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Summary: Harvested banana undergoes rapid softening, which limits its shelf life. To delay softening, banana fruit was treated with hydrogen sulfide (H2S) emitted by 0.6 mm sodium hydrosulfide (NaHS) and stored at 15 °C for 16 days. The effects of H2S on cell wall degradation and other physiological characteristics were investigated. In comparison to control fruits, H2S‐treated bananas retained a higher level of fruit firmness, but lower hue values. Ethylene metabolism analysis suggested that H2S inhibited the production of ethylene and the accumulation of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) and decreased the activities of ACC synthase (ACS) and ACC oxidase (ACO). Cell wall polysaccharides determination assays suggested that H2S treatment increased the proportion of HCl‐soluble pectin (HSP), NaOH‐soluble pectin (NSP), cellulose and hemicellulose but decreased water‐soluble pectin (WSP) in fruits. H2S treatment also inhibited the activities of polysaccharide degrading enzymes such as polygalacturonase (PG), pectin methylesterase (PME), pectin lyase (PL), cellulase (CL) and β‐galactosidase (β‐Gal). Transmission electron microscopy analysis suggested that H2S protected cell walls from structural breakdown. These results indicated that H2S is effective in delaying banana softening by regulating cell wall polysaccharide metabolism. [ABSTRACT FROM AUTHOR]

Highlights • Three polysaccharides were identified in banana by NMR. • Starch was disassembled and degraded during storage. • Arabinogalactan proteins could be a marker for banana quality. Abstract The degradation of cell wall polysaccharides is highly associated with the softening process of banana. In this work, banana was treated by morin to delay softening during storage. Water-soluble polysaccharides were extracted from banana pulp at four storage stages. Their levels increased when the banana was green, but decreased when turned to yellow. Three types of polysaccharides were identified by nuclear magnetic resonance spectroscopy, including starches, homogalacturonans and arabinogalactan proteins. (1 → 4)-α-D-galacturonan constructed the backbone of homogalacturonans, which was the leading water-soluble polysaccharide in the last stage. Starch was the dominant polysaccharide at all stages in morin-treated banana. Deassembly of insoluble starch granules and degradation of soluble starches were responsible for its high level in banana. Arabinogalactan proteins were only detected in late stages, and could be a marker for banana deterioration. The inhibited degradation of cell wall polysaccharides contributed to the preservative effect of morin. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • α-(1 → 6)- d -glucan was a chemical contributing to the health benefit of banana. • α-(1 → 6)- d -glucan was abundant in banana. • α-(1 → 6)- d -glucan had good immunostimulatory activities. Abstract Banana is a fruit widely accepted by people over the world. Besides having delicious taste, it shows multiple health benefits. In this work, the major polysaccharide was isolated from banana and purified. It was identified to be α-(1 → 6)- d -glucan. The in vivo immunomodulatory activity assay indicated that α-(1 → 6)- d -glucan could improve the immune status by elevating T cell proliferation, phagocytic function of macrophage, CD3+ T cell level, CD4+/CD8+ ratio, IL-6, IgG, IgM, TNF-α and hemolysin antibody levels. The immunostimulatory activities of α-(1 → 6)- d -glucan were similar to β-(1 → 3)- d -glucan, a clinical immunostimulatory drug. This work revealed that α-(1 → 6)- d -glucan was an important bioactive chemical for the immunostimulatory activity of banana. It could be used as a nutraceuticals candidate. [ABSTRACT FROM AUTHOR]

Papaya is a fruit mainly grown in tropical and subtropical regions. The structural changes of polysaccharides are highly involved in the organoleptic property change of papaya. However, it remains unclear how the structure characteristics of water-soluble polysaccharides are changed during postharvest ripening. It is interesting to work on this topic. In this work, the dominant water-soluble polysaccharide in papaya was purified. It was identified to be α-(1 → 4)-D-galacturonan by NMR. It remained stable during postharvest ripening. β-(1 → 4)-D-galactan was only detected in fully green papaya. Once the postharvest ripening initiated, this polysaccharide was rapidly degraded. There were no significant differences in the structure changes of water-soluble polysaccharides for the naturally ripening papaya and ethylene-treated papaya. These results extended the understanding about the relationship between polysaccharide structure and papaya ripening during postharvest storage. [ABSTRACT FROM AUTHOR]

Okra is a widely accepted vegetable in subtropical and tropical regions due to the good palatability. However, the polysaccharide compositions remain unclear. In this work, the water extract of okra pod was prepared and the leading polysaccharide fraction was purified. The precise structural characteristics were identified. It was a polysaccharide “rhamnogalacturonan” as shown below, and the structure was different to previously reported rhamnogalacturonans. The hypoglycemic effect of rhamnogalacturonan was determined in vivo . By comparing with streptozotocin-induced diabetic mice group, the high-dose group showed decreased blood glucose level and glucose tolerance. The body weight of all groups were not significantly different. The results indicated that the rhamnogalacturonan was responsible for the hypoglycemic effect of okra. [ABSTRACT FROM AUTHOR]

The water-soluble bioactive polysaccharides can contribute to the health benefits of Lycium barbarium fruit. However, the structure characteristics of these polysaccharides remain unclear yet. An important polysaccharide (LBPA) was isolated and purified from L. barbarium in this work. It was identified by chemical and spectroscopic methods as arabinogalactan with β- d -(1 → 6)-galactan as backbone, which was different to any reported polysaccharides from this species before. This arabinogalactan was comprised of Ara f , Gal p , Glc p A and Rha p with a molar ratio of 9.2:6.6:1.0:0.9. The side chains, including α- l -Ara f -(1→, α- l -Ara f -(1 → 5)-α- l -Ara f -(1→, β- l -Ara f -(1 → 5)-α- l -Ara f -(1→ and α- l -Rha p -(1 → 4)-β- d -Glc p A-(1 → 6)-β- d -Gal p -(1→, were linked to β- d -(1 → 6)-galactan at O-3. The putative structure was drawn as below. The molecular weight was determined to be 470,000 g/mol by gel permeation chromatography. [ABSTRACT FROM AUTHOR]