Yoghurt Production from Germinated Native Black Rice (Maepayatong Dum Rice)

Abstract

The incubation period of 12, 24, 36, 48, 60, and 72h for germination on the quantity of γ-amino butyric acid of native black rice (Maepayatong dum rice) were conducted. The result found that the 48h of germination time had significantly (p ≤ 0.05) the highest amount of γ-amino butyric acid (27.99 ± 1.44 mg/100 g). This treatment was therefore selected to further determine the product development of germinated native black rice yoghurt. Changes in physical and chemical properties during fermentation under controlled conditions (42°C) at 0h, 2h, 4h, 6h and 8h fermentation were evaluated. The result found that change in the amount of titratable acidity expressed as lactic acid and apparent viscosity of germinated black rice yoghurt were increased at the end of 8h fermentation. On the other hand, the consistency, pH, and total soluble solid were slightly decreased and the lowest at the end of 8h fermentation. From sensory evaluation, the germinated native black rice yoghurt fermentation by 20% w/w of Revon starter) had the highest overall acceptability (6.88: moderately like). It was then chosen to study on the effect of shelf life on yoghurt properties every week until 4 weeks of storage. The consistency, pH, and viable cell count were slightly decreased; while apparent viscosity, lightness, redness and lactic acid were increased when the shelf life was longer. Interestingly, the free radical scavenging capacity assayed by DPPH method showed that IC₅₀ values had significantly (p≤0.05) higher than the control (86.92±1.21 and 96.61±1.25 mg/ml, respectively). Although, the amount of γ-aminobutyric acid (GABA) content exhibited significantly (p≤0.05) two fold lower than the control (0.99±0.03 and 1.80±0.07 mg/100g, respectively). It concluded that the research finding could increase the value addition of native black rice and should be guided to develop the other healthy food in the future.