Lactic Acid Content And Β-Galactosidase Activity Of Yoghurt With Starter Added Bifidobacteria Bifidum At Storage And Its Organoleptic Tests

Bifidobacteria bifidum as probiotic bacteria added in yoghurt starter can increase yoghurt quality. To know B. bifidum yoghurt quality, lactic acid content and β-galactosidase activity of yoghurt with starter (Lactobacillus bulgaricus : Streptococcus thermophillus = 1:1) added B. bifidum at storage and its organoleptic test, was observed. Comparison of B. bifidum concentration added were 1:1:0, 1:1:1, 1:1:1, 1:1:1.5; and storage times were 0, 5 (milk at expiry date), 10, 15 and 20 days. Organoleptic tests were conducted by 18 panelists, β-Galactosidase activity and lactic acid content were detected by ONPG and titration methods, respectively. The results show that organoleptic scores of probiotic fat yoghurt were more acceptable than that of skim. Lactic acid contents and β-galactosidase activities of probiotic fat yoghurt, at 0 and 5 days, with percentages in the range 0.440 – 0.540 persen and 0.2287-0.2803 U/mL, respectively, were higher than that of skim, with 0.400 – 0.500 persen and 0.1250 - 0.2083 U/mL, on the contrary, at 10, 15 and 20 days, those of the fat yoghurt, were lower than that of skim (P<0.05). Based on organoleptic tests, lactic acid contents, and β- galactosidase activities, probiotic fat yoghurt were more acceptable than probiotic skim yoghurt.Key words: yoghurt, skim, Bifidobacteria bifidum, β- galactosidase, lactic acid. Berk. Penel. Hayati Edisi Khusus Vol. 4C. 2011. P: 79–82