Studies on the growth kinetics of lactic acid bacteria under controlled pH cultivation environment using alginate capsules

Abstract

End-product inhibition in LAB fermentation has initiates the development of various approaches to minimize the inhibition effect on LAB growth. The inhibition effect can be minimized by controlling the pH in LAB fermentation. In this study, a novel method has been developed by encapsulating calcium carbonate (CaCO3) into alginate capsules. The capsules were produced by a simple dripping technique which is known as extrusion to control the pH during LAB fermentation. Capsules were formed by extruding the mixture of CaCO3, calcium chloride (CaCl2) and carboxylmethyl cellulose (CMC) through a needle into alginate solution containing sodium alginate and Tween 80. The diameter and membrane thickness of the capsules were varied to study their effects on growth kinetics of LAB. The studied parameters included pH, lactic acid concentration, glucose concentration and viable cell count. The use of capsules gave good pH control and the pH value was within the desired range of pH 4 to 7. High lactic acid production rate was also obtained when capsules with small diameter and thin membrane layer were used. The results showed that encapsulation of CaCO3 in alginate capsules is simple and the capsules are capable to control pH of LAB fermentation in order to improve the viable cell concentration and lactic acid production at the end of the fermentation.