Chinese chestnut sauce processing method

Abstract

The invention relates to a Chinese chestnut sauce processing method, and belongs to the technical field of food processing. The method comprises the following steps: raw material treatment: soaking shelled and peeled Chinese chestnuts in a color protection solution containing citric acid and ascorbic acid to inhibit browning; cooking: cooking the Chinese chestnuts until the Chinese chestnuts are thoroughly cooked; pulping: mixing the steamed Chinese chestnuts with softened water, pulping and filtering; blending: adding white granulated sugar, malt syrup, vegetable oil, an emulsifier and a stabilizer, and uniformly stirring; homogenizing: homogenizing for 2 to 3 times under the pressure of 20 to 40 MPa; concentrating: concentrating at the vacuum degree of 0.08-0.09 MPa and the temperature of 60-70 DEG C until the content of soluble solids reaches 60%-65%; performing sterilization: performing sterilization for 20-30 minutes by adopting a segmented temperature control process; and filling: filling while hot and sealing. Through composite color protection, low-temperature vacuum concentration, segmented sterilization and compound emulsification stabilization of a system, browning is remarkably inhibited, flavor and nutrition are reserved, texture stability is improved, and the shelf life is prolonged to 12 months. The method is simple and efficient in process, suitable for industrial production and high in market application value.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and particularly relates to a processing method of chestnut paste. Background Art

[0002] Chestnuts are a kind of nuts rich in nutrients, containing starch, protein, vitamin C, minerals and polyphenols, and having high edible and medicinal values. However, chestnuts are prone to enzymatic browning and non-enzymatic browning during the processing, resulting in dull product color, deteriorated flavor, and its high starch content is likely to cause unstable texture (such as layering, water separation, etc.). The existing chestnut paste processing technologies have the following prominent problems:

[0003] The polyphenol oxidase in chestnuts is prone to contact with oxygen during the processing, leading to enzymatic browning. At the same time, the Maillard reaction and caramelization reaction further exacerbate non-enzymatic browning. Traditional processes mostly use a single color fixative (such as sulfite), although it has certain effects, there is a risk of sulfur dioxide residue. Experiments show that the ΔE value of chestnut paste without color protection treatment is as high as 8.5 after processing, seriously affecting the appearance of the product. In addition, the high-temperature concentration and sterilization processes will also exacerbate browning, resulting in uneven product color.

[0004] The volatile flavor substances in chestnuts (such as pyrazines and aldehyde compounds) are sensitive to heat. The traditional high-temperature sterilization process (such as 121°C / 15 min) results in a flavor substance loss rate of more than 40% (Literature "Food Science" 2020, 41(5): data). At the same time, vitamin C and polyphenols are easily degraded at high temperatures. The retention rate of vitamin C in traditional processes is less than 70%, and the total phenol content decreases by 30%-40%. In addition, the unsaturated fatty acids in chestnuts are easily oxidized during the processing, producing bad flavors (such as rancid smell).

[0005] The high starch content and oil addition of chestnut paste are likely to cause unstable texture. In the prior art, the addition amount of emulsifiers (such as monoglyceride) is too high (0.3%-0.5%). Although it can improve the emulsification effect, it is easy to produce a greasy feeling, and oil-water separation is likely to occur during the storage period. In addition, the pressure of the traditional homogenization process is insufficient (≤20 MPa), resulting in larger emulsion particle size (≥10 μm), low product viscosity (≤3500 mPa·s), and rough taste.

[0006] The traditional atmospheric pressure concentration process takes as long as 4-6 hours, with high energy consumption and is likely to exacerbate the Maillard reaction (the ΔE value increases by 2-3 units). In addition, although the traditional sterilization process (such as high-temperature short-time sterilization) can shorten the time, it has high requirements for equipment and is likely to damage heat-sensitive components.

[0007] In view of the above problems, the existing improvement scheme uses microwave enzyme inactivation technology, which shortens the processing time, but increases the equipment cost by 30%, and significantly damages the chestnut texture (viscosity decreases by 15%-20%). Another scheme uses high-pressure homogenization (≥50MPa) to improve the texture, but energy consumption increases by 25%, and the effect on retaining flavor substances is limited. Therefore, there is an urgent need for a low-cost, efficient chestnut sauce processing method that takes into account color, flavor and nutrition. Summary of the invention

[0008] A method for processing chestnut paste comprises the following steps:

[0009] (1) Raw material processing: soaking the shelled and peeled chestnuts in a color protection solution containing 0.1%-0.3% citric acid and 0.05%-0.1% ascorbic acid for 30-60 minutes;

[0010] (2) Steaming: Steam the soaked chestnuts until fully cooked;

[0011] (3) beating: mixing the steamed chestnuts with water in a weight ratio of 1:1-1:2 and beating the mixture to obtain chestnut pulp;

[0012] (4) Preparation: Add white sugar, maltose syrup, vegetable oil, emulsifier and stabilizer to the chestnut pulp and stir evenly;

[0013] (5) Homogenization: The mixed material is homogenized 2-3 times at a pressure of 20-40 MPa;

[0014] (6) Concentration: vacuum concentration is performed at a vacuum degree of 0.08-0.09 MPa and a temperature of 60-70° C. until the soluble solid content reaches 60%-65%;

[0015] (7) Sterilization: sterilize the concentrated chestnut paste at 85-90° C. for 20-30 minutes;

[0016] (8) Filling: Fill the sterilized chestnut paste into a sterilized container while it is still hot and seal it.

[0017] As a preferred technical solution of the present invention, the pH value of the color protection solution in step (1) is 2.5-3.5, and the chestnuts need to be precooled before soaking in the color protection solution, the precooling temperature is 0-4°C, and the precooling time is 10-20 minutes.

[0018] As a preferred technical solution of the present invention, the water added in the pulping process in step (3) is softened water treated by reverse osmosis, and after pulping, it is filtered through a 200-300 mesh sieve to remove coarse fibers and unbroken particles.

[0019] As a preferred technical solution of the present invention, in step (4), the emulsifier is a complex of glycerol monostearate and sucrose fatty acid ester, and the mass ratio of the two is 1:1 - 1:2, and the total addition amount is 0.1% - 0.3% of the total weight of the chestnut paste; the stabilizer is a compound of xanthan gum and carrageenan, and the mass ratio of the two is 2:1 - 3:1, and the total addition amount is 0.05% - 0.15% of the total weight of the chestnut paste.

[0020] As a preferred technical solution of the present invention, the homogenization treatment in step (5) is carried out in two stages: the pressure in the first stage is 10 - 15 MPa, the pressure in the second stage is 25 - 40 MPa, and the interval time between the two homogenizations is 5 - 10 minutes.

[0021] As a preferred technical solution of the present invention, nitrogen is synchronously injected for protection during the vacuum concentration process in step (6), the nitrogen flow rate is 0.5 - 1.0 L / min, and the concentration end point is monitored in real time by an online refractometer.

[0022] As a preferred technical solution of the present invention, the sterilization in step (7) adopts a segmented temperature control process: in the first stage, the temperature is raised to 70 - 75 °C at a rate of 2 - 3 °C / min and kept warm for 5 minutes; in the second stage, the temperature is raised to 85 - 90 °C at a rate of 1 - 2 °C / min and kept warm for 20 - 30 minutes.

[0023] As a preferred technical solution of the present invention, the chestnut paste is rapidly cooled before filling in step (8), the cooling rate is 5 - 8 °C / min, the cooling end point temperature is 45 - 50 °C, and then it is filled in a sterile environment.

[0024] As a preferred technical solution of the present invention, 0.01% - 0.03% of sodium phytate and 0.005% - 0.01% of D-isoascorbic acid sodium are further added to the color protection solution to synergistically inhibit enzymatic browning and non-enzymatic browning.

[0025] As a preferred technical solution of the present invention, the vegetable oil is a mixed oil of high-oleic sunflower oil and rice bran oil, and the volume ratio of the two is 3:1 - 5:1, and the mixed oil needs to be ultrasonically treated at 40 - 50 °C for 10 - 15 minutes in advance, and the ultrasonic frequency is 25 - 40 kHz.

[0026] Beneficial effects:

[0027] Through technologies such as compound color protection liquid, low-temperature vacuum concentration, and segmented temperature-controlled sterilization, the quality of chestnut paste has been significantly improved in the present invention. The degree of browning (ΔE value) is reduced by 60%-65%, the retention rate of vitamin C is increased to 92%, the loss of flavor substances is reduced by 25%-30%, and at the same time, the viscosity of the product is stabilized at 4300-4800 mPa·s through a compound emulsification and stabilization system, and the shelf life is extended to 12 months. These improvements make the chestnut paste superior to the traditional process in terms of color, flavor, nutrition, and texture stability.

[0028] The present invention has also achieved remarkable results in terms of processing efficiency and cost control. The vacuum concentration time is shortened to 2-2.5 hours, the energy consumption is reduced by 35%, and through nitrogen protection and ultrasonic modification of oil technology, the oxidation loss and equipment maintenance cost are further reduced. The overall process is simple and efficient, suitable for industrial production, and has high market competitiveness and industrialization potential. Detailed implementation manners

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0030] The following describes the detailed implementation manners of the present invention in combination with several embodiments.

[0031] Example 1:

[0032] Raw material treatment: Select fresh chestnuts, remove the shells and skins, wash them, and soak them in a color protection liquid containing 0.2% citric acid and 0.08% ascorbic acid for 45 minutes, and the pH value of the color protection liquid is 3.0.

[0033] Cooking: Cook the chestnuts until they are fully cooked, and the cooking time is 20 minutes.

[0034] Pulping: Mix the cooked chestnuts with softened water at a ratio of 1:1.5, use a high-speed pulper to pulp for 3 minutes, and filter through a 200-mesh sieve.

[0035] Formulation: Add granulated sugar (10%), malt syrup (5%), a mixed oil of high-oleic sunflower oil and rice bran oil (8%, volume ratio 4:1), glycerol monostearate (0.15%), and xanthan gum (0.08%) to the chestnut pulp, and stir evenly.

[0036] Homogenization: Homogenize the mixed liquid twice at 30 MPa with an interval of 5 minutes.

[0037] Concentration: The homogenized chestnut pulp was concentrated at a vacuum degree of 0.085 MPa and a temperature of 65° C. until the soluble solid content reached 62%. During the concentration process, nitrogen was injected at a flow rate of 0.8 L / min for protection.

[0038] Sterilization: The concentrated chestnut paste was sterilized at 88°C for 25 minutes using a segmented temperature control process: in the first stage, the temperature was raised to 75°C at a rate of 2°C / min and kept warm for 5 minutes; in the second stage, the temperature was raised to 88°C at a rate of 1.5°C / min and kept warm for 25 minutes.

[0039] Filling: Fill the chestnut paste into sterilized containers while it is still hot and seal them.

[0040] Embodiment 2:

[0041] Raw material processing: Select fresh chestnuts, peel and shell them, wash them and soak them in a color-protecting solution containing 0.15% citric acid and 0.06% ascorbic acid for 50 minutes. The pH value of the color-protecting solution is 2.8.

[0042] Steaming: Steam the chestnuts until cooked through, the steaming time is 25 minutes.

[0043] Beating: Mix the steamed chestnuts and softened water in a ratio of 1:1.2, beat with a high-speed beater for 4 minutes, and filter through a 250-mesh sieve.

[0044] Preparation: Add white sugar (12%), maltose syrup (6%), corn oil (10%), glyceryl monostearate (0.2%) and xanthan gum (0.1%) to chestnut pulp and mix well.

[0045] Homogenization: Homogenize the mixture at 25 MPa for 3 times with an interval of 10 minutes.

[0046] Concentration: The homogenized chestnut pulp was concentrated at a vacuum degree of 0.09 MPa and a temperature of 68° C. until the soluble solid content reached 63%. During the concentration process, nitrogen was injected at a flow rate of 1.0 L / min for protection.

[0047] Sterilization: The concentrated chestnut paste was sterilized at 90°C for 20 minutes using a segmented temperature control process: in the first stage, the temperature was raised to 70°C at a rate of 2.5°C / min and kept warm for 5 minutes; in the second stage, the temperature was raised to 90°C at a rate of 2°C / min and kept warm for 20 minutes.

[0048] Filling: Fill the chestnut paste into sterilized containers while it is still hot and seal them.

[0049] Embodiment 3:

[0050] Raw material processing: Select fresh chestnuts, peel and shell them, wash them and soak them in a color-protecting solution containing 0.25% citric acid and 0.09% ascorbic acid for 40 minutes. The pH value of the color-protecting solution is 3.2.

[0051] Steaming: Steam the chestnuts until cooked through, the steaming time is 18 minutes.

[0052] Beating: Mix the steamed chestnuts and softened water in a ratio of 1:1.8, beat with a high-speed beater for 5 minutes, and filter through a 300-mesh sieve.

[0053] Preparation: Add white sugar (8%), maltose syrup (4%), peanut oil (6%), glyceryl monostearate (0.1%) and xanthan gum (0.05%) to chestnut pulp and stir well.

[0054] Homogenization: Homogenize the mixture at 35 MPa twice with an interval of 8 minutes.

[0055] Concentration: The homogenized chestnut paste is concentrated at a vacuum degree of 0.08MPa and a temperature of 70°C until the soluble solid content reaches 64%. During the concentration process, nitrogen is injected at a flow rate of 0.5L / min for protection. Sterilization: The concentrated chestnut paste is sterilized at 85°C for 30 minutes, using a segmented temperature control process: in the first stage, the temperature is raised to 75°C at a rate of 3°C / min and kept warm for 5 minutes; in the second stage, the temperature is raised to 85°C at a rate of 1°C / min and kept warm for 30 minutes.

[0056] Filling: Fill the chestnut paste into sterilized containers while it is still hot and seal them.

[0057] Comparative Example:

[0058] Raw material processing: Select fresh chestnuts, peel and shell them, wash them and steam them directly without color protection treatment.

[0059] Steaming: Steam the chestnuts until cooked through, the steaming time is 20 minutes.

[0060] Beating: Mix the steamed chestnuts with ordinary tap water in a ratio of 1:1.5, and beat them using a high-speed beater for 3 minutes without filtering.

[0061] Preparation: Add white sugar (10%), maltose syrup (5%), ordinary vegetable oil (8%), glyceryl monostearate (0.15%) and xanthan gum (0.08%) to the chestnut pulp and stir well.

[0062] Homogenization: Homogenize the mixture at 30 MPa twice with an interval of 5 minutes.

[0063] Concentration: The homogenized chestnut pulp is heated and concentrated under normal pressure until the soluble solid content reaches 62%.

[0064] Sterilization: The concentrated chestnut paste is sterilized at 88°C for 25 minutes without using a segmented temperature control process.

[0065] Filling: Fill the chestnut paste into sterilized containers while it is still hot and seal them.

[0066] Data table:

[0067]

[0068] illustrate:

[0069] Examples 1-3 adopt the process of the present invention, and the comparative example adopts the traditional process;

[0070] The degree of browning was measured by a colorimeter, and the smaller the ΔE value, the lighter the browning;

[0071] The flavor score was evaluated by 10 professional tasters and the average value was taken;

[0072] The nutrient retention rate was measured by vitamin C and total phenolic content;

[0073] The viscosity was measured using a rotational viscometer;

[0074] Shelf life is determined by accelerated testing and microbiological testing.

[0075] Conclusion: The chestnut paste processing method provided by the invention can effectively inhibit browning, retain flavor and nutrition, and significantly extend the shelf life, and has high practical value and market prospects.

[0076] The present invention significantly improves the quality of chestnut paste through multi-link collaborative innovation, and the specific effects are as follows:

[0077] 1. Significant browning inhibition effect

[0078] The synergistic effect of the composite color-protecting liquid (citric acid + ascorbic acid + sodium phytate) and the pre-cooling treatment inhibited the activity of polyphenol oxidase (PPO) by more than 90% (see Table 1). The ΔE values of Examples 1-3 were only 3.0-3.5, which was 60%-65% lower than that of the comparative example (8.5), and were close to the color of fresh chestnuts (ΔE=2.8).

[0079] 2. Highly efficient preservation of flavor and nutrition

[0080] (1) Low temperature vacuum concentration technology: Concentration is completed at 60-70°C. Compared with traditional atmospheric pressure concentration (100°C), the vitamin C retention rate is increased from 75% to 92% (Example 1), and the total phenol content is increased by 18%;

[0081] (2) Segmented temperature control sterilization: Through gradient temperature increase (70°C → 88°C), the retention rate of flavor substances (such as pyrazine compounds) is increased by 25%-30% (GC-MS test data);

[0082] (3) Nitrogen protection process: During the concentration process, the oxygen content drops below 0.5%, and the lipid oxidation value (TBARS) decreases by 40%.

[0083] 3. Optimization of texture and stability

[0084] (1) Compound emulsifying and stabilizing system: The synergistic effect of monoglyceride and sucrose ester makes the emulsion particle size ≤ 5 μm (measured by laser particle size analyzer), and the viscosity is stabilized at 4300 - 4800 mPa·s (only 3800 mPa·s in the comparative example);

[0085] (2) Ultrasonic modification of oil: After high-oleic sunflower oil is treated at 40 kHz, the oxidation induction period is extended to 12 hours (6 hours for ordinary oil), and the shelf life reaches 12 months (only 6 months in the comparative example)

[0086] 4. Improvement of processing efficiency

[0087] The vacuum concentration time is shortened to 2 - 2.5 hours (4 hours in the comparative example), the energy consumption is reduced by 35%, and the soluble solid content is accurately controlled (the error of the online refractometer ≤ ±0.5%).

[0088] Table 1 Comparison of key indicators (Example 1 vs. Comparative Example)

[0089]

[0090] Conclusion

[0091] Through process innovation and multi-technology coupling, the present invention is significantly superior to the prior art in terms of color protection, nutrient retention, texture stability and processing efficiency, can meet the requirements of industrial production, and has outstanding market competitiveness and industrialization potential.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A processing method for chestnut paste, characterized in that The following steps are involved: (1) Raw material processing: soaking the shelled and peeled chestnuts in a color protection solution containing 0.1%-0.3% citric acid and 0.05%-0.1% ascorbic acid for 30-60 minutes; (2) Steaming: Steam the soaked chestnuts until fully cooked; (3) beating: mixing the steamed chestnuts with water in a weight ratio of 1:1-1:2 and beating the mixture to obtain chestnut pulp; (4) Preparation: Add white sugar, maltose syrup, vegetable oil, emulsifier and stabilizer to the chestnut pulp and stir evenly; (5) Homogenization: homogenize the mixed material at a pressure of 20-40 MPa for 2-3 times; (6) Concentration: vacuum concentration is performed at a vacuum degree of 0.08-0.09 MPa and a temperature of 60-70° C. until the soluble solid content reaches 60%-65%; (7) Sterilization: sterilize the concentrated chestnut paste at 85-90° C. for 20-30 minutes; (8) Filling: Fill the sterilized chestnut paste into a sterilized container while it is still hot and seal it.

2. The processing method of chestnut jam according to claim 1, wherein The pH value of the color protection solution in step (1) is 2.5-3.5, and the chestnuts need to be precooled before being soaked in the color protection solution, the precooling temperature is 0-4°C, and the precooling time is 10-20 minutes.

3. The processing method of chestnut paste according to claim 1, characterized in that The water added during the pulping process in step (3) is softened water that has been treated with reverse osmosis, and after pulping, it is filtered through a 200-300 mesh sieve to remove coarse fibers and unbroken particles.

4. The processing method of chestnut jam according to claim 1, characterized in that, The emulsifier described in step (4) is a complex of monostearate glyceryl and sucrose fatty acid ester, the mass ratio of the two is 1:1-1:2, and the total added amount is 0.1%-0.3% of the total weight of the chestnut paste; the stabilizer is a complex of xanthan gum and carrageenan, the mass ratio of the two is 2:1-3:1, and the total added amount is 0.05%-0.15% of the total weight of the chestnut paste.

5. The processing method of chestnut paste according to claim 1, characterized in that, In step (5), the homogenization treatment is carried out in two stages: the pressure of the first stage is 10-15 MPa, and the pressure of the second stage is 25-40 MPa. The interval between the two homogenizations is 5-10 minutes.

6. The processing method of chestnut paste according to claim 1, characterized in that During the vacuum concentration process in step (6), nitrogen protection is injected simultaneously, the nitrogen flow rate is 0.5-1.0 L / min, and the concentration endpoint is monitored in real time by an online refractometer.

7. The processing method of chestnut paste according to claim 1, characterized in that In step (7), sterilization adopts a staged temperature control process: in the first stage, the temperature is raised to 70-75°C at a rate of 2-3°C / min and kept warm for 5 minutes; in the second stage, the temperature is raised to 85-90°C at a rate of 1-2°C / min and kept warm for 20-30 minutes.

8. The processing method of chestnut paste according to claim 1, characterized in that, In step (8), the chestnut paste is rapidly cooled before filling, with a cooling rate of 5-8°C / min and a cooling end point temperature of 45-50°C, and then filled in a sterile environment.

9. The processing method of chestnut paste according to claim 1, characterized in that, 0.01%-0.03% of sodium phytate and 0.005%-0.01% of sodium D-isoascorbate are further added to the color protection liquid to synergistically inhibit enzymatic browning and non-enzymatic browning.

10. The processing method of chestnut jam according to claim 4, characterized in that, The vegetable oil is a mixed oil of high oleic sunflower oil and rice bran oil, the volume ratio of the two is 3:1-5:1, and the mixed oil needs to be pre-ultrasonicated at 40-50° C. for 10-15 minutes, and the ultrasonic frequency is 25-40 kHz.

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