Enhancement of antioxidant activity of mulberry juice by lactic acid bacteria fermentation

• Main Authors: Suwannee Norasatvorachai, 蘇文妮
• Other Authors: Pao-Chuan Hsieh
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/98110853623003031127

碩士 === 國立屏東科技大學 === 食品科學國際碩士學位學程 === 104 === The effect of lactic acid bacterial fermentation on sugars, organic acids, bio-transformation of phenolic compounds (e.g. anthocyanins, quercetin, rutin), and antioxidant activity was investigated in mulberry juice. L. plantarum and L. acidophilus were used as probiotic starter organisms. Both bacteria strains were able to grow in the juice and their viable cells reached to 8.51x109 CFU/mL after 72 h of fermentation. Glucose content of the juice was significantly decreased by both probiotic starter cultures, and L. plantarum utilized more sugars in comparison with L. acidophilus. The concentration of organic acid was significantly increase by both bacteria through the first 24 h of the process (P<0.05). Lactic acid was detected as the most abundant acidic metabolite produced within the fermentation, especially by L. plantarum. HPLC analysis of different phenolic compound such as rutin, quercetin and quercetin 3-glucoside revealed that these compounds were significantly increased after fermentation. The result from anthocyanins showed anthocyanins from mulberry fruit pigment were stabilized in solution pH < 5, from red to purple-black, but unstable in neutral or solution pH > 5, from colorless to blue. With regard to DPPH radical scavenging activity, trolox equivalent antioxidant activity capacity, reducing power, total flavonoid and total phenolic showed that the fermentation of mulberry juice using L. plantarum and L. acidophilus ratio 1:5 as probiotic starters were 89.93%, 5356.65 µMol, 2.21 Abs, 1078.54 QE µg/ml and 2587.34 GAE µg/ml respectively, and the highest antioxidant activities were found in day 3 of fermentation. The results of this study showed that fermentation of mulberry juice by probiotic bacteria would enhance health benefit of the juice.