Investigation of the microbial distribution and physicochemical properties of Taiwanese fermented sausages inoculated with lactic acid bacteria

• Main Authors: Tzu-Li Chen, 陳姿利
• Other Authors: 陳明汝
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/24482706511732732046

碩士 === 國立臺灣大學 === 動物科學技術學研究所 === 99 === Fermented sausage is a fermented meat product resulting from a serial biochemical, microbiological and physical changes during a defined condition of fermentation and ripening process. Fermented sausages in Taiwan are expensive due to lack of related indigenous products and needing to be imported. In our previous study, we isolated two dominant strains, Leuconostoc mesenteroides N35 and Lactobacillas sakei S3, from Taiwan natural fermented ham and sausage, respectively. Thus, in the present study, we inoculated these two strains individually as starter cultures to develop indigenous fermented sausages in Taiwan. We investigated microbial dynamics and physicochemical properties of sausage samples using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) by culture-dependent and culture-independent methods. DNA sequencing technique was performed to confirm the DGGE results. Furthermore, scanning electron microscope (SEM) and texture analyzer were also equipped to analyze the meat structure. Usually, foods with a low pH value (high acidity) develop resistance against microbial spoilage and can last a longer shelf life. Results indicated that cultured group rapidly decreased in pH rate, and then slowly increased at the end of the ripening period because of the protein and lipid decompositions. The degradation of protein and lipid also had effects on the sausage texture. The cultured group samples were much firmer than the controlled ones. The adhesion between fat particles and the meat matrix of the control group was not as tight as the cultured group. Culture-dependent results indicated that 4 dominant LAB species (Leu. mesenteroides, Lb. sakei, Lb. planterum and Pediococcus stilesii) were isolated during the whole manufacturing process. For the culture-independent results, other 3 patterns (Enterococcus faecalis, P. pentosaceus and Bifidobacterium sp.,) were identified by sequencing. In addition, the SEM results demonstrated that the structures of the initial meat matrix were mud-like with small amount of microorganisms, while in the final products, the meat products were wrinkled because of the evaporation and large amount of microorganisms existed on the matrix. In conclusion, our findings suggested that microbial distributions and the physicochemical characteristics of fermented sausage were significantly affected by the addition of starter cultures. Inoculation of Lb. sakei strain in the fermented sausage could shorten the process and improve the quality and stability of the final products. The information will help the design of indigenous starter cultures and develop new meat products in Taiwan.