PENGARUH LAMA FERMENTASI DAN KONSENTRASI GLUKOSA TERHADAP AKTIVITAS ANTIBAKTERI, POLIFENOL TOTAL DAN MUTU KIMIA KEFIR SUSU KACANG MERAH THE EFFECT OF FERMENTATION DURATION AND GLUCOSE CONCENTRATION ON ANTIBACTERIAL ACTIVITY, TOTAL POLYPHENOL AND CHEMICAL QUALITY OF KIDNEY BEAN MILK KEFIR

Abstract

Kidney bean milk kefir is one product of Lactate Acid Bacteria (LAB) fermentation. Kefir is very useful for health e.g. recovering digestive process and producing antibacterial compound. The purpose of study is to know the effect of fermentation duration and glucose concentration on antibacterial activity, total polyphenol, and the chemical quality of kidney bean milk kefir. This study used the completely randomized design with 3 by 3 factorial and 3 repetitions. The materials used were kidney beans, bacteria starter Lactobacillus bulgaricus and Candida kefir with glucose concentration of 5%, 10%, 15%. The duration of fermentation used were 18, 21 and 24 hours. The variables measured were antibacterial activity (by agar diffusion), total polyphenol (by Folin-Ciocalteu with spectrophotometer UV-Vis) and chemical quality of kidney bean milk kefir (total acid, pH and alcohol content). Data were analysed using ANOVA technique, which were followed by LSD, if there was a treatment effect. The result of this study showed that there was an effect of the fermentation duration on antibacterial activity (p=0.001) and chemical quality (total acid, p=0.001; pH, p=0.001; alcohol content, p=0.008) of kidney bean milk kefir. On the other hand, it had no effect on total polyphenol (p>0.05). The glucose concentration showed an effect on antibacterial activity (p=0.001), but it had no effect on total polyphenol and chemical quality of kidney bean milk kefir (p>0.05) .The total acid of kidney bean milk kefir on all treatments increased after 24-hour-fermentation. On all treatment, pH of kidney bean milk kefir decreased after 24 hours fermentation. The alcohol content increased after 21 hours fermentation, but then decreased after 24 hours fermentation. It was concluded that the most effective antibacterial activity of kidney bean milk kefir was on the 24 hours fermentation and 5% of glucose concentration, which resulted in 1,50 mm. The total polyphenol increased after fermentation. Kefir susu kacang merah merupakan salah satu produk fermentasi Bakteri Asam Laktat (BAL). Kefir bermanfaat bagi kesehatan antara lain memperbaiki proses pencernaan dan memproduksi senyawa antibakteri. Tujuan penelitian adalah mengetahui pengaruh lama fermentasi dan konsentrasi glukosa terhadap aktivitas antibakteri, polifenol total dan mutu kimia kefir susu kacang merah. Penelitian ini menggunakan rancangan acak lengkap faktorial 3x3 dengan ulangan 3 kali. Materi yang digunakan adalah kacang merah, starter bakteri Lactobaccillus bulgaricus dan khamir Candida kefir dengan perlakuan konsentrasi glukosa 5%, 10%, 15% dan lama fermentasi 18 jam, 21 jam, 24 jam. Variabel yang diukur adalah aktivitas antibakteri menggunakan difusi agar, polifenol total menggunakan reagen Folin-Ciocalteu dengan spektrofotometer UV-Vis dan mutu kimia (Total asam, pH, kadar alkohol) kefir susu kacang merah. Analisis data menggunakan Analisis varians (Anova). Apabila ada pengaruh perlakuan terhadap variabel yang diukur, dilanjutkan dengan uji LSD pada taraf 5%. Hasil penelitian menunjukkan ada pengaruh lama fermentasi terhadap aktivitas antibakteri (p=0,001) dan mutu kimia (asam laktat, p=0,001; pH, p=0,001; alkohol, p=0,008) kefir susu kacang merah, tetapi tidak berpengaruh terhadap polifenol total (p>0,05). Konsentrasi glukosa berpengaruh terhadap aktivitas antibakteri (p=0,001), tetapi tidak berpengaruh terhadap polifenol total dan mutu kimia kefir susu kacang merah (p>0,05). Total asam kefir susu kacang merah pada semua perlakuan mengalami peningkatan setelah dilakukan fermentasi 24 jam. Terjadi penurunan pH kefir susu kacang merah pada semua perlakuan setelah fermentasi 24 jam. Kadar alkohol kefir susu kacang merah meningkat pada lama fermentasi 21 jam, tetapi mengalami penurunan setelah dilakukan fermentasi 24 jam. Simpulan penelitian ini adalah aktivitas antibakteri kefir susu kacang merah paling efektif pada perlakuan lama fermentasi 24 jam dengan konsentrasi glukosa 5% yaitu 1,50 mm. Polifenol total kefir susu kacang merah meningkat setelah fermentasi