A method for treating excessive peroxide value of palm oil in fruit and vegetable chips

Abstract

The present application is in the technical field of palm oil treatment, and in particular to a method for treating fruit and vegetable crisp slice palm oil with excessive peroxide value, comprising the following steps: Step one, preparing a complex reducing agent solution: mixing palmitate vitamin C and vitamin E at a mass ratio of 2:3, with a total additive amount of 0.05% of the mass of the palm oil, and pre-dissolving in food-grade ethanol to form a uniform complex reducing agent solution; Step two, adding the reducing agent under nitrogen protection: passing nitrogen into the palm oil to be treated through a nitrogen protection system to make the oxygen content of the system ≤2%, and maintaining a positive pressure state, then adding the complex reducing agent solution into the palm oil; Step three, temperature control and stirring reaction: controlling the temperature of the palm oil at 40-50℃, and treating for 2-3 hours at a stirring speed of 50-60 revolutions per minute; this method effectively reduces the peroxide value of the palm oil to below 0.25g / 100g, the total additive amount of the complex system is only 0.05%, which is much lower than the 0.2% required for single use of AP, significantly reducing the treatment cost.

Description

Technical Field

[0001] This invention relates to the field of palm oil remediation, and particularly to a method for treating excessive peroxide value in palm oil used in fruit and vegetable crisps. Background Technology

[0002] As a representative of modern snack foods, the quality and safety of fruit and vegetable crisps directly affect consumers' health. Palm oil, as the main oil in the processing of fruit and vegetable crisps, has a peroxide value that is an important indicator for measuring the degree of oil oxidation. According to GB2716-2018 "National Food Safety Standard for Vegetable Oils", the peroxide value of edible vegetable oils should be ≤0.25g / 100g. However, the excessive peroxide value of palm oil in fruit and vegetable crisp products has become a common pain point in the industry.

[0003] In the existing technology, there is a lack of a remedial treatment method that can effectively reduce the peroxide value of palm oil that exceeds the standard, is easy to operate, has controllable cost, and meets food-grade safety requirements, especially for the problem of excessive peroxide value of palm oil in fruit and vegetable crisps. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for treating excessive peroxide value in palm oil used in fruit and vegetable crisps.

[0005] In a first aspect, the present invention provides a method for treating excessive peroxide value in palm oil used in fruit and vegetable crisps, comprising the following steps:

[0006] Step 1: Preparation of compound reducing agent solution: Mix vitamin C palmitate and vitamin E at a mass ratio of 2:3, with a total addition amount of 0.05% of the mass of palm oil, and pre-dissolve them in food-grade ethanol to form a homogeneous compound reducing agent solution;

[0007] Step 2: Adding reducing agent under nitrogen protection: Nitrogen gas is introduced into the palm oil to be treated through a nitrogen protection system to make the oxygen content of the system ≤2% and maintain a positive pressure. Then, the compound reducing agent solution is added to the palm oil.

[0008] Step 3, Temperature-controlled stirring reaction: The palm oil temperature is controlled at 40–50℃, and it is stirred at 50–60 rpm for 2–3 hours to allow the compound reducing agent to undergo an oxidation-reduction reaction with the hydroperoxide in the palm oil, reducing it to hydroxyl compounds.

[0009] Step 4, Cooling and Testing: After the reaction is complete, quickly cool the palm oil to room temperature and test the peroxide value to ensure it is ≤0.25g / 100g.

[0010] Preferably, step one specifically includes:

[0011] The chemical structure of the vitamin C palmitate is 6-palmitoyl-L-ascorbic acid, and its molecular formula is C2. 22 H 38 O7 has a molecular weight of 414.54 g / mol.

[0012] Preferably, step one specifically includes:

[0013] The compound reducing agent is pre-dissolved in the food-grade ethanol at a concentration of 5% before use to ensure uniform dispersion in the palm oil.

[0014] Preferably, step one further includes:

[0015] Based on the critical control point setting of the HACCP system, the addition step of vitamin C palmitate was set as the critical control point, with critical limits of 0.02% ± 0.005% for its concentration and 0.03% ± 0.005% for vitamin E concentration.

[0016] Preferably, step two specifically includes:

[0017] The nitrogen protection system includes a nitrogen cylinder, a pressure reducing valve, and a nitrogen injection port on the top of the reactor, maintaining a pressure of 0.5 kPa during the process.

[0018] Preferably, steps two and three further include:

[0019] The reactor used in the process is made of 304 stainless steel and is equipped with a PID temperature control system and a frame stirrer, with a temperature control accuracy of ±0.3℃.

[0020] Preferably, step four specifically includes:

[0021] After processing, palm oil needs to be rapidly cooled to room temperature. Cooling methods include plate heat exchanger cooling or jacketed water cooling to ensure that the peroxide value remains stable and meets the standards.

[0022] Preferably, the method further includes:

[0023] Online monitoring: The peroxide value is monitored in real time using an electrochemical sensor method with a detection limit of 4.94 μmol / L. The monitoring frequency is once per hour, and it is periodically calibrated with the ferric thiocyanate method to ensure that the deviation is ≤5%.

[0024] Preferably, the color, flavor, and nutritional components of the treated palm oil do not change significantly, and the peroxide value is ≤0.25g / 100g.

[0025] Preferably, the method is applicable to the remedial treatment of finished products with excessive palm oil peroxide value during the production of fruit and vegetable crisps, and can also be used as a preventive control measure in the production process.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] It effectively reduces the peroxide value of palm oil to below 0.25g / 100g, with a total addition amount of only 0.05% in the compound system, far lower than the 0.2% required for using AP alone, significantly reducing processing costs. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0029] Figure 2 This is a test result table for Embodiment 1 of the present invention. Detailed Implementation

[0030] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0031] like Figure 1 The method shown here for treating excessive peroxide value in palm oil used in fruit and vegetable crisps includes the following steps:

[0032] Step 1: Preparation of compound reducing agent solution: Mix vitamin C palmitate and vitamin E at a mass ratio of 2:3, with a total addition amount of 0.05% of the mass of palm oil, and pre-dissolve them in food-grade ethanol to form a homogeneous compound reducing agent solution;

[0033] Step 2: Adding reducing agent under nitrogen protection: Nitrogen gas is introduced into the palm oil to be treated through a nitrogen protection system to make the oxygen content of the system ≤2% and maintain a positive pressure. Then, the compound reducing agent solution is added to the palm oil.

[0034] Step 3, Temperature-controlled stirring reaction: The palm oil temperature is controlled at 40–50℃, and it is stirred at 50–60 rpm for 2–3 hours to allow the compound reducing agent to undergo an oxidation-reduction reaction with the hydroperoxide in the palm oil, reducing it to hydroxyl compounds.

[0035] Step 4, Cooling and Testing: After the reaction is complete, quickly cool the palm oil to room temperature and test the peroxide value to ensure it is ≤0.25g / 100g.

[0036] As an optional embodiment, step one specifically includes:

[0037] The chemical structure of the vitamin C palmitate is 6-palmitoyl-L-ascorbic acid, and its molecular formula is C2. 22 H 38 O7 has a molecular weight of 414.54 g / mol.

[0038] As an optional embodiment, step one specifically includes:

[0039] The compound reducing agent is pre-dissolved in the food-grade ethanol at a concentration of 5% before use to ensure uniform dispersion in the palm oil.

[0040] As an optional embodiment, step one further includes:

[0041] Based on the critical control point setting of the HACCP system, the addition step of vitamin C palmitate was set as the critical control point, with critical limits of 0.02% ± 0.005% for its concentration and 0.03% ± 0.005% for vitamin E concentration.

[0042] As an optional embodiment, step two specifically includes:

[0043] The nitrogen protection system includes a nitrogen cylinder, a pressure reducing valve, and a nitrogen injection port on the top of the reactor, maintaining a pressure of 0.5 kPa during the process.

[0044] As an optional embodiment, steps two and three further include:

[0045] The reactor used in the process is made of 304 stainless steel and is equipped with a PID temperature control system and a frame stirrer, with a temperature control accuracy of ±0.3℃.

[0046] As an optional embodiment, step four specifically includes:

[0047] After processing, palm oil needs to be rapidly cooled to room temperature. Cooling methods include plate heat exchanger cooling or jacketed water cooling to ensure that the peroxide value remains stable and meets the standards.

[0048] As an optional embodiment, the method further includes:

[0049] Online monitoring: The peroxide value is monitored in real time using an electrochemical sensor method with a detection limit of 4.94 μmol / L. The monitoring frequency is once per hour, and it is periodically calibrated with the ferric thiocyanate method to ensure that the deviation is ≤5%.

[0050] As an optional embodiment, the color, flavor and nutritional components of the treated palm oil did not change significantly, and the peroxide value was ≤0.25g / 100g.

[0051] As an optional embodiment, the method is applicable to the remedial treatment of finished products with excessive palm oil peroxide value during the production of fruit and vegetable crisps, and can also be used as a preventive control measure in the production process.

[0052] Example 1

[0053] Small-scale laboratory experiments

[0054] This embodiment aims to verify the effect of the vitamin C palmitate (AP) and vitamin E (VE) compound system on reducing the peroxide value of palm oil through laboratory-scale experiments, and to determine the optimal process parameters.

[0055] Step 1: Prepare test samples: Take three 500mL sealed glass containers and number them 1, 2 and 3 respectively. Add 1500g of palm oil with a peroxide value in the range of 0.36 to 0.56g / 100g to each container.

[0056] Step 2: Prepare the compound reducing agent solution: Weigh vitamin C palmitate (AP) and vitamin E (VE) at a mass ratio of 2:3, place them in a beaker, add 50 mL of food-grade ethanol (5% concentration), and stir until completely dissolved to form a homogeneous solution. To investigate the effect of different addition amounts,

[0057] The addition amounts for the three groups of experiments were set as follows:

[0058] Container 1 (low concentration): AP 3.0g + VE 4.5g

[0059] Container #2 (medium concentration): AP 6.0g + VE 9.0g

[0060] Container #3 (High Concentration): AP 9.0g + VE 13.5g

[0061] Step 3: Add reducing agent: Slowly pour the prepared reducing agent solution into the corresponding glass containers, and at the same time start the magnetic stirrer to stir at a speed of 50 rpm to make the reducing agent and palm oil fully mixed.

[0062] Step 4, Nitrogen protection: Immediately introduce high-purity nitrogen (purity ≥99.9%) into each container, bubble through the tube inserted below the liquid surface to remove oxygen from the top space of the container and dissolved in the oil, continuously introduce nitrogen, and use a portable oxygen content meter to monitor and ensure that the oxygen content in the container is ≤2% and maintain a slight positive pressure (about 0.5 kPa).

[0063] Step 5, Temperature-controlled stirring reaction: Place the three containers in constant temperature water baths at different temperatures:

[0064] Container No. 1: 40℃

[0065] Container #2: 50℃

[0066] Container #3: 60℃

[0067] Temperature control accuracy was ±1℃. Under continuous nitrogen protection, the mixture was stirred at 50 rpm for 1 hour, 2 hours and 3 hours respectively. At each time point, approximately 50 mL of sample was taken from each container using a pipette, rapidly cooled to room temperature and immediately stored in a 20℃ refrigerator for later testing.

[0068] Step 6, Peroxide value detection: The peroxide value of the samples at each time point was determined using the ferric thiocyanate method (FTC method);

[0069] Specific procedure: Weigh 2.0g of oil sample into a test tube, add 3mL of isooctane to dissolve it, then add 0.02mL of ammonium thiocyanate solution and 0.02mL of ferrous chloride solution in sequence, shake to mix, let stand for 5 minutes, and then measure the absorbance at a wavelength of 500nm. Calculate the peroxide value according to the standard curve.

[0070] Step 7, Result Analysis: The test results are as follows Figure 2 As shown

[0071] Test results: Under the conditions of 40-50℃ and 2 hours of treatment, the peroxide value of all samples decreased to below 0.25g / 100g, which meets the GB2716-2018 standard. The treatment effect was slightly lower at 60℃, and the self-oxidation of the reducing agent was observed (the solution color darkened slightly). Considering both effect and cost, the preferred addition amount is 0.05% of the total oil mass (i.e., AP 0.02% + VE 0.03%). This addition amount was verified in subsequent pilot tests.

[0072] Example 2

[0073] pilot production

[0074] This embodiment verifies the feasibility and stability of the compound reducing agent treatment method under simulated production scale conditions.

[0075] Step 1, Equipment Preparation: Select a 1.5m³ 304 stainless steel reactor and equip it with the following systems:

[0076] Electric heating system: PID temperature control, accuracy ±0.3℃;

[0077] Mixing system: Frame mixer, adjustable speed range 30-80 rpm;

[0078] Nitrogen system: nitrogen cylinder, pressure reducing valve, mass flow meter, nitrogen injection port at the top of the reactor; nitrogen purity ≥ 99.9%;

[0079] Cooling system: Jacketed water cooling, which can quickly reduce temperature;

[0080] Metering pump: Used for precise addition of reducing agent solution.

[0081] Step 2, Palm oil pretreatment: Pump the palm oil to be treated (peroxide value 0.40~0.60g / 100g) into the reactor, turn on the stirring and heat to 40℃, and remove any possible impurities and moisture through the bottom drain. The amount of oil after pretreatment is 1200kg.

[0082] Step 3, Preparation and addition of compound reducing agent: Weigh 240g of vitamin C palmitate (AP) and 360g of vitamin E (VE) (total addition 0.05%) at a mass ratio of 2:3, dissolve them in 12L of food-grade ethanol (concentration 5%), stir until completely dissolved, and spray the reducing agent solution into the reaction vessel at a constant flow rate using a metering pump, while simultaneously turning on the stirrer (50 rpm) to ensure uniform dispersion.

[0083] Step 4, Nitrogen protection and reaction: Nitrogen gas is introduced from the bottom of the reactor at a flow rate of 10 L / min to maintain the oxygen content in the reactor at ≤2% and a positive pressure of 0.5 kPa. The temperature is raised to 45°C and stirred continuously at a speed of 55 rpm. The reaction time is set to 3 hours. During this period, peroxide value is measured every 30 minutes through the sampling port to monitor the reaction process.

[0084] Step 5, Cooling and Testing: After the reaction is completed, immediately switch the jacket cooling water and cool the palm oil to room temperature at a rate of not less than 10℃ / min. After cooling, take samples from different parts of the reactor, mix them, and determine the peroxide value using the titration method specified in GB5009.227-2016. At the same time, perform sensory evaluation (color, odor) on the treated oil.

[0085] Step 6: Results

[0086] The average peroxide value of the treated palm oil was 0.21 g / 100 g (range 0.19–0.23 g / 100 g), with a compliance rate of over 95%. Sensory evaluation showed that the oil was clear and bright in color, without significant darkening or turbidity, with normal flavor and no unpleasant odor. The loss rate of reducing agent was calculated by measuring the content of reducing agent before and after the reaction. The AP loss rate was about 30%, and the VE loss rate was about 20%, which was much lower than the 51.88% when AP was used alone. The processing volume of this batch was 1200 kg, the processing cycle was about 4 hours, and the production efficiency reached 5000 kg / day.

[0087] Example 3

[0088] HACCP system application

[0089] This embodiment integrates the aforementioned treatment method into the HACCP (Hazard Analysis and Critical Control Points) system to ensure the quality and safety of the production process.

[0090] Step 1: Establish a HACCP plan: Form an HACCP team to analyze the hazards of excessive peroxide value of palm oil in the production of fruit and vegetable chips, identify the main hazards as peroxides produced by oil oxidation, and possible sources include oxidation of the raw palm oil itself, contact with oxygen during processing, and improper addition of reducing agents.

[0091] Step 2: Determine the Critical Control Point (CCP): Based on the hazard analysis, the addition step of the compound reducing agent is determined as the CCP, because this step directly determines whether the concentration of the reducing agent is sufficient to reduce the peroxide value to a safe level, and insufficient addition will lead to the final product being unqualified.

[0092] Step 3: Set critical limits: Based on the previous experimental data, set the critical limits as follows:

[0093] Vitamin C palmitate (AP) concentration: 0.02% ± 0.005% (i.e., 0.015% to 0.025% of the oil mass);

[0094] Vitamin E (VE) concentration: 0.03% ± 0.005% (i.e., 0.025% to 0.035%).

[0095] Exceeding this range may affect the processing results or lead to increased costs.

[0096] Step 4, Monitoring Measures: Before each addition, the concentration of the reducing agent solution is monitored in real time using an online refractometer or a concentration detector in the pre-dissolving tank. At the same time, the actual addition ratio is calculated by the flow rate of the metering pump and the palm oil feed rate. Data is recorded every 15 minutes, and the operator reviews the records every hour.

[0097] Step 5, Corrective Action: When monitoring results show that AP or VE concentrations deviate from critical limits, take corrective measures immediately:

[0098] If the concentration is too low, calculate the required reducing agent based on the deviation and add it again using a metering pump;

[0099] If the concentration is too high, record the deviation and assess its impact on the final product. If necessary, extend the reaction time or increase the detection frequency.

[0100] After corrective action, the peroxide value is resampled and tested. Only after confirming that it meets the standard can the next process be carried out.

[0101] Step 6, Verification and Recording: After each batch is processed, the quality inspection department will test the peroxide value of the finished palm oil and compare it with the online monitoring data to verify the effectiveness of the HACCP system. All monitoring records, corrective action reports and verification results will be archived for future reference to ensure traceability.

[0102] Example 4

[0103] Online monitoring technology

[0104] This embodiment introduces online peroxide value monitoring technology to achieve real-time control of the processing, thereby improving production efficiency and product quality stability.

[0105] Step 1: Install an online detector: Install an electrochemical sensor peroxide value detector on the outlet pipe of the reactor. The detector uses FeCo nanocomposite material modified electrode, with a detection limit of 4.94 μmol / L, which is more accurate than the traditional ferric thiocyanate method. The sensor directly contacts the flowing oil, and the signal is converted into a 4-20mA standard signal by a transmitter and connected to the PLC control system.

[0106] Step 2, Calibrate the instrument: Before use, calibrate the detector with a standard oil sample of known peroxide value. The calibration range is 0.10~0.60g / 100g. Establish a standard curve and perform automatic or manual calibration with a standard solution every 4 hours to ensure that the measurement deviation is ≤5%.

[0107] Step 3, Real-time monitoring: During the reaction, the detector continuously monitors the peroxide value of the effluent oil. The data is recorded every hour. When the monitored value approaches the target value (0.25g / 100g), the system can issue an early warning to prompt the operator to prepare to end the reaction. The monitoring data is displayed on the control room screen in real time and stored in the database.

[0108] Step 4, Data Recording and Feedback: The PLC system automatically adjusts the reaction time based on the monitoring data. When the peroxide value drops below 0.24g / 100g, the system can automatically end the reaction and start the cooling program. At the same time, the monitoring data is used to verify the effect of the reducing agent addition. If the peroxide value is found to decrease slowly, the stirring speed or temperature can be adjusted in time.

[0109] Step 5: Regular maintenance: Clean the sensor weekly to remove any grease and impurities that may be attached, verify linearity monthly with a standard solution to ensure long-term stability, and include maintenance records in the equipment file.

[0110] After adopting online monitoring, the peroxide value fluctuation between treated batches decreased from ±0.05g / 100g to ±0.02g / 100g, the compliance rate increased to over 99%, and the workload and error of manual testing were reduced.

[0111] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for treating excessive peroxide value in palm oil used in fruit and vegetable crisps, characterized in that, Includes the following steps: Step 1: Preparation of compound reducing agent solution: Mix vitamin C palmitate and vitamin E at a mass ratio of 2:3, with a total addition amount of 0.05% of the mass of palm oil, and pre-dissolve them in food-grade ethanol to form a homogeneous compound reducing agent solution; Step 2: Adding reducing agent under nitrogen protection: Nitrogen gas is introduced into the palm oil to be treated through a nitrogen protection system to make the oxygen content of the system ≤2% and maintain a positive pressure. Then, the compound reducing agent solution is added to the palm oil. Step 3, Temperature-controlled stirring reaction: The palm oil temperature is controlled at 40–50℃, and it is stirred at 50–60 rpm for 2–3 hours to allow the compound reducing agent to undergo an oxidation-reduction reaction with the hydroperoxide in the palm oil, reducing it to hydroxyl compounds. Step 4, Cooling and Testing: After the reaction is complete, quickly cool the palm oil to room temperature and test the peroxide value to ensure it is ≤0.25g / 100g.

2. The method for treating excessive peroxide value in palm oil used in fruit and vegetable crisps according to claim 1, characterized in that, Step one specifically includes: The chemical structure of the vitamin C palmitate is 6-palmitoyl-L-ascorbic acid, and its molecular formula is C2. 22 H 38 O7 has a molecular weight of 414.54 g / mol.

3. The method for treating excessive peroxide value in palm oil used in fruit and vegetable crisps according to claim 1, characterized in that, Step one specifically includes: The compound reducing agent is pre-dissolved in the food-grade ethanol at a concentration of 5% before use to ensure uniform dispersion in the palm oil.

4. The method for treating excessive peroxide value in palm oil of fruit and vegetable crisps according to claim 1, characterized in that, Step one also includes: Based on the critical control point setting of the HACCP system, the addition step of vitamin C palmitate was set as the critical control point, with critical limits of 0.02% ± 0.005% for its concentration and 0.03% ± 0.005% for vitamin E concentration.

5. The method for treating excessive peroxide value in palm oil of fruit and vegetable crisps according to claim 1, characterized in that, Step two specifically includes: The nitrogen protection system includes a nitrogen cylinder, a pressure reducing valve, and a nitrogen injection port on the top of the reactor, maintaining a pressure of 0.5 kPa during the process.

6. The method for treating excessive peroxide value in palm oil of fruit and vegetable crisps according to claim 1, characterized in that, Steps two and three also include: The reactor used in the process is made of 304 stainless steel and is equipped with a PID temperature control system and a frame stirrer, with a temperature control accuracy of ±0.3℃.

7. The method for treating excessive peroxide value in palm oil of fruit and vegetable crisps according to claim 1, characterized in that, Step four specifically includes: After processing, palm oil needs to be rapidly cooled to room temperature. Cooling methods include plate heat exchanger cooling or jacketed water cooling to ensure that the peroxide value remains stable and meets the standards.

8. The method for treating excessive peroxide value in palm oil of fruit and vegetable crisps according to claim 1, characterized in that, The method further includes: Online monitoring: The peroxide value is monitored in real time using an electrochemical sensor method with a detection limit of 4.94 μmol / L. The monitoring frequency is once per hour, and it is regularly calibrated with the ferric thiocyanate method to ensure that the deviation is ≤5%.

9. The method for treating excessive peroxide value in palm oil of fruit and vegetable crisps according to claim 1, characterized in that, The color, flavor and nutritional components of the processed palm oil did not change significantly, and the peroxide value was ≤0.25g / 100g.

10. The method for treating excessive peroxide value in palm oil of fruit and vegetable crisps according to claim 1, characterized in that, The method is applicable to the remedial treatment of finished products with excessive peroxide value of palm oil during the production of fruit and vegetable crisps, and can also be used as a preventive control measure in the production process.

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