Thermotolerance Study of Bagasse-alginate Encapsulant Using Effective Thermal Conductivity Model for Sustainable Probiotic Feed

Abstract

A great potential in the synthesis of heat resistant microcapsules for probiotic was developed via the synthesis of heterogeneous material. In the study of heterogeneous material, effective thermal conductivity is widely used in measuring the thermal behaviour of the material and is regarded as a key thermophysical property. Production of heterogeneous material could be created via filler incorporation. Incorporation of filler in the microcapsule matrix could enhance the thermotolerance characteristic of the microcapsule. The encapsulation wall concentration also could contribute to the value of effective thermal conductivity of the heterogeneous material. This research is aimed to model fitting the series model of effective thermal conductivity using data collected from immobilised Lactobacillus rhamnosus NRRL 442 in alginate microcapsule (NaA) with incorporated sugarcane bagasse (SB). Different alginate concentration of 1 %, 2 % and 3 % and NaA : SB ratio of 1 : 0, 1 : 1 and 1 : 1.5 were used in synthesising the microcapsules. The microcapsules were produced using the extrusion method. The lowest effective thermal conductivity was obtained from the same microcapsule preparation using 3 % of alginate concentration and at a NaA : SB concentration ratio of 1 : 1.5. The microcapsules prepared using 1 % of alginate concentration and a NaA : SB concentration ratio of 1:0 showed the highest effective thermal conductivity. The regression values (R2) for all alginate concentrations (1 %, 2 % and 3 %) were found to be 0.9997, 1.0000, and 0.9973. The regression models of the effective thermal conductivity in all alginate concentrations versus filler (SB) concentration were plotted. High coefficient of determination was obtained and showed strong correlation between effective thermal conductivity and SB concentration for different alginate concentration. This study could be beneficial in the production of products that necessitate heat treatment thermo tolerance especially in pelleted probiotic feed.