Rheological behavior of bacuri yogurt: effects of temperature and fat content

Abstract

This work aimed to evaluate the preparation and rheological characterization of a bacuri yogurt with reduced-fat content. Three types of yogurts from UHT whole milk, semi-skimmed and skimmed were elaborated. The rheological analyses were performed in four different temperatures (5 °C, 15 °C, 30 °C and 45 °C) and the experimental data were adjusted for Power Law model. The relation of temperature with apparent viscosity was described by Arrhenius equation. The values of yield stress and apparent viscosity for yogurts decreased with increasing temperature as well as with fat content. The model used was adequate to describe the rheological behavior of the yogurts according to the statistics parameters evaluated. The low values obtained for the behavior index indicated a characteristic behavior of pseudoplastic fluids (n<1). The Arrhenius equation described properly the effect of temperature in apparent viscosity. The values of activation energy were 2.66 kcal g mol^-1, 3.81 kcal g mol^-1 and 3.93 kcal g mol^-1, with respect to the samples of whole yogurt, semi-skimmed and skimmed, respectively. Regarding the physicochemical characterization, the fat levels were similar for the skimmed and semi-skimmed yogurts, demonstrating no significant difference. The semi-skimmed and skimmed yogurts were considered light or with reduced-fat content, thus determining a decrease in values of 75% and 79.1%, respectively.

Keywords:
Platonia insignis Mart.; Temperature; Fat content; Apparent viscosity; Fermentation