Bacteria 1 Central composite designs 1 Central-composite design 1 Cheese industry 1 Fermentation 1 Fermented milk 1 Fermented milk drink 1 Functional beverages Functional-beverage 1 Kefir grains 1 Lactic acid 1 Lactic acid bacteria 1 Lactic fermentation 1 Lactic fermentations 1 Multiobjective optimization 1 Optimal conditions 1 Probiotics 1 Response surface methodology 1 Response-surface methodology 1 Surface properties 1 Whey powder 1 Whey powders 1 Yeast 1