College of food science and technology,Yunnan Agricultural University
Yunnan Agricultural University Natural Science Youth Research Fund (2016ZR04); Yunnan Provincial Key Laboratory of Food Processing and Safety Control Open Fund Project (YJK16 KF06); Yunnan Province established agricultural science and education combined with new agricultural socialization service system pilot project (2014NG004-08); Key Technology Research and Product Development of Yunnan Special Coffee Processing (KX141733)
Chinese coffee is mainly produced in Yunnan, Yunnan coffee is lacking in flower and fruit flavor, and fermentation is one of the important factors affecting the quality of coffee flavor. Using yeast to ferment coffee fresh fruit under low temperature anaerobic conditions, adding vanilla, cinnamon, tropical fruit, honey and other raw materials as the base for co-fermentation, and finally analyzing the physicochemical, aroma components and cup measurement of fermented coffee beans, and exploring the effects of co-fermentation on the quality of coffee. The results showed that the coffee added with spices, apple, orange, banana and honey had no difference in ash and fat content (p>0.05) and soluble protein content (p<0.05). The addition of the substrate has different significant and insignificant effects on the polysaccharide, reducing sugar, total protein and polyphenol in the final coffee bean, and there is no obvious rule. Aroma analysis by gas chromatography-ion migration preliminary identified a total of 36 compounds, 9 esters, 6 ketones, 8 aldehydes, 6 alcohols, 5 olefins, 1 furan, 1 acid and 17 unknown signal components. The ketones, aldehydes, alcohols and esters of coffee green beans account for more than 60% of the volatile components. Combined with the cup test results, the co-fermentation of spices, fruits and coffee can impart coffee fruit aroma and enhance the coffee flower fruit characteristics. Among them, the vanilla cinnamon and sweet orange group cups have reached the standard of fine coffee, and the banana group aroma is more prominent. The co-fermentation of honey and coffee has no outstanding features in terms of aroma, and the poor acidity measured indicates insufficient improvement in sweetness. This study provides a theoretical basis and data support for further improving the sweet and fragrant characteristics of Yunnan coffee and fruit and improving the flavor of coffee.