultrasonic grinding, and crystal induction into a single continuous production line, which significantly reduces equipment investment and floor space.
[0021] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description
[0022] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings.
[0023] Figure 1 This is a continuous process flow diagram of this application.
[0024] Figure 2 This relates to the effect of the amount of phospholipid added on the time (in days) for blooming to occur.
[0025] Figure 3 This describes the effect of PPoP addition on the anti-blooming properties of cocoa.
[0026] Figure 4 This refers to the effect of electric field strength on the fineness of cocoa grinding.
[0027] Figure 5 This relates to the effect of ultrasonic frequency on the fineness of cocoa grinding. Detailed Implementation
[0028] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.
[0029] In response to the aforementioned issues, several new technologies have emerged in the food processing field in recent years. In the field of oleoglycerol science, it has been discovered that the symmetrical triglyceride PPoP (1,3-dipalmitoyl-2-palmitoyl-sn-glycerol) has the function of inhibiting the crystal form transformation of cocoa butter. Specific phospholipid molecules can self-assemble in cocoa butter to form micelle structures, interacting strongly with the most abundant triglyceride in cocoa butter, POS (palmitoyl-oleoyl-stearoylglycerol), acting as seed surfaces to induce the formation of Form V crystals, thereby obtaining the ideal crystal structure without relying on complex shear and temperature gradients. Pulsed electric field (PEF) technology has been proven in fruit and vegetable processing to induce cell electroporation and improve the release rate of cell contents. Ultrasonic-assisted extraction technology is used in the oleoglycerol industry to enhance mass transfer. However, there are currently no reports of systematically integrating these interdisciplinary technologies and applying them to the continuous preparation of cocoa liquor.
[0030] Unless otherwise specified, all reagents and materials used in the following examples were purchased from the market.
[0031] To achieve the above objectives, this application adopts the following technical solution: Step 1: Preparation of Anti-Frosting Oil Base PPoP (1,3-dipalmitoyl-2-palmitoyl-sn-glycerol), cocoa butter and phospholipids were mixed in a mass ratio of 5:24:1 and melted and stirred at 50℃-60℃ to obtain an "anti-frost nucleating premix".
[0032] The phospholipid is selected from one or more of dimyristoyl phosphatidylcholine (DMPC) and dipalmitoyl phosphatidylethanolamine (DPPE).
[0033] Table 1. Differences between DMPC and DPPE Certain phospholipids (such as DMPC) can self-assemble into various micelle structures in cocoa butter. These micelles, as confirmed by small-angle neutron scattering (SAXS) studies, interact strongly with POS (palmitoyl-oleoyl-stearoylglycerol), the most abundant triglyceride in cocoa butter. This interaction can be observed using SAXS, interfacial tension measurements, and infrared spectroscopy. DMPC micelles act as seed surfaces, influencing the crystallization behavior of POS and templating the growth of Form V-type crystals.
[0034] PPoP is a symmetrical triglyceride that can be embedded in the crystal structure of cocoa butter, delaying the polymorphic transformation of cocoa butter from Form V to Form VI, thus solving the blooming problem at the molecular level. Pre-melting PPoP with cocoa butter ensures its uniform distribution in subsequent processes.
[0035] Step 2: Low-Temperature Embrittlement Pretreatment The peeled cocoa kernels are cooled to below -50°C using liquid nitrogen and then crushed into brittle particles with a diameter d < 2 mm using an impact crusher.
[0036] Cocoa kernels are rich in oils, which are tough and sticky at room temperature, making direct grinding inefficient and prone to clogging equipment. Ultra-low temperature treatment causes the oils to solidify and become brittle, significantly improving grindability, while the low temperature environment inhibits flavor loss during the grinding process.
[0037] Step 3: Liquid-solid mixing and continuous feeding The embrittled particles and the anti-frost premix were fed into the feed inlet of a twin-screw extruder at a mass ratio of 1:(0.15-0.3).
[0038] Twin-screw extruders possess excellent mixing and conveying capabilities, enabling continuous and uniform mixing of liquid and solid phases. This application preferably utilizes a co-rotating twin-screw structure with a screw length-to-diameter ratio (L / D) of 20:1 to 40:1.
[0039] Step 4: Pulsed electric field (PEF) cell disruption In the middle section of the twin-screw extruder, when the material is initially formed into a slurry, a PEF treatment zone is set up, and a pulsed electric field with an electric field strength of 15-35kV / cm and a frequency of 200-800Hz is applied to induce electroporation of cocoa cells.
[0040] Pulsed electric fields disrupt cell membrane structure through electroporation, promoting the release of cocoa butter from cells and increasing oil extraction rate. They also help release flavor precursors from cells.
[0041] Step 5: Ultrasonic Coupled Fine Grinding Downstream of the PEF treatment zone, an ultrasonic generator is installed, applying an ultrasonic frequency of 20-40 kHz and a power density of 0.5-1.5 W / cm².3 High-power ultrasonic waves, combined with the mechanical shearing force of a twin-screw extruder, are used for deep grinding.
[0042] The cavitation effect generated by ultrasound can produce strong shock waves and microjets at the microscale, effectively breaking up agglomerated particles, preventing the "reverse grinding" phenomenon, and rapidly reducing the fineness of materials to below 20μm.
[0043] Step Six: Precision Temperature Control and Crystal Form Induction A segmented cooling jacket is installed at the outlet section of the twin-screw extruder. The outlet material temperature is controlled at 28-33℃ by circulating cooling medium, which induces cocoa butter to form stable Form V-shaped crystal nuclei.
[0044] Precise temperature control at the outlet section allows the material to begin pre-crystallization during the extrusion process, laying the foundation for subsequent temperature adjustment processes and shortening the subsequent temperature adjustment time.
[0045] Process principle: This application is the first to integrate five major technical modules: oil crystallization regulation (PPoP addition), low-temperature embrittlement (liquid nitrogen freezing), cell wall disruption (pulsed electric field), cavitation pulverization (ultrasound), and continuous extrusion (twin-screw extrusion), forming a continuous grinding process with multi-dimensional physical field coupling.
[0046] Table 2 shows the interaction mechanisms and synergistic effects of each physical field. The following implementation method is adopted based on the above technical solution: Example 1 Raw material preparation: Take 100kg of Hainan cocoa kernels, use a vibrating screen (screen mesh size 2-5mm) to remove broken shells, dust and particles that do not meet the size requirements, and use an air classifier to remove metal impurities, stones and light foreign objects before use.
[0047] Step 1: Preparation of anti-frost nucleation matrix Weigh out 5 kg of PPoP (1,3-dipalmitoyl-2-palmitoyl-sn-glycerol), 24 kg of cocoa butter, and 1 kg of DMPC (dimyristoyl phosphatidylcholine) (the amount of phospholipid added is 0.8% of the mass of DMPC). Place them in a melting tank, heat to 55°C and stir for 30 minutes until completely melted and mixed. Keep warm for later use to obtain the anti-frost nucleating premix.
[0048] Step 2: Low-Temperature Embrittlement Pretreatment The cocoa kernels are cooled to -60°C (exit temperature monitored) by passing them through a liquid nitrogen immersion freezing tunnel, and then immediately fed into an impact crusher to be crushed to a particle size of less than 2mm.
[0049] Step 3: Liquid-solid mixing and continuous feeding The brittle particles and the anti-frost nucleation premix are fed synchronously into the feed inlet of a co-rotating twin-screw extruder through a loss-in-weight feeding system配套 with the twin-screw extruder at a mass ratio of 1:0.3 (i.e., 100 kg of cocoa beans and 30 kg of anti-frost nucleation premix). The screw speed is set at 450 rpm.
[0050] The barrel is partitioned successively from the feed inlet to the outlet, and is respectively set as: Zone 1, Zone 2, Zone 3, Zone 4, Zone 5, and Zone 6.
[0051] The barrel zoning follows the principle of "segmenting by process function and adapting temperature to the physical field": Zone 1 is a low-temperature feed mixing zone (20 °C) to preliminarily mix the materials; Zones 2-3 are set as the PEF treatment zone (30-50 °C). Since the pulsed electric field has the best effect when applied after the materials form a slurry, and this temperature range is conducive to cell membrane electroporation; Zones 4-5 are set as the ultrasonic coupling grinding zone (40-50 °C). Placing the ultrasonic wave after the PEF can efficiently refine the materials after cell wall rupture under the协同作用 of cavitation effect and mechanical shear; Zone 6 is the outlet temperature control zone (31 °C), and the crystal form is induced by water cooling to form a temperature gradient. It should be noted that this process采用 a twin-screw extruder for continuous production. The barrel is provided with多个 independent temperature zones一次性 along the material flow direction. The temperatures of each zone are set and controlled independently at the same time. The materials flow continuously under the推动 of the screw and successively pass through each temperature zone. Their residence time is jointly determined by the screw speed and the length of the temperature zone (the total passing time is about 8 minutes in the embodiment), and there is no time interval for heat preservation in segments; this sequence is based on the progressive logic of solid-state mixing → slurry cell wall rupture → deep grinding → temperature-controlled crystallization of the material state, ensuring the协同作用 of each physical field under the best material conditions.
[0052] The temperature of Zone 1 is 20 °C, and material mixing is carried out; the temperature of Zone 2 is 30 °C, and the temperature of Zone 3 is 40 °C. Pulsed electric field intervention is carried out in both Zone 2 and Zone 3; the temperature of Zone 4 is 50 °C, and the temperature of Zone 5 is 40 °C. Both Zone 4 and Zone 5 are ultrasonic coupling grinding; Zone 6 is 31 °C. The crystal form induction采用 a circulating water cooling jacket for precise temperature control to form a temperature gradient in the outlet section of the material, and induce the phospholipid micelle templating to directly generate stable Form V crystals of cocoa butter.
[0053] Pulsed electric field (PEF) intervention: In Zones 2-3 (corresponding to the barrel temperature range of 40-50 °C) where the materials are preliminarily mixed to form a slurry state, PEF treatment electrodes are set, and an electric field intensity of 25 kV / cm, a frequency of 500 Hz, and a pulse width of 20 μs are applied, and the treatment time is about 10 seconds.
[0054] Ultrasonic coupling grinding: In Zones 4-5 downstream of the PEF treatment zone, an ultrasonic generating device is set, and a frequency of 25 kHz and a power density of 1.0 W / cm 3The ultrasonic waves, combined with the shearing force of the twin-screw extruder, enable deep grinding. The total material throughput time is approximately 8 minutes.
[0055] Step 4: Temperature-controlled extrusion A circulating water cooling jacket is installed in Zone 6 (exit section) to precisely control the material temperature at 31±1℃ during extrusion. At this temperature, DMPC micelles act as nucleation surfaces, inducing cocoa butter to directly form Form V-shaped crystals.
[0056] Test results: The fineness d of the finished product was measured using a laser particle size analyzer. 90 =17.2μm, d 50 =8.6μm. The obtained cocoa liquor was directly poured into molds (without traditional tempering). The resulting chocolate was placed in a 20 / 30℃ constant temperature chamber (cycled every 12 hours) for accelerated blooming. No visible white bloom was observed on the surface after 120 days, and the luster remained good. X-ray diffraction analysis confirmed that the cocoa butter in the product was mainly in the Form V type crystals. Sensory evaluation showed that the product had a rich cocoa aroma, a delicate and smooth taste, and no obvious sourness or astringency.
[0057] Example 2 The difference between this embodiment and Embodiment 1 is that the type of phospholipid is adjusted to DPPE (dispalmitoylphosphatidylethanolamine), and the amount added is 0.8% of the mass of DMPC. The remaining steps are the same as in Embodiment 1.
[0058] Test results: Finished product fineness d 90 =18.8μm. In the accelerated blooming test, the chocolate developed a slight white bloom after 105 days. Its anti-blooming performance was slightly lower than that of DMPC but significantly better than that of the traditional process.
[0059] Example 3 The difference between this embodiment and Embodiment 1 is that the amount of phospholipid added is adjusted to 0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% of the mass of DMPC. Fixed conditions: PPoP 5kg / 100kg cocoa kernels, cocoa butter 24kg / 100kg cocoa kernels, PEF 25kV / cm, ultrasonic 25kHz, and twin-screw extrusion process parameters are the same as in Embodiment 1.
[0060] The results are as follows Figure 2As shown, the effect of phospholipid (DMPC) addition on the anti-blooming properties of chocolate is illustrated. The results indicate a positive correlation between the anti-blooming effect and the amount of phospholipid added, but with an optimal range: when the addition amount increases from 0 to 0.6 wt%, the time to bloom increases from approximately 30 days to approximately 85 days; when the addition amount reaches 0.8 wt%, the blooming time significantly increases to 126 days, reaching a peak; further increasing to 1.0 wt%, the blooming time slightly decreases to approximately 118 days. This trend verifies the phospholipid micelle nucleation mechanism—DMPC self-assembles in cocoa butter to form micelles, interacting with triglycerides (POS) and acting as a nucleation surface template to guide the growth of Form V-shaped crystals. Insufficient addition results in a limited number of micelles and inadequate nucleation induction, while excessive addition may interfere with the ordered arrangement of micelles. Figure 2 The data shows that 0.8 wt% is the optimal addition amount, and the anti-blooming time is more than 4 times longer than that without phospholipid addition (about 30 days), which is consistent with the data of Comparative Example 2, further confirming the key role of phospholipids in the anti-blooming mechanism.
[0061] Example 4 The difference between this embodiment and Embodiment 1 is that PPoP is not added; only DMPC and cocoa butter are used to prepare the nucleation matrix (DMPC addition amount 0.8wt%). The remaining steps are the same as in Embodiment 1.
[0062] Test results: Finished product fineness d 90 =19.5 μm. In the accelerated blooming experiment, the chocolate developed a slight white bloom after 93 days. The results show that DMPC alone can effectively induce the formation of Form V-type crystals, and the addition of PPoP can further enhance stability.
[0063] Example 5 The difference between this embodiment and Embodiment 1 is that the amount of PPoP added (the percentage of PPoP mass to cocoa kernel mass) is adjusted to 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, and 7wt%. Fixed conditions: DMPC 0.8wt%, cocoa butter 24kg / 100kg cocoa kernel, PEF 25kV / cm, ultrasonic 25kHz, and twin-screw extrusion process parameters are the same as in Embodiment 1.
[0064] The results are as follows Figure 3 As shown, the effect of PPoP addition amount on cocoa grind fineness (d) is illustrated. 90The study investigated the effects of PPoP addition on anti-blooming performance (blooming time). Results showed that anti-blooming performance improved with increasing PPoP addition, but with a marginal effect: when the addition amount increased from 2wt% to 5wt%, the blooming time increased from approximately 75 days to 126 days; further increases to 6wt% and 7wt% resulted in blooming times of 128 days and 127 days, respectively, with the increase becoming relatively gradual, indicating that 5wt% was close to the optimal addition amount. PPoP had a relatively small impact on grinding fineness; within the addition range of 2wt%-7wt%, the fineness d... 90 The particle size consistently fluctuated between 17-19 μm, indicating that PPoP primarily functions in crystallization regulation rather than grinding efficiency. This trend validates the anti-blooming mechanism of PPoP—as a symmetrical triglyceride, PPoP can embed itself within the cocoa butter crystal structure, delaying the polymorphic transition from Form V to Form VI. Insufficient addition results in inadequate crystal stabilization, while excessive addition no longer significantly enhances the anti-blooming effect. In summary... Figure 3 The data shows that 5 wt% is the optimal addition amount of PPoP, at which point the anti-frosting time reaches 126 days, which is consistent with the data of Example 1. Under the condition of a fixed addition amount of 0.8 wt% of DMPC, the synergistic effect of PPoP and DMPC can extend the anti-frosting time by about 35% compared with the use of DMPC alone (Example 4, frosting time 93 days).
[0065] Example 6 The difference between this embodiment and Embodiment 1 is that the pulsed electric field strength was adjusted to 0 kV / cm (frequency 500 Hz), 5 kV / cm (frequency 500 Hz), 10 kV / cm (frequency 500 Hz), 15 kV / cm (frequency 500 Hz), 20 kV / cm (frequency 500 Hz), 25 kV / cm (frequency 500 Hz), 30 kV / cm (frequency 500 Hz), and 35 kV / cm (frequency 500 Hz). A fixed frequency of 500 Hz was used for all electric field strengths to investigate the effect of electric field strength on grinding fineness.
[0066] Fixed conditions: DMPC 0.8wt%, PPoP 17wt%, cocoa butter 24kg / 100kg cocoa kernel, ultrasonication 25kHz, twin-screw extrusion process parameters and other steps are the same as in Example 1.
[0067] The results are as follows Figure 4 As shown: When the pulse electric field strength is 15kV / cm and the frequency is 500Hz, the fineness d of the finished product is... 90 =20.8μm (PEF strength is low, oil release rate is slightly reduced), slight white frost appeared after 112 days of accelerated frosting experiment. Electric field strength and grinding fineness are negatively correlated but there is an inflection point: when the electric field strength is 0kV / cm (i.e. no PEF treatment is applied), the fineness d 90Approximately 25 μm; when the electric field strength increases to 15 kV / cm, the fineness d 90 When the particle size drops to approximately 20.8 μm, the grinding effect begins to improve; when the electric field strength reaches 2 kV / cm, the fineness d... 90 The particle size decreased significantly to 17.2 μm, achieving the best grinding effect; when the electric field strength was further increased to 35 kV / cm, the fineness d... 90 The particle size was further reduced to approximately 16.8 μm, with the improvement rate plateauing. This trend validates the cell disruption mechanism of pulsed electric fields (PEF) – PEF disrupts the cocoa cell membrane structure through electroporation, promoting the release of intracellular cocoa butter and flavor compounds, increasing oil extraction rate, thereby reducing mechanical grinding load and accelerating the decrease in fineness. When the electric field strength is insufficient (<15 kV / cm), the electroporation effect is weak, cell disruption is incomplete, and oil release rate is limited. When the electric field strength exceeds 25 kV / cm, the cell disruption effect tends to saturate, and further increasing the intensity contributes less to the improvement in fineness. Figure 4 Data shows that 25 kV / cm is the optimal electric field strength, at which point the fineness d... 90 The thickness reached 17.2 μm, which is consistent with the data in Example 1, while taking into account both the processing effect and energy consumption cost.
[0068] Example 7 The difference between this embodiment and Embodiment 1 is that the ultrasonic frequency is adjusted to 0kHz, 5kHz, 10kHz, 15kHz, 20kHz, 25kHz, 30kHz, and 35kHz, with a power density of 1.0W / cm². 3 The ultrasonic waves were used. Fixation conditions: DMPC 0.8wt%, PPoP 17wt%, cocoa butter 24kg / 100kg cocoa kernels, PEF 25 kV / cm, twin-screw process parameters, and other steps were the same as in Example 1.
[0069] Test results: Finished product fineness d 90 =16.5μm, with better grinding effect, and slight white frost appeared after 118 days of accelerated frosting test.
[0070] The results are as follows Figure 5 As shown, the data indicates a non-linear relationship between ultrasonic frequency and grinding effect: when the frequency is 20kHz, the fineness d... 90 Approximately 18.5 μm; as the frequency increases to 25 kHz, the fineness d 90 The fineness d90 decreased to 17.2 μm, achieving the best grinding effect; when the frequency was further increased to 30 kHz, the fineness d90 slightly increased to 17.5 μm; when the frequency reached 35 kHz and 40 kHz, the fineness d90... 90The particle sizes were 17.0 μm and 16.5 μm, respectively, showing a further decrease. This trend verifies the mechanism of ultrasonic cavitation effect—the generation and collapse intensity of cavitation bubbles are affected by frequency. Too low a frequency results in insufficient cavitation effect, while too high a frequency reduces the number of cavitation bubbles and decreases cavitation intensity. However, at 40 kHz, the fineness was further optimized to 16.5 μm, indicating that higher frequencies still have an advantage for dispersing fine particles. Combined with data from Example 7 (40 kHz, power density 1.5 W / cm³), this further demonstrates the effectiveness of higher frequencies in dispersing fine particles. 3 Fineness d 90 =16.5μm, frost time 118 days) and Example 1 (25kHz, power density 1.0 W / cm²) 3 (Grinding fineness d90=17.2 μm, frost time 126 days). It can be seen that while 40 kHz can further improve grinding fineness, the anti-frost performance decreases slightly, indicating that excessively high ultrasonic frequencies may slightly interfere with crystal form induction. In summary... Figure 5 According to the data from the examples, 25-30 kHz is the preferred frequency range that balances grinding efficiency and anti-blooming performance.
[0071] Comparative Example 1 (Traditional process + temperature control) Take 100kg of cocoa kernels from the same batch, grind them using a traditional ball mill, add 5kg of PPoP and 24kg of cocoa butter (without adding phospholipids), grind for 48 hours at 50℃, take the liquid block and process it according to the traditional tempering process (45℃→27℃→32℃), after tempering, pour it into a mold to form a chocolate product, and after cooling and demolding, obtain the finished chocolate product.
[0072] Test results: Finished product fineness d 90 =24.3μm. In the accelerated blooming experiment, the chocolate began to show obvious white bloom after 45 days, and the white bloom coverage rate reached more than 30% after 60 days.
[0073] Comparative Example 2 (This application's process does not involve the addition of phospholipids) Take 100 kg of cocoa kernels from the same batch and use the method of Example 1 of this application, but without adding phospholipids to the anti-frost nucleating matrix (only PPoP and cocoa butter). The remaining steps are the same as in Example 1. Take the obtained liquid block and directly cast it into a mold (without temperature adjustment).
[0074] Test results: Finished product fineness d 90 =17.5μm. In the accelerated blooming experiment, the chocolate began to show obvious white bloom after 30 days, and the white bloom on the surface was severe after 50 days. X-ray diffraction analysis showed that there were a large number of mixed Form IV and Form VI crystals in the product. The results indicate that stable Form V crystals cannot be directly generated by temperature control alone without the addition of phospholipids.
[0075] Comparative Example 3 (Traditional phospholipids with added ingredients + no temperature adjustment) Take 100kg of cocoa kernels from the same batch, grind them using a traditional ball mill, add 5kg of PPoP, 24kg of cocoa butter and 1kg of DMPC, grind for 48 hours at 50℃, and take the liquid block to directly pour into a mold to form a shape (without temperature adjustment).
[0076] The results in Table 3 show that the fineness d of the finished product 90 =21.3μm. In the accelerated blooming experiment, the chocolate showed obvious white bloom after 65 days. The results indicate that even with the addition of phospholipids, without the continuous process of multidimensional physical field coupling of this application, intermittent grinding alone is insufficient to fully exert the nucleation regulation function of phospholipids.
[0077] Table 3 Summary of the comparison between the examples and the comparative examples Industrial application possibilities This method enables continuous and efficient production of cocoa liquor. Simultaneously, it significantly simplifies or even eliminates traditional tempering processes through a phospholipid self-assembly nucleation mechanism. The equipment investment is moderate, operation is simple, and product quality is stable, making it a promising candidate for industrial applications. It is particularly suitable for large-scale chocolate manufacturing enterprises undergoing technological upgrades and is also applicable to the construction of new high-standard cocoa processing production lines.
[0078] Table 4. Comparison of nutritional content and sensory quality between chocolate produced by the method of this application and chocolate produced by conventional methods. Protein retention: Kjeldahl method, following GB 5009.5-2016 "National Food Safety Standard - Determination of Protein in Food". Specific steps: The sample is digested with sulfuric acid to convert organic nitrogen into inorganic ammonium salts. After alkalization and distillation, the solution is absorbed with boric acid and then titrated with standard hydrochloric acid. The protein content was calculated by multiplying the measured total nitrogen content by the nitrogen-protein conversion factor (6.25). The protein content (g / 100g) = (V-V0)×c×0.0140×F×100 / m (where V: volume of hydrochloric acid standard solution consumed by the sample (mL); V0: volume of hydrochloric acid standard solution consumed by the reagent blank (mL); c: concentration of hydrochloric acid standard solution (mol / L); 0.0140: mass of nitrogen (g) equivalent to 1.0 mL of sulfuric acid [c(1 / 2H2SO4)=1.000 mol / L] standard titration solution; F: nitrogen to protein conversion factor; m: sample mass (g)). The protein retention rate = protein content of unground cocoa beans / protein content of ground cocoa beans. The result was the arithmetic mean of three parallel determinations.
[0079] Dietary fiber retention rate: The dietary fiber retention rate was determined according to the enzymatic gravimetric method in GB 5009.88-2016 "National Food Safety Standard - Determination of Dietary Fiber in Food". After drying and defatting, the sample was sequentially hydrolyzed with heat-stable α-amylase, protease and amyloglucosidase to remove starch and protein. Ethanol was added to precipitate soluble dietary fiber, and the sample was filtered. The residue was washed, dried and weighed. At the same time, the protein and ash content in the residue were determined to correct the dietary fiber quality. The dietary fiber content was calculated as the proportion of the residue mass minus the protein and ash mass to the sample mass. The dietary fiber retention rate was expressed as the percentage of total dietary fiber content in unground cocoa kernels to the total dietary fiber content in ground cocoa liquor. The result was the arithmetic mean of three parallel determinations.
[0080] The degree of cocoa butter oxidation (peroxide value) was determined by titration according to GB 5009.227-2016 "National Food Safety Standard: Determination of Peroxide Value in Food". 2.0 g of cocoa butter sample was accurately weighed and placed in an iodine flask. After dissolving in a mixture of chloroform and glacial acetic acid, a saturated potassium iodide solution was added and reacted in the dark for 3 minutes. The precipitated free iodine was titrated with a standard sodium thiosulfate solution, and the endpoint was determined using a starch indicator. The peroxide value was calculated by multiplying the difference between the volume of standard sodium thiosulfate solution consumed by the sample and the volume consumed by the blank solution by the solution concentration, then by the conversion factor, and finally by the ratio of this value to the sample mass. The result was expressed in millimoles per kilogram (meq / kg), and the arithmetic mean of two parallel determinations was taken.
[0081] Moisture content was determined according to the direct drying method in GB 5009.3-2016 "National Food Safety Standard - Determination of Moisture in Food": After drying a clean weighing bottle to constant weight, accurately weigh about 2g of cocoa sample into the weighing bottle and dry it in a drying oven at 105℃ to constant weight. The moisture content in the sample was calculated by the mass difference before and after drying. The moisture content was expressed as the mass percentage of the sample mass lost during drying, and the result was the arithmetic mean of two parallel determinations.
[0082] The total phenol content was determined according to the principle of GB / T 44349-2024 "Determination of Total Polyphenols in Bee Pollen - Folin-Ciocalteu Reagent Colorimetric Method", combined with the extraction characteristics of cocoa matrix: After defatting, cocoa polyphenols were extracted with methanol or acetone-water solution using ultrasonic assistance. The extract reacted with Folin-Ciocalteu reagent, and under alkaline conditions, phenolic compounds reduced phosphomolybdic acid to form a blue complex. The absorbance was measured at a wavelength of 765 nm. A standard curve was established using gallic acid as a standard, and the total phenol content in the sample (calculated as gallic acid equivalent, unit: mg GAE / g) was calculated based on the standard curve. The result was the arithmetic mean of three parallel determinations.
[0083] The total flavonoid content was determined according to the principles of GB / T 22244-2008 "Determination of Total Flavonoids in Health Foods" and relevant research literature on cocoa matrix: After defatting, the total flavonoids in cocoa were extracted with ethanol solution using ultrasonic assistance. The extract was reacted with a sodium nitrite-aluminum nitrate-sodium hydroxide colorimetric system. Flavonoids complexed with aluminum ions under alkaline conditions to form a red complex, and the absorbance was measured at a wavelength of 510 nm. A standard curve was established using rutin as a standard, and the total flavonoid content in the sample (calculated as rutin equivalent, unit: mg / g) was calculated based on the standard curve. The result was the arithmetic mean of three parallel determinations.
[0084] Antioxidant activity was determined using the DPPH free radical scavenging method: Cocoa samples were defatted and extracted to prepare a series of concentration solutions, which were then mixed with DPPH working solution and reacted in the dark for 30 minutes. The absorbance was measured at 517 nm, and the scavenging rate of each concentration against DPPH free radicals was calculated. Linear regression analysis was performed using scavenging rate-concentration curves, and the concentration at which the scavenging rate reached 50% was determined as the IC50. 50 Value; IC 50 Values are expressed in micrograms per milliliter (μg / mL), and the results are the arithmetic mean of three parallel determinations.
[0085] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A continuous grinding process for preventing cocoa blooming, characterized in that, The continuous grinding process includes the following steps: S1, PPoP, cocoa butter and phospholipids are mixed in a mass ratio of 5:24:1 and melted and stirred at 50℃-60℃ to obtain anti-frost nucleation premix; S2, after cooling the peeled cocoa kernels to below -50°C, crush them to obtain brittle granules; S3, the brittle particles from step S2 and the anti-frost premix from step S1 are fed into a twin-screw extruder at a mass ratio of 1:(0.15-0.3) to complete the grinding; The twin-screw extruder is equipped with a PEF treatment zone where a pulsed electric field is applied; downstream of the PEF treatment zone, high-power ultrasonic waves are applied.
2. The continuous grinding process according to claim 1, characterized in that, The length-to-diameter ratio (L / D) of the screw in the twin-screw extruder in step S3 is 20:1 to 40:
1.
3. The continuous grinding process according to claim 1, characterized in that, In step S3, the electric field strength of the pulsed electric field is 15-35 kV / cm and the frequency is 200-800 Hz.
4. The continuous grinding process according to claim 1, characterized in that, In step S3, the outlet material temperature of the twin-screw extruder is 28-33℃.
5. The continuous grinding process according to claim 1, characterized in that, In step S3, the high-power ultrasound has a frequency of 20-40 kHz and a power density of 0.5-1.5 W / cm². 3 .
6. The continuous grinding process according to claim 1, characterized in that, In step S2, the diameter d of the embrittled particles is less than 2 mm.
7. The continuous grinding process according to claim 1, characterized in that, The phospholipids in step S1 are selected from one or more of dimyristoyl phosphatidylcholine (DMPC) and dipalmitoyl phosphatidylethanolamine (DPPE).
8. An application of the continuous grinding process described in claims 1-7 in the preparation of chocolate.