Abstract

Mixed lactic acid bacteria culture is commonly used in yogurt production. In the present study, two lactic acid bacteria (Lactobacillus bulgaricus and Streptococcus thermophillus) was used as starter culture. Calcium carbonate was added to the starter culture to increase the quality of mixed starter culture of L. bulgaricus and S. thermophillus with ratio of 4:1. The present study was directed to investigate the chemical composition of mixed starter culture with and without calcium carbonat addition. Furthermore, the effect of each starter culture on yogurt product chemical composition was also examined. The pH, lactose, soluble protein and acid content was determined as chemical composition parameters. For starter culture without calcium carbonate addition, the yogurt has pH, lactose, soluble protein and acid content of 4.18–4.39, 4.18–4.39% w/v, 2.88–4.36% w/v and 0.82–0.99% w/v, respectively. While for starter culture with calcium carbonate addition, the yogurt product has pH, lactose, soluble protein and acid content of 4.26–4.37, 1.47–1.75% b/v, 3.42–4.95% w/v and 0.86–1.11% w/v, respectively. Addition of 0.05% w/v calcium carbonate to mixed starter culture gave effect on lactose consumption, where it still can convert lactose to lactic acid up to 45 days of storage. Furthermore, the yogurt product made with starter culture with calcium carbonate addition has higher soluble protein content compared to yogurt made with starter culture without calcium carbonate addition

Highlights

  • Mixed lactic acid bacteria culture is commonly used in yogurt production

  • Calcium carbonate was added to the starter culture to increase the quality of mixed starter culture

  • soluble protein and acid content was determined as chemical composition parameters

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Summary

BAHAN DAN METODE

Alat-alat yang digunakan pada penelitian ini adalah autoclave, ruang steril, pembakar Bunsen, lemari pendingin, spektrofotometer UV-vis Jenway 6105, pH meter Mettler Toledo MP220, sentrifugasi Beckman TJ-6, peralatan titrasi, penangas air dan alat-alat gelas yang umum digunakan di laboratorium. Sebanyak 50 mL susu skim yang telah dipasteurisasi pada suhu 80–90°C selama 20 menit di dalam labu Erlenmeyer diinokulasi dengan satu ose L. bulgaricus. Sebanyak 100 mL susu skim dalam labu Erlenmeyer dipasteurisasi pada suhu 80–90°C selama 20 menit. Kemudian ditambahkan air suling sebanyak 100 mL dan dipasteurisasi pada suhu 80–90°C selama 20 menit. Setelah mencapai ±40°C diinokulasi dengan kultur starter campuran L. bulgaricus dan S. thermophillus yang telah dibuat sebelumnya. Susu tersebut dimasukkan ke dalam dua labu Erlenmeyer dan ke dalamnya dimasukkan kultur starter campuran yang telah dibuat. Kadar laktosa dalam sampel diukur dengan menggunakan metode kolorimetri sesuai yang dijelaskan oleh Somogyi (1952) dan Nelson (1944). Sebanyak 0,1 mL larutan standar BSA (0,00; 0,5; 1,0; 2,0; 3,0; 4,0 dan 5,0 mg/mL) atau sampel yang akan ditentukan kadar proteinnya dimasukkan ke dalam tabung reaksi. Hasil pengukuran serapan standar dibuat kurva baku, dan serapan sampel diplotkan pada kurva baku tersebut untuk menghitung konsentrasi protein yang terkandung dalam sampel

Susu Murni
DAFTAR PUSTAKA
Full Text
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