CN-121970807-A - Composite fresh-keeping coating liquid containing chitosan and hydroxypropyl starch for coffee grounds extract, preparation method and application thereof in storage, transportation and fresh-keeping of thin-skin fruits

CN121970807ACN 121970807 ACN121970807 ACN 121970807ACN-121970807-A

Abstract

The invention belongs to the technical field of fruit and vegetable fresh-keeping, and discloses a coffee grounds extract composite fresh-keeping film coating liquid containing chitosan and hydroxypropyl starch, a preparation method and application thereof in storing, transporting and fresh-keeping of thin-skin fruits, wherein each 1000 mL fresh-keeping liquid comprises 20: 20g of chitosan, 20: 20g of waste coffee grounds extract, 7.5: 7.5 g of hydroxypropyl starch, 2: 2 mL of glycerol and 1000: 1000 mL of distilled water. The invention provides a green composite fresh-keeping film coating liquid containing chitosan-hydroxypropyl starch-coffee grounds extract, which realizes the improvement of the storage, transportation and fresh-keeping quality of small-sized vulnerable fruits with thin skin, has all natural sources, no peculiar smell, stability and durability, is easy to clean, meets the higher requirements of the market on clean labels and healthy products, and simultaneously effectively solves the problems of high-value utilization deficiency and environmental pollution of agricultural byproducts of coffee grounds.

Inventors

JIANG YUQIAN
LI MIN
YANG XIANGZHENG
JIA LIANWEN
TANG YAO
ZHANG QIANQIAN
DU HAIYU

Assignees

天津科技大学
中华全国供销合作总社济南果品研究所

Dates

Publication Date: 20260505
Application Date: 20260130

Claims (10)

1. A coffee grounds extract composite fresh-keeping film coating liquid containing chitosan and hydroxypropyl starch is characterized in that each 1000 mL fresh-keeping liquid comprises: chitosan 20g, waste coffee extract 20g, hydroxypropyl starch 7.5, g, glycerin 2 mL, distilled water to 1000 mL.
2. The composite fresh-keeping film coating liquid according to claim 1, wherein the chitosan is food grade, the deacetylation degree is more than or equal to 85%, and the composite fresh-keeping film coating liquid conforms to GB 29941-2013.
3. The composite fresh-keeping film coating liquid according to claim 1 or 2, wherein the preparation method of the waste coffee grounds extract is as follows: (a) Uniformly spreading the waste coffee grounds on a tray, drying in a 45 ℃ oven until the weight is constant, vacuum sealing after drying, and storing in a dark place at room temperature; (b) Weighing the dried waste coffee grounds in the step (a), fully mixing the waste coffee grounds with ethanol solution containing 0.1% of glacial acetic acid with the mass concentration of 0.1% and the volume concentration of 70% according to the feed-liquid ratio of 1:5 (g: mL), carrying out ultrasonic treatment on the mixture under the condition of 240W, carrying out ultrasonic treatment on the mixture under the condition of 30: 30 min, carrying out shaking extraction on the mixture at room temperature and in a dark place for 2: 2h, after the extraction is finished, placing the mixed solution in a centrifuge for 4 ℃, centrifuging the mixture at 6000 Xg for 20: 20 min, collecting supernatant, and carrying out secondary extraction on residues to obtain an SCG crude extract; (c) The SCG crude extract was transferred to a clean petri dish and dried in an oven at 50 ℃ for 12 h. And after the drying is finished, obtaining the waste coffee grounds extract.
4. The composite fresh-keeping film coating liquid according to claim 1 or 2, wherein the main component of the waste coffee grounds extract is total phenol content 12.92 mg/g and total flavone content 85.41 mg/g.
5. The method for preparing the composite fresh-keeping film coating liquid according to any one of claims 1 to 4, wherein the method adopts secondary alcohol extraction to extract polyphenol substances in waste coffee grounds with high efficiency, and prepares the composite fresh-keeping film coating liquid by compounding chitosan and hydroxypropyl starch.
6. The method of claim 5, comprising the steps of: (1) Adding chitosan into distilled water which is preheated to 55 ℃ and contains glacial acetic acid with the mass concentration of 1%, wherein the ratio g of the chitosan to the distilled water is 20:400, and magnetically stirring the mixture by 300 rpm to obtain 2: 2h until the chitosan is completely dissolved to obtain a chitosan base solution; (2) Weighing hydroxypropyl starch, mixing with distilled water, wherein the ratio g of the hydroxypropyl starch to the distilled water is 7.5:100, heating to 75 ℃ in water bath, stirring with 200 rpm to maintain 30: 30min, forming transparent gelatinized liquid, obtaining hydroxypropyl starch gelatinized liquid, and cooling to room temperature for standby; (3) Mixing the waste coffee grounds extract with distilled water, wherein the ratio g of the waste coffee grounds extract to the distilled water is 20:400, and the ratio g of the distilled water to the mL is 40 kHz, and the ratio g of the distilled water to the mL is 240W, and carrying out ultrasonic treatment on the mixture to obtain 10: 10 min, so as to form a uniform dispersion, thereby obtaining SCGE dispersion; (4) Slowly adding the hydroxypropyl starch gelatinized liquid into the chitosan base liquid under the continuous magnetic stirring of 300 rpm, uniformly mixing, adding the SCGE dispersion liquid, then adding glycerol, and continuously carrying out the magnetic stirring of 300 rpm for 30 min until the system is uniform; (5) Adding part of distilled water into the mixed system, carrying out ultrasonic treatment on the mixture by 40 kHz and 200W for 30min, and finally adding the rest distilled water to obtain a tan sticky uniform dispersion liquid, namely the composite fresh-keeping film coating liquid, wherein the film coating liquid is prepared and used at present, and is stored at 4 ℃ in a dark place and does not exceed 12 h.
7. The method of claim 5 or 6, wherein the method of producing the spent coffee grounds extract comprises the steps of: (a) Uniformly spreading the waste coffee grounds on a tray, drying in a 45 ℃ oven until the weight is constant, vacuum sealing after drying, and storing in a dark place at room temperature; (b) Weighing the dried waste coffee grounds in the step (a), fully mixing the waste coffee grounds with ethanol solution containing 0.1% of glacial acetic acid with the mass concentration of 0.1% and the volume concentration of 70% according to the feed-liquid ratio of 1:5 (g: mL), carrying out ultrasonic treatment on the mixture under the condition of 240W, carrying out ultrasonic treatment on the mixture under the condition of 30: 30 min, carrying out shaking extraction on the mixture at room temperature and in a dark place for 2: 2h, after the extraction is finished, placing the mixed solution in a centrifuge for 4 ℃, centrifuging the mixture at 6000 Xg for 20: 20 min, collecting supernatant, and carrying out secondary extraction on residues to obtain an SCG crude extract; (c) The SCG crude extract was transferred to a clean petri dish and dried in an oven at 50 ℃ for 12 h. And after the drying is finished, obtaining the waste coffee grounds extract.
8. The method for using the composite fresh-keeping film coating liquid according to any one of claims 1 to 4, which is characterized by comprising the following steps: (a) Immersing intact and harmless small-sized thin-skin vulnerable fruits in the composite fresh-keeping coating liquid with a feed liquid ratio of 1:3 (kg: L) to ensure that the fruits are completely immersed in the coating liquid, fishing out the fruits by a strainer after the immersion is finished, and draining 10 min in an environment with the temperature of 25℃, RH being less than or equal to 60%; Or (b) spraying, namely uniformly spraying the fruits 2 times from 20 cm to 1 time in the front and back by using a small handheld sprayer with the diameter of 0.2 MPa and the diameter of 0.5 mm, wherein the single spraying amount is 1.5 mL/100 g of the fruits, and naturally airing the fruits on the surface of a ventilated place after the spraying is finished; and cleaning before eating, namely removing the composite fresh-keeping coating liquid through a simple cleaning step before eating the fruits treated by the composite fresh-keeping coating liquid.
9. The method of using the compound preservative film according to claim 8, wherein the fruits treated by the compound preservative film coating liquid are placed under clean running water and gently rinsed for 10-15 s ℃ at 15-20 ℃, i.e. the surface compound film is completely removed, and the fruits can be directly eaten after 30-s draining.
10. The use of the composite fresh-keeping film coating liquid according to any one of claims 1to 4 in fresh-keeping of small vulnerable fruits of thin skin (such as grape, winter jujube, cherry tomato).

Description

Composite fresh-keeping coating liquid containing chitosan and hydroxypropyl starch for coffee grounds extract, preparation method and application thereof in storage, transportation and fresh-keeping of thin-skin fruits Technical Field The invention belongs to the technical field of fruit and vegetable fresh-keeping, and in particular relates to a coffee grounds extract composite fresh-keeping coating liquid containing chitosan and hydroxypropyl starch, a preparation method and application thereof in storage, transportation and fresh-keeping of thin-skin fruits. Background The waste coffee grounds are rich in chlorogenic acid, caffeine, protocatechuic acid, flavonoid compounds and other active ingredients, and the extract (SCGE) thereof has certain application potential in the field of food preservation, wherein the SCGE can obviously inhibit the proliferation of microorganisms, maintain the antioxidation capability and prolong the shelf life when being used for treating chicken breast meat, the SCGE edible film prepared by compounding with carboxymethyl cellulose can be applied to lantern fruits, reduce the weight loss rate and the respiratory strength, inhibit the growth of microorganisms and improve the storage quality, and the active package taking the SCGE as an antioxidant also has good preservation effect when being used for refrigerating food. The natural extract preservative is gradually paid attention to the field of preservation by virtue of the advantages of high safety, environmental friendliness, lower cost and the like. However, the existing natural extract still has the problems of low mechanical property, uneven coating, quick loss of active ingredients and cleaning residue before eating in the fresh-keeping coating film reported by the research under the conditions of high humidity and easy mechanical damage of thin-skin fruits. Specifically, the following problems exist in the prior art: (1) The fresh-keeping film coating agent has uneven extension and insufficient mechanical property, and is difficult to meet the conditions that thin small berries are easy to be damaged mechanically and infected by microorganisms; (2) The natural active ingredients are easy to migrate and separate out in the storage process of the coating film and have unstable efficacy; (3) The surface residue is caused by difficult cleaning before eating. By searching, the following patent publications related to the present patent application are found: 1. Patent document CN 202510457411.1 (publication day: 2025, 5 and 27) discloses a chitosan composite preservative film, which is prepared by compositing oxidized starch, phytic acid, carvacrol and chitosan, so that the decay rate of strawberries and grapes is reduced, the fruit senescence of the strawberries and the grapes is delayed, and the growth of Alstonia and Alstonia in the fungi causing corrosion in the strawberries and the grapes is inhibited. The method has the problems that (1) the mechanical property index of a composite coating film is not explicitly mentioned, the oxidized starch is poor in mechanical property and strong in water absorption, even if the oxidized starch is compounded with chitosan, certain limitation exists in improving the mechanical strength of the coating film, and mechanical damage of strawberries and grapes in the storage and transportation process is difficult to effectively resist, (2) carvacrol is extracted depending on plants, the yield is limited, the cost is high, and (3) carvacrol has volatile smell, and when the carvacrol is used for preserving strawberries and grapes, the oxidized starch can remain on the surfaces of fruits to influence the original flavor of the fruits and the sensory experience of consumers. 2. Patent document CN 201610684462.9 (publication day: 2017, 1 month and 7 days) discloses a chitosan composite preservative film. Dissolving flos Caryophylli extract, calcium chloride, vitamin C, and potassium sorbate in water, and adding chitosan citric acid solution to obtain grape antistaling agent. The antistaling agent has simple process and less surface chemical residue, and can greatly reduce or delay the quality degradation and spoilage of the grape in the storage process. The potassium sorbate preservative has the problems that (1) potassium sorbate is used as a common chemical preservative, is safe in a specified use range, can possibly have certain influence on human health after being taken for a long time in a large amount, cannot meet the higher requirements of consumers on green natural preservation, and (2) a preservative is prepared by mixing various components, so that the situation of uneven component distribution possibly occurs in actual production and use, and the preservation effect is unstable. (3) Vitamin C has poor stability, is easily affected by temperature, light and the like, may have multiphase separation problems, and cannot be kept fresh for a long time. By contrast, the present patent