Berries, antioxidant capacity

Sanchez-Morcno (2002) considered that this assay is an easy and accurate method for determining antioxidant capacity in fruit and vegetable samples. The DPPH assay has been used to determine the antioxidant activity of polyphenols (Sanchez-Moreno and others 1998 Bao and others 2004) flavonols (Jimenez and others 1998 1999 Choi and others 2002) anthocyanin-based natural colorants from berries (Espin and others... 

C24. Chevion, S., Berry, E. M., Kitrossky, N., and Kohen, R., Evaluation of plasma low molecular weight antioxidant capacity by cyclic voltammetry. Free Radic. Biol. Med. 22,411-421 (1997). 

Due to the different methods used for evaluating antioxidant capacity of flavonoid from grapes and berries, direct comparisons between various species and products often cannot be made. However, a wide range of berry extracts, wines and juices... 

In nature, flavonoids usually occur as mixtures of several compounds rather than as pure solutions of one single polyphenol. To simulate this, attempts have been made to deduce the antioxidant capacity in fruits and berries and their products from the antioxidant capacity of their individual polyphenols. Frankel et al. (1995) calculated the antioxidant capacity of 14 red and 6 white wines from the antioxidant activity of the individual polyphenols determined in the wines. The calculated antioxidant activity accounted for only 25% of the measured value. The difference was partly ascribed to unidentified polyphenols and polyphenolic acids and their polymers. Thus, there apparently is still no complete understanding of the factors contributing to the antioxidative capacity of a product. The best strategy at present seems to be to measure the products of interest directly. 

More recently, studies on the absorption of flavonoid glycosides typical of berries and grapes are reported. Lapidot et al. (1998) traced anthocyanins in human urine after the intake of 300 ml red wine, corresponding to 218 mg of anthocyanins. Totals of 1.5-5.1% of the anthocyanins were recovered in the urine within 12 h after wine consumption, two compounds were unchanged, whereas other compounds seemed to have undergone molecular modifications. The anthocyanin levels of the urine reached a peak within 6 h of consumption. Serafini et al. (1998) tested the effects of the intake of the nonalcoholic fraction of red or white wine on plasma antioxidant capacity, measured as total radical-trapping parameter (TRAP), and on... 

Fruits, and in particular berries, tend to contain the highest antioxidant capacity (Table... 

Taruscio, T. G., Barney, D. L., Exon, J. Content and profile of flavanoid and phenolic acid compounds in conjunction with the antioxidant capacity for a variety of northwest Vaccinium berries. J. Agric. Food Chem. 52(10), 3169-76,2004. 

Li W, Hydamaka AW, Lowry L, Beta T (2009) Comparison of antioxidant capacity and phenolic compounds of berries, chokecherry and seabuckthom. Cent Eur J Biol 4 499-506. doi 10.2478/sll535-009-0041-l... 

Juranic Z, Zizak Z (2005) Biological activities of Berries from antioxidant capacity to anticancer effects. Biofactors 23 207-211... 

Postharvest treatment conditions in order to extend berries shelf-life can exert a strong influence on bioactivity of compoimds. Postharvest storage can affect anthocyanins, phenolic compounds levels, and antioxidant capacity in berries. Controlled atmosphere (CA) storage of strawberries did not affect anthocyanins content in external tissues but decreased anthocyanins content in internal tissues (Holcroft and Kader 1999). Processing also has a marked influence on phenolic content and antioxidant capacity in fmits. Strawberry processing to produce jams... 

The high antioxidant capacity of berry extracts is particularly due to their content of various phenols, anthocyanins, and ascorbic acid (Pantelidis et al., 2007). Resides the health benefits related to their natural antioxidants, the color attributes of berry extracts are also of interest in food processing, as color plays a vital role in the acceptability of foods. 

The DPPH assay (5) was used to evaluate the free-radical-scavenging capacity of extracts prepared by the methods outlined above, whole berry extract and commercial cranberry juice cocktail (Ocean Spray Inc.). Activity was compared to that of a standard antioxidant (Vitamin E, Aldrich Chemical Co.) measured using the same methods. Varying concentrations of cranberry extracts were mixed with a 60 pM solution of DPPH in methanol. Quenching of the violet DPPH radical was observed as a decrease in absorbance at 515 nm over one hour. EC50 values are measured as the sample concentration required to decrease DPPH absorption by 50%. Results are shown in Table I. The DPPH assay was also used to evaluate the extracts of peel, solids and juice EC50 values are reported in Table V. 

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