Effects of concentrations, temperature, pH and co-solutes on the rheological properties of mucilage from Dioscorea opposita Thunb. and its antioxidant activity.

The mucilage from Dioscorea opposita (DOM) dispersions presented shear-thinning behaviour that well fitted to the Power Law model. The effects of different concentrations (2%-10% w/v), temperatures (25-80 °C), pH (3.0-9.0), freeze-thaw conditions (thawed at 25 °C and 4 °C), co-salts (KCl and CaCl2) and co-sugars (sucrose, fructose and mannose) on the rheological properties were investigated. Generally, higher concentrations, neutral pH, Ca2+ and sugars increased the viscosity of DOM, while increasing temperature (25-65 °C) had opposite effects. The results suggested that cross-linked networks exist in DOM, and viscosity changes may be related to the ionisation of carboxyl groups, structural changes and enhancement/reduction of molecular interactions. Particularly, Ca2+ could interact with uronic acids of two or more polysaccharide molecules, modify the network-structure through cross-linking with carboxyl groups, and enhance the stronger carboxylate-cation2+-carboxylate interactions. Therefore, DOM is suitable for food applications as thickening or gelling agents in aqueous solutions.

Quality assessment of baby food made of different pre-processed organic raw materials under industrial processing conditions.

The market for processed food is rapidly growing. The industry needs methods for "processing with care" leading to high quality products in order to meet consumers' expectations. Processing influences the quality of the finished product through various factors. In carrot baby food, these are the raw material, the pre-processing and storage treatments as well as the processing conditions. In this study, a quality assessment was performed on baby food made from different pre-processed raw materials. The experiments were carried out under industrial conditions using fresh, frozen and stored organic carrots as raw material. Statistically significant differences were found for sensory attributes among the three autoclaved puree samples (e.g. overall odour F = 90.72, p < 0.001). Samples processed from frozen carrots show increased moisture content and decrease of several chemical constituents. Biocrystallization identified changes between replications of the cooking. Pre-treatment of raw material has a significant influence on the final quality of the baby food.