Fresh bamboo shoots → raw material pretreatment → cooking → cooling and rinsing → trimming → grading and bagging → soup injection → sealing → sterilization → cooling → finished products.

2. Key points of operation

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(2) Cooking Put bamboo shoots in a steamer, cover them with 0.2% citric acid, and cook for 20 minutes until they are completely rotten but not rotten enough to tear, then immediately take them out and cool them with cold water. Cooling must be thorough, otherwise the color of bamboo shoots will darken, and there will be softening and rancidity after maturity.

(3) Cooling and rinsing: soak the treated bamboo shoots in a running water tank for bleaching 16 h~20 h, and all the water must be changed every 5 h. The rinsing time can be appropriately adjusted according to the local air temperature, water temperature, water quality and pH value of bamboo shoots. Too long rinsing time will affect the taste, color and nutritional components of bamboo shoots.

(4) Trimming and selecting bamboo shoots with the same size, color and quality, cutting them into bamboo shoots according to the tip of the bamboo shoots, and then bagging the raw materials.

(5) Grading and bagging are based on the size, meat thickness, luster and fragrance of bamboo shoots. The first-class bamboo shoots are bell-shaped or cannonball-shaped, with short internode fat, fresh and tender bamboo shoots and good color and fragrance; The second grade is angular bamboo shoots, with long internodes and slightly curved; The third grade is slender and curved bamboo shoots. Before bagging, the bamboo shoots should be washed with clear water, and the mass ratio of the largest bamboo shoot to the smallest bamboo shoot in the same bag should not exceed 2. When bagging, the bamboo shoots should be staggered, neat and beautiful, and the packaging material should be composite transparent retort pouch.

(6) Add 0.2% citric acid, 0. 15% fruit and vegetable crispness-keeping additive (ZB), 0.2% fruit and vegetable freshness-keeping additive (ZB2), sun-resistant universal color fixative (HA) and 3% salt into water, dissolve and filter, put them into a barrel, and then add them into a composite transparent retort bag.

(7) Generally, vacuum sealing should be adopted, and the air in the bag should be exhausted as far as possible, and it should be sealed immediately after the soup is injected. If there is still a small amount of water vapor attached to the inner wall of the bag mouth after adding the soup, it can be dried with a clean dry cloth and sealed.

(8) sterilizing and cooling, namely pasteurizing the finished product, wherein the sterilization temperature is 65438 000 DEG C and the sterilization time is 65438±05min；; After sterilization, the finished product is taken out and cooled.

3. Preventive measures

(1) The main reason for preventing the rancidity and juice turbidity of bamboo shoots is that the bamboo shoots are not cooled in time after cooking or the cooling water is insufficient, which leads to the high temperature of bamboo shoots for a long time and the residual heat cannot be released in time. In addition, too long rinsing time, stagnant water in the pool and not changing water in time will all lead to rancidity. Therefore, the washing conditions should be strictly controlled, the pool water should be able to flow or change water in time, and sufficient water should be prepared to ensure sufficient washing.

(2) Adjustment of pH value The quality of soft-packed bamboo shoots is closely related to pH value. Adjusting pH has the following four functions:

① Tyrosine is easy to dissolve out under acidic conditions. Therefore, adjusting the pH value to 4.2~4.5 can effectively control the formation of white material. (2) Reducing pH value can better inhibit the chemical reddening caused by polyphenol oxidase in bamboo shoots. ③ Browning of bamboo shoots can be avoided. Retort pouch used for soft packaging of canned bamboo shoots is transparent, and bamboo shoots will inevitably turn brown when exposed to sunlight. If citric acid solution with pH of about 4.5 is added to the bag, the above phenomenon can be reduced. ④ Reduce the occurrence of soft rot. Soft and rotten bamboo shoots look normal from the outside, but in fact they will deteriorate, soften and destroy tissues. Some scholars believe that bacteria that are easy to reproduce at 37℃ can be isolated from soft rotten bamboo shoots, and this bacteria cannot grow in an environment with pH below 4.7. Therefore, keeping the pH value of soup below 4.7 can reduce the occurrence of soft rot.