Studies on the application of alginate capsules to control pH of lactic acid fermentation

Abstract

A novel approach has been developed to produce alginate capsules composed of calcium carbonate (CaCO3) using extrusion method to control pH in lactic acid bacteria (LAB) fermentation. In this method, mixture of CaCO3 (6% - 40% (w/v)) together with 1.5% (w/v) Calcium Chloride (CaCl2) and 1.5% (w/v) Carboxylmethyl Cellulose (CMC) were extruded through needles of different sizes (0.8mm, 1.2mm, 2.3mm). The capsules formed were allowed to drip into gelling bath containing 1.5% (w/v) Sodium alginate and 0.15% (v/v) Tween 80 for capsules formation. For variables such as: the effects of CaCO3 loading, needle size, gelation time for membrane formation, and suitable ratio of capsules to the fermentation broth were investigated. The result indicated that capsules with 40% (w/v) CaCO3 diameter of 4.50mm and thickness of 0.81mm in capsules to fermentation broth ratio of 1: 3 ratio were capable to control the pH in LAB fermentation to pH 5.50 compare to the control medium (pH 3.86). Although direct adding of 3% (w/v) in medium showed slightly better control (pH 5.83) compare to using capsules, the purification process of the medium was complex. Furthermore, the differences were merely 4.8%. Therefore, encapsulations of CaCO3 in capsules are preferable. In conclusion, this study showed a new method for pH control application using liquid core capsule technology.