Identification and analysis of cell wall glycan epitopes and polyphenol oxidase in pawpaw (Asimina triloba [L.] Dunal) fruit pulp as affected by high pressure processing and refrigerated storage.

This research explores the cell wall composition and polyphenol oxidase activity of two pawpaw (Asimina triloba) fruit varieties, Susquehanna and Green River Belle, that were subjected to high pressure processing and 45 days of refrigerated storage. We hypothesize that high pressure processing may inhibit enzymatic action responsible for pawpaw's deleterious postharvest tissue softening and browning. Glycome profiling uses mAb groupings that recognize 19 groups of glycan epitopes present in most major classes of cell wall glycans and was used to determine cell wall composition. Results show that both varieties have typical type I primary cell walls of flowering dicots. However, differences in the fine cell wall structure between the varieties can be inferred and the varieties behaved differently during refrigerated storage, likely indicating of a difference in cell wall-modifying enzymes present in the primary cell walls. High pressure processing treatment does not seem to be effective at eliminating polyphenol oxidase activity.

Valorization of underutilized North American pawpaw (Asimina triloba): investigation as a lipid oxidation inhibitor in turkey homogenate model system.

BACKGROUND: The objective of this study was to characterize the ability of extracts from nine varieties of pawpaw pulp standardized to the phenolics level of 0.1% grape seed extract (GSE) on inhibition of the formation of thiobarbituric reactive substances (TBARS) in a turkey model system. The antioxidant activity of the extracts was also determined using four common assays. RESULTS: Over the 240 min sampling time, the standardized pawpaw extracts from all nine varieties were as effective as GSE in inhibiting TBARS formation in turkey muscle homogenate compared to the untreated control. Extracts from all pawpaw varieties and GSE began to inhibit TBARS formation at 60 min of incubation, and by 240 min TBARS were reduced from 35 µmol malondialdehyde kg-1 tissue in the homogenate to which no antioxidant was added to 4-18 µmol malondialdehyde kg-1 tissue in the antioxidant-enriched extracts. There does not appear to be a clear relationship between inhibition of TBARS and any of the antioxidant capacity measurements (ORAC, DPPH inhibition, reducing potential as measured by FRAP assay, or pyrogallol red bleaching). CONCLUSION: The results of this research indicate that there is potential to add value to pawpaw as a functional food source of natural antioxidants, particularly in meat products. © 2017 Society of Chemical Industry.

Phytochemical analysis of ten varieties of pawpaw (Asimina triloba [L.] Dunal) fruit pulp.

Pawpaw (Asimina triloba [L.] Dunal) is a tree fruit with the potential to become a high-value fruit crop, however, its rapid perishability is a significant obstacle. The objective was to determine the phytochemical content and quality characteristics of pawpaw pulp from ten varieties. This study reports for the first time the mass spectral characterization of phenolic acids and flavonoids of pawpaw, which indicated that the predominant polyphenolic compounds were three phenolic acids, protocatechuic acid hexoside, p-coumaroyl hexoside, and 5-O-p-coumaroylquinic acid, and flavonols, particularly (-)-epicatechin, B-type procyanidin dimers and trimers. The relationship between the polyphenolics identified in the current study and future work on polyphenolic oxidase activity will help the process of assessing whether pawpaws should be selected based on potential health benefits, i.e. high polyphenolic content, or increased shelf life in the form of decreased browning that may be afforded pawpaws containing low polyphenolic levels via decreased action of polyphenol oxidase.