酿酒酵母多物混合发酵对咖啡豆风味品质的影响

中国咖啡主产于云南,云南咖啡在花果风味及甜香风味方面有所欠缺,发酵是影响咖啡风味品质的重要因素之一。利用酿酒酵母在低温厌氧条件下发酵咖啡鲜果,添加香草、肉桂、热带水果、蜂蜜等原料为基底共同发酵,最终对发酵咖啡豆进行理化、香气成分分析及主观评价,探究发酵对咖啡品质的影响。结果表明:添加香草、肉桂、苹果、甜橙、香蕉、蜂蜜发酵的咖啡与无添加的对照组咖啡相比,灰分和脂肪含量无差异(P＞0.05),可溶性蛋白质含量显著提高(P＜0.05),底物的添加对最终咖啡豆中多糖、还原糖、总蛋白质、多酚有不同程度的影响,无明显规律。采用气相离子迁移色谱(gas chromatography-ion mobility spectrometry, GC-IMS)对发酵咖啡生豆挥发性成分进行分析,共定性出36种化合物,9种酯、6种酮、8种醛、6种醇、5种烯萜、1种呋喃、1种酸类,其中酮、醛、醇、酯类共占挥发性成分的60%以上。结合感观评价结果,香草、肉桂、热带水果与咖啡发酵可赋予咖啡水果香气,提升咖啡花果香特质,其中香料组、甜橙组达精品咖啡标准,香蕉组香气较为突出,蜂蜜组在香气方面未有突出特点,且酸度过高对甜度提升不足。研究为进一步改善云南咖啡花果甜香特质,提升咖啡风味提供一定理论依据和数据支持。

Effect of Multi-Composition Mixed Fermentation of Saccharomyces cerevisiae on Flavor Quality of Coffee Beans

Chinese coffee is mainly produced in Yunnan, which is lacking in flower and fruit flavor and sweet flavor. Fermentation is one of the important factors affecting the quality of coffee flavor. The physicochemical analysis, aroma composition analysis, and sensory evaluation were used to analyze the coffee beans, which were fermented under low temperature and anaerobic conditions using Saccharomyces cerevisiae adding vanilla, cinnamon, tropical fruits, honey and other raw materials. And the effect of fermentation on coffee quality was explored. The results showed that the ash and fat content had no significant difference (P>0.05) and soluble protein content was significantly increased (P<0.05) in coffee after fermentation with vanilla, cinnamon, apple, sweet orange, banana and honey compared with that in the control group. The addition of the substrates had various effects on the polysaccharide, reducing sugar, total protein and polyphenol in the final coffee bean without obvious regularity. A total of 36 compounds including 9 esters, 6 ketones, 8 aldehydes, 6 alcohols, 5 olefins, 1 furan and 1 acid were preliminarily identified by gas chromatography-ion mobility spectrometry in fermented coffee green bean. The ketones, aldehydes, alcohols and esters accounted for more than 60% of the volatile components in coffee green beans. Combined with the results of sensory evaluation, vanilla, cinnamon, tropical fruit fermentation with coffee could increase fruit aroma of coffee and promote the flower and fruit aroma characteristics of coffee. Among them, the spice group and sweet orange group met the standard of specialty coffee, the banana group had a more prominent aroma. However, there was no obvious change of aroma in the honey group accompanied with high acidity and no enough sweetness. This study provided a theoretical basis and data support for further improving the sweet and fragrant characteristics of Yunnan coffee and improving the flavor of coffee.