Effects of Chemical Composition on Sensory Properties of Coffee after Inoculation with Yeast
學生姓名:
鄭宇君
指導教授:
劉修銘
學期:
111上
摘 要:
The surface of cherry coffee content natural microorganisms such as bacteria, yeast, and fungi. Pectinase secreted by yeast can remove pectin from the outer layer of fresh coffee bean. Therefore, this study investigated the effects of yeast inoculation on sensory changes by changing the chemical composition . The first study inoculated Coffea canephora with Meyerozyma caribbica and Pichia kluyveri using the Natural (NAT) method. The analysis of microbial phase, the persistence of inoculated yeasts, organic acid, and sugar content were carried out in cherry coffee and the analysis of volatile compounds content and sensory score were carried out in roasted coffee. The microbial phase result shows that the yeast in the 300 m sample had the largest microbial population at 48 hours and the number of fungi in the 300 m coffee inoculated with M. caribbica decreased by 2 logs. After roasting, 24 volatile compounds were identified, of which pyrazine was the most important component of coffee flavor. The results of sensory analysis indicated that the sensory scores of M. caribbica inoculated in 600 m coffee were higher than those of the other two groups. The second study inoculated Coffea arabica with M.caribbica, Saccharomyces cerevisiae, Candida parapsilosis, and Torulaspora delbrueckii, and further fermented by the NAT and Pulped natural (PN) method. The analysis of fermentation temperature, the persistence of inoculated yeasts, organic acid, volatile compounds, and sensory score were carried out. At the start of fermentation, 40 compounds were found in NAT samples and 20 compounds were found in PN samples
illustrating that removing the pulp changed the compounds in the coffee. In the sensory analysis, NAT and PN samples inoculated with S. cerevisiae had the highest scores, which showing acidity, medium to high sweetness, and medium body. Yeast inoculation can alter the content of organic acids, sugars and volatile compounds to improve sensory scores, and the consequence of yeast can depend on coffee variety and altitude. Overall, the use of yeast for fermentation increases the value of coffee beverages.
illustrating that removing the pulp changed the compounds in the coffee. In the sensory analysis, NAT and PN samples inoculated with S. cerevisiae had the highest scores, which showing acidity, medium to high sweetness, and medium body. Yeast inoculation can alter the content of organic acids, sugars and volatile compounds to improve sensory scores, and the consequence of yeast can depend on coffee variety and altitude. Overall, the use of yeast for fermentation increases the value of coffee beverages.
20221026專題討論_摘要_鄭宇君.pdf