Liquid nitrogen frozen bamboo shoots

1. Process flow of frozen bamboo shoots

Raw material selection -Cleaning - peeling - removing bamboo shoots and coarse fibers - slicing (silk) - blanching - cold water spray cooling - cold water soaking cooling - frozen water soaking cooling - draining - quick freezing - inspection - packaging - sampling - refrigeration - cold chain transportation - refrigerated sales.

2. Key points of operation

Raw material selection:Select fresh and pest free hemp (sweet) bamboo shoots that meet the safety requirements of national hygiene standards for pollution-free vegetables.

Raw material pretreatment:Clean the raw materials thoroughly, then use a sheller to peel off the bamboo shoot shell, manually remove the bamboo shoot coat, cut off the fibrotic part of the bamboo shoot base, slice or shred according to specifications, and immediately rinse with running water to prevent browning and fermentation of the bamboo shoot meat.

float Hot:The purpose is to inactivate the activity of enzymes in bamboo shoot tissues and kill bacteria, prevent bamboo shoot flesh fibrosis, oxidative discoloration, and microbial contamination Blanch in hot water at 96-98 degrees for 2 minutes. As this process is related to the microbiological hygiene standards of the product, the process conditions should be strictly controlled.

Select fresh bamboo shoots that are plump, intact, clean, have good color, no decay, no mold, no odor, and no pests, diseases, or mechanical damage that affect consumption. After harvestingPre cool in 1-5 cold storage for 10-24 hours within 2-8 hours;

Fresh bamboo shoots that have been pre cooled are first subjected to shell removal, cleaning, and sectioning treatment;

Soak in a solution of composite brittle protectants with added antioxidant or polymer substances20-60 minutes;

After soaking, drain the water from the bamboo shoots and pour in liquid nitrogen to make them soak-Quickly freeze to the center temperature of bamboo shoots in an environment ranging from -10 to -20 degrees Celsius.

Fresh bamboo shoots that have been rapidly frozen are placed in-Frozen bamboo shoots can be stored in a 10-25 cold storage for less than 24 months.

Measuring the glass transition temperature of bamboo shoots is crucial for ensuring their quality stability. It is of great significance for developing reasonable freeze-drying or rapid freezing processes, preserving freshness, reducing losses caused by mold, and thawing.

Pre cooling treatment:The closer the temperature of the material is to the freezing point before freezing, the faster the material freezes and the better the quality of the product. Therefore, before quick freezing, it undergoes cold water spraying, cold water soaking, and frozen water soaking -In two stages, gradually reduce the material temperature to around 10 degrees. In order to control the growth and reproduction of microorganisms, chlorine containing disinfectant is added to the cold water and frozen water used to soak bamboo shoots. The cold water and frozen water should be in a flowing state to improve the cooling effect.

drip Water:The pre cooled bamboo shoots are transported to the freezing area by a stainless steel conveyor belt and first subjected to vibration and air blowing to remove moisture from the surface of the shoots and prevent them from sticking together during freezing.

quick Frozen:Adopting the method of rapid freezing with Zhuoda Yuntong liquid nitrogen freezer, temperature -70 degrees; The rapid freezing process of bamboo shoots is divided into two sections, the first section is the surface freezing zone, and the second section is the deep temperature freezing zone. After entering the freezing chamber, the bamboo shoots are first rapidly cooled, that is, the surface is cooled to the freezing point temperature to freeze the surface, and then enter the second section for deep temperature freezing until the center temperature is below -18 degrees. The entire freezing process is completed within about 20 minutes.