Chitosan-Based Oleogels: Emulsion Drying Kinetics and Physical, Rheological, and Textural Characteristics of Olive Oil Oleogels

Oleogels are of high interest as promising substitutes for trans fats in foods. An emulsion-templated method was used to trap olive oil in the chitosan crosslinked with vanillin matrix. Oil in water emulsions (50:50 w/w) with different chitosan content (0.7 and 0.8% w/w) with a constant vanillin/chitosan ratio (1.3) were air-dried at different temperatures (50, 60, 70, and 80 °C) and freeze-dried (-26 °C and 0.1 mbar) to produce oleogels. Only falling rate periods were determined during air-drying kinetics and were successfully modeled with empirical and diffusional models. At a drying temperature of 70 °C, the drying kinetics were the fastest. The viscoelasticity of oleogels showed that the elastic modulus significantly increased after drying at 60 and 70 °C, and those dried at 50 °C and freeze-dried were weaker. All oleogels showed high oil binding capacity (>91%), but the highest values (>97%) were obtained in oleogels with a threshold elastic modulus (50,000 Pa). The oleogels' color depended on the drying temperature and chitosan content (independent of the drying method). Significant differences were observed between air-dried and freeze-dried oleogels with respect to oxidative stability. Oxidation increased with the air-drying time regardless of chitosan content. The found results indicated that drying conditions must be carefully selected to produce oleogels with specific features.

Heat- and shear-reversible networks in food: A review

While nature behaves like an irreversible network with respect to entropy and time, certain systems in nature exist that are, to some extent, reversible. The property of reversibility imparts unique benefits to systems that possess them, making them suitable for designing self-healing, stimuli-responsive, and smart materials that can be used in widely divergent fields. Reversible networks are currently being exploited for applications in tissue engineering, drug delivery, and soft robotics. They are also being utilized as low-calorie fat mimetics with melt-in-your-mouth textures, as well as being explored as potential scaffolds for three-dimensional (3D) printable food, among other applications. This review aims to gather representative examples of heat- and shear-reversible networks in the food science literature from the last 30 or so years, in other words, reversible food gels made either from linear biopolymers or from colloidal, particulate dispersions, including those that have been modified specifically to induce reversibility. An overview of the network mechanisms involved that impart reversibility, including a discussion of the strength and range of forces involved, will be highlighted. A model that explains why certain networks are thermoreversible while others are shear-reversible, and why others are both, will also be proposed. A fundamental understanding of these mechanisms will prove invaluable when designing reversible networks in the future, making possible the precise control of their properties, thus fostering innovative applications within the food industry and beyond.

Synergistic effect of extrusion and polyphenol molecular interaction on the short/long-term retrogradation properties of chestnut starch

The retrogradation properties of starch are closely related to the processing quality of starch-based foods. In this study, the synergistic effects of extrusion and the presence of polyphenols on the water distribution, rheological properties and short-term (1 day)/long-term (21 day) retrogradation of chestnut starch paste were investigated. Post extrusion complexation with catechins (CC)/proanthocyanidins (PC), the short- and long-term retrogradation were both inhibited and the anti-retrogradation rates (AR) during 1 and 21 days were as high as 100% and 44.17-69.30%, respectively. Owing to the destruction of starch chains by extrusion and interaction between starch and polyphenol molecules, the approach, entanglement and aggregation tendencies of starch molecules were all inhibited, which decreased the relative crystallinity (RC), flow resistance and storage modulus of starch paste and also increased the water-holding capacity. The starch retrogradation was thus suppressed. These results are beneficial for the development of starch-based products with high quality and lower retrogradation rate.

Dual-process of starch modification: Combining ozone and dry heating treatments to modify cassava starch structure and functionality

This work evaluated for the first time the effect of dual modification of cassava starch by using ozone (O₃) and dry heating treatment (DHT). The dual modification was capable to promote fissures on the surface of the starch granule (DHT + O₃), affected the starch amorphous domains, presented greater degree of starch oxidation (DHT + O₃) and different profiles of starch molecular size distribution. These modifications resulted in starches with different properties. Moreover, the sequence of treatments was decisive for the hydrogel properties: while DHT + O₃ resulted in formation of stronger gels, O₃ + DHT resulted in weaker gels. In conclusion, this proposed dual modification was capable to produce specific modified starch when compared with the isolated treatments, also expanding the potential of cassava starch applications.