Rheological properties of fermented rice extract with probiotic bacteria and different concentrations of waxy maize starch

Abstract

Fermented rice extracts (FRE) obtained from bran and broken grains in a proportion of 8:92, and probiotic bacteria with different concentrations of waxy maize starch (WMS) were elaborated. Pearson correlations and multivariate analysis by Principal Component Analysis (PCA) were applied to evaluate the rheological behaviour of FRE. A completely randomized design was used, with five treatments from FRE1 to FRE5 (0, 4, 8, 12 and 16 g 100 g−1 of WMS, respectively), in four original repetitions. The multivariate analysis using PCA found that the shear stress and the WMS percentage showed a higher contribution in the first component (CP1 47.5%), and the viscosity in the second component (CP2 29.0%). The FRE5 presented the highest hysteresis, 128.12 Pa s−1. The Ostwald-de Waele model showed the best fit for the flow curves with R2 > 0.99 and a relative approximate error of 3.14%. All FRE presented non-newtonian behaviour, with n < 1. The FRE with different concentrations of WMS presented rheological behaviour similar to yogurts and lactic beverages described in the literature, indicating that such products can be comparable to traditional yogurts in relation to viscosity and to the flow characteristics. The results also suggest an improvement in the sensory properties of FRE.