PENENTUAN AKTIVITAS -Glukosidase PADA FERMENTASI SARI KEDELAI DENGAN KULTUR STARTER Lactobacillus plantarum B1765 DETERMINATION OF -Glucosidase ACTIVITY IN FERMENTATION EXTRACT SOYA WITH STARTER CULTURE Lactobacillus plantarum B1765

Abstract

Abstrak. Penelitian ini bertujuan untuk mengetahui pengaruh lama fermentasi sari kedelai terhadap pertumbuhan Lactobacillus plantarum B1765, pH, total asam, serta aktivitas enzim -glukosidase yang dilakukan masing-masing selama 6, 12, 18, dan 24 jam pada suhu37 ^oC. Penelitian ini dilakukan pengukuran terhadap beberapa parameter yang meliputi pertumbuhan Lactobacillus plantarum B1765 diukur dengan metode spektrofotometer UV-Vis pada panjang gelombang 252 nm, pH dan total asam diukur dengan metode AOAC 1995, serta aktivitas -glukosidase dengan metode Otieno (2007) yang diukur pada panjang gelombang 402 nm. Hasil penelitian menunjukkan pertumbuhan bakteri Lactobacillus plantarum B1765 mencapai fase log  mulai pada jam ke-6 hingga jam ke-24 fermentasi. Perhitungan jumlah total asam tertitrasi didapatkan nilai tertinggi sebesar 1,19% dengan pH terendah sebesar 4,24 pada jam ke-24. Aktivitas -glukosidase tertinggi terjadi pada jam ke-18, dengan aktivitas enzim mencapai 0,868 U/mL.

Kata kunci: sari kedelai, Lactobacillus plantarum B1765, -glukosidase

Abstract. This study aimed to determine the effect of fermentation time of soymilk on the growth of  Lactobacillus plantarum B1765, pH, total acid, and β-glucosidase enzyme activity were conducted respectively for 6, 12, 18, and 24 hours at temperatures of 37 ^oC. This research was conducted measurements of several parameters which include the growth of Lactobacillus plantarum B1765 measured by spektrofotometer UV-Vis method at a wavelength of 252 nm, pH and total acid measured by AOAC 1995 method, and β-glucosidase activity by Otieno (2007) method were measured at a wavelength of 402 nm. The results showed the growth of Lactobacillus plantarum B1765 reached log phase occurred from 6th hour until the 24th hour of fermentation. The calculation of the total amount of acid titration obtained the highest value of 1.19% with a pH lowest at 4.24 at the 24^th hour. β-glucosidase activity was highest at the 18^th, with the enzyme activity reached 0.868 U/mL.

Keywords: Extract soya, Lactobacillus plantarum B1765, -glucosidase