The crude polysaccharide extracted from Cordyceps militaris was chemically modified to obtain carboxymethylated derivatives (CM-CPS) and acetylated derivatives (AC-CPS). The physicochemical characterizations were comparatively investigated by chemical methods, high-performance gel permeation chromatography, FT-IR spectra, NMR analysis, Congo red test, scanning electron microscopy, atomic force microscopy and differential scanning calorimetry. Then α-glucosidase inhibitory activities were conducted to determine the structure-bioactivity relationship. Results indicated that carboxymethylation and acetylation modification of polysaccharide were successful with the carboxymethyl substitutions might being C-6, C-2 and acetyl substitutions at C-3, C-6 inferred from NMR analysis. In addition, the tertiary structure, ultrastructure, melting properties were also different from native polysaccharide. Besides, α-glucosidase inhibitory activities of derivatives exhibited differently with CM-CPS to be the lowest. Therefore, it was concluded that change of structure in polysaccharide had certain effect on bioactivity with degree of substitution and substituents position being the influence factors.
Rhizopus oryzae
lipase (ROL) is very attractive in biotechnology and industry as a safe and environmentally friendly biocatalyst. Functional expression of ROL in
Escherichia coli
facilitates effective high-throughput screening for positive variants.
A red-colored carotenoid pigment called astaxanthin possess high antioxidant capability, which is valued in biochemical research. Beside the pharmaceutical and cosmetic industries, it has a potential application in food, especially in foods that are beneficial to human health. Natural astaxanthin is abundantly distributed in food, especially in aquatic products, which is the secret of high-quality aquatic products. While the general extraction of natural astaxanthin has low purity and high cost, it is crucial to search a more economical, efficient and environmental-friendly purification method further. Meanwhile, due to the instability and low biological utilization of astaxanthin, the encapsulation of astaxanthin through delivery system plays a vital role in overcoming the challenges mentioned above and breaking the limitation of astaxanthin in food production and application.
Iron deficiency is a global issue, influencing more than one-third of the population in the world. Ferritin as a natural iron-containing protein is considered marvelous iron supplement due to its...
Firmness and soluble solids content in Annona squamosa during storage were studied. Changes in total Annona squamosa polysaccharides (TASP) obtained by alcohol precipitation and corresponding ethanol supernatants (TASP‐S) during storage were analyzed. Ethanol supernatants from Annona squamosa stored for 3 days (TASP‐S3) were chosen and small molecule carbohydrate (TASP‐S3‐1) in it was characterized in structure. Activities of related enzyme during storage were determined. Results indicated firmness exhibited a significant decline from 1 day to 3 days and soluble solids content fluctuated during storage. With prolonged storage time, relative content of each component in TASP varied and that of carbohydrate with higher molecular weight gradually decreased. So was the compositions in TASP‐S during storage. TASP‐S3‐1 was ultimately identified to be saccharose. Enzyme assays indicated activities of related enzymes varied during storage, and acid invertase, sucrose synthase might play more important roles in improving the quality and nutrition of postharvest Annona squamosa.
Practical applications
This work lay the foundation for further studying carbohydrate metabolism and controlling the quality of postharvest Annona squamosa. Because the relative contents of each components in TASP and TASP‐S, changed with the extension of storage time. Besides, among these related enzymes, acid invertase and sucrose synthase would be more important in postharvest Annona squamosa, which provided critical information on improving the quality and nutrition of Annona squamosa in further study.
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