CN105123901B - Fresh-cut cress cold storage and preservation method - Google Patents

Abstract

The invention discloses a cold preservation method for fresh-cut cress, which mainly includes the following steps: (1) low-temperature cleaning of fresh cress; (2) low-temperature soaking and ozone water sterilization; (3) draining, cutting into sections, preserving (4) Vacuum packaging, refrigerated at 2~4°C to get the finished product. The method of the present invention effectively slows down the photosynthetic, respiration, transpiration and other physiological metabolic activities of fresh-cut water celery, effectively inhibits colony proliferation; passivates the activity of endogenous enzymes such as polyphenol oxidase, slows down its color brown during storage Change, the nutritional quality and flavor of the cress are well maintained, and the fresh-keeping method can make the effective fresh-keeping period of the cress up to more than 60 days. The inventive method has the advantages of simple and easy processing technology, strong operability, low energy consumption cost, no need for too much investment, green, safe and pollution-free process, and the obtained product is convenient to eat, and the shelf life of fresh-cut cress can be greatly extended, making cress The high-value utilization of products has opened up new ways.

Description

A kind of cold preservation method of fresh-cut cress

technical field

The invention belongs to the technical field of fresh-keeping and storage of aquatic vegetables, and in particular relates to a cold-keeping and fresh-keeping method of fresh-cut cress.

Background technique

Cress ( Oenanthe javanica ) belongs to the Umbelliferae plant and is cultivated all over the country. It is rich in nutritional and health ingredients and physiologically active substances, including protein, carbohydrates, carotene, B vitamins, essential amino acids in the human body, unsaturated fatty acids, Butylphenols, flavonoids and trace elements such as calcium, phosphorus, iron, sodium, etc., also have the functions of calming the liver and clearing away heat, expelling wind and dampness, reducing swelling and troubles, cooling blood to stop bleeding, detoxifying the lungs, invigorating the stomach and promoting blood, clearing It has the effects of facilitating the intestines, nourishing the lungs and relieving coughs, lowering blood pressure, strengthening the brain and calming down, and has become a daily delicacy on people's tables. There are many processed products of water celery on the market, such as pickled celery, preserved celery, quick-frozen celery, etc., and pickled celery and preserved celery lose or partially lose the nutritional value and local flavor of fresh celery; The quality of fresh celery, but because of the high cost of production and transportation, and due to the generation of ice crystals, the inherent texture characteristics of fresh celery after thawing will change, resulting in varying degrees of deterioration in its flavor and taste; The value and food value are very high and favored by consumers. However, fresh cress has poor storability due to its short harvest period, high levels of physiology, biochemistry and metabolism. At room temperature, fresh celery is very easy to brown, rot and deteriorate. Even under refrigerated conditions (2-4 ℃), its storage and transportation period is generally about 10 days, and its commercial value is low.

Gu Xin et al disclosed "a method of using water celery green-protecting and fresh-keeping compound (publication number: CN103749661A)". The water celery was successively selected, washed, pre-cooled with ice water, cut into sections, and added to calcium lactate, zinc acetate, water, etc. Soak in the green-protecting preservative solution composed of salicylic acid, drain the product and put it into a fresh-keeping bag with ventilated holes. Under the refrigeration condition of 4 ℃, the shelf life of fresh-cut cress is extended to 15-25 days. Xie Jing et al disclosed "A fresh-keeping method for prolonging the shelf life of celery (public number: CN102550649A)". Compared with cold storage, this method can obviously prolong the shelf life of celery by 20 days. At the same time, Xie Jing and others disclosed "a fresh-keeping method for fresh-cut celery (public number: CN102805144A)". After soaking in ozone water and draining, the corresponding products were obtained by modified atmosphere packaging, which can extend the shelf life of fresh-cut celery to 50 days under refrigeration (2-4 ℃). The freshness period of the former two is about 25 days, and the commercial value is not high; the freshness period of the latter can reach 50 days, and the commercial value is high, but the process is relatively complicated, and special modified atmosphere packaging equipment is required. Therefore, finding a simple and efficient fresh-cut watercress preservation technology is of great significance for improving the industry level of watercress, increasing the added value of watercress, and meeting consumer demand.

Contents of the invention

The invention aims to overcome the deficiencies of the prior art, and provides a cold storage method for fresh-cut cress.

In order to achieve the above object, the technical solution provided by the invention is:

The refrigerated fresh-keeping method of described fresh-cut cress comprises the following steps:

(1) Store and transport freshly picked cress at low temperature (2-4°C) at the place of picking to the place of production. After removing the leaves and tendons, wash it in a low-temperature pool at 2-4°C;

(2) Soak the cleaned cress in 2-4 ℃ low-temperature water for 1-2 h, drain and soak in ozone water with a concentration of 10-15 mg/L for 2-3 min;

(3) Drain the water celery soaked in ozone water, cut into sections (cutting sections can adopt different specifications according to product requirements), and then put it in the compound color-protecting and fresh-keeping liquid (cool the pre-prepared color-protecting and fresh-keeping liquid to the processing temperature 2~4 ℃) for 5~10 minutes, drained to form a film; the composite preservation solution is a sodium citrate-citric acid buffer solution system dissolved in nano starch, with a pH value of 4.5~5.5, preferably 4.5, nano The mass percentage of starch in the buffer system is 1.0~2.0%;

(4) Vacuum pack the cress treated in step (3) and refrigerate.

Preferably, when soaking cress in low-temperature water in step (2), the volume-to-mass ratio of water to cress is (2-3):1, the volume unit is L, and the mass unit is kg.

Preferably, when soaking cress in the step (3), the volume-to-mass ratio of the compound color-preserving liquid to the cress is (2~3):1, the volume unit is L, and the mass unit is kg.

Preferably, the refrigerated temperature in step (4) is 2-4°C.

The present invention is further explained and illustrated below:

The low-temperature storage, transportation, cleaning and soaking of freshly picked cress described in step (1) aims to reduce or partially inactivate the biological activities of polyphenol oxidase and peroxidase through low-temperature storage, transportation and low-temperature cleaning and soaking of the freshly picked cress , reduce respiration and transpiration of fresh cress, and slow down color changes of cress such as browning that may be caused by high ambient temperature during harvesting, storage and transportation. In step (2), immerse in 10-15 mg/L ozone water for 2-3 minutes, aiming to kill microbes on the surface of cress and prevent it from causing corruption during storage and transportation, which is different from previous patents by Xie Jing et al. In the document, low-concentration (0.9~1.0 mg/L) ozone water is used for treatment. The present invention uses high-concentration ozone water for immersion treatment. Not only is it more efficient, but high-concentration ozone water was also difficult to achieve in the past few years. The cuts of fresh water celery mentioned in step (3) are screened and grouped strictly according to color, hardness and aroma, etc., each group selects seven mature water celery with uniform length and size, removes leaves, tendons, and washes and then cuts into sections , the length can adopt different specifications according to production requirements. In the preparation of the color-preserving and fresh-keeping coating liquid in step (3), the easy-to-dissolvability and film-forming properties of nano-starch are cleverly used, and the sodium citrate-citric acid buffer system is organically combined to realize the color-preserving and fresh-keeping effect of cress; while maintaining a low pH range, it has a good inhibitory effect on the growth of biological enzymes and microorganisms. Due to the excellent film-forming properties of nano-starch solution, a sodium citrate-citric acid buffer system containing 1.5-2.0% nano-starch was selected as the color-preserving solution through a large number of experimental studies. Step (4) Drain the fresh-cut cress that has been treated with color-protecting fresh-keeping soaking coating solution and film, and put it into a polypropylene film bag under aseptic conditions, and use a vacuum packaging machine for aseptic sealing Pack and refrigerate at 2~4°C.

Compared with the prior art, the present invention has the advantages of:

1. The method of the present invention adopts the low-temperature pretreatment in the place of origin to solve the key technical problems such as the large color change of fresh cress caused by high temperature in the traditional picking process, reduces the activity of polyphenol oxidase, and slows down the color change of fresh-cut cress. Reduced respiration loss of fresh-cut cress.

2. The method of the present invention adopts high-concentration (10-15 mg/L) ozone water treatment, which is 10 times the concentration of ozone water (0.9-1.0 mg/L) used in the past, and is carried out under relatively low temperature conditions, and the sterilization treatment is more efficient efficient.

3. The method of the present invention adopts color-preserving and fresh-keeping immersion coating method, fully utilizes the good solubility and film-forming properties of nano-starch (different from chitosan, pullulan, etc.) and the sodium citrate-citric acid buffer system The effect of color protection and fresh-keeping, the effective combination of the two, realizes the high-efficiency color protection and fresh-keeping of fresh-cut cress, has little damage to the nutritional value of water-cress, and maintains the original color and flavor of fresh-cut water-cress.

4. The present invention effectively slows down the respiration and transpiration of fresh-cut cress through the method of color-protecting and fresh-keeping vacuum packaging, so that fresh-cut cress is in a weak life state, effectively prolonging the shelf life of fresh-cut cress, and the product is better The original flavor, nutritional content and sensory quality are maintained, and the effective fresh-keeping period is more than 60 days at a low temperature of 2-4 °C, which greatly prolongs the shelf life of fresh-cut cress and increases the added value of cress products.

In a word, the method of the invention has the advantages of simple processing technology, low cost, safety and pollution-free, convenient eating, greatly prolongs the shelf life of fresh-cut cress, and opens up a new way for high-value utilization of cress products.

Detailed ways:

Example 1

300 kg freshly picked watercress from the place of origin was immediately transported to the place of production in a low-temperature transport vehicle at 4°C. After removing the leaves and ribs, screening and grouping, it was washed in a low-temperature pool at 4°C, and then soaked in low-temperature water at 4°C for 2 hours. When soaking, the volume-to-mass ratio of water and cress is (2~3):1, the volume unit is L, and the mass unit is kg; fill the low-temperature soaking pool with 15 mg/L ozone water and soak for 2 min, without Under bacterial environment, drain, cut into sections, each section is 3-5 cm long, soak fresh-cut watercress in the pre-prepared nano-starch 1.5% sodium citrate-citric acid composite system for 10 minutes, compound color protection The volume-to-mass ratio of the preservation solution to the cress is (2-3):1, the volume unit is L, and the mass unit is kg. Drain, put into polypropylene film bags, seal and pack with a vacuum packaging machine, and refrigerate at a low temperature of 4 °C for 60 days. The shape of fresh-cut cress has no adverse changes, and the color is uniform, just like freshly picked cress.

Example 2

500 kg freshly picked watercress from the place of origin, immediately transported to the place of production in a low-temperature transport vehicle at 2°C. After removing the leaves and tendons, screening and grouping, it was washed in a low-temperature pool at 2°C, and then soaked in a low-temperature pool at 2°C for 1.5 hours. , the volume-to-mass ratio of water to cress is (2~3):1, the volume unit is L, and the mass unit is kg; fill the low-temperature soaking pool with 10 mg/L ozone water and soak for 3 minutes, without Under bacterial environment, drain, cut into sections, each section is 3-5 cm long, soak fresh-cut watercress in the sodium citrate-citric acid composite system with a mass percentage of 2.0% of nano-starch prepared in advance for 5 minutes, compound color protection The volume-to-mass ratio of the preservation solution to the cress is (2-3):1, the volume unit is L, and the mass unit is kg. Drain, put into polypropylene film bags, seal and pack with a vacuum packaging machine, and refrigerate at a low temperature of 2 °C for 65 days. The appearance of fresh-cut cress has no adverse changes, and the color is uniform, just like freshly picked cress.

Claims (4)

1. a cold preservation method of fresh-cut water celery, is characterized in that, described method comprises the following steps: (1) Clean the freshly picked cress in a low-temperature pool at 2-4 °C after removing the leaves and tendons; (2) Soak the cleaned cress in 2-4 ℃ low-temperature water for 1-2 h, drain and soak in ozone water with a concentration of 10-15 mg/L for 2-3 min; (3) Drain the cress soaked in ozone water, cut into sections, soak in the composite color-preserving liquid for 5-10 minutes, and then drain to form a film; the composite color-preserving liquid is nano-starch dissolved Sodium citrate-citric acid buffer solution system, the pH value is 4.5~5.5, and the mass percentage of nano starch in the buffer solution system is 1.0~2.0%; (4) Vacuum pack the cress treated in step (3) and refrigerate. 2. The method according to claim 1, characterized in that, in step (2), when soaking cress in low-temperature water, the volume-to-mass ratio of water to cress is (2 ~ 3): 1, and the volume unit is L , the mass unit is kg. 3. The method according to claim 1, characterized in that, in step (3), when the watercress is soaked in the compound color-preserving liquid, the volume-to-mass ratio of the compound color-protecting liquid and cress is (2 ~ 3): 1. The volume unit is L, and the mass unit is kg. 4. The method according to claim 1, characterized in that the refrigerated temperature in step (4) is 2-4 °C.