| Summary: | 博士 === 國立中興大學 === 動物科學系所 === 100 === The purpose of this study was the utilization of mushroom extracts as prebiotic of bifidobacteria, and new functional product was develop for consumer use. Ten strains screened from newborns’ feces in Taiwan were detected by physiological analysis and identified by Biolog system. The DNA probe analysis was also utilized to confirm that all strains belonged to bifidobacteria. In order to verify the functional characteristics of human origin strains, the antimicrobial assay, bile tolerance, and antioxidative activity of 10 strains and its extracellular materials were determined. The results in the antimicrobial activities showed that 10 strains had the inhibition for Listeria monocytogens, Salmonella typhimurium, S. choleraesuis subsp. choleraesuis, and Escherichia coli. Four strains proliferated normally in bile acid or conjugated bile salt added MRS broth. In addition, these bifidobacteria strains had good scavenging effect on α,α-diphenyl-2-picryl hydrazyl (DPPH) radicals, and the glutathione peroxidase activities by 10 strains were also high. These results proved that 10 bifidobacteria were suitable used in functional yogurt as probiotic.
Hot water extracts of three kind of gelatinous fungi were added in MRS broth, and the growth rate and the number of viable bifidobacteria count per unit time were determined as screen factor. In conclusion, the hot water extract of white variety of Auricularia fuscosuccinea were selected as prebiotic to solve the subsistence of bifidobacteria when incubated in milk. The proximate chemical composition, the functional components and the antioxidant activities were analysis. When compared with two other common gelatinous mushrooms, A. polytricha and Tremella fuciformis, white variety of A. fuscosuccinea had the highest fat (5.06%), protein (20.21%) and soluble dietary fiber (31.65%). High total polyphenols (1.86%) and ascorbic acid (0.38%) content of white variety of A. fuscosuccinea might be the main reason of its better antioxidant activity.
As prebiotics, the hot water extract of white variety of A. fuscosuccinea was added into milk and incubated by yogurt starter cultures that contained commercial strain YC-350 (mixed strain of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) and probiotic strains (B. longum BCRC 14605 and B pseudocatenulatum 01709 selected from newborn feces) or just by commercial strain YC-350. The chemical and physical properties of milk (during incubation period) and yogurt (during storage period) were analyzed, in order to assess the feasibility as a prebiotics and the stability of the yogurt with supplemented the hot water extract of white variety of A. fuscosuccinea. The antioxidant activities of yogurt were also discussed to estimate the functional developments of white variety of A. fuscosuccinea extract in yogurt product.
As a result, just like xylooligosaccharide treatment, white variety of A. fuscosuccinea extracts revealed a faster proliferation rate of yogurt starter cultures and a shorter fermentation time (1.3 hour earlier) than control (requires 7 hours). During a storage period of 35 days at 4℃, white variety of A. fuscosuccinea extract could enhance the culture viability of yogurt when compared with xylooligosaccharide treatment. Besides, the amount of whey removed significantly declined for white variety of A. fuscosuccinea extract treatment when compared with control and xylooligosaccharide treatment yogurt. Although some antioxidant components like peroxidase, ascorbic acid, and peptide were no significantly different between control yogurt and two treatment yogurt, but the reducing ability of white variety of A. fuscosuccinea extract treatment was improved for 9% and 10% when compared with control and xylooligosaccharide treatment yogurt. The glutathione peroxidase activity of white variety of A. fuscosuccinea extract treatment was 2.28 times than control. The result reveals that the advantageous antioxidant properties associated with hot water extract of white variety of A. fuscosuccinea. In conclusions, the additions of bifidobacteria selected from newborn feces and white variety of A. fuscosuccinea extract were no negative influence on the chemical or physical properties of yogurt. Otherwise, the preservation, stability, and antioxidant properties of yogurt were improved. According this study, white variety of A. fuscosuccinea extract addition to a probiotic containing yogurt has the potential to manufacture as a functional yogurt.
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