Effect of κ-carrageenan on bacteria and some characteristics of yoghurt

In this study, different concentrations (0.01, 0.03, 0.05 and 0.08%) of K-carrageenan were added to milk for yoghurt production. Streptococcus salivarius ssp. thermophilus (ST), Lactobacillus delbrueckii ssp. bulgaricus (LB) and/or L. acidophilus (LA) were used as starter cultures; in samples of groups A and B, respectively, ST-LB and ST-LB-LA. Inoculated milks were incubated at appropriate temperatures until the pH reached 4.7. All samples were stored for 21 d at 4°C. During storage pH, titratable acidity (TA) (as % lactic acid) and whey separations (WS) of all samples were measured. There was significant effect of different concentrations of K-carrageenan on the growth of ST, LB and LA during the storage. Similarly, K-carrageenan was effective on values of pH, TA and WS. But, K-carrageenan was ineffective on the total solid and ash. Structure and appearance were affected by the different concentrations of K-carrageenan. Consequently, the concentrations of 0.01 and 0.03% of K-carrageenan may be used for yoghurt production.