Preservation of Kefir Grains, a Comparative Study

Abstract

The microflora of kefir grains of household origin was isolated and identified. At least two lactococci, two lactobacilli, two yeast and one mould were detected. Different methods for kefir grain preservation were studied. Metabolic activity of grains preserved frozen at −20 °C and −80 °C and grains stored at 4 °C was evaluated. Grains stored at −20 °C and −80 °C maintained their microflora and increased their weights at a rate comparable to that found with nonstored grains. Fermented milk obtained with the grains stored at −20 °C and −80 °C showed the same microflora, rheological behaviour, acidity and carbon dioxide content as fermented milk obtained with nonstored grains. Grains stored at 4 °C did not increase their weight and the product obtained did not have the acidity and viscosity of the standard product. Storage at −20 °C is a good method to preserve kefir grains for household manufacture of fermented milk.