体外模拟发酵对咖啡理化性质及品质的影响

Effects of in vitro digestion on the physicochemical property and quality of Arabica coffee

以云南阿拉比卡卡蒂姆咖啡为原料进行体外模拟发酵,分析不同阶段咖啡理化性质及品质因子变化,并以美国精品咖啡协会评分标准对烘焙后咖啡杯测,结合Pearson,分析杯测指标与理化特征成分、风味特征成分间关联性。结果表明,咖啡生豆经10~12 h浸泡充分吸胀,渗出物少。复水咖啡豆多糖、脂肪含量显著下降(P<0.05),还原糖、总蛋白、可溶性蛋白和酚类变化均不显著(P>0.05)。在发酵过程中多糖先呈现下降趋势,至8 h含量达到最低(3.22±0.28)%(质量分数),而后又显著上升(P<0.05);还原糖含量呈现逐渐上升趋势,至8 h含量达到最高,而后又显著下降(P<0.05);脂肪在发酵2 h后变化均不显著(P>0.05);总蛋白含量先下降而后上升再下降,在6 h含量最高为(8.54±0.17)%(质量分数);可溶性蛋白、酚类发酵2 h后下降趋势显著(P<0.05);膳食纤维、灰分均未发生显著变化(P>0.05)。咖啡豆游离氨基酸中谷氨酸含量占比最高,其次为天门冬氨酸、赖氨酸和亮氨酸,不同发酵阶段游离氨基酸随发酵时间的增减变化无规律。咖啡风味特征成分绿原酸和柠檬酸随发酵阶段逐渐增加,苹果酸含量减少,咖啡因含量基本不变。绿原酸会极显著影响咖啡风味表现,柠檬酸和苹果酸含量高低决定了咖啡的酸质,可溶性蛋白含量高低影响咖啡余韵,多糖、灰分、葫芦巴碱、奎宁酸过高则会降低咖啡杯品醇厚度。该研究为益生菌发酵咖啡的创新加工,清洁化、批量化生产提供理论依据。

Using Yunnan Arabica coffee as raw material for in vitro simulated fermentation,the physicochemical property and the precusor substances at different stages was analyzed and cupped by SCA(The Specialty Coffee Association of America)coffee cupping for analyzing the relationship between coffee cupping and physicochemical and flavor characteristics by Pearson analysis.The results showed that the water absorption and expansion rate of green beans increased as immersion time increased to 10-12 h.The polysaccharide and fat in rehydrated beans decreased significantly(P<0.05),and the changes of reducing sugar,total protein,soluble protein,phenols were not significant(P>0.05).During the simulated digestion,polysaccharide decreased to the lowest(3.22±0.28)%at 8 h and then increased significantly(P<0.05);reducing sugar increased gradually and reached the highest at 8 h and then decreased significantly(P<0.05);the changes of fat were not significant(P>0.05)after 2 h;total protein content reached the highest(8.54±0.17)%in 6 h,which first decreased then increased and decreased;soluble protein and phenols decreased significantly(P<0.05);the change of dietary fiber and ash were not significant(P>0.05)during the digestion.Glutamic acid accounted for the highest proportion followed by asparaginic acid,lysine and leucine,while the changes of free amino acids were not regular in different stages.The chlorogenic acid and citric acid increased gradually,while the malic acid content decreased and the caffeine content remained almost unchanged.Chlorogenic acid were significantly correlated with the flavor of coffee,the citric acid and malic acid contributed to the acidity of coffee,the soluble protein content influenced on the aftertaste of coffee.Polysaccharide,ash,gynesine and quininic acid played inactive roles in the body of coffee cupping.The research provides theoretical basis of processing innovation of fermentation of coffee by probiotics.