Physicochemical and microbial evaluation of Kefir produced with sesame seed (Sesamum indicum l) extract as a goat milk substitute

Abstract

Kefir is one of traditional beverage made by milk fermentation using kefir grain. Kefir can be produced with the addition or substitution with plant based ingredients to enhance it nutritional and functional properties. the objective of this research to investigate the influence of substituting with various concentration of sesame seed extract on physicochemical and microbiological characteristic of kefir goat milk. The present study was consisting of five concentrations of sesame seed extract (10%, 20%, 30%, 40% and 50%) using completely randomized design. The parameter assessed were pH, syneresis, WHC, total Lactic Acid Bacterial (LAB) count, total yeast count and antibacterial activity (Escherichia coli and Staphylococcus aureus). The experimental data statically analyzed using analysis of variance and followed with Duncan test. The result indicated that increasing sesame seed extract causes decrease in pH and water holding capacity while syneresis increased. The finding of the research revealed that with increasing the sesame seed concentration resulted in reduction of pH and WHC while increased syneresis of kefir. Total LAB increase until 40% substitution of sesame seed extract (15.73x 10⁶CFU/g) and total yeast count fluctuated among treatment with the highest yeast in 20% substitution (25.43 x 10⁶CFU/g). Kefir with sesame seed extract demonstrated antibacterial activity against E. coli and S. aureus with the highest activity from substitution 30% (E. coli: 2.15cm) and 40% (S. aureus: 2,18cm). Thus, sesame seed extract demonstrated for substituting goat milk for making kefir with optimal concentration level extract 30-40%.