Process optimization of partially hydrolyzed guar gum using response surface methodology
Process variables for maximum viscosity reduction of guar gum were studied using response surface methodology. Central composite design with four independent variables: pH, temperature, reaction time and enzyme concentration was used to study the response variable i.e. viscosity. The experimental values of viscosity ranged between 14 and 348 cPs. The second-order model obtained for viscosity values revealed coefficient of determination of 0.9629. The optimum conditions for enzymatic hydrolysis of guar gum were obtained with 0.19 mg/g enzyme concentration, 5.59 pH and 3.99 h hydrolysis time at 49.84ºC. Confirmatory studies revealed that guar gum soluble fibre of very low viscosity i.e. 10 cPs (1 cP = 0.001 Pa.s) was obtained with enzymatic hydrolysis under optimized conditions of process variables.
Seeds of leguminous crops are rich source of dietary fibre that promotes various beneficial physiological effects for human health (1). Guar gum is the highly viscous water soluble galactomannan obtained from the seeds of plant Cyamopsis tetragonolobus. Guar galactomannan is composed of galactose and mannose units in 1:2 ratios. High viscosity of guar gum is due to its high molecular weight which ranges from 0.1-2.8 million. Guar gum finds extensive application as a thickener, stabilizer and texture improver in various food products (2, 3). In last few decades, interest in incorporation of dietary fibre in food products has increased. Soluble and fermentable dietary fibres are more beneficial in diabetes, appetite regulation and heart diseases (4-6). Recently, guar gum has been studied extensively for its health benefits (7, 8) Partially hydrolyzed guar gum (PHGG) has attracted attention as a water-soluble dietary fibre as it is beneficial in diabetes, heart disease and digestive problems (9). PHGG can be produced by enzymatic hydrolysis, acid hydrolysis, irradiation, microwave and ultrasonication techniques (10-12). For food applications, P ...