Application of ultrasonic synergistic supercritical CO2 puffing technology to preparation of fruit and vegetable crisp chips

Abstract

The invention discloses application of a puffing process based on ultrasonic wave and supercritical CO2 in preparation of fruit and vegetable crisp chips. The method mainly comprises the following steps: cleaning, peeling and slicing fruits and vegetables, and performing ultrasonic-assisted permeation for 10-30 minutes; putting the fully infiltrated fruit and vegetable slices into a supercritical CO2 extraction kettle in which ultrasonic wave synergy is started, and puffing; and after puffing, rapidly cooling to room temperature, and sealing and packaging. The oil content of the fruit and vegetable crisp chips is reduced to 1% or below, the retention rate of the vitamin C content reaches up to 80% or above, and meanwhile the taste of the fruit and vegetable crisp chips is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of food processing, and particularly relates to application of an ultrasonic wave and supercritical CO2 puffing process in preparation of fruit and vegetable chips. BACKGROUND

[0002] As a kind of leisure food rich in nutrition and crisp in taste, fruit and vegetable chips are favored by consumers. Traditional fruit and vegetable chip preparation methods such as frying and hot air drying have problems such as large loss of nutritional ingredients, high oil content, high energy consumption and unstable product quality. For example, high temperature in the frying process can cause a large loss of nutritional ingredients such as vitamins and minerals in fruits and vegetables, and the product has a high oil content, which is not conducive to health if consumed for a long time; although hot air drying can reduce the oil content, it can easily make the fruit and vegetable chips dry and hard in taste, and the drying time is long and the energy consumption is high. In order to solve these problems, some new technologies have appeared in recent years, such as vacuum freeze-drying and microwave puffing. Vacuum freeze-drying can better preserve the nutritional ingredients of fruits and vegetables, but the equipment investment is large and the cost is high; although microwave puffing can make the product have a certain crisp taste, when used alone, the puffing effect is not ideal, and the porous structure of the product is not uniform enough, which affects the taste and rehydration. SUMMARY

[0003] This section aims to summarize some aspects of the embodiments of the application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the application.

[0004] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0005] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art and provide an application of an ultrasonic wave and supercritical CO2 puffing process in preparation of fruit and vegetable chips.

[0006] To solve the above technical problems, the present application provides the following technical scheme: an application of an ultrasonic wave and supercritical CO2 puffing process in preparation of fruit and vegetable chips, characterized in that: after pretreatment of the fruits and vegetables, ultrasonic wave assisted infiltration is performed, and after sufficient infiltration, ultrasonic wave assisted supercritical CO2 puffing is performed, and after puffing, rapid cooling to room temperature is performed for sealing and packaging.

[0007] As a preferred scheme of the preparation method, the fruits and vegetables include one or more of apples, kiwis, bananas, carrots and shiitake mushrooms.

[0008] As a preferred scheme of the preparation method, in the pretreatment, the fruits and vegetables are washed with clean water to remove the surface dirt and impurities; for the fruits and vegetables that need to be peeled, the peel is removed by mechanical peeling or manual peeling; for the fruits and vegetables with core or seed, the core or seed is removed; and the fruits and vegetables are cut into uniform-thickness slices, and the thickness is controlled to be 2-5 mm.

[0009] As a preferred scheme of the preparation method, in the ultrasonic-assisted penetration, the ultrasonic frequency is 20-50 kHz, the ultrasonic power is 300-600 W, and the treatment time is 10-30 min.

[0010] As a preferred scheme of the preparation method, in the ultrasonic-assisted penetration, the penetration liquid comprises 0.2%-0.5% of sodium erythorbate by mass fraction, 0.1%-0.3% of citric acid by mass fraction, 0.1%-0.2% of calcium chloride by mass fraction, and the balance is water. As a preferred scheme of the preparation method, in the ultrasonic-assisted penetration, the supercritical CO2 pressure is 10-25 Mpa, the temperature is 35-40℃, the ultrasonic frequency is 20-40 kHz, the ultrasonic power is 200-500 W, and the ultrasonic time is 10-30 min, and then the pressure is rapidly reduced to normal pressure. Still another object of the present application is to provide a fruit and vegetable crisp slice prepared in the application.

[0011] The present application has the following beneficial effects: (1) The present application adopts the ultrasonic-assisted supercritical CO2 puffing process, and the whole process is carried out under relatively low temperature, so that the loss of the nutritional components such as vitamins, minerals, dietary fibers and bioactive components in the fruits and vegetables is effectively reduced, and the nutritional value of the fruits and vegetables is maximally retained; through the ultrasonic-assisted penetration treatment, the inside of the fruit and vegetable slice is filled with the swelling medium, and in the puffing process, a uniform and rich porous structure can be formed, and the product has a more crisp taste, and has better taste and chewiness compared with the fruit and vegetable crisp slice prepared by the traditional process. (2) Through the synergistic effect of the ultrasonic, the puffing time is shortened, the production efficiency is improved, and the energy consumption is reduced. At the same time, the high-energy-consumption links such as oil frying and hot air drying in the traditional process are reduced, and the production cost is further reduced; the puffing effect of the fruit and vegetable slice is more uniform, and the product quality stability is significantly improved. In terms of appearance, taste and rehydration, the fruit and vegetable crisp slices produced in different batches can maintain consistent quality, which is beneficial to the large-scale industrial production and market promotion of the product. DETAILED DESCRIPTION

[0012] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the embodiments of the present application.

[0013] In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the concept of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0014] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. "In one embodiment" appearing in different places in the specification does not mean the same embodiment, nor is it an embodiment that is separate or alternative to other embodiments.

[0015] The raw materials used in the embodiments of the present application are all commercially available unless otherwise specified.

[0016] The fruit and vegetable chips prepared in the embodiments and comparative examples of the present application are tested for quality according to the following method: Determination of oil content: The oil content is determined by the Soxhlet extraction method according to GB / T 5009.6-2016 "National Food Safety Standard Determination of Fat in Food".

[0017] Determination of hardness and brittleness: The hardness and brittleness of the fruit and vegetable chips are determined by a texture analyzer. The specific test parameters are as follows: the probe is selected as HDP / 3PB, the pressure mode, the trigger force is 5N, the test distance is 2mm, the pre-test speed is 2mm / s, the test speed is 1mm / s, and the post-test speed is 2mm / s. The maximum force value is called hardness, and the distance at the breaking point is the bending resistance of the sample, which can represent the brittleness of the sample.

[0018] Determination of vitamin C content: The content of vitamin C in the fruit and vegetable chips is determined by HPLC method. 5g of fruit and vegetable chip is crushed through an 80 mesh sieve, 20mL of 0.1% metaphosphoric acid is added, and homogenate is obtained by grinding under ice bath conditions. Transfer to a 50mL volumetric flask and dilute with 0.1% metaphosphoric acid, extract for 15min, then centrifuge at 4℃, 8000rpm / min for 10min and pass through a membrane (0.22μm organic phase filter), to obtain the test solution. DHAA is used as the standard, and the chromatographic conditions are as follows: C18 reversed-phase chromatographic column (Agilent ZORBAX SB-C18, 4.6x250mm, 5μm); mobile phase is 0.1% phosphoric acid aqueous solution, flow rate is 1.0mL / min, column temperature is 30℃, sample size is 20μL, and detection wavelength is 245nm.

[0019] Sensory evaluation method: an evaluation team consisting of 10 trained sensory personnel scored the appearance, color, and taste of the fruit and vegetable chips, with a total score of 30 points. The specific scoring criteria are shown in the table below.

[0020] Table 1 Sensory evaluation criteria for fruit and vegetable chips

[0021] Example 1 (1) Select fresh and mature apples, wash them with clean water, remove the skin and core, and cut them into 3mm thick slices.

[0022] (2) Prepare a permeation solution with a sodium erythorbate mass fraction of 0.4%, a citric acid mass fraction of 0.2%, and a calcium chloride mass fraction of 0.2%, with the remainder being water. Place the apple slices in the permeation solution and perform ultrasonic treatment for 30 minutes under the conditions of an ultrasonic power of 300W and a frequency of 30kHz. (3) After permeation, place the apple slices in the extraction kettle of the supercritical CO2 equipment and introduce supercritical CO2 into the extraction kettle. Control the pressure at 20Mpa and the temperature at 40℃, maintain the pressure and temperature of the supercritical CO2, turn on the ultrasonic generator, adjust the ultrasonic power to 400W, and set the frequency to 40kHz. After 10 minutes of continuous ultrasonic treatment, rapidly reduce the pressure in the extraction kettle to atmospheric pressure to cause the supercritical CO2 inside the apple slices to instantaneously expand and vaporize, achieving the effect of puffing. After puffing is complete, rapidly cool to room temperature.

[0023] Comparative Example 1 The difference from Example 1 is that in step (3), the apple slices are placed in the extraction kettle of the supercritical CO2 equipment and supercritical CO2 is introduced into the extraction kettle. The pressure is controlled at 20Mpa and the temperature is controlled at 40℃, and no ultrasonic treatment is performed. After maintaining the pressure and temperature of the supercritical CO2 for 20 minutes, the pressure in the extraction kettle is rapidly reduced to atmospheric pressure to cause the supercritical CO2 inside the apple slices to instantaneously expand and vaporize, achieving the effect of puffing. After puffing is complete, rapidly cool to room temperature.

[0024] Comparative Example 2 The difference from Example 1 is that in step (3), the pressure of the supercritical CO2 is set to 10Mpa and the temperature is set to 40℃, and the rest of the process is the same as in Example 1. The apple slices are puffed under these conditions.

[0025] Comparative Example 3 The difference from Example 1 is that in step (3), the pressure of the supercritical CO2 is set to 30Mpa and the temperature is set to 40℃, and the rest of the process is the same as in Example 1. The apple slices are puffed under these conditions.

[0026] Comparative Example 4 The difference between Example 1 is that the pressure of supercritical CO2 in step (3) is set to 20 Mpa, and the temperature is set to 32℃, and the rest of the process is the same as Example 1, and the apple slices are expanded under this condition.

[0027] Comparative Example 5 The difference between Example 1 is that the pressure of supercritical CO2 in step (3) is set to 20 Mpa, and the temperature is set to 45℃, and the rest of the process is the same as Example 1, and the apple slices are expanded under this condition.

[0028] Comparative Example 6 Apple chips are prepared by traditional hot air drying method. The apples are washed, peeled and cored, and soaked in the penetration liquid for 30 min, then drained and directly placed in the hot air drying equipment, dried at 70℃ for 6 h, so that the moisture content is reduced to 4%.

[0029] The hardness and brittleness of the apple chips of each example and comparative example are measured. The results are shown in the following table: Table 2 Hardness and brittleness of apple chips dried and expanded by different methods

[0030] From the data in Table 2, it can be seen that the peak force and breaking distance of the apple chips prepared in Comparative Example 2 and Comparative Example 4 are much higher than those of Example 1. This shows that reducing the pressure and temperature of supercritical CO2 reduces the penetration rate of CO2, making it difficult to penetrate into the inside of the apple chips, resulting in insufficient expansion and a dense product structure, thus increasing the hardness and requiring greater deformation when breaking. The peak force and breaking distance of the apple chips of Example 1 are significantly lower than those of Comparative Example 1, which shows that the apple chips expanded by ultrasonic and supercritical CO2 have lower hardness and higher brittleness than those expanded by supercritical CO2 alone, and the expansion is more uniform. The apple chips prepared by the present application have a significantly better taste than those prepared by the hot air drying method.

[0031] The content of vitamin C in the apple chips of each example and comparative example is measured, and the retention rate is calculated. The retention rate decreases significantly outside the process range of the present application, among which the temperature of Comparative Example 5 exceeds the suitable tolerance temperature range of vitamin C, accelerating the oxidation reaction rate, resulting in a significant decrease in the retention rate of vitamin C, but still higher than that of the apple chips prepared by hot air drying.

[0032] And, the comparative example 1 does not use the ultrasonic assisted supercritical CO2 penetration, the appearance, color, and taste are all decreased to different degrees. The comparative example 2 and the comparative example 4 are low in pressure and temperature, so that the CO2 penetration is insufficient, the edges of the apple chips are shrunk, the puffing is insufficient, the color is uneven, and the taste has a slight fiber feeling, and the score is significantly reduced. The comparative example 3 is high in pressure, so that the edges of the apple chips have small cracks, and the taste is rough. The comparative example 5 is high in temperature, so that there is slight browning, and the crispness is good. The apple chips prepared by the present application are all better than the comparative examples.

[0033] Example 2 (1) Fresh carrots were selected, washed, peeled, and cut into slices with a thickness of 4 mm. (2) The dipping solution was prepared, in which the mass fraction of sodium erythorbate was 0.5%, the mass fraction of citric acid was 0.25%, the mass fraction of calcium chloride was 0.18%, and the rest was water. The carrot slices were placed in the dipping solution, and ultrasonic treatment was performed under the condition that the ultrasonic power was 400 W and the frequency was 25 kHz for 20 min.

[0034] (3) After the penetration was completed, the carrot slices were placed in the extraction kettle of the supercritical CO2 equipment, and supercritical CO2 was introduced into the extraction kettle. The pressure was controlled to be 25 MPa, and the temperature was controlled to be 35℃. The pressure and the temperature of the supercritical CO2 were kept, the ultrasonic generator was started, the ultrasonic power was adjusted to be 300 W, and the frequency was 20 kHz. After 15 min of continuous ultrasonic treatment, the pressure of the extraction kettle was rapidly reduced to the atmospheric pressure to make the supercritical CO2 in the carrot slices instantaneously expand and vaporize, so as to realize the puffing effect. After the puffing was completed, the carrot slices were rapidly cooled to room temperature.

[0035] Comparative example 7 The carrot chips were prepared by using the vacuum low-temperature frying method. The carrots were washed, peeled, and cut into slices, and were penetrated in the penetration solution for 25 min. After being drained, the carrot slices were placed in the vacuum low-temperature frying equipment, and were fried at 100℃ under the vacuum degree of-0.08 MPa for 8 min, and then were deoiled.

[0036] The oil content of the fruit and vegetable chips in each example and comparative example was determined. The results are shown in the following table: Table 3 Oil content of fruit and vegetable chips dried by different methods

[0037] It can be known from the data in Table 3 that the oil content of the fruit and vegetable chips prepared in the example 2 is significantly lower than that of the comparative examples 6 and 7, which indicates that the method of the present application can effectively avoid the introduction of oil, and the oil content of the product can be reduced to below 1%.

[0038] The hardness and crispness of the fruit and vegetable chips in each example and comparative example were determined. The results are shown in the following table: Table 4 Hardness and crispness of puffed fruit and vegetable chips dried by different methods

[0039] From the data in Table 4, it can be seen that the peak force and breaking distance of the carrot chips of Example 2 are significantly lower than those of Comparative Example 7. The fruit and vegetable chips prepared by the present application have a significantly better taste than those prepared by the vacuum low-temperature frying method, making them more crisp.

[0040] Nutrient retention rate test: The content of vitamin C in the fruit and vegetable chips of each example and comparative example was determined, and the retention rate was calculated. The results are shown in the following table: Table 5 Vitamin C retention rate of puffed fruit and vegetable chips dried by different methods

[0041] From the data in Table 5, it can be seen that the vitamin C retention rate of Example 2 is significantly higher than that of Comparative Example 7, indicating that the preparation method of the present application can better retain the nutrients in the fruit and vegetable.

[0042] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and they should be covered in the scope of the present application.​

Claims

1. Application of ultrasonic wave combined with supercritical CO2 puffing process in the preparation of fruit and vegetable chips, characterized by: The method comprises the following steps: pre-treating fruits and vegetables, then performing ultrasonic-assisted penetration, and then performing ultrasonic-assisted supercritical CO2 puffing after sufficient penetration, and then rapidly cooling to room temperature and sealing and packaging.

2. Use according to claim 1, characterized in that: The fruits and vegetables include one or more of apples, kiwifruits, bananas, carrots, shiitake mushrooms and okra.

3. Use according to claim 1, characterized in that: The pre-treatment comprises the following steps: washing the fruits and vegetables with clean water to remove surface dirt and impurities; removing the skin of the fruits and vegetables by mechanical or manual peeling; removing the core or seeds of the fruits and vegetables; and cutting the fruits and vegetables into uniform-thickness slices with a thickness of 2-5 mm.

4. The use according to claim 1, characterized in that: In the ultrasonic-assisted penetration, the ultrasonic frequency is 20-50 kHz, the ultrasonic power is 300-600 W, and the treatment time is 10-30 min.

5. The use according to claim 4, characterized in that: In the ultrasonic-assisted penetration, the ultrasonic frequency is 25-30 kHz, the ultrasonic power is 300-400 W, and the treatment time is 20-30 min.

6. Use according to claim 5, wherein: In the ultrasonic-assisted penetration, the penetration liquid comprises 0.2%-0.5% by mass fraction of sodium erythorbate, 0.1%-0.3% by mass fraction of citric acid, 0.1%-0.2% by mass fraction of calcium chloride, and the rest is water.

7. Use according to claim 6, wherein: In the ultrasonic-assisted penetration, the penetration liquid comprises 0.4%-0.5% by mass fraction of sodium erythorbate, 0.2%-0.25% by mass fraction of citric acid, 0.18%-0.2% by mass fraction of calcium chloride, and the rest is water.

8. The use according to claim 1, characterized in that: The supercritical CO2 has a pressure of 10-25 MPa and a temperature of 35-40℃, the ultrasonic frequency is 20-40 kHz, the ultrasonic power is 200-500 W, and the ultrasonic time is 10-30 min, and then the pressure is rapidly reduced to normal pressure.

9. Use according to claim 8, wherein: The supercritical CO2 has a pressure of 20-25 MPa and a temperature of 35-40℃, the ultrasonic frequency is 25-40 kHz, the ultrasonic power is 300-400 W, and the ultrasonic time is 10-15 min, and then the pressure is rapidly reduced to normal pressure.

10. The fruit and vegetable chips prepared in the application of any one of claims 1-9.

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