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Microbiology and Biotechnology Letters

Research Article(보문)

Fermentation Microbiology  |  Applied Microbiology

Microbiol. Biotechnol. Lett.

Received: December 18, 2023; Revised: March 14, 2024

Modification of substrate and fermentation process to increase mass and customize physical properties of Lacticaseibacillus rhamnosus and Limosilactobacillus fermentum exopolysaccharides in Kefiran

Dandy Yusuf 1, 2*, Raden Haryo Bimo Setiarto 1, 2, Andi Febrisiantosa 2, Angga Maulana Firmansyah 2, Taufik Kurniawan 2, Ahmad Iskandar Setiyawan 2, Rina Wahyuningsih 2, Tri Ujilestari 2, Satyaguna Rakhmatulloh 3 and Heni Rizqiati 4

1Research Centre for Applied Microbiology, National Research and Innovation Agency (BRIN). Jakarta-Bogor Street Km 46, Soekarno Science Centre, Cibinong 16911, West Java, Indonesia, 2Research Center for Food Technology and Processing, National Research and Innovation Agency (BRIN), Yogya-Wonosari Street Km 31,5 Playen, Gunungkidul 55861, Yogyakarta, Indonesia, 3Department of Animal Products Technology, Faculty of Animal Science, Universitas Gadjah Mada, Fauna Street No. 3, Bulaksumur, Yogyakarta 55281, Indonesia., 4Department of Agriculture, Faculty of Animal and Agricultural Sciences, Diponegoro University, Tembalang Campus, Semarang 50275, Indonesia.

Correspondence to :
Dandy Yusuf, Jakarta-Bogor Street Km 46, Soekarno Science Centre, Cibinong, West Java, Indonesia [16911]
Fax : +62 82174144100, E-mail :


The microbial starter used to produce kefir beverages, kefir grain, contains a microbial exopolysaccharide called kefiran. Kefir grain consisting of water-insoluble polysaccharides, proteins, and fats, which can be applied as a multi-functional biopolymer. The mass of kefir grain can increase in the fermentation process of Kefir, but it is considered very slow. The purpose of this research is to study the impact of ammonium sulfate supplementation and yeast extract on reconstituted skim milk to increase the mass kefir grain and physical properties of kefiran. Results showed that the ammonium sulfate-supplemented substrate increased the mass of kefir grain by 547% in 14 days, with the condition that the substrate must be renewed every 2 days. Refreshing the substrate is considered one of the important factors. Supplementation on substrate did not appear to affect the viability of bacterial and yeast cells. Kefir grain produced from supplemented substrate also yields better thermal stability properties and has more functional groups than without supplementation. Two Lacticaseibacillus rhamnosus (RAL27 and RAL43) and one Limosilactobacillus fermentum (RAL29) were found to produce EPS. The three isolates also showed good skim milk fermentation ability after purification from kefir grain. The kefir grain produced in this study has the potential for wider application. This study also showed that kefir grain can be adjusted in quantity and quality through fermentation substrate engineering.

Keywords: fermentation, exopolysaccharide, kefiran, kefir

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