CN107361132A - A kind of chitosan salicylic acid composite preservative and preparation method and application - Google Patents

Abstract

The invention discloses a chitosan-salicylic acid composite antistaling agent and its preparation method and application. Calcium chloride 0.5-2g; add salicylic acid into the aqueous solution and stir until completely dissolved to obtain a salicylic acid aqueous solution, then add calcium chloride to the solution and stir until dissolved, slowly add chitosan to salicylic acid-chlorination In the calcium solution, stir at a constant temperature of 37°C for 0.5-1h to obtain the complex, disperse it with ultrasonic waves for 10-20min, until the chitosan is uniformly dispersed, let it stand still, and completely remove the air bubbles to obtain the chitosan-salicylic acid composite preservative. The composite antistaling agent soaks the grapefruit fruit, can significantly reduce the grapefruit fruit decay rate and water loss rate, maintain the unique flavor, color and luster and hardness of the grapefruit fruit, and prolong the storage period of the fruit. Problems such as the residue of chemical agents and environmental pollution are reduced, and the method is simple in operation, low in cost, easy to popularize and apply, and is suitable for large-scale commercial application.

Description

A kind of chitosan-salicylic acid composite antistaling agent and its preparation method and application

technical field

The invention relates to the technical field of fruit fresh-keeping, in particular to a chitosan-salicylic acid composite preservative and its preparation method and application.

Background technique

Grapefruit (Citrus paradise Macf.) belongs to the genus Citrus of Rutaceae, one of the four major groups of citrus in the world. It is called grapefruit because of its habit of fruiting in clusters. The pulp is soft and juicy, with a slightly bitter taste in sweet and sour, unique flavor and good taste. It is also rich in vitamins, flavonoids, naringin and orange glycosides. It has high economic value and medicinal value. During the storage and sale of grapefruit, the fruit is susceptible to latent infection before harvest and cross-infection by pathogenic bacteria after harvest, causing postharvest diseases and rot, resulting in very serious fruit losses, among which Penicillium is the most serious. Aiming at postharvest diseases of grapefruit, the commonly used grapefruit storage methods are mainly low-temperature storage and chemical preservative storage. This kind of treatment can inhibit fruit respiratory metabolism and inhibit microbial growth, and is widely used. However, the above-mentioned methods have problems such as high equipment cost and operating cost, drug residues and environmental pollution. Therefore, it is necessary to find a new safe and efficient method for grapefruit fruit preservation. .

Chitosan is a white or off-white translucent biopolymer. It has low cost, good film-forming properties, transparent, colorless or slightly yellow film, non-toxic and easy to biodegrade. It is listed as a thickener and coating agent Enter the national food additive use standard GB-2760. Chitosan has the function of inhibiting the growth and reproduction of pathogenic microorganisms, can improve the fruit's own disease resistance, delay fruit aging and other functional properties, and has a good control effect on various fruit diseases. Therefore, chitosan has been widely used in the field of fruit storage and preservation as a new natural fresh-keeping agent. Salicylic acid is a simple phenolic compound produced in plants and widely exists in higher plants. Salicylic acid is a signal molecule required for plants to produce disease resistance responses. It can activate plant defense and protection mechanisms, and can also serve as an anti-stress signal molecule that induces plant responses to abiotic stress. Salicylic acid can enhance the resistance of fruits to pathogens such as fungi and bacteria, increase the activity of active oxygen scavenging enzymes in plants, remove excessive active oxygen, improve cell metabolism, and delay fruit aging. The application of salicylic acid in fruits has the advantages of less dosage, safety, and can be applied in various growth stages of fruits, etc., and meets the requirements of green and pollution-free agricultural development.

Contents of the invention

The object of the present invention is to aim at the above-mentioned problems that exist in the prior art, provide a kind of chitosan-salicylic acid compound antistaling agent and preparation method thereof, to control the disease of grapefruit fruit storage period, delay fruit aging, solve traditional The fresh-keeping method has problems such as high equipment cost and operating cost, drug residues and environmental pollution, and the method is simple to operate, low in cost, easy to popularize and apply, and is suitable for large-scale commercial applications.

In order to achieve the above object and achieve the above effect, the present invention is achieved through the following technical solutions:

A chitosan-salicylic acid composite antistaling agent, its formula specifically is: it comprises the raw material according to following ratio: chitosan 0.5～2g, salicylic acid 0.01～0.2g and calcium chloride 0.5～2g, adjust The pH value is 5.8-6.

Preferably, the chitosan-salicylic acid composite preservative includes raw materials in the following proportions: every 100ml contains 2g chitosan, 0.2g salicylic acid, 1g calcium chloride, and the balance is water to adjust the pH The value is 5.8-6.

Preferably, the chitosan-salicylic acid composite antistaling agent comprises raw materials according to the following ratio: every 100ml contains 0.5g chitosan, 0.2g salicylic acid, 1.5g calcium chloride, and the balance is water, Adjust the pH value to 5.8-6.

The preparation method of chitosan-salicylic acid composite preservative of the present invention comprises the following steps:

Add salicylic acid into the aqueous solution and stir until completely dissolved to obtain a salicylic acid aqueous solution, then add calcium chloride to the solution and stir until dissolved, slowly add chitosan to the salicylic acid-calcium chloride solution, 37°C Stir at a constant temperature for 0.5-1 hour to obtain the compound, disperse it with ultrasonic waves for 10-20 minutes, until the chitosan is uniformly dispersed, let stand, and completely remove air bubbles to obtain the chitosan-salicylic acid composite preservative.

The application of chitosan-salicylic acid composite antistaling agent of the present invention comprises the following steps:

(1) Picking and pretreatment of grapefruit: select fresh grapefruit fruits with no mechanical damage, no pests and diseases, uniform size, and consistent maturity, wash the surface with clean water, and dry the surface moisture of the grapefruit naturally;

(2) Soaking treatment: Soak the dried grapefruit fruit in the pre-prepared preservative solution for 3 to 5 minutes, take it out and dry it naturally;

(3) Storage: After the soaking solution is dried, the single fruit is packaged and stored at room temperature (20°C, relative humidity 85-95%);

Among them, the time from picking grapefruit fruit to bagging should be ≤24 hours.

The beneficial effects of the present invention are as follows: (1) reduce the water loss of grapefruit fruit, maintain the appearance and nutritional quality of grapefruit fresh fruit, and effectively prolong the storage period of grapefruit fresh fruit; It has a significant inhibitory effect and effectively prevents the corruption of grapefruit fruit; (3) the antistaling agent is easy to be cleaned by water, can be naturally degraded, reduces the residue of chemical antistaling agents, is non-toxic to the human body, has high safety, has no pollution to the environment, and is green Environmental protection; (4) The method is simple, easy to operate, low in cost and easy to popularize.

detailed description

In conjunction with the following specific examples, the present invention will be further described in detail, and the protection content of the present invention is not limited to the following examples. Without departing from the spirit and scope of the inventive concept, changes and advantages conceivable by those skilled in the art are all included in the present invention, and the appended claims are the protection scope. The process, conditions, reagents, experimental methods, etc. for implementing the present invention are general knowledge and common knowledge in the art except for the content specifically mentioned below, and the present invention has no special limitation content.

Example

1) Preparation steps of chitosan-salicylic acid composite preservative:

Add salicylic acid into the aqueous solution and stir until completely dissolved to obtain a salicylic acid aqueous solution, then add calcium chloride to the solution and stir until dissolved, slowly add chitosan to the salicylic acid-calcium chloride solution, 37°C Stir at a constant temperature for 0.5-1 hour to obtain the compound, disperse it with ultrasonic waves for 10-20 minutes, until the chitosan is uniformly dispersed, let stand, and completely remove air bubbles to obtain the chitosan-salicylic acid composite preservative.

According to the ratio of chitosan, salicylic acid and calcium chloride, set different ratios of composite preservatives:

T1: Each 100ml contains 2g chitosan, 0.2g salicylic acid, 1g calcium chloride, the balance is water, adjust the pH value to 5.8-6;

T2: Each 100ml contains 0.5g chitosan, 0.2g salicylic acid, 1.5g calcium chloride, the balance is water, adjust the pH value to 5.8-6;

T3: Each 100ml contains 2g chitosan, 0.01g salicylic acid, 1g calcium chloride, the balance is water, adjust the pH value to 5.8-6;

T4: Each 100ml contains 0.5g chitosan, 0.01g salicylic acid, 1.5g calcium chloride, the balance is water, adjust the pH value to 5.8-6;

T0: distilled water.

2) Grapefruit soaking treatment:

Wash the surface of the harvested grapefruit with clean water, dry the surface moisture of the grapefruit naturally, then soak the dried grapefruit fruit in the pre-prepared preservative 1-5 solution for 3-5 minutes, take it out at room temperature After natural drying, the single fruit is packaged and stored at room temperature (20°C, relative humidity 85-95%). The time from grapefruit fruit picking to bagging should be ≤ 24 hours.

In this example, the 'Rio Red' grapefruit picked from the orchard of Southwest Forestry University without any treatment was used as the experimental material, and fresh grapefruit fruits with no mechanical damage, no pests and diseases, uniform size and consistent maturity were selected, and the fruits were washed with clean water After the surface, dry the surface moisture naturally, soak in different proportions of antistaling agents in the experimental example for 3 to 5 minutes, take it out and dry it naturally at room temperature, pack single fruit, and store at room temperature (20°C, relative humidity 85% to 95%). 15 fruits were treated in each group, and samples were taken every 5 days, and each sampling was carried out at the same time period. Three fruits were randomly selected from each group for determination and analysis of fruit firmness, weight loss rate, and rot rate indicators.

(1) Changes in the hardness of grapefruit fruit during storage

Measured by GY-2 type hardness tester, the probe diameter is 3.5mm, and each fruit is peeled and evenly distributed at three places on the trunk, and the average value is taken, and the unit is N.

The change of grapefruit fruit hardness during storage with different proportions of chitosan-salicylic acid compound preservatives showed a trend of first increasing and then stabilizing. When measured on the 5th day, the fruit hardness of T0 was the lowest, only 0.75N, and T1 in the treatment group was the lowest. The increase range of is the smallest and the most stable, so T1 has a better effect in maintaining fruit firmness than other treatment groups.

(2) Changes in weight loss rate of grapefruit fruit during storage

Measured by weighing method, fruit weight loss rate (%)=[(fruit mass before storage-fruit mass after storage for a certain period of time)/fruit mass before storage]×100.

The changes in the weight loss rate of grapefruit fruit during storage with different proportions of chitosan-salicylic acid compound preservatives showed an overall trend of first increasing and then decreasing, among which the weight loss in the T0 group was the most obvious and the value was larger. On the 20th day, the T0 The weight loss rate of the group was as high as 1.6%, while the other treatment groups were only basically maintained at about 1.2%. The weight loss rate of T1 was always low and stable. On the 25th day, the weight loss rate of T1 was only 0.8%, which was significantly lower than other treatment groups, so T1 treatment could better reduce the weight loss of fruit.

(3) Changes in the rot rate of grapefruit fruit during storage

Fruit rot rate (%) = (number of stored rotten fruits/total number of stored fruits) × 100

Treatment with different proportions of chitosan-salicylic acid compound preservatives reduced the increase in the rot rate of grapefruit fruit during storage. When stored for 30 days, the incidence rate of T1 soaking treatment was 5%, which was lower than that of T0 treatment. When stored for 60 days, the incidence rate of T1 soaking treatment was only 22%, significantly lower than other treatment groups. Compared with other treatment groups, T1 has a better effect on inhibiting fruit rot.

The results showed that the chitosan-salicylic acid composite preservative prolongs the fresh-keeping period of 'Rio Red' grapefruit fruit to a certain extent, which is better than that of untreated fruit, slows down the loss of fruit water, and delays the aging of grapefruit fruit. The good fruit rate of commercial products reaches over 94%, and the original fruit nutritional quality of grapefruit can be well maintained, so it has good commercial value.

The above is only a preferred specific embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field within the technical scope disclosed in the present invention can obviously obtain the simplicity of the technical solution. Changes or equivalent replacements all fall within the protection scope of the present invention.

Claims (6)

1. A chitosan-salicylic acid composite antistaling agent, characterized in that: every 100ml antistaling agent contains chitosan 0.5～2g, salicylic acid 0.01～0.2g and calcium chloride 0.5～2g, adjusts the pH value 5.8-6. 2. a kind of chitosan-salicylic acid composite antistaling agent as claimed in claim 1, is characterized in that: contain 2g chitosan in every 100ml, 0.2g salicylic acid, 1g calcium chloride, surplus is water , adjust the pH value to 5.8-6. 3. a kind of chitosan-salicylic acid composite antistaling agent as claimed in claim 1, is characterized in that: contain 0.5g chitosan in every 100ml, 0.2g salicylic acid, 1.5g calcium chloride, surplus It is water, and the pH value is adjusted to 5.8-6. 4. a kind of chitosan-salicylic acid composite antistaling agent as described in any one of claim 1-3, its preparation method comprises the following steps: adding salicylic acid in the aqueous solution is stirred to dissolving completely, obtains salicylic acid Aqueous solution, then add calcium chloride to the solution and stir until dissolved, slowly add chitosan into the salicylic acid-calcium chloride solution, stir at a constant temperature of 37°C for 0.5-1h to obtain a compound, and disperse with ultrasonic waves for 10-20min , until the chitosan is uniformly dispersed, left to stand, and the air bubbles are completely removed, and the chitosan-salicylic acid composite preservative is obtained. 5. a kind of chitosan-salicylic acid composite preservative as described in any one of claim 1-3, its application method may further comprise the steps: (1) Picking and pretreatment of grapefruit: select fresh grapefruit fruits with no mechanical damage, no pests and diseases, uniform size, and consistent maturity, wash the surface with clean water, and dry the surface moisture of the grapefruit naturally; (2) Soaking treatment: Soak the dried grapefruit fruit in the pre-prepared preservative solution for 3 to 5 minutes, take it out and dry it naturally; (3) Storage: After the soaking solution is dried, the single fruit is packaged and stored at room temperature (20°C, relative humidity 85-95%). 6. the application method of a kind of chitosan-salicylic acid composite antistaling agent as claimed in claim 5, wherein, grapefruit fruit is plucked to bagging time and should≤24 hours.