The acid and bile resistant ability of probiotics and its application in yoghurt
| Autor: | Shu-Hui Yu, 游淑惠 |
|---|---|
| Rok vydání: | 2005 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 94 The healthy benefits of probiotics have been demonstrated in recent years, but most probiotics are low acid- and bile-resistant. The survival of probiotics passing through the digestive tract was very low, and these probiotics couldn’t grow well in milk. Therefore the cultures for probiotic yoghurt need to be selected or microencapsulated appropriately to process healthy probiotic products. The purpose of this study was to investigate the acid and bile resistant ability of probiotics and its application in yoghurt. The acid and bile resistant probiotics were selected under pH 1.0, 2.0 and 0.3% bile potassium chloride buffer. The ability to hydrolyze resistant starch（RS）by these probiotics which grew on broth containing RS as the sole carbon source was measured. In addition, the growth ability of the acid and bile resistant probiotic culture in milk at 37 and 43℃ was tested. Finally, the yoghurt was manufactured by using the strains that showed the best survival under gastric fluid tests and growth rate in milk in combination with yoghurt starter. The physicochemical characteristics and sensory evaluation were investigated. The results demonstrated that these probiotics utilized RS with different ability and three probiotics（Bifidobacterium bifidum CCRC 14146, B. catenulatum CCRC 14667, and Lactobacillus acidophilus CCRC 10695）had the highest survival under gastric fluid tests. Further study showed that the B. bifidum CCRC 14146 grew well in milk at 37 and 43℃ and reached the pH 4.6 after 21 and 12 hours, respectively, with a viable count of 108 cfu/mL. The viable counts of B. bifidum CCRC 14146 could’t enhance in probiotic yoghurt containing resistant starch during 35d storage at 4℃. There were no significant differences of the sensory evaluation scores between probiotic yoghurt and traditional yoghurt（P＞0.05）. The viable counts of yoghurt starter and probiotics were 107 cfu/mL and 108 cfu/mL, respectively. According to this study, B. bifidum CCRC 14146 might be a promising new yoghurt culture for probiotic yoghurt. The low acid- and bile-resistant probiotics were microencapsulated by mixing with equal volume of the uncooked or precooked RS. Then, the viable counts of free and microencapsulated probiotics in the simulated digestive tract and yoghurt during storage were measured respectively. This study aimed to test how microencapsulation with RS affected the acid- and bile-resistant properties of probiotic culture. The results demonstrated that low acid- and bile-resistant probiotics were B. bifidum CCRC 11844 and B. longum CCRC 11847. Microencapsulation with precooked RS improved the acid- and bile-resistant by 1 and 4 log cfu/mL respectively compared with those of the free cultures. Furthermore, the counts of precooked RS-microencapsulated cultures were 3 log cfu/mL higher than free cultures in the simulated digestive tract test. The counts of precooked RS-microencapsulated B. longum CCRC 11847 were enhanced by 1 log cfu/mL in yoghurt stored at 4℃ for 35 days. Therefore the low acid- and bile-resistant probiotics could be microencapsulated by mixing with precooked resistant starch and application in probotic yoghurt. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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