阅读说明：本技术 一种冰鲜无硫笋及其制备方法 (Frozen fresh sulfur-free bamboo shoot and preparation method thereof ) 是由 靳岳 赵志峰 蒋茜 刘亚娟 于 2019-07-17 设计创作，主要内容包括：本发明公开了一种冰鲜无硫笋及其制备方法,新鲜竹笋去除笋衣后,依次用0.1％盐水漂洗、清水浸泡,随后对其进行切割,再在清水中浸泡,捞出预煮、冷却,分三次进行液氮速冻,最后渡冰衣、真空包装、冷藏,即得一种冰鲜无硫笋。本发明采用盐洗以及预煮工艺脱去竹笋的苦味,钝化酶活,不采用任何硫制剂进行护色处理,用液氮速冻工艺,最大维护产品色泽与质构,冰鲜笋色泽接近鲜笋色泽,品质佳。后期运用三阶段式液氮速冻技术,降低制冷能耗的同时还能最大程度保留竹笋的脆嫩的口感及其淡黄色泽。在笋外壳渡冰衣工艺,能减缓竹笋的色泽变化,以及质构破坏,提升产品品质,且煮制后的口感比清水笋更为脆嫩,适用范围更广。(the invention discloses a frozen fresh sulfur-free bamboo shoot and a preparation method thereof, wherein the frozen fresh sulfur-free bamboo shoot is prepared by removing the bamboo shoot skin from fresh bamboo shoots, sequentially rinsing the fresh bamboo shoots with 0.1% saline water, soaking the fresh bamboo shoots in clear water, then cutting the fresh bamboo shoots, soaking the fresh bamboo shoots in the clear water, fishing out, pre-boiling, cooling, quickly freezing by liquid nitrogen for three times, finally coating ice, vacuum packaging and refrigerating. The invention removes the bitterness of the bamboo shoots by adopting a salt washing and pre-boiling process, passivates enzyme activity, does not adopt any sulfur preparation for color protection treatment, adopts a liquid nitrogen quick-freezing process, maintains the color and texture of the product to the maximum extent, and the color and the texture of the ice fresh bamboo shoots are close to those of the fresh bamboo shoots, thereby having good quality. And a three-stage liquid nitrogen quick-freezing technology is applied at the later stage, so that the crisp and tender taste and light yellow color of the bamboo shoots can be kept to the maximum extent while the refrigeration energy consumption is reduced. The process of coating ice on the bamboo shoot shell can slow down the color change and the texture damage of the bamboo shoots, improve the product quality, and ensure that the boiled bamboo shoots are more crisp and tender than the boiled bamboo shoots, and have wider application range.)

1. a preparation method of frozen fresh sulfur-free bamboo shoots is characterized by comprising the following steps:

(1) Cleaning: rinsing the fresh bamboo shoots without the bamboo shoot skins for 2-3 times with saline water to remove surface impurities, soaking for 3-5min with clear water, and changing water for 1-2 times to obtain fresh bamboo shoots for later use;

(2) Finishing and slitting: removing old root of fresh bamboo shoot, cutting into 10-15cm long pieces, cutting into two halves, soaking in clear water, and collecting cut bamboo shoot;

(3) Pre-cooking: adding water into the interlayer pot, boiling, pre-boiling the cut bamboo shoots in the interlayer pot, and taking out to obtain pre-boiled bamboo shoots for later use;

(4) And (3) cooling: soaking the pre-cooked bamboo shoots in clear water, repeatedly changing water for 3-4 times, cooling to normal temperature, and draining for later use;

(5) Liquid nitrogen quick freezing: placing the cooled pre-cooked bamboo shoots on a mesh belt of a liquid nitrogen instant freezer to carry out three-stage sectional type liquid nitrogen instant freezing;

(6) Ice coating: soaking the quick-frozen bamboo shoots in a cold water tank through a mesh belt, taking out the quick-frozen bamboo shoots along with the mesh belt, draining, and repeatedly soaking for 3-4 times;

(7) and (3) vacuum packaging: carrying out vacuum packaging on the ice fresh bamboo shoots individually;

(8) And (3) refrigerating: and (4) refrigerating and storing the packaged fresh frozen bamboo shoots at the temperature of 18 ℃ below zero.

2. The method as claimed in claim 1, wherein the brine concentration in the step (1) is 0.1%, and the rinsing time is 3-5min per time.

3. the preparation method of claim 1, wherein the mass ratio of the water to the cut bamboo shoots in the step (3) is 3: 1.

4. The method of claim 1, wherein the precooking time of step (3) is 20 min.

5. the preparation method according to claim 1, wherein the temperature of the clean water in the step (4) is 20-25 ℃, and the soaking time is 5-10min each time.

6. The method for preparing the compound of claim 1, wherein the three-stage sectional type liquid nitrogen quick freezing in the step (5) is as follows: the temperature of the first stage is-40 deg.C for 5min, the temperature of the second stage is-90 deg.C for 10min, and the temperature of the third stage is-50 deg.C for 5 min.

7. The preparation method according to claim 1, wherein the temperature of the cold water pool in the step (6) is 0-4 ℃, and the soaking time is 70-90s each time.

8. the method as claimed in claim 1, wherein the time interval between the repeated soaking in step (6) is 100-120 s.

9. The method for preparing the ice coating of claim 1, wherein the air temperature of the ice coating in the step (6) is less than or equal to-8 ℃, and the thickness of the ice shell is 0.3-0.5 cm.

10. a frozen fresh sulphur-free bamboo shoot obtainable by the method of any one of claims 1 to 9.

Technical Field

the invention relates to the field of food processing, in particular to a preparation method of a frozen fresh sulfur-free bamboo shoot and the frozen fresh sulfur-free bamboo shoot prepared by the method.

background

Bamboo shoots are the buds of bamboo, also known as bamboo shoots. The bamboo is perennial evergreen herbaceous plant, and the edible part is primary, tender and fat, short and strong bud or penis. The bamboo is native to China, and has various types, strong adaptability and wide distribution. Bamboo shoots are sweet and slightly cold in nature and have the effects of clearing heat and dissolving phlegm, benefiting diaphragm and cooling stomach, quenching thirst and tonifying qi and the like. Bamboo shoots also contain a large amount of cellulose, and not only can promote intestinal peristalsis, remove food retention and prevent constipation, but also are good food for fat people to lose weight.

in recent years, with the popularization of high-yield technology of bamboo shoot forests and bamboo shoot and bamboo dual-purpose forests, the yield of fresh bamboo shoots in China is gradually increased year by year. The bamboo shoots are strong in seasonality and not storage-resistant, and the pulp fibers are easy to age and rot and are not beneficial to long-distance transportation, so that the rest of the bamboo shoots are all used for processing canned bamboo shoots and dried bamboo shoots (including various fresh-keeping bamboo shoots such as boiled bamboo shoots, seasoned bamboo shoots, sheep tail bamboo shoots and salted bamboo shoots, and special dried bamboo shoots such as green dried bamboo shoots, dried Tianmu bamboo shoots, fermented dried bamboo shoots, magnolia slices and dried salted bamboo shoots) except 40% of fresh bamboo shoots.

at present, the most utilized bamboo shoots are clear water bamboo shoots, the processing technology is mature, and the production equipment is complete. Most bamboo shoot processing enterprises in China adopt normal-pressure direct heating sterilization to process bamboo shoots, which easily causes the phenomena of nonuniform heating of products, microbial hazards such as rancidity, soft rot and bag expansion and the like, and influences the quality of the products. In order to guarantee the shelf life of the product, most of the commercially available clear water bamboo shoot cans are added with chemical preservatives such as sodium benzoate and potassium sorbate to prolong the shelf life of the product. However, recent food safety studies have shown that excessive addition and abuse of chemical preservatives present a greater potential health hazard to consumers. Meanwhile, in order to ensure that bamboo shoot raw materials are not rotten or deteriorated, a large amount of sodium sulfite is used for corrosion prevention and decolorization in the pretreatment of the raw materials in the conventional processing technology, and long-time desulfurization is forced in the later stage of production, so that the mode not only causes pollution to the environment, but also increases the production period and the cost; if the desulfurization is not thorough, the sulfur content in the product can exceed the standard, and the health of consumers is harmed.

Application number 201010579476.7 discloses a processing method for fresh-keeping bamboo shoots, which comprises the following specific steps: (1) and de-enzyming: placing the collected fresh bamboo shoots for 2-4 hours, boiling the fresh bamboo shoots with water for 15-20 minutes, taking out and draining the water; (2) and pickling: adding salt and sodium pyrosulfite into the de-enzymed bamboo shoots, uniformly stirring for 3-4 times, storing the bamboo shoots in a shady and cool place in a dark place, and pickling for 5-8 days; by mass: 15% of salt and 0.5% of sodium metabisulfite; (3) rinsing and removing impurities; (4) and (3) sterilization: soaking the bamboo shoots in 0.04-0.06% (mass percentage concentration) of chlorine dioxide disinfectant for 8-12 minutes; (5) preparing fresh-keeping liquid according to 100 kg of water, 6-8 kg of salt, 40-50 g of sodium benzoate and 80-100 g of edible alcohol with the purity of 95%; (6) and vacuum packaging: packaging the bamboo shoots with a packaging bag, adding 40 percent (mass percent) of fresh-keeping liquid, and packaging with a vacuum packaging machine to obtain the finished product. The main disadvantages of the method are that the used sodium metabisulfite has sulfur dioxide smell, acid and salt, the applied sodium benzoate is used as a chemical preservative, a series of carcinogenic hidden dangers exist, the salt content is high, the sodium metabisulfite has certain alcohol smell, and the vacuum packaging is complex.

application No. 200910264845.0 discloses a fresh bamboo shoot coating preservative prepared from an edible material, and particularly discloses a fresh bamboo shoot coating preservative prepared from all edible materials. The main components of the antibacterial agent comprise one or more of natural plant gum, polysaccharides, natural high molecular substances, stabilizing agents, bacteriostatic agents and the like. The preparation method comprises dissolving the above materials at a certain ratio, stirring, heating to accelerate dissolution, cooling, and making into aqueous solution or colloidal solution. The preservative has certain potential safety hazard because of the existence of substances such as stabilizers, bacteriostats and the like with unknown components, and meanwhile, the bacteriostats also influence the microbial population in the gastrointestinal tract to a greater or lesser extent or have residues.

Application No. 201110414487.4 discloses a bamboo shoot preservative and application thereof, and discloses a coating preservation method of fresh dendrocalamus latiflorus, namely soaking cleaned bamboo shoots in the bamboo shoot preservative, and drying the soaked bamboo shoots, and specifically discloses that the formula of the bamboo shoot preservative is as follows: 0.05 to 0.1 mass percent of salicylic acid aqueous solution and 1.0 to 1.5 mass percent of chitosan coating liquid. The disadvantages of this method are: the long-term eating of the health food can cause the poisoning of salicylic acid and salts thereof, the toxicological action of the health food is mainly shown as direct stimulation to the central nervous system and the digestive tract, and the like, and potential safety hazards exist.

In view of the analysis, the chilled sulfur-free bamboo shoots which can maintain the color and texture of the product to the maximum extent without any sulfur preparation, have crisp and tender mouthfeel and light yellow color, are more crisp and tender in mouthfeel than the fresh bamboo shoots after being directly cooked and have wide application range are urgently needed in the industry at present.

Disclosure of Invention

in view of the defects, the invention provides the frozen and fresh sulfur-free bamboo shoots which can maintain the color and texture of the product to the maximum extent without adopting any sulfur preparation for color protection treatment, have crisp and tender mouthfeel and light yellow color, are more crisp and tender in mouthfeel than the fresh water bamboo shoots after being directly cooked, and have wide application range. The invention is realized by the following means:

A preparation method of frozen fresh sulfur-free bamboo shoots comprises the following steps:

(1) Cleaning: rinsing the fresh bamboo shoots without the bamboo shoot skins for 2-3 times with saline water to remove surface impurities, soaking for 3-5min with clear water, and changing water for 1-2 times to obtain fresh bamboo shoots for later use;

(2) finishing and slitting: removing old root of fresh bamboo shoot, cutting into 10-15cm long pieces, cutting into two halves, soaking in clear water, and collecting cut bamboo shoot;

(3) Pre-cooking: adding water into the interlayer pot, boiling, pre-boiling the cut bamboo shoots in the interlayer pot, and taking out to obtain pre-boiled bamboo shoots for later use;

(4) And (3) cooling: soaking the pre-cooked bamboo shoots in clear water, repeatedly changing water for 3-4 times, cooling to normal temperature, and draining for later use;

(5) Liquid nitrogen quick freezing: placing the cooled pre-cooked bamboo shoots on a mesh belt of a liquid nitrogen instant freezer to carry out three-stage sectional type liquid nitrogen instant freezing;

(6) Ice coating: soaking the quick-frozen bamboo shoots in a cold water tank through a mesh belt, taking out the quick-frozen bamboo shoots along with the mesh belt, draining, and repeatedly soaking for 3-4 times;

(7) And (3) vacuum packaging: carrying out vacuum packaging on the ice fresh bamboo shoots individually;

(8) and (3) refrigerating: and (4) refrigerating and storing the packaged fresh frozen bamboo shoots at the temperature of 18 ℃ below zero.

Further, the concentration of the saline water in the step (1) is 0.1%, and each rinsing time is 3-5 min.

Further, the mass ratio of the water to the cut bamboo shoots in the step (3) is 3: 1.

Further, the precooking time in the step (3) is 20 min.

Further, the temperature of the clean water in the step (4) is 20-25 ℃, and the soaking time is 5-10min each time.

Further, the three-stage sectional type liquid nitrogen quick freezing in the step (5) is as follows: the temperature of the first stage is-40 deg.C for 5min, the temperature of the second stage is-90 deg.C for 10min, and the temperature of the third stage is-50 deg.C for 5 min.

Further, the temperature of the cold water pool in the step (6) is 0-4 ℃, and the soaking time is 70-90s each time.

further, the time interval of the repeated soaking in the step (6) is 100-120 s.

further, the air temperature of the ice coating in the step (6) is less than or equal to-8 ℃, and the thickness of the ice shell is 0.3-0.5 cm.

the invention also discloses the frozen fresh sulfur-free bamboo shoot prepared by any preparation method.

the method adopts liquid nitrogen quick-freezing three-stage temperature regulation to treat the bamboo shoots, aims to reduce energy consumption, simultaneously furthest retains the crisp and tender taste and the yellowish color thereof, has low damage degree on cells and protoplasm, and has small damage to the texture of the bamboo shoots during thawing. Therefore, a thermometer is adopted to measure the central temperature of the bamboo shoots, the central temperature of the bamboo shoots is recorded to be reduced by 0 ℃, 0-5 ℃ and-5 ℃ to-18 ℃, and the specific operation process is as follows:

Group 1 is subjected to quick-freezing treatment at-30 ℃;

2 groups adopt quick-freezing treatment at-50 ℃;

quick-freezing at-90 deg.C in group 3;

The 4 groups adopt a first stage with the temperature set at-30 ℃ for 5min, a second stage with the temperature set at-90 ℃ for 10min, and a third stage with the temperature set at-50 ℃ for 5 min.

the center fall time of bamboo shoots for each group of samples is shown in table 1.

TABLE 1 center falling time of bamboo shoot at different quick-freezing temperatures

。

as can be seen from Table 1, the single liquid nitrogen quick freezing temperature treatment is adopted, 17.7min is required for quick freezing treatment at the set temperature of minus 18 ℃, 23.3min is required for quick freezing treatment at the set temperature of minus 30 ℃, the longer the quick freezing time is, the greater the damage to the texture of bamboo shoots is, the freezing requirement can be met at 18.1min through three-stage temperature adjustment treatment, the energy consumption is lower, and the reasonable mode is that in order to set the liquid nitrogen quick freezing machine, according to different temperature conditions, the section from room temperature to 0 ℃ is set as the processing time of minus 30 ℃ for 5min, the section from 0 ℃ to minus 5 ℃ is set as the processing time of minus 90 ℃ for 10min, and the section from minus 5 ℃ to minus 18 ℃ is set as the processing time of minus 50 ℃ for 5 min.

The invention has the beneficial effects that:

(1) The invention removes the bitterness of the bamboo shoots by adopting a salt washing and pre-boiling process, passivates enzyme activity, does not adopt any sulfur preparation for color protection treatment, adopts a liquid nitrogen quick-freezing process, maintains the color and texture of the product to the maximum extent, and the color and the texture of the ice fresh bamboo shoots are close to those of the fresh bamboo shoots, thereby having good quality.

(2) The three-stage liquid nitrogen quick freezing technology and the sectional facility temperature can achieve the same quick freezing effect and reduce the refrigeration energy consumption. After quick freezing by liquid nitrogen, the bamboo shoots retain the crisp and tender mouthfeel and the light yellow color thereof to the maximum extent, have low damage degree on cells and protoplasm and have small damage to the texture of the bamboo shoots during thawing.

(3) The invention adopts the process of coating ice on the bamboo shoot shell, forms a layer of transparent ice shell outside the bamboo shoot to increase the added value of the appearance of the product, isolates air, reduces drying loss, slows down the color change and the texture damage of the bamboo shoot, improves the product quality, and has more crisp and tender mouthfeel after being boiled than the fresh water bamboo shoot, and has wider application range.

drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description