Research And Development Of L.acidophilus Viable Preparations

Based on research literature and reports of Lactobacillus acidophilus, as well as domestic and international L. acidophilus Viable preparations, recognizing that viable count has been a problem and needs urgently solved. Studying of domestic and foreign products status, L. acidophilus medium, fermentation cultivation process and freeze-drying technology have been researched, in order to improve living number, to satisfy production and human life.This study contains L. acidophilus basic physiological activity determination, culture medium research, exploration of ferment, centrifugal collection, and freeze-drying protection formula. Firstly, simulating the human gastrointestinal tract, bile and acid resistance of L. acidophilus, restraining harmful bacteria, resisting antibiotic and other experiments have been researched. The result showed that L. acidophilus has strong acid and bile resistant capability, strong ability to inhibit the harmful bacteria, strong resistance to antibiotics, can pass through gastro- intestine in high activity to play a probity role.Secondly, based on the basis MRS medium, optimized carbon source, nitrogen source and probiotics factor, got the best culture medium formula: 2% Glucose, 0.5% Oligo-ismaltose, 0.1% Lactose, 0.6% Peptone, 0.45% Pancreatic Peptone, 0.45% Soy Peptone, 0.15% L-cysteine hydrochloride, 1.0% beef extract, 0.5% yeast extract, 0.1% Tween -80, 0.25g MnSO4, 5.0g Acetate Sodium, 2.0g Diammonium hydrogen citrate, 0.58g MgSO₄, 2.0g K₂HPO₄·3H₂O, adding distilled water to 1000mL, 121℃high-pressure sterilized 15min. L. acidophilus could be cultivated to 2.90×10⁹cfu/mL, twice of MRS.Thirdly, simulated industrial fermentation in laboratory Swiss 3.7L fermentor, got the optimum fermentation conditions, temperature 37℃, pH 5.85, rotate speed 100r/min, neutrallized by 20% NH₃·H₂O. Inoculated 2% L. acidophilus into culture, from 8h to 10h, added glucose with the speed of 2.5g/L*h, 10h 12h, fed of 2.5g/L*h, harvested at 12h. Finally, the number of bacteria increased 6 to 7 times, from 1.21×10⁹ of MRS to 7.01×10⁹cfu/mL.Fourthly, researched on centrifugal technology, got the best centrifugal program, centrifuging 20 minutes with the force of 6000g at 4℃. L. acidophilus was collected by 82.71 percent, with centrifugal survival rate of 82.73%.At last, freeze-drying protection of L. acidophilus has been studied, the optimum formula of cryoprotectant was determined as: skim milk 20%, Trehalose 6%, PVPK-30 4%, Sodium glutamate 0.5%, Glycerol 4%, protecting L.acidophilus with the survival rate of 93.33%. L. acidophilus probiotics product was obtained, with the viable count of 1.35×10¹⁰ cfu/g, water of 2.15%.