深冷冻主要是利用低温制冷剂(液氮、液态、CO2等)为冷却介质,通过热量的对流和传导使冻品快速冻结达到低温处理的目的。冻品以足够快的冷却速度实现玻璃态,从而降低菌体细胞损伤。在益生菌生产中,深度冷冻效果好、菌体失活少、生产效率高、设备投资维护费用低,优于传统的冷冻干燥。益生菌生产中主要利用颗粒滴冻式设备,比传统冷冻装置有更多优点。深冷冻过程中主要存在胞外冻结和胞内冻结伤害两方面,但结合使用合理的保护剂可以降低细胞伤害,保护剂分为渗透性和非渗透性两大类。

Cryogenic freezing mainly uses low temperature refrigerants(e.g.liquid nitrogen,liquid carbon dioxide(CO2),etc.) as cooling medium to achieve low temperature through heat conduction and convection.The glass state may reduce damage of bacterial cell with rapid freezing rate.Cryogenic depth frozen is superior to freeze drying due to its high frozen quality,low devitalization rate,high efficiency and low cost for investment and equipment maintenance in the production of probiotics.The particle cryogenic refrigerating device is widely used in manufacture of probiotics and precedes to traditional facility.Although cryogenic freezing process results in exocellular and intracellular freezing damages,permeable or impermeable protectants can be used to reduce those damages.