Optimization xanthan gum, Roselle seed and egg white powders levels based on textural and sensory properties of gluten-free rice bread

A response surface methodology based on Box-Behnken design was deployed to optimize gluten-free bread formulation based on rice flour. Roselle seed powder (15, 25 and 35%), egg white powder (10, 20 and 30%) and xanthan gum (0.5, 0.75 and 1%) were selected as independent variables. The purpose of the optimization was to achieve maximum porosity and sensory properties as well as minimum hardness of bread samples. The results showed that the Roselle seed and egg white powders had a significant effect (p ≤ 0.05) on hardness, porosity and sensory characteristics of bread. However, xanthan gum did not show a significant effect (p > 0.05) on sensory properties. The design revealed the optimum formulation for gluten-free rice bread with low crumb firmness and improved porosity and sensory values by using 0.73, 30 and 25% of xanthan gum, Roselle seed and egg white powders, respectively. In addition, the optimized gluten-free bread showed higher nutritional properties in terms of total protein, ash, oil and fiber contents as well as lower staling rate compared to the control.

Convective Air Drying of Spondias Dulcis and Product Quality

Kedondong (Spondias dulcis) contains polyphenols, vitamin C and carotenoids which are beneficial to human health. Fresh kedondong has short shelf life and drying is an option to preserve the fruit in dried form to avoid spoilage. In this research, kedondong slices were dried at three temperatures (60 °C, 70 °C and 80 °C) using convective air and RH was fixed at 30 %. High drying temperature facilitated faster drying rate but resulted in poor product quality when compared to freeze dried samples. Drying rates were observed only occurred within falling rates period. Effective diffusivities were estimated in the order of magnitude 10–7 - 10–9 m2/s based on Fick’s second law. Quality assessment showed that samples dried at 60 °C had the lowest hardness and the highest total polyphenols content was observed from samples dried at 80 °C. In addition, kedondong flavour note was found favourable from samples dried at 70 °C and 80 °C based on penalty analyses.

Description of Osmotic Dehydration of Melon Cubes using a Three-dimensional Diffusion Model: An Algorithm to Determine the Effective Diffusivity

This paper aims to study the transient mass diffusion during the osmotic dehydration of melon cubes, using the analytical solution of the diffusion equation with boundary condition of the first kind. Two techniques are used to determine the effective mass diffusivity, using experimental data. In technique 1, available in the literature, the domain of the effective diffusivity is scanned from a value close to zero, until the minimum value of the objective function (Chi-square) is determined. Technique 2, proposed in this paper, uses an algorithm based on the optimal removal of experimental points, until obtaining the objective function with a minimum value, allowing to determine the optimal value for the effective mass diffusivity. The obtained values for diffusivity and statistical indicators revealed that both techniques generate equivalent results and allowed to satisfactorily describe the kinetics of osmotic dehydration of melon cubes. However, technique 2, proposed in this paper, is much faster than technique 1, in the determination of effective mass diffusivity, for all analyzed sets of experimental data.

Guava Osmotic Dehydration: Description by Two-Dimensional Diffusion Models Considering Shrinkage and Variations in Process Parameters

This article describes the osmotic dehydration of guava dipped in sucrose solutions using two-dimensional numerical solutions of the diffusion equation with boundary condition of the first kind. Two models are used: model 1 disregards the shrinkage of the product and assumes that effective mass diffusivity does not vary during the process; model 2 takes into account shrinkage, considering effective mass diffusivity as variable. Process parameters estimation is obtained by means of an optimizer. Comparative analyzes indicate that the proposed models have similar statistical indicators. However, model 2 is recommended, for it presents much higher physical fitness when describing mass migrations. Comparison between two-dimensional numerical models presented in this research and one-dimensional models found in the literature reveals that one-dimensional models overestimate process parameters. In addition, one-dimensional models present limitations in predicting the distributions of water and sucrose on guava slices.

Osmotic Dehydration of Tomato Assisted by Ultrasound: Evaluation of the Liquid Media on Mass Transfer and Product Quality

The treatment of a food in liquid media involves mass transfer and could aid to preserve some food properties. The assistance of ultrasound (US) could even improve the process. Therefore, the aim of this study was to evaluate US (frequency 25 kHz, powder intensity 8 kW m–3) in tomato treatment in sucrose and NaCl solutions, common osmotic agents. Moreover, for testing the influence of the media, distilled water and maltodextrin solution completed the set of tested liquids. Water loss (WL), solid gain (SG), water activity (aw), color parameters, like the total color difference (ΔE) and microstructure were evaluated. The advantages of NaCl and sucrose solutions were the high WL and SG values besides low aw and ΔE. The alterations in the microstructure of US-treated samples in distilled water or maltodextrin suggested that a product with low solid incorporation and reduced drying time could be obtained in a further drying.