摘要
本文研究了藏灵菇发酵奶发酵过程中酸度、有机酸、挥发性风味物质及微生物数量的变化,在发酵0、4、8、12、16、20h时采样,用高效液相色谱(HPLC)跟踪发酵过程中乳酸、乙酸和柠檬酸的变化;用气相色谱(GC)跟踪了发酵过程中乙醇、丁二酮、乙醛和丙酮的变化。实验结果表明,乳酸和乙酸在发酵过程中都呈上升趋势,发酵4h时,乳酸的生成量约是乙酸的20倍,发酵结束乳酸的量为8.56g/L(TK1),7.73g/L(TK2);乙酸的量为0.71g/L(TK1),0.81g/L(TK2),乳酸的量约是乙酸的9～12倍。柠檬酸从发酵开始就呈下降趋势。挥发性风味物质中乙醇的生成量最大,发酵结束分别达到3134mg/L(TK1),4994mg/L(TK2);丁二酮和乙醛的量较普通酸奶高,分别达到62.4mg/L(TK1)和37.8mg/L(TK1)。本研究也对发酵过程中微生物进行了分析,发酵结束,发酵奶中乳杆菌达到2.3×109CFU/ml(TK1),1.3×108CFU/ml(TK2);乳球菌达到1.3×109CFU/ml(TK1),1.1×108CFU/ml(TK2);酵母菌1.6×106CFU/ml(TK1),6.6×106CFU/ml(TK2)。TK1和TK2之间存在较大差异,TK1的风味好于TK2。
The changes of pH, organic acids, volatile flavor and microbial counts were studied on Tibetan kefir fermentation. Samples were collected at 0,4,8,12,16 and 20h of fermentation respectively. Lactic, acetic and citric acids were analyzed by HPLC. Ethanol, diacetyl, acetaldehyde and acetone were monitored with GC. The results showed that the content of lactic and acetic acids is increasing during fermentation. The production of lactic acid is 20 times more than acetic acid at 4 h, and 9- 12 times at the end of fermentation, reaching respectively 8.56g/L （TK1） and 7.73g/L（TK2）, while the acetic acid reaches 0.71 g/L （TK1） and 0.81 g/I_（TK2） respectively. The concentration of citric acid gradually decreases with fermentation time. Among volatile flavors, ethanol is produced most, reaching 3134mg/L （TK1） and 4994mg/LtTK2）respectively at the end of fermentation. The production of diacetyl and acetaldehyde is higher than common yoghourL with the concentration reaching 62.4mg/L （TK 1 ） and 37.8mg/L （TK 1 ） respectively. In addition, microbial counts were evaluated in the paper. At the end of fermentation, the colony counts of lactococcus reach respectively 2.3 × 10^9CFU/ml（TK1） and 1.3 × 10^8 CFU/ml（TK2）, lactococcus 1.3 × 10^9CFU/ml（TK1） and 1.1× 10^8CFU/mI（TK2）, and yeasts 1.6 × 10^6CFU/ml（TK1） and 6.6 × 10^6 CFU/ml（TK2）. The results show the great differences between TK1 and TK2.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2006年第8期29-33,共5页
Food Science
基金
国家863计划(2002AA248041)
关键词
藏灵菇
发酵
有机酸
挥发性风味物质
微生物
Tibetan kefir
fermentation
organic acids
volatile flavor
microbial counts
