Optimization of process parameters for preparation of rice extrudates from short and long Indica rice cultivars milled to varying degree of milling.

Extrusion behavior of extrudates prepared from short (PR113) and long (PUSA1121) Indica rice cultivars milled to 0-8% degree of milling (DOM) extruded at variable extrusion temperature (150-190 °C) and feed moisture (15-19%) was studied. The physico-chemical and functional properties of extrudates prepared from both the cultivars varied significantly with variation in DOM as well as extrusion variables. DOM showed more pronounced effect for all the responses studied for both the cultivars. Expansion, L*, water absorption and overall acceptability increased whereas hardness, water solubility and bulk density decreased with increase in DOM. Extrusion temperature increase led to increase in expansion and water solubility and decreased L*, bulk density and water absorption. Feed moisture showed significant positive effect on hardness and water absorption and negative effect on expansion, L* and water solubility. Formation of amylose-lipid complexes were also observed during extrusion cooking for both the cultivars which showed negative correlation with DOM. Both the cultivars also showed different behavior for these responses at same values of independent variables.

Optimization of process parameters on hydroxymethylfurfural content, diastase and invertase activity of coriander honey.

Floral authenticity of coriander (Coriandrum sativum) honey samples was confirmed by melissopalynology. Effect of temperature, time and pH on quality parameters i.e. hydroxymethylfurfural (HMF) content, diastase and invertase activity of coriander honey was analysed using response surface methodology. Central composite rotatable design was adopted for optimization of process variables. An increased in HMF content was observed with increase in temperature and pH whereas diastase activity decreased with increase in temperature and with a pH value other than the optimum value of 4.6-5.6. Invertase activity was maximum at 4.8 pH. Interaction effect of temperature and pH was significant for HMF whereas interaction effect of temperature and time was significant for HMF, diastase and invertase activity. Optimization of variables was done by the mathematical method, and optimized values of HMF content, diastase, and invertase activity were obtained as 7.78 (mg/kg), 17.95 DN and 13.96 IN, respectively at 47.5 °C (temperature), 4.7 (pH) and 9 min (time).

Effect of degree of milling on physicochemical, structural, pasting and cooking properties of short and long grain Indica rice cultivars.

The effects of degree of milling (DOM) between 0 and 8% on physico-chemical, structural, pasting and cooking properties of short and long grain Indica rice cultivars were studied. Ash, protein, lipids and minerals decreased while blue value and crystallinity increased with increase in DOM. The colour parameters (a∗, b∗) and cooking time (CT) decreased while L∗(lightness) increased with increase in DOM. Elongation ratio (ER), gruel solid loss (GSL), length/breadth (L/B) and paste viscosities during cooking increased with increase in DOM. Short grain rice contained lower ash, protein, lipids, Mn, K, Ca, CT and GSL than long grain while the later showed higher crystallinity, Mn, P, K, Ca and ER. Paste and dough characteristics measured using Rheometer and Mixolab, respectively correlated well and differed with cultivar and DOM. Short and long grain cultivars showed variation in loss of different chemical constituents during varied DOM causing variation in cooking characteristics.