Evaluation of Antioxidant Capacity (ABTS and CUPRAC) and Total Phenolic Content (Folin-Ciocalteu) Assays of Selected Fruit, Vegetables, and Spices.

Antioxidant (AOX) capacity assays are important analytical tools, used worldwide to measure the AOX capacities of various food commodities. Although numerous protocols have been published to ascertain AOX capacities, there are increasing concerns about the reliability of many of these assays. Poor correlation of results between various assays, as well as problems with reproducibility, consistency, and accuracy, is to blame.

Organic acids in Kakadu plum (Terminalia ferdinandiana): The good (ellagic), the bad (oxalic) and the uncertain (ascorbic).

The phenolic ellagic acid (EA) is receiving increasing attention for its nutritional and pharmacological potential as an antioxidant and antimicrobial agent. The Australian native Kakadu plum (Terminalia ferdinandiana) fruit is an abundant source of this phytochemical. The fruit also contains large amounts of vitamin C (mainly as ascorbic acid, AA) and possibly the undesirable oxalic acid (OA).

Increase in β-ionone, a carotenoid-derived volatile in zeaxanthin-biofortified sweet corn.

Carotenoids are responsible for the yellow color of sweet corn (Zea mays var. saccharata), but are also potentially the source of flavor compounds from the cleavage of carotenoid molecules. The carotenoid-derived volatile, β-ionone, was identified in both standard yellow sweet corn ('Hybrix5') and a zeaxanthin-enhanced experimental variety ('HZ') designed for sufferers of macular degeneration.

Key role of Fe(2+) in epithiospecifier protein activity.

The chemical nature of the hydrolysis products from the glucosinolate-myrosinase system depends on the presence or absence of supplementary proteins such as epithiospecifier proteins (ESPs). ESPs promote the formation of epithionitriles from terminal alkenyl glucosinolates and, as recent evidence suggests, simple nitriles at the expense of isothiocyanates. From a human health perspective isothiocyanates are the most important because they are major inducers of carcinogen-detoxifying enzymes.

Screening sweetcorn for enhanced zeaxanthin concentration.

Background: New varieties of fruits and vegetables, with higher carotenoid levels, are being developed to improve the potential health benefits to consumers. To assist the development of a new variety of high zeaxanthin sweetcorn, an analytical screening method was developed, including chromameter measurement of hue angle and optimized extraction for HPLC, and applied to 385 lines of a breeding population and six commercial varieties.

Results: Saponification had no effect on carotenoid extraction.

Differing mechanisms of simple nitrile formation on glucosinolate degradation in Lepidium sativum and Nasturtium officinale seeds.

Glucosinolates are sulphur-containing glycosides found in brassicaceous plants that can be hydrolysed enzymatically by plant myrosinase or non-enzymatically to form primarily isothiocyanates and/or simple nitriles. From a human health perspective, isothiocyanates are quite important because they are major inducers of carcinogen-detoxifying enzymes. Two of the most potent inducers are benzyl isothiocyanate (BITC) present in garden cress (Lepidium sativum), and phenylethyl isothiocyanate (PEITC) present in watercress (Nasturtium officinale).

Epithiospecifier protein activity in broccoli: the link between terminal alkenyl glucosinolates and sulphoraphane nitrile.

The chemical nature of the hydrolysis products from the glucosinolate-myrosinase system depends on the presence or absence of supplementary proteins, such as epithiospecifier proteins (ESPs). ESPs (non-catalytic cofactors of myrosinase) promote the formation of epithionitriles from terminal alkenyl glucosinolates and as recent evidence suggests, simple nitriles at the expense of isothiocyanates. The ratio of ESP activity to myrosinase activity is crucial in determining the proportion of these nitriles produced on hydrolysis.