JPH03980B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a shelf-stable fresh food and a method for processing the same. In recent years, it has become possible to extend the storage period and transportation distance of fresh foods such as fruits and vegetables due to the development of low temperature preservation methods. However, since these fresh foods are usually displayed and sold on display at store shelves rather than at low temperatures, their shelf life at the distribution end is extremely short. This means that the dealer bears a considerable amount of risk, and is also a factor in the high selling price. On the other hand, consumers would also benefit greatly if fresh foods could last even a day longer and the loss of useful ingredients could be prevented. In particular, peeled fruits can be said to be highly sought after fresh foods because they look appetizing and can be eaten immediately. The only way to preserve the natural flavor of these fresh foods is to immerse them in concentrated sugar or salt, heat sterilize them and bottle or can them, or freeze or dry them. It had a defect in that the texture, taste, active ingredients, etc. were significantly impaired. Furthermore, conventionally, as a long-term preservation method for fresh fruit,
A method has been developed to delay ripening by suppressing the respiration of the fruit itself. One method is to apply a special wax to fruits that are relatively hard or have good shape retention, such as citrus fruits and apples. There is a method of suppressing breathing by forming a film on the outer surface, but this method of waxing has problems with the digestibility and sealing properties of the wax itself. That is, in the case of strawberries and other peeled fruits, the coating completely seals the skin, which excessively suppresses respiration and accelerates autolysis, making it difficult to apply. The present invention has been made in view of the above-mentioned conventional problems,
To provide fresh foods such as fruits and vegetables which can maintain and suppress proper respiration and maintain flavor, texture, taste, and active ingredients for a long period of time, and a processing method therefor. The basic technical idea of the present invention is to apply a selectively permeable, colorless, odorless, and digestible thin film to the surface of fresh food, thereby preventing the food from spoiling due to the invasion of bacteria in the air. The purpose is to prevent this, moderately suppress respiration, and improve its shelf life at room temperature. The preservative fresh food according to the present invention, which embodies this technical idea, is characterized by having a digestible, limited permeability thin film formed from sodium alginate and polylysine produced by a fermentation method adhered to the surface. . The processing method according to the present invention for processing fresh foods to improve their shelf life includes a step of washing the fresh foods;
A step of immersing the food in an aqueous solution containing about 0.01% to 0.1% of sucrose ester and about 0.8 to 1.6% of sodium alginate, and a step of forming a gel of sodium alginate on the surface of the food by immersing it in an about 15% calcium chloride solution. A step of washing and stabilizing the above gel by immersing it in a phosphoric acid or sulfonic acid buffer solution of pH 7.0, and a step of immersing it in an approximately 1% aqueous solution of polygiene obtained by a fermentation method to cause interfacial polymerization with the above gel to form a film. It is characterized by comprising the step of forming. The sucrose ester, sodium alginate, calcium chloride, and polylysine used in the processing method of the present invention are all permitted as food additives. Among these, sucrose ester is used as a surfactant to improve the adhesion of sodium alginate, which is a digestible gel-forming agent, to food surfaces, and polylysine obtained by fermentation has a molecular weight of 1,000 to 300,000. It is a mixture that reacts with sodium alginate to cause interfacial polymerization, forming a film that is impermeable to microorganisms but allows a small amount of moisture and air to pass through, and is extremely effective from the viewpoint of edibility. There are various amino acid polymers, lactic acid polymers, gelatin, etc. as substances that interfacially polymerize with sodium alginate to form a non-toxic, non-irritating and digestible film. This is because it forms a film that completely blocks permeation, leading to early deterioration of the food tissue when applied to fresh foods. The coating applied to fresh foods by the processing method of the present invention is colorless, tasteless, and odorless, so it does not impair commercial value, and since it is unlikely to stick to each other, it is easy to handle the food as a commercial product. Since it is soft and thin, it does not affect the texture of food such as chewiness. Note that the shelf life of fresh foods processed by the method of the present invention can be further improved by taking into consideration the packaging and transportation methods. That is, as an auxiliary means to suppress the respiration of plant tissue, it is wrapped in vinylidene chloride packaging material that is difficult to pass oxygen, and if necessary, an oxygen absorber is enclosed, and when transported, it is
If the temperature is maintained at a low temperature of ℃, the freshness period will be extended. Next, the present invention will be explained in more detail using processing examples, storage test examples, etc. Processing example 1 Processing of fresh strawberries 1 kg of freshly picked strawberries is washed with an aqueous solution of neutral detergent for food washing, rinsed with water, and loaded into a basket. Four 3-volume polyethylene buckets are prepared in advance as treatment tanks, and two volumes of the following solution are poured into each of these four tanks. 1st tank: Aqueous solution containing 0.02% sucrose ester and 0.7% sodium alginate 2nd tank: 15% calcium chloride aqueous solution 3rd tank: Phosphate buffer (PH7.0) 4th tank: 1% polylysine aqueous solution (by fermentation method) The obtained polylysine has a molecular weight of
5,000 to 150,000 mixture) The above-mentioned strawberries stuffed in a basket were first immersed in the first tank, and the basket was raised and lowered several times while being careful not to let the strawberries float, so that the sodium alginate solution was sufficiently attached to the surface of the strawberries.
Next, after pulling up the basket and draining off the excess liquid, the strawberries stuffed in the basket are immersed in a second tank and subjected to the same treatment, so that the sodium alginate solution adhering to the surface of the strawberries turns into a gel. Next, the basket-stuffed strawberries are immersed in the third tank and treated in the same manner, thereby achieving cleaning and stabilization of the gel. Third
The strawberries are taken out of the tank, drained, and immersed in a fourth tank to form a film with the gel. The immersion time in this fourth tank is required to be at least about 10 minutes. After being treated in the fourth tank, the strawberries are washed with water and packed in a predetermined number into sealed vinylidene chloride packaging containers. In addition, an oxygen absorber (usually a tablet) is placed inside the above packaging container.
When stored at 5 to 10°C, the treated strawberries retained their freshness for three times as long as untreated strawberries. Note that similar gel cleaning and stabilizing effects were obtained even when a sulfonic acid buffer (PH7.0) was used instead of the phosphate buffer (third tank solution). Processing Example 2 Processing of Matsutake Mushrooms Matsutake mushrooms were collected and washed, and then treated in the same manner as in Processing Example 1 to coat their surfaces. These treated matsutake mushrooms can be shipped and stored for a long period of time by placing absorbent cotton soaked in sufficient water in a container similar to that described in Processing Example 1, arranging them on top of the cotton, and then sealing the container. can. Furthermore, when sliced matsutake mushrooms were treated in the same manner and sealed in a container, the original flavor could be maintained for a long period of time without showing signs of dehydration or spoilage. Processing Example 3 Processing of Citrus Fruits The outer skin of 10 summer mandarin oranges was removed, and the thin skin was also thoroughly removed to obtain 800 g of pulp. This pulp is subjected to the treatment described in Processing Example 1, taking care not to disintegrate the pulp. By arranging this processed pulp in a vinylidene chloride container and sealing the container containing an oxygen absorber, a new type of fresh fruit product that can withstand distribution can be created. Note that fruits other than citrus fruits such as cherries can also be treated in the same manner to improve their shelf life. Application example Add an appropriate amount of sugar, citric acid, etc. to 1 part of water to create isotonic pressure, add 25g of gelice to this, heat and dissolve, then rapidly cool to 40℃, then dispense into containers such as cups. . Cut the banana with the outer skin removed and insert it into each of the above containers, and place the container in the refrigerator.
Hold at 5°C for 60 minutes to solidify the contents. If the exposed surface of the container mouth side of this solid (banana-containing jelly) is sequentially treated with each liquid described in Processing Example 1, a protective thin film that is impermeable to sterilization and slightly permeable to air and moisture will be formed. As a result, fruit jelly with good shelf life can be obtained. Room temperature storage test Foods processed according to the methods described in Processing Examples 1 to 3 and Application Examples were used as the test group, and corresponding untreated foods were used as the control group. The food was left at room temperature (varying from 10 to 25°C), and the occurrence of autolysis of the food itself and the degree of mold growth were observed over time. The results shown in Table 1 below were obtained. Although it was not possible to completely prevent the growth of mold because the coating treatment was performed only by washing without sterilization, the food in the test group showed a clear difference compared to that in the control group. This shows improved storage stability.

[Table] Low-temperature storage test Foods processed according to the methods described in Processing Examples 1 to 3 and Application Examples were sealed in a vinylidene chloride container together with a commercially available oxygen absorber to serve as a test group, and corresponding untreated foods were As a control group, each sample food was stored at low temperature (5 to 10℃) without packaging.
The occurrence of autolysis and the degree of mold growth were observed over time, and the results shown in Table 2 below were obtained. In the case of this test, the food was only washed and not sterilized, but the low-temperature storage significantly suppressed mold growth and self-digestion, and the food in the test group was different from the food in the control group. The test results clearly demonstrate that the storage stability is improved in comparison.

[Table] Changes in sugar concentration of strawberries during storage Samples were freshly picked strawberries. A: Sample strawberries that were washed and left at room temperature. B: Sample strawberries that were washed, processed according to the present invention, and left at room temperature. , sample strawberries processed according to the present invention, sealed in a vinylidene packaging container with an oxygen absorber (the same agent used in the low-temperature storage test), and left at room temperature, and D washed in the same manner as in C above; When we measured the change over time in the sugar concentration in the pulp of the sample strawberries that had been processed and sealed and kept cool at 0 to 10°C, and plotted the results, we obtained the graph shown in the attached drawing. . This graph shows that the processing, oxygen-blocking packaging, and low-temperature storage according to the present invention effectively reduce sugar content and maintain food freshness. Note that in this graph, there are variations in the initial sugar concentration, but this is due to variations in sugar concentration among the individual strawberries used as specimens.

[Brief explanation of the drawing]

The attached drawings are graphs showing changes in sugar concentration over time when strawberries are stored as specimens. Curve A is for the control specimen, curve B is for the control specimen, curve B is for the processed specimen according to the present invention, and curve C is for the original specimen. Curve D shows the case where the processed product according to the present invention is packaged in an oxygen-blocking manner, and the curve D shows the case where the processed product according to the present invention is packaged in an oxygen-blocking manner and maintained at a low temperature.

Claims (1)

[Scope of Claims] 1. A non-perishable fresh food product, characterized in that a digestible, limited permeability thin film formed from sodium alginate and polylysine produced by a fermentation method is adhered to the surface of the food product. 2. The process of washing fresh foods and the production of sucrose esters
0.01-0.1% and about 0.8-1.6% sodium alginate solution; 15% calcium chloride solution to form a gel of sodium alginate on the food surface; A step of washing and stabilizing the gel by immersing it in a phosphoric acid or sulfonic acid buffer solution, and a step of immersing it in an approximately 1% aqueous solution of polylysine obtained by a fermentation method to form a film by interfacial polymerization with the gel. A method for processing fresh foods to enhance their shelf life, characterized by comprising: