Composite film coating liquid based on water-soluble araboxylan as well as preparation method and application of composite film coating liquid

Abstract

The invention provides a composite film coating liquid based on water-soluble araboxylan as well as a preparation method and application thereof, the preparation method of the composite film coating liquid comprises the following steps: preparing water-soluble araboxylan from wheat gluten processing waste liquid, and then preparing the composite film coating liquid from the water-soluble araboxylan, the water-soluble araboxylan from the vital gluten processing waste liquid is used for preparing the composite film coating liquid, the composite film coating liquid is applied as a cherry film coating preservative, and the shelf life of cherries can be remarkably prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of separation, extraction and purification, and in particular to a composite coating liquid based on water-soluble arabinoxylan, and a preparation method and application thereof. Background Art

[0002] Gluten, also known as active gluten flour and wheat gluten protein, is a natural protein extracted from wheat (flour). It is light yellow and has a protein content of up to 75% to 85%. It is a nutritious plant protein resource with viscosity, elasticity, extensibility, film-forming and liposorption properties. Gluten is an excellent dough improver and is widely used in the production of bread, noodles and instant noodles. It can also be used as a water retaining agent in meat products. It is also the basic raw material for high-end aquatic feed. At present, gluten production enterprises in my country often use the three-phase horizontal screw centrifugation method to produce gluten. After the flour is mixed and homogenized on the water surface, it is separated into three parts: gluten, starch and production wastewater by three-phase horizontal screw centrifugation. The amount of water and steam consumed per unit product is large. If the wastewater is discharged directly, it will cause secondary pollution while wasting resources, causing serious damage to the environment. The main components of gluten wastewater are starch, arabinoxylan (AX), protein, lipids and ash. The wastewater from the gluten factory does not contain toxic substances such as heavy metals and chemical reagents, and is rich in nutrients, making it an ideal material for extracting AX and ensuring product safety.

[0003] Water-soluble arabinoxylan is the main non-starch polysaccharide in cereals, consisting of a linear chain of β-(1→4)-linked xylose units, with α-l-arabinose substituents linked by O-2, O-3, or both. Water-soluble arabinoxylan is a promising film-forming material due to its biocompatibility, film-forming properties, and solubility. Compared with traditional plastic packaging and chemical treatment methods, polysaccharide coatings have higher safety and better prospects for fruit preservation. Most fruits remain metabolically active during postharvest storage, resulting in water loss, reduced sweetness and hardness, and aging and decay in appearance. Polysaccharide coatings do not usually completely seal fruits and vegetables, but cover their surfaces, providing positive effects. Polysaccharide-based coatings can regulate the internal tissue climate of fruits, slow down water loss, block the movement of O2, CO2, and volatiles, slow metabolism, delay fruit aging, and maintain the quality of fruits and vegetables.

[0004] Cherries have thin skins, tender flesh and are juicy. Cherries are harvested during the hot and rainy season. After harvest, the cherries are still in a state of vigorous physiological metabolism, and are prone to dry and falling stalks, softening and rotting flesh due to water loss, and mold and browning of the skin surface, which causes serious economic losses to producers and is not conducive to the research and development of the cherry industry. Therefore, in-depth research on cherry preservation methods has great economic significance and market prospects.

[0005] Therefore, in response to the above technical problems, the composite coating liquid prepared by using water-soluble arabinoxylan extracted from gluten processing waste liquid can be used as a new and green preservation technology to improve the storage quality of fruits and vegetables. The excellent mechanical properties, water barrier properties, uniformity and other properties of the composite coating can extend the shelf life of cherries at room temperature and improve the storage quality of cherries. Summary of the invention

[0006] In order to address the deficiencies in the prior art, the present invention provides a composite coating liquid based on water-soluble arabinoxylan, a preparation method and application thereof. The composite coating liquid is prepared using water-soluble arabinoxylan derived from gluten processing waste liquid. The composite coating liquid is used as a cherry coating preservative, which can significantly extend the shelf life of cherries.

[0007] In order to achieve the above object, the specific scheme adopted by the present invention is: On the one hand, the present invention discloses a method for preparing a composite coating liquid based on water-soluble arabinoxylan, which mainly comprises the following steps: S1. Preparation of water-soluble arabinoxylan S11, removing insoluble substances in the gluten processing waste liquid by centrifugation, and collecting the supernatant; S12, concentrating the supernatant in step S11 by rotary evaporation, precipitating with alcohol, and centrifuging to collect the precipitate; S13, dissolving the precipitate collected in step S12 in water, dialyzing to remove small molecules, and collecting the dialysate; S14, concentrating the dialysate collected in step S13 and freeze-drying it to obtain a crude extract; S15, subjecting the crude extract in step S14 to static adsorption purification to obtain purified water-soluble arabinoxylan; S2. Preparation of composite coating liquid S21, weighing water-soluble arabinoxylan and dissolving it in deionized water to prepare a solution with a concentration of 0.5-1.5%; S22, adding 2-4% glycerol to the solution prepared in step S21, and stirring the solution by magnetic stirring for 30-40 minutes to fully mix; then standing the solution for 0.5-1.5 hours to remove bubbles in the solution, thereby obtaining a composite coating solution.

[0008] Furthermore, in step S11, the gluten processing waste liquid is centrifuged at a rate of 4000-5000 r / min for 15 min.

[0009] Furthermore, in step S12, when alcohol precipitation is performed, ethanol is added until the final ethanol concentration of the system is 70-80%; after alcohol precipitation, centrifugation is performed at a rate of 4000-5000 r / min for 15 minutes.

[0010] Furthermore, in step S13, the dialysis time is 24 hours, and the dialysis fluid is changed every 4-6 hours.

[0011] Furthermore, in step S14, the adsorption material used for static adsorption purification is any one of macroporous resins AB-8, DM130, JK008 or cellulose DE-52, and the adsorption material-liquid ratio is 1:15-1:25.

[0012] On the other hand, the present invention discloses a composite coating liquid based on water-soluble arabinoxylan, which is actually prepared by the above method.

[0013] In another aspect, the present invention discloses an application of a composite coating liquid based on water-soluble arabinoxylan in the preservation of cherries.

[0014] Further, as in the above application, the cherries are immersed in the composite coating liquid for 2 to 5 minutes, taken out and naturally dried, and stored at 20 to 25°C.

[0015] Beneficial effects:

[0016] (1) The present invention uses water-soluble arabinoxylan extracted from gluten processing waste liquid as the raw material of the composite coating liquid. The water-soluble arabinoxylan is a water-soluble polysaccharide, a branched polysaccharide, mainly containing a xylose skeleton and arabinose side chains, as well as a small amount of rhamnose and uronic acid, and has good biocompatibility, film-forming property and solubility, and can better extend the shelf life of cherries; and the water-soluble arabinoxylan is widely available, green and pollution-free, and is significantly better than chitosan coating in terms of safety and hygiene, and is more conducive to consumers purchasing fruits and vegetables, and is suitable for promotion and application.

[0017] (2) The water-soluble arabinoxylan used in the present invention is extracted from gluten production wastewater, which can lay a certain theoretical foundation for the use of arabinoxylan in gluten production wastewater in the preparation of edible film materials or food preservation, and provide a new idea for the comprehensive development and utilization of gluten production wastewater.

[0018] (3) The present invention soaks fresh cherries in a coating solution containing water-soluble arabinoxylan, which can extend the shelf life of cherries at room temperature while maintaining the original quality of the cherries. In addition, since arabinoxylan contains multiple bioactive ingredients, it has good effects on antibacterial, anti-oxidation, and lowering blood sugar, and thus has the effect of nutritional enhancement. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an appearance diagram of the water-soluble arabinoxylan in the present invention.

[0020] Figure 2 This is the monosaccharide composition diagram of the water-soluble arabinoxylan extracted in Examples 1-4.

[0021] Figure 3 This is a graph showing the molecular weight determination of the water-soluble arabinoxylan extracted in Examples 1-4.

[0022] Figure 4 This graph shows the effect of the composite coating solution on the appearance quality of cherries stored at room temperature. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] The present invention provides a composite coating liquid based on water-soluble arabinoxylan, a preparation method and application thereof, wherein the preparation method of the composite coating liquid mainly comprises the following steps: S1. Preparation of water-soluble arabinoxylan S11, centrifuging (4000-5000r / min, 15min) to remove insoluble substances in the gluten processing waste liquid, and collecting the supernatant; S12, concentrating the supernatant in step S11 by rotary evaporation, precipitating with alcohol (adding ethanol until the final ethanol concentration of the system is 70-80%), centrifuging (4000-5000 r / min, 15 min), and collecting the precipitate; S13, dissolving the precipitate collected in step S12 in water, dialyzing (dialysis time is 24 hours, and the dialysate is changed every 4-6 hours) to remove small molecules, and collecting the dialysate; S14, concentrating the dialysate collected in step S13 and freeze-drying it to obtain a crude extract; S15, subjecting the crude extract in step S14 to static adsorption purification (the adsorption material used for static adsorption purification is any one of macroporous resins AB-8, DM130, JK008 or cellulose DE-52, and the adsorption material-liquid ratio is 1:15-1:25), to obtain purified water-soluble arabinoxylan; S2. Preparation of composite coating liquid S21, weighing water-soluble arabinoxylan and dissolving it in deionized water to prepare a solution with a concentration of 0.5-1.5%; S22, adding 2-4% glycerol to the solution prepared in step S21, and stirring by magnetic force for 30-40 minutes to fully mix; then standing for 0.5-1.5 hours to remove bubbles in the solution, to obtain a composite coating solution.

[0025] When preserving cherries, immerse the cherries in the composite coating liquid for 2 to 5 minutes, take them out and dry them naturally, and store them at 20 to 25°C.

[0026] The technical solution of the present invention is described in detail below in conjunction with specific embodiments. It should be noted that the embodiments of the present invention are divided into two categories, the first category is embodiments related to water-soluble arabinoxylan, and the second category is embodiments related to a method for preserving cherries.

[0027] Example 1-1 A method for preparing water-soluble arabinoxylan mainly comprises the following steps: (1) removing insoluble substances from the gluten processing waste liquid by centrifugation at 4000 r / min for 15 min, and collecting the supernatant; (2) The supernatant was concentrated by rotary evaporation, precipitated by alcohol (ethanol was added until the final ethanol concentration of the system was 80%), centrifuged, and the precipitate was collected; (3) After the precipitate is dissolved in water, it is dialyzed for 24 hours, with the dialysate replaced every 6 hours to remove small molecules; (4) concentrating the dialysate and then freeze-drying it to obtain crude water-soluble arabinoxylan; (5) The crude extract was purified by static adsorption using macroporous resin AB-8 at a solid-liquid ratio of 1:25 to obtain purified water-soluble arabinoxylan.

[0028] Example 1-2 A method for preparing water-soluble arabinoxylan mainly comprises the following steps: (1) removing insoluble substances from the gluten processing waste liquid by centrifugation at 4000 r / min for 15 min, and collecting the supernatant; (2) The supernatant was concentrated by rotary evaporation, precipitated by alcohol (ethanol was added until the final ethanol concentration of the system was 80%), centrifuged, and the precipitate was collected; (3) After the precipitate is dissolved in water, it is dialyzed for 24 hours, with the dialysate replaced every 6 hours to remove small molecules; (4) concentrating the dialysate and then freeze-drying it to obtain crude water-soluble arabinoxylan; (5) The crude extract was purified by static adsorption using macroporous resin DM130 at a solid-liquid ratio of 1:25 to obtain purified water-soluble arabinoxylan.

[0029] Examples 1-3

[0030] A method for preparing water-soluble arabinoxylan mainly comprises the following steps: (1) removing insoluble substances from the gluten processing waste liquid by centrifugation at 4000 r / min for 15 min, and collecting the supernatant; (2) The supernatant was concentrated by rotary evaporation, precipitated by alcohol (ethanol was added until the final ethanol concentration of the system was 80%), centrifuged, and the precipitate was collected; (3) After the precipitate is dissolved in water, it is dialyzed for 24 hours, with the dialysate replaced every 6 hours to remove small molecules; (4) concentrating the dialysate and then freeze-drying it to obtain crude water-soluble arabinoxylan; (5) The crude extract was purified by static adsorption using macroporous resin JK008 at a solid-liquid ratio of 1:25 to obtain purified water-soluble arabinoxylan.

[0031] Examples 1-4

[0032] A method for preparing water-soluble arabinoxylan mainly comprises the following steps: (1) removing insoluble substances from the gluten processing waste liquid by centrifugation at 4000 r / min for 15 min, and collecting the supernatant; (2) The supernatant was concentrated by rotary evaporation, precipitated by alcohol (ethanol was added until the final ethanol concentration of the system was 80%), centrifuged, and the precipitate was collected; (3) After the precipitate is dissolved in water, it is dialyzed for 24 hours, with the dialysate replaced every 6 hours to remove small molecules; (4) concentrating the dialysate and then freeze-drying it to obtain crude water-soluble arabinoxylan; (5) The crude extract was purified by static adsorption using cellulose DE52 at a solid-liquid ratio of 1:25 to obtain purified water-soluble arabinoxylan.

[0033] Examples 1-5

[0034] A method for preparing water-soluble arabinoxylan mainly comprises the following steps: (1) removing insoluble substances from the gluten processing waste liquid by centrifugation at 4000 r / min for 15 min, and collecting the supernatant; (2) The supernatant was concentrated by rotary evaporation, precipitated by alcohol (ethanol was added until the final ethanol concentration of the system was 80%), centrifuged, and the precipitate was collected; (3) After the precipitate is dissolved in water, it is dialyzed for 24 hours, with the dialysate replaced every 6 hours to remove small molecules; (4) concentrating the dialysate and then freeze-drying it to obtain crude water-soluble arabinoxylan; (5) The crude extract was purified by static adsorption using cellulose DE52 at a solid-liquid ratio of 1:15 to obtain purified water-soluble arabinoxylan.

[0035] Examples 1-6

[0036] A method for preparing water-soluble arabinoxylan mainly comprises the following steps: (1) removing insoluble substances from the gluten processing waste liquid by centrifugation at 4000 r / min for 15 min, and collecting the supernatant; (2) The supernatant was concentrated by rotary evaporation, precipitated by alcohol (ethanol was added until the final ethanol concentration of the system was 80%), centrifuged, and the precipitate was collected; (3) After the precipitate is dissolved in water, it is dialyzed for 24 hours, with the dialysate replaced every 6 hours to remove small molecules; (4) concentrating the dialysate and then freeze-drying it to obtain crude water-soluble arabinoxylan; (5) The crude extract was purified by static adsorption using cellulose DE52 at a solid-liquid ratio of 1:20 to obtain purified water-soluble arabinoxylan.

[0037] Examples 1-7

[0038] A method for preparing water-soluble arabinoxylan mainly comprises the following steps: (1) removing insoluble substances from the gluten processing waste liquid by centrifugation at 4000 r / min for 15 min, and collecting the supernatant; (2) The supernatant was concentrated by rotary evaporation, precipitated by alcohol (ethanol was added until the final ethanol concentration of the system was 80%), centrifuged, and the precipitate was collected; (3) After the precipitate is dissolved in water, it is dialyzed for 24 hours, with the dialysate replaced every 6 hours to remove small molecules; (4) concentrating the dialysate and then freeze-drying it to obtain crude water-soluble arabinoxylan; (5) The crude extract was purified by static adsorption using cellulose DE52 at a solid-liquid ratio of 1:30 to obtain purified water-soluble arabinoxylan.

[0039] Comparative Example 1-1

[0040] The difference between this comparative example and Examples 1-4 is that step (5) is not included.

[0041] Comparative Example 1-2

[0042] The difference between this comparative example and Examples 1-4 is that in step (5), the material-liquid ratio is 1:10.

[0043] The relevant indicators of Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-2 were determined as follows: the total sugar content was determined by the phenol-sulfuric acid method, the protein content was determined by the Coomassie Brilliant Blue G250 method, the total phenol content was determined by the Folin phenol method, and the water-soluble arabinoxylan content was determined by the phloroglucinol-glacial acetic acid method. The determination results are shown in Tables 1 to 2.

[0044] Table 1 Composition of polysaccharide extracts in Examples 1-1 to 1-4 and Comparative Example 1-1 Group protein / % Total sugar / % Total phenol / % Example 1-1 16.25±3.01 81.46±7.34 0.17±0.16 Example 1-2 10.64±1.91 59.28±5.50 0.00±0.00 Examples 1-3 15.59±3.00 72.93±11.03 1.84±0.39 Examples 1-4 6.74±1.39 92.99±3.26 0.13±0.23 Comparative Example 1-1 12.91±2.30 57.11±12.55 0.14±0.23

[0045] Note: The values ​​in the table are expressed as mean ± standard deviation.

[0046] As can be seen from Table 1, the protein content in Examples 1-4 is 6.74%, the total sugar content is 92.99%, and the total phenol content is 0.13%. The total sugar content is the highest, the total phenol content is low, the protein content is the lowest, and the purification effect is the best. Therefore, the extraction conditions in Examples 1-4 are selected as the extraction conditions for water-soluble arabinoxylan.

[0047] Table 2 Purity and yield of water-soluble arabinoxylan in Examples 1-4 to 1-7 and Comparative Example 1-2 Group purity / % Yield / % Examples 1-4 83.78±0.85 31.70±0.41 Examples 1-5 79.77±0.90 31.09±1.11 Examples 1-6 81.57±1.44 28.79±0.51 Examples 1-7 82.27±1.62 28.37±0.46 Comparative Example 1-2 78.19±3.52 22.16±0.31

[0048] Note: The values ​​in the table are expressed as mean ± standard deviation.

[0049] As shown in Table 2, in Examples 1-4, the purity of arabinoxylan after adsorption was the highest, 83.78%, and the yield after adsorption was 31.70%. Therefore, in order to efficiently separate polysaccharides, the conditions in Examples 1-4 are the most appropriate.

[0050] Therefore, the present invention provides a method for extracting water-soluble arabinoxylan from gluten processing waste liquid, and the optimal method mainly includes the following steps: centrifugation at 4000r / min, 15min to remove insoluble substances in gluten processing waste liquid, and collect the supernatant; rotary evaporation and concentration of the supernatant, alcohol precipitation (adding ethanol to a final ethanol concentration of 80% in the system), centrifugation, and collection of the precipitate; after the precipitate is dissolved in water, dialyzed for 24h, and the dialysate is changed every 6h to remove small molecular substances; the dialysate is concentrated and freeze-dried to obtain a crude extract; and the crude extract is subjected to static adsorption purification by cellulose DE52 to obtain purified water-soluble arabinoxylan. The water-soluble arabinoxylan obtained by this extraction method has a high yield and purity, such as Figure 2 and Figure 3 It can be seen that the monosaccharide composition is arabinose (38.37%), xylose (43.71%), galactose (13.29%), glucose (4.33%) and glucuronic acid (0.30%), and the molecular weight is 4.57×10 4 Da.

[0051] Figure 1 The appearance of water-soluble arabinoxylan is given by Figure 1 It can be seen that arabinoxylan with good water solubility is indeed obtained through the extraction method of the present invention.

[0052] Example 2-1

[0053] This embodiment provides a method for preserving cherries by coating, comprising the following steps: 1) preparing water-soluble arabinoxylan by the same steps as in Example 1-4; 2) taking 1 g of water-soluble arabinoxylan and adding 99 g of deionized water to completely dissolve the water-soluble arabinoxylan to form a transparent solution, thereby obtaining a solution with a water-soluble arabinoxylan mass concentration of 1%; then adding glycerol at a volume of 4% by volume of the solution, and mixing by magnetic stirring for 30 min to obtain a composite coating solution; 3) Soak fresh cherries in the prepared composite coating solution for 3 minutes, remove them from the solution, drain excess water, dry them naturally, and store them at 20°C.

[0054] Example 2-2

[0055] This embodiment provides a method for preserving cherries by coating, comprising the following steps: 1) preparing water-soluble arabinoxylan by the same steps as in Example 1-4; 2) taking 0.5 g of water-soluble arabinoxylan and adding 99.5 g of deionized water to completely dissolve the water-soluble arabinoxylan to form a transparent solution, and obtaining a solution with a water-soluble arabinoxylan mass concentration of 0.5%; then adding 2% of the solution volume of glycerol, and stirring magnetically for 30 minutes to fully mix, to obtain a composite coating solution; 3) Soak fresh cherries in the prepared composite coating solution for 2 minutes, remove them from the solution, drain excess water, dry them naturally, and store them at 20°C.

[0056] Example 2-3

[0057] This embodiment provides a method for preserving cherries by coating, comprising the following steps: 1) Water-soluble arabinoxylan was prepared by the same steps as in Example 1-4. 2) 1.5 g of water-soluble arabinoxylan was added to 98.5 g of deionized water to completely dissolve the water-soluble arabinoxylan to form a transparent solution, thereby obtaining a solution with a water-soluble arabinoxylan mass concentration of 1.5%; then 3% of the solution volume of glycerol was added, and the mixture was fully mixed by magnetic stirring for 40 min to obtain a composite coating solution; 3) Soak fresh cherries in the prepared composite coating solution for 5 minutes, remove them from the solution, drain excess water, dry them naturally, and store them at 20°C.

[0058] Comparative Example 2-1

[0059] The cherry processing method of this comparative example comprises the following steps: soaking fresh cherries in deionized water for 3 minutes, taking them out and draining the water, and storing them at 20° C. This is recorded as a blank group.

[0060] Comparative Example 2-2

[0061] The cherries coating preservation method of this comparative example comprises the following steps:

[0062] 1) Preparation of a single glycerol solution: Accurately weigh 4 g of glycerol and dissolve it in 96 g of deionized water to completely dissolve it into a transparent solution, thereby preparing a 4% glycerol coating solution.

[0063] 2) Cherry preservation: Soak fresh cherries in glycerin coating solution for 3 minutes, remove them and drain excess water, dry them naturally, and store them at 20℃.

[0064] Comparative Examples 2-3

[0065] The cherries coating preservation method of this comparative example comprises the following steps:

[0066] 1) Water-soluble arabinoxylan was prepared by the same steps as in Example 1-4.

[0067] 2) Preparation of a single water-soluble arabinoxylan solution: Accurately weigh 1 g of water-soluble arabinoxylan and dissolve it in 99 g of deionized water to completely dissolve it into a transparent solution, thereby preparing a 1% water-soluble arabinoxylan coating solution.

[0068] 3) Cherry preservation: Soak fresh cherries in the water-soluble arabinoxylan coating solution for 3 minutes, remove them from the water, drain excess water, dry them naturally, and store them at 20°C.

[0069] Comparative Examples 2-4

[0070] The cherries coating preservation method of this comparative example comprises the following steps: 1) Water-soluble arabinoxylan was prepared by the same steps as in Example 1-4. 2) Preparation of modified arabinoxylan solution: accurately weigh 1 g of arabinoxylan and dissolve it in 99 g of deionized water, add 2 g of soy protein and 0.03 g of calcium chloride to the aqueous solution, raise the temperature to 50°C, and react in a water bath for 60 minutes to obtain a modified arabinoxylan coating solution. 3) Cherry preservation: Soak fresh cherries in the modified arabinoxylan coating solution for 3 minutes, remove them and drain excess water, dry them naturally, and store them at 20°C.

[0071] Fresh cherries of the same variety were picked and divided into seven groups, and were treated simultaneously by the methods of Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-4, and stored at 20° C. for 5 days.

[0072] I) Record the overall appearance of cherries once a day. The appearance of cherries treated by the methods of Example 2-1 and Comparative Examples 2-1 to 2-3 is shown in Table 1. Figure 1 .

[0073] Depend on Figure 4 It can be seen that the decay rate of Example 2-1 is significantly lower than that of Comparative Examples 2-1 to 2-3. During storage, the appearance of cherries in Example 2-1 changes the least, and has a good preservation effect on cherries, which is better than that of other treatment groups.

[0074] II) Determination of weight loss of cherries

[0075] The daily weight loss was determined by measuring the weight of the cherries at the same time each day using an analytical balance and expressed as a percentage of the initial weight. The results of the weight loss of cherries during storage are shown in Table 3. Weight loss rate was calculated according to the following formula: Where WL is the weight loss rate, %; M0 is the initial weight of the sample, g; M n is the weight of the sample during measurement, g.

[0076] Table 3 Weight loss rate measurement results

[0077] Note: The values ​​in the table are expressed as mean ± standard deviation.

[0078] The weight loss of the fruit after harvest is mainly caused by water loss and nutrient consumption during respiration and transpiration. As shown in Table 3, during storage, the weight loss rate of cherries in different treatment groups showed an upward trend over time, but the weight loss rate of cherries in Example 2-1 was lower than that of other groups, and the preservation effect was better.

[0079] III) Determination of the rot rate of cherries

[0080] The sensory evaluation method was used. Ten fruits were randomly selected from each group for evaluation of the fruit decay rate. Fruits were identified as rotten when they showed bacterial spots, water flow, mildew, etc. The number of rotten fruits was recorded regularly, and the fruit decay rate was calculated according to the formula: The calculation formula for the degree of decay is as follows: Fruit rot rate / %=(number of rotten fruits after storage / piece) / (total number of fruits before storage / piece)×100.

[0081] The results of the rot rate of cherries during storage are shown in Table 4.

[0082] Table 4 Determination results of decay rate

[0083] Note: The values ​​in the table are expressed as mean ± standard deviation.

[0084] As shown in Table 4, compared with other treatment groups, the cherry rot rate of Example 2-1 is the lowest. The results show that Example 2-1 has the best effect on the cherry rot rate.

[0085] IV) Determination of cherry firmness

[0086] The hardness of cherries was measured using a food property analyzer. A P / 36R cylindrical probe was used in the compression mode to measure the hardness of the whole cherry. The test parameters were: compression speed of 2 mm / s, compression depth of 5 mm, and the maximum pressure that the sweet cherry could withstand during the compression process was taken as the hardness of the fruit. The results of the hardness test of cherries during storage are shown in Table 5.

[0087] Table 5 Hardness test results

[0088] Note: The values ​​in the table are expressed as mean ± standard deviation.

[0089] As shown in Table 5, after the fifth day of storage, compared with Comparative Examples 2-1 to 2-4, the change in cherry hardness during storage in Example 2-1 was the smallest, which delayed the decrease in cherry hardness during storage.

[0090] V) Soluble solids content of cherries

[0091] The soluble solids content of fresh cherries (0 days) and cherries stored at room temperature for 5 days was measured using a handheld refractometer. The results are shown in Figure 6.

[0092] Table 6 Soluble solids determination results

[0093] Note: The values ​​in the table are expressed as mean ± standard deviation.

[0094] As shown in Table 6, the soluble solids of cherries showed a trend of gradual increase during storage, and the soluble solids content of Example 2-1 was always lower than that of Comparative Examples 2-1 to 2-4. The results show that the composite film of Example 2-1 has the best water barrier and the slowest water loss, which delays the increase of cherry solubility and helps to maintain the good edible taste of cherry fruit.

[0095] In summary, the composite coating liquid in the present invention is compounded by water-soluble arabinoxylan and glycerol. When preserving cherries, the effect is better than that of using glycerol or water-soluble arabinoxylan alone, because water-soluble arabinoxylan and glycerol have certain functional complementarity. Arabinoxylan mainly provides film-forming property and biocompatibility, while glycerol mainly provides hygroscopicity and plasticity. This complementarity makes the composite coating liquid show more superior performance in cherry preservation. Not only that, glycerol can be embedded in the polymer matrix of arabinoxylan, reduce the intermolecular interaction force, increase the mobility of the polymer, and thus enhance the flexibility and plasticity of the film. At the same time, glycerol can also improve the water vapor permeability of the film, promote the penetration of water vapor molecules, and help maintain the water balance inside the cherry. Further, the composite coating liquid can form a dense film on the surface of the cherry, effectively preventing the invasion of external oxygen, carbon dioxide and microorganisms. This can not only delay the respiration of the cherry, reduce the consumption of nutrients, but also prevent the cherry from rotting due to bacterial infection. At the same time, glycerol can also absorb and retain the moisture on the surface of cherries, preventing cherries from drying out due to water loss, thereby further extending the shelf life of cherries. Through the above examples and comparative examples, Example 2-1 has the best preservation effect on cherries stored at room temperature. The water-soluble arabinoxylan coating solution prepared under this condition can reduce the weight loss rate and decay rate of cherries, delay the reduction of cherry hardness and the increase of soluble solids.

[0096] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any equivalent changes or modifications made according to the essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a composite coating liquid based on water-soluble arabinoxylan, characterized in that: The main steps are as follows: S1. Preparation of water-soluble arabinoxylan S11, removing insoluble substances in the gluten processing waste liquid by centrifugation, and collecting the supernatant; S12, concentrating the supernatant in step S11 by rotary evaporation, precipitating with alcohol, and centrifuging to collect the precipitate; S13, dissolving the precipitate collected in step S12 in water, dialyzing to remove small molecules, and collecting the dialysate; S14, concentrating the dialysate collected in step S13 and freeze-drying it to obtain a crude extract; S15, subjecting the crude extract in step S14 to static adsorption purification to obtain purified water-soluble arabinoxylan; S2. Preparation of composite coating liquid S21, weighing water-soluble arabinoxylan and dissolving it in deionized water to prepare a solution with a concentration of 0.5-1.5%; S22, add 2-4% glycerol to the solution prepared in step S21, stir magnetically for 30-40 minutes to fully mix; then let stand for 0.5-1.5 hours to remove bubbles in the solution, and obtain a composite coating solution.

2. The method for preparing a composite coating liquid based on water-soluble arabinoxylan according to claim 1, characterized in that: In step S11, the gluten processing waste liquid is centrifuged at a rate of 4000-5000 r / min for 15 minutes.

3. The method for preparing a composite coating liquid based on water-soluble arabinoxylan according to claim 1, characterized in that: In step S12, when alcohol precipitation is performed, ethanol is added until the final ethanol concentration of the system is 70-80%; after alcohol precipitation, centrifugation is performed at a rate of 4000-5000 r / min for 15 minutes.

4. The method for preparing a composite coating liquid based on water-soluble arabinoxylan according to claim 1, characterized in that: In step S13, the dialysis time is 24 hours, and the dialysis fluid is changed every 4-6 hours.

5. The method for preparing a composite coating liquid based on water-soluble arabinoxylan according to claim 1, characterized in that: In step S14, the adsorption material used for static adsorption purification is any one of macroporous resins AB-8, DM130, JK008 or cellulose DE-52, and the adsorption material-liquid ratio is 1:15-1:

25.

6. A composite coating liquid based on water-soluble arabinoxylan, characterized in that: The method is prepared by any one of claims 1 to 5.

7. Use of the composite coating liquid based on water-soluble arabinoxylan as claimed in claim 6 in preserving cherries.

8. The use according to claim 7, characterized in that: Soak the cherries in the composite coating liquid for 2 to 5 minutes, take them out and dry them naturally, and store them at 20 to 25°C.

Images