Application of Whey Permeate Fermented with Kefir Grains for the Shelf-Life Improvement of Food and Feed

Abstract

Fungal contamination by Aspergillus parasiticus and A. flavus causes negative effects on the production of food cereals. Kefir is an ancient fermented beverage obtained by the fermentation of different substrates with kefir grains. An important waste produced by the dairy cheese industry is the whey permeate, which nowadays is a strong ambient contaminant. The aim of this work was the standardization of the whey permeate fermenting conditions with kefir grains, the assessment of the antifungal activity of the cell-free-supernatants (CFS) from these fermentations and to compare it with that obtained with CFS of milk fermented with kefir grains. Finally, we studied if the addition of kefir fermented whey permeate to food (bread) and feed (poultry) could produce shelf life improvement. The optimal condition to obtain CFS with fungicidal effect was a fermentation with 10% w/v of kefir grains, at 30˚C, for 24 hours until a pH 3.7. We found that CFS from whey permeate caused fungal inhibition, whereas CFS of kefir grains grown in milk showed lower antifungal activity. Additionally, the addition of kefir-fermented whey permeates in food (bread) and feed (poultry) improved their resistance to fungal contamination. This is the first report about the application of kefir-fermented whey permeate to improve the shelf life, suggesting its potential use as a biopreservative.