Identification and analysis of cell wall glycan epitopes and polyphenol oxidase in pawpaw ( [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 () 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.

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.

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.

Relating instrumental texture, determined by variable-blade and Allo-Kramer shear attachments, to sensory analysis of rainbow trout, Oncorhynchus mykiss, fillets.

Unlabelled: Texture is one of the most important quality attributes of fish fillets, and accurate assessment of variation in this attribute, as affected by storage and handling, is critical in providing consistent quality product. Trout fillets received 4 treatments: 3-d refrigeration (R3), 7-d refrigeration (R7), 3-d refrigeration followed by 30-d frozen storage (R3F30), and 7-d refrigeration followed by 30-d frozen storage (R7F30). Instrumental texture of raw and cooked fillets was determined by 3 approaches: 5-blade Allo-Kramer (AK) and variable-blade (VB) attachment with 12 blades arranged in perpendicular (PER) and parallel (PAR) orientations to muscle fibers.

Effect of N-acetyl-cysteine on liposomal and muscle model oxidation induced by reactive oxygen, nitrogen, and sulfur.

N-acetyl-cysteine (NAC), a naturally occurring thiol, is found in some fruits and vegetables, sometimes in concentrations higher than glutathione. The objective of this research was to determine the antioxidative effect of NAC in liposomal and muscle models challenged by different oxidizing systems, three that produce reactive oxygen species, two that produce reactive nitrogen species, and two that produce reactive sulfur. The antioxidative effect of cysteine and NAC was compared in the liposomes and NAC and BHT were compared in the muscle homogenates.

Reactive sulfur species act as prooxidants in liposomal and skeletal muscle model systems.

Reactive sulfur species (RSS) are redox-active sulfur compounds formed under conditions of oxidative stress that may be capable of initiating oxidation reactions. The objective of this research was to determine if two RSS, sulfite radicals and disulfide S-oxides (DSSO), induce oxidation in n-3 liposomes and muscle homogenates. Sulfite radicals and DSSO caused an increase in secondary oxidation products compared to the unoxidized control within 5 min of addition to liposomes.

Grape seed extract inhibits lipid oxidation in muscle from different species during refrigerated and frozen storage and oxidation catalyzed by peroxynitrite and iron/ascorbate in a pyrogallol red model system.

The antioxidant effect of grape seed extract (GSE) was determined by assessing the bleaching of pyrogallol red (PGR) by peroxynitrite or iron/ascorbate, and the formation of lipid hydroperoxides (LOOH) and thiobarbituric acid substances (TBARS) in raw or cooked ground muscle during refrigerated or frozen storage. In PGR models, GSE was more effective than gallic acid in inhibiting oxidation. The formation of LOOH and TBARS was inhibited by GSE (0.

Degradation of γ- and α-tocopherol and formation of 5-nitro-γ-tocopherol induced by peroxynitrite in liposomes and skeletal muscle.

Peroxynitrite, formed from the reaction between nitric oxide and superoxide, can participate in free radical-mediated reactions with cellular components in muscle to (1) initiate lipid oxidation via the production of lipid hydroperoxides, and (2) produce novel nitrated products. 5-Nitro-γ-tocopherol (NGT) is formed by the electrophilic substitution reaction between peroxynitrite and γ-tocopherol. The objective of this research was to examine the utility of NGT as a lipid-phase, peroxynitrite-specific biomarker in muscle foods.

Nitric oxide synthase activity in muscle foods.

Nitric oxide is enzymatically produced in animals by nitric oxide synthase (NOS). Nitric oxide reacts with superoxide to form peroxynitrite, which initiates oxidative reactions. To assess the potential for nitric oxide formation in muscle, NOS activity was determined in fresh muscle (<8 h post-mortem) from several species under conditions expected in muscle foods.

Potential of peroxynitrite to alter the color of myoglobin in muscle foods.

Superoxide anion and nitric oxide can react to form the highly oxidizing species peroxynitrite. The objective of this research was to determine if peroxynitrite can promote the discoloration of myoglobin under conditions expected in muscle foods. Reagent peroxynitrite (25-100 microM) caused rapid and extensive formation of metmyoglobin from oxymyoglobin with the majority of metmyoglobin formation occurring during the first 5-10 min of incubation.