CARBOHYDRATE BASED PREBIOTIC EFFECTS ON QUALITY ATTRIBUTES OF YOGHURT AND ITS PROBIOTIC ENDURANCE

Abstract

The research work was done to evaluate suitability of guar gum (CGG, PGG, AHGG, BHGG and EHGG) utilization as prebiotic on probiotic (BB) behavior in yogurt. CGG was purified (ethanol, 95:5v/v) and hydrolyzed using HCl, [Ba(OH)2] and mannanase enzyme. SEM characterization exhibited rough surface morphology in CGG, PGG and BHGG, powdery and fluffy appearance in AHGG and well defined porous structure in EHGG. The consequences of XRD displayed amorphous structure and less crystallinity in CGG, PGG and AHGG while EHGG slightly increased in crystallinity but lower than BHGG. FTIR analysis revealed no major transformation of functional groups after hydrolysis of guar gum. TGA evaluation of hydrolyzed guar gums indicated more heat stability than the crude ones. Rheological studies revealed shear thinning non-Newtonian behavior at high shear rate and Newtonian flow at low shear rate [high viscosity CGG (1.34 Pa.s); low viscosity AHGG (0.15 Pa.s), EHGG (0.22 Pa.s)] while, in oscillatory inferences (viscous modulus, Gʺ; elastic modulus, Gʹ), guar gums exhibited typical characteristics of weak viscoelastic gel. The small intestine model (SIM) evaluation exposed non-significant difference in physiological behavior of guar gums in reducing the glucose level. Haemolysis study showed non-toxic effect (haemolysis, 1.9±0.03% to 7.24±0.02%) of guar gums to human RBC’s. Guar gum treatments were evaluated for their prebiotic and probiotic endurance on yogurt quality attributes. Periodic physico-chemical, sensory characteristics and bacterial viability of the functional yogurt (Lactobacillus bulgaricus, Streptococcus thermophilus and Bifidobacterium bifidum + 0.1%, 0.5%, 1.0% of AHGG and EHGG) at 4-6°C revealed significant syneresis reduction, increase in WHC and viscosity exhibiting higher sensory acceptability of prebiotic and probiotic endurance. Cryo-scanning electron microscopy proved well embedded continuous casein network imparted by AHGG and EHGG granules. In the whole, acidity and syneresis increased but pH, viscosity, WHC, bacterial viability and consumer’s acceptability decreased with passage of time. The presence of guar gum as prebiotic also caused a significant effect on organic acids contents in yogurt due to metabolic activities of probiotic. The data obtained was analyzed using two-factor factorial design under CRD in Statistix 8.1 software. Key words: Guar gum hydrolysis, Characterization, Prebiotic, Probiotic, Functional Yogurt, Health benefits