Kefir粒发酵过程中核桃乳的品质变化

Quality Change of Walnut Milk During Fermentation by Kefir Grains

以Kefir粒为发酵剂制备核桃发酵乳,研究了核桃乳在发酵过程中的微生物、pH值、可滴定酸、蛋白质、氨基态氮及抗氧化活性等指标的动态变化。结果表明,在发酵过程中核桃乳中的乳酸菌和酵母菌的数量逐渐增加,发酵16 h后的乳酸菌和酵母菌活菌数分别达到 6.41 lg cfu/mL和6.26 lg cfu/mL;此时,pH值从6.86下降到3.48,可滴定酸相应的从6.75 °T增加到了58 °T;蛋白质含量由16.55 mg/mL下降到10.51 mg/mL,而氨基态氮含量从9.8 mg/100 mL增加到21.0 mg/100 mL;发酵后核桃乳对DPPH和ABTS自由基清除率分别达到90.9%和86.8%,抗氧化活性显著提高。

Fermented walnut milk was prepared with kefir grains as starters.The dynamic changes of microorganisms,pH,titratable acid,protein,amino nitrogen and antioxidant activity of walnut milk during fermentation were studied.The results showed that the counts of lactic acid bacteria and yeasts increased gradually during the whole fermentation process,after 16 hours of fermentation,the viable counts of lactic acid bacteria and yeasts were 6.41 lg cfu/mL and 6.26 lg cfu/mL,respectively.At this moment,the pH value dropped from 6.86 to 3.48,the titratable acid content increased from 6.75 °T to 58 °T,and protein content decreased from 16.55 mg/mL to 10.51 mg/mL,while the content of amino nitrogen increased from 9.8 mg/100 mL to 21.0 mg/100 mL.After fermentation,the scavenging rates of DPPH and ABTS free radicals were 90.9% and 86.8%,respectively,and the antioxidant activity of walnut milk was significantly increased.