在发酵肉制品的发与应用生产中,浓缩型冻干发酵剂的制备具有重要的研究价值。该研究以植物乳杆菌为目标菌株,首先,研究不同生长因子对菌株的增殖作用,利用正交实验设计对生长因子进行复配,得到佳增殖培养条件;其次,研究离心条件在菌体富集时对菌体损失率和存活率的影响;后,研究冻干条件以及冻干保护剂选择对浓缩发酵剂菌粉成品特性的影响。结果表明,在MRS液体培养基内添加8%胡萝卜汁、8%番茄汁、0.75%CaCO3为佳增殖培养条件,活菌数达2.68×109CFU/mL;菌体佳富集条件为离心机转速4 000 r/min离心10 min,离心收得率达到96.87%;佳冻干条件是作为悬浮基质的脱脂乳浓度为10%,冻干厚度为0.5cm,冻干保护剂组合为:海藻糖(10%)、麦芽糖(12%)、谷氨酸钠(8%),此条件下活菌数为3.71×109CFU/mL,菌体存活率达到75.43%;菌体冻干36 h后,其水分含量可满足储藏要求(1.5%~3.0%)。

Concentrated freeze-dried starter plays an important role in development and application of fermented meat products.The Lactobacillus plantarum was chosen to be the target strain.Firstly,orthogonal experimental design was used to explore the effects of different growth factors on strain proliferation and got optimal conditions.Sceondly, the effect of centrifuge conditions on loss rate and survival rate of the strains were studied.Lastly,the effect of freezedrying conditions and different cryoprotectants on concentrated lyophilized fermented starter products were studied.The results showed that the enrichment medium of the strain was given below: carrotjuice 8%,tomato juice8%,CaCO 3 0.75% were added to MRS medium and the cell density could reach 2.682 × 109CFU/mL.The optimal centrifuge conditions were 4 000r/min for 10min,the rate of the strains yields reached 96.87%.The optimal freeze-drying conditions were the concentration of skim milk used as suspended matrix 10% and freeze-dried thickness was 0.5cm; The optimal cryoprotectant were trehalos 10%,maltose 12%,sodium glutamate 8%,and the survival rate of the freezedried starter reached 75.43%.When the bacteria freeze-drying time reached 36h,its moisture content was fit for storage requirements( 1.5% ~ 3.0%).