No abstract

Purple sweet potato is rich in anthocyanins. The influence of hot air drying on the physical properties, anthocyanin profile and antioxidant capacity of purple sweet potato was explored at six different temperatures (60, 70, 80, 90, 100, and 110°C), three different paving densities and six different dimensions. The results show that the hot air drying kinetics of purple sweet potato were best described by the Page model. The samples dried at 60°C had the highest rehydration rate (2.64), and there was no significant difference between 80 and 60°C. There were no significant differences among the colors of the samples dried at 60, 70, 80, and 90°C, but they were quite different from that dried at 110°C. Four anthocyanins were identified by HPLC–MS/MS as cyanidin 3‐sophoroside‐5‐glucoside, peonidin 3‐sophoroside‐5‐glucoside, cyanidin 3‐p‐hydroxybenzoylsophoroside‐5‐glucoside and peonidin 3‐p‐hydroxybenzoylsophoroside‐5‐glucoside and determined by HPLC‐DAD, and the anthocyanin contents of the samples dried at 80°C were 609.08 ± 3.26, 82.75 ± 0.33, 265.88 ± 0.93, and 179.74 ± 1.35 mg/100 g DW, respectively. The highest ORAC antioxidant capacity was found in samples dried at 80°C (130.94 ± 2.59 μmol TE/g). Based on these studies, 80°C is most suitable for the hot air drying of purple sweet potato. Practical applications Purple sweet potatoes have good antioxidant capacity, which is good for health and loved by consumers. Fresh purple sweet potatoes are not easy to store, but the storage time can be prolonged after hot air drying. This study detected the influence of hot air drying on the drying kinetic, color, rehydration, microstructure, and anthocyanin content of purple sweet potato. Compared with dimension and paving density, the influence of drying temperature is greater. Among six temperatures, 80°C is most suitable for the hot air drying of purple sweet potato. This study provides a theoretical basis for the development and utilization of purple sweet potato as a functional food.

Tremella sanguinea is a traditional Chinese medicinal and edible mushroom. Polysaccharides from Tremella mushrooms have received increasing amounts of research attention due to their diverse pharmacological activities. In this study, via the incubation of basidiospores collected from fresh artificially cultivated basidiocarps of T. sanguinea, a haploid yeast strain of T. sanguinea was obtained, and it was found to be a typical loose-slime-forming yeast capable of producing a large amount of exopolysaccharides (EPS). Using DEAE-52 cellulose column chromatography and Sephadex G-100 gel permeation chromatography, the major polysaccharide, named TSPS-1, was separated and purified from the EPS produced by the haploid yeast strain of T. sanguinea. TSPS-1 was a homogeneous polysaccharide with a molecular weight of 2.5 × 103 kDa and consisted of rhamnose, glucose, xylose, mannose and glucuronic acid at a molar ratio of 1: 0.7: 62.2: 24.6: 11.5. The bioactivity of the TSPS-1 polysaccharide was evaluated. The results show that TSPS-1 exhibited noticeable antioxidant activity by scavenging hydroxyl radicals (EC50 = 1.92 mg/mL) and superoxide radicals (EC50 = 1.33 mg/mL), and prebiotic activity by promoting the growth of different probiotic strains in the genus Lactobacillus and Bifidobacterium. These results suggest that the cultivation of the haploid yeast strain can be a promising alternative for the efficient production of valuable T. sanguinea polysaccharides with antioxidant and prebiotic potential.

No abstract