Rathy Ponnampalam

Some functional properties of acetylated and succinylated oat protein concentrates and a blend of succinylated oat protein and whey protein concentrates

Abstract Protein extract from oat groats was acylated to various degrees with acetic and succinic anhydrides to produce acetyl protein concentrate (APC), and succinyl protein concentrate (SPC), respectively. With both the acylating agents, approximately 36% (APC-37, SPC-35) and 76% (APC-76, SPC-76) of the e-amino groups of lysine were acylated, and changes in functional properties were monitored. Size exclusion-HPLC showed some dissociation of oat proteins with acylation. Nitrogen solubility, emulsifying properties, water hydration and fat binding capacities were improved by acylation, and the effect was more pronounced with succinylation. Although the nitrogen solubility of the blend (SPC-76 and whey protein concentrate, 1:1 ratio on protein basis) was slightly lower than that of the whey protein concentrate (WPC), the other functional properties such as emulsifying properties, water hydration, and fat binding capacities were improved in comparison with that of the WPC. The results suggest that acylated oat protein and the blend may serve as a valuable functional ingredient in emulsion food products.

Inhibition of 1-aminocyclopropane-1-carboxylic acid-dependent ethylene production in tomato-tissue discs by biochemical treatments

Abstract Ethylene production in tomato-tissue discs was inhibited to different extents by an uncoupler of oxidative phosphorylation (2,4-dinitrophenol), an inhibitor of oxygen affinity (2,3-diphosphoglycerate), free radical scavengers (ascorbic acid, n-propyl gallate, sodium benzoate), chelating agents (citric acid, diethyldithiocarbamate, EDTA, NaN3), sulfhydryl reagents (cysteine, dithioerythritol, glutathione, CoCl2), and polyamines (spermine, spermidine, putrescine, cadavarine). Among all the inhibitors tested, agents which are multifunctional such as DNP, n-propyl gallate, NaN3 and polyamines were most effective in inhibiting ethylene production. Based on these results and the mode of action of these compounds, the relative importance of various factors for ethylene production has been identified and methods to control ethylene biosynthesis are discussed.