Study On Protection With Gelatin/Acacia Complex Coacervation Microencapsulation Technology To Lactobacillus

With the increase of the social material level and the continuous pursuit of the health status, the intake of the lactobacillus products have gradually been transited from the traditional intake of the lactein to a direct access to the live lactobacillus. However, if these lactobacillus products to achieve the effect of health care, the number of viable lactobacillus in the products must be at least 106 - 107cfu / g, and the products also had a sufficient period of stability, so the products can tolerate harsh environments such as the gastric juice, bile and so on, and have a commercial value. Therefore, how to improve the survival rate of lactobacillus during the processing and storage of the lactobacillus products becomes the focus of the study in recent years. Six contents as follow were studied in the paper: The complex coacervation microencapsulation technology with the Gelatin and Acacia as wall materials and the embedding technology of lactobacillus micro-capsules. The protective effects on the survival rate of lactobacillus with the microencapsulation by complex protective agent. Detecting the survival rate of lactobacillus in the microcapsules with the freeze-drying conditions. Detecting the effects of the microencapsulation on the survival rate of lactobacillus in the artificial gastric juice. Detecting the dissolution of lactobacillus from the micro-capsules in the artificial intestinal fluid. Detecting the effects of the cold storage at low temperature (4℃) on the survival rate of lactobacillus. The conclusions as follow: The optimal growth temperature of all lactobacillus was 37±1℃. If the temperature was lower than 20℃or higher than 50℃, the growth of all lactobacillus was inhibited. Cultured for 36h, all lactobacillus entered the quiescent period, and the quiescent period was about 36h ~ 54h.The optimum methods to prepare the microcapsule of lactobacillus: the ratio of lactobacillus and gum was 1:6; the concentration of compound gum (glutin / Acacia) was15%; pH was 3.8 at coacervating; stirring speed was 600rpm; reaction temperature was 30℃. At this condition, the embedding rates of the lactobacillus microcapsules were 92.8%±1.16%. The average particle size was 283um and standard deviation was±56um, which formed the skewed normal distribution. The survival rate of lactobacillus in the microcapsule after the freeze-drying was 2.65×108 cfu/g. The survival rate of lactobacillus in the microcapsule after the freeze-drying was 7.16×1010cfu/g, with the single freeze-drying protective agent– the skimmed milk powder. The survival rate of lactobacillus in the microcapsule after the freeze-drying was 7.55×1010cfu/g, with the single freeze-drying protective agent– the trehalose. The optimum ratio of the freeze-drying protective agent: the skimmed milk powder was 60g / L; the trehalose was 20g / L. The survival rate of lactobacillus was 96.8% and the number of living lactobacillus was 9.97×1010cfu / g, which increased three orders of magnitude compared to the control with no protective agent and more than one times higher than that by the single protective agent. Simulation experiments showed that lactobacillus in the microcapsule could significantly improve the survival rate compared with original lactobacillus. After 3 hours treatment the survival rate of lactobacillus in the four experimental groups (the microcapsule without the protective agent, the freeze-drying microcapsule without the protective agent, the microcapsule with the protective agent and the freeze-drying microcapsule with the protective agent) of the microencapsulation was more than 65%. No lactobacillus could be detected in the original lactobacillus. The freeze-drying protective agents helped to further enhance the resistance of lactobacillus in the microcapsule to gastric acid .The survival rate of lactobacillus in the microcapsule with the protective agent increased about 10%, compared with the controls without the protective agent. Simulation experiments of the artificial intestinal juice showed that in both the experimental group of the microcapsule with the freeze-drying protection agent and the control, after 40 min, the absorbance was stable and the solution did not contain solid particles, which indicated the microcapsule could decompound better in the artificial intestinal juice, and then achieve the role of prebiotics. After stored for 60 days at 4℃, the survival rate of lactobacillus in the original lactobacillus was only 9.3%, but the survival rate of microencapsulated lactobacillus was more than 80%. It was showed that microencapsulation could significantly improve storage activity of lactobacillus at 4℃. After stored for at 4℃, the survival rate of lactobacillus in the microcapsules with the freeze-drying protective agent was still up to 96.1%, and living lactobacilli were 9.58×1010cfu / g, which was approximately 10% higher than that without the protective agent. It showed that microencapsulation with agents could significantly enhance the storage activity at 4℃. Calculated by first-degree irreversible reaction formula, freeze-drying microcapsules with protective agents could store 174.5 days, and the survival rate of lactobacillus was not less than 90%.