Convective Baking Characteristics and Effective Moisture Diffusivities of Yellow Mealworms

Yellow mealworm is an alternative protein source studied by researchers to provide an alternative supply of protein to meet the growing demands of human consumption. In this research, convective baking of yellow mealworms at 80°C, 100°C, and 120°C was carried out to study the baking kinetics and product quality. Studies showed the typical falling trend of the moisture ratio curves, which are typical for most bioproducts that undergo hot air treatment. Mathematical modelling showed that the Page model gave a good prediction on the baking kinetics with high fitting accuracy (R2>0.99). Effective diffusivities were determined from 1.66 x 10-11 to 2.88 x 10-11 m2/s within the temperatures tested. The activation energy was estimated at 15.7 kJ/mol based on the Arrhenius equation. The final baked samples appeared darker in color because the browning reaction and reduction in bulk density and product length were observed in the range of 48-54% and 3.0-16.3%, respectively.

The Combination of Hot Air and Chitosan Treatments on Phytochemical Changes during Postharvest Storage of ‘Sanhua’ Plum Fruits

Plum fruits would become putrid quickly after harvest. In order to prolong postharvest life, ‘Sanhua’ plum fruits were treated by hot air combined with a chitosan coating, and stored at low temperature. Fruit firmness, total soluble solids, total phytochemical contents were evaluated along with total antioxidant activities and phytochemical components. Results showed that hot air treatment delayed softening process of plum fruit. The total phenolics and flavonoids accumulated and antioxidant activities increased in both control and treatment samples during storage. These values in the samples treated with hot air and chitosan were all higher than control and hot air treatments. Phytochemicals of epicatechin, cyanidin, pelargonidin, and hesperetin were all upregulated by hot air and chitosan treatment, especially epicatechin. This suggested that chitosan might play an important role in regulating phytochemical profiles of ‘Sanhua’ plum fruits during storage.

Effects of Pichia guilliermondii and Hot Air Treatment on the Postharvest Preservation of Red Fuji Apple Quality Attributes

ABSTRACT The effects of individual and combined Pichia guilliermondii (at 1 × 108 CFU mL−1) and hot air (at 38°C for 96 h) treatments on the three major postharvest diseases Botrytis cinerea, Penicillium expansum, and Colletotrichum gloeosporioides, as well as the quality and antioxidant content of Red Fuji (Malus pumila var. domestica) apple fruit, were investigated in this work. Results suggested that the combined hot air and antagonistic yeast (P. guilliermondii) treatment effectively and completely inhibited the infection of apple fruit wounds by the three major postharvest diseases. Furthermore, apple fruit treated with antagonistic yeast or heat alone maintained better quality, which included mass loss, firmness, solid/acid ratio, and ascorbic acid content, than the control. The combination of the two treatments yielded the optimum apple quality. Moreover, the combined hot air and P. guilliermondii treatment also maintained or enhanced the antioxidative enzyme activities and total phenolic content of apple fruit. All results demonstrated that the combined antagonistic yeast and hot air treatment maintained the postharvest freshness of apple fruit.