Descripción en formato extendido de los casos de uso del negocio

Red wines have been shown to have higher antioxidant capacity than rosé and white wines when analyzed by a linoleic acid peroxidation assay based on measuring chemiluminescence (Kondo et al., 1999). The higher antioxidant activity was related TABLE 3.6

ORAC Values (µµµµmol Trolox Equivalents/g Fresh Fruit) of Selected Grapes and Berry Fruits

Bilberry Vaccinium myrtillus L. 45 282 1 Prior et al., 1998² Blueberry, lowbush Vaccinium

angustifolium Aiton Blueberry, rabbiteye Vaccinium ashei Reade 14–38 85–207 6 Prior et al., 1998² Blueberry, highbush Vaccinium

corymbosum L.

17–37 63–183 8 Prior et al., 1998²

Strawberry Fragaria x ananassa Duch.

Raspberry, red Rubus idaeus Michx. 21 — 1 Kalt et al., 1999a³

Grape, red Vitis 7.4 36 3 Wang et al., 1996

Grape, white Vitis 4.5 26 3 Wang et al., 1996

Juices

Strawberry Fragaria x ananassa Duch.

12–17 121–172 9 Wang et al. 1996³; Wang and Lin, 2000 Blackberry, thornless Rubus spp. 20–22 121–146 3 Wang and Lin, 2000 Raspberry, black Rubus occidentalis L. 28 136 1 Wang and Lin, 2000 Raspberry, red Rubus idaeus L. 16–20 91–115 3 Wang and Lin, 2000

1Sum of clones/cultivars in referred studies.

2ORAC as µmol TE/g dry weight calculated from fresh weight and dry matter.

3ORAC as µmol TE/g fresh weight only.

Flavonoids from Berries and Grapes 113

to the higher concentrations of polyphenols such as anthocyanins and flavanols in the red wines.

In products with complex combinations of various types of flavonoids and other phenolic compounds, effort has been made to ascribe the antioxidant activity of the product to different classes of polyphenols. Frankel et al. (1995) studied 20 selected California wines and related the antioxidant activity to the polyphenolic components of the wines, rather than to resveratrol. Antioxidant activity was measured by the ability of the wines to inhibit copper-catalyzed oxidation of human LDL. The correlation coefficient between antioxidant activity and total phenolic components of the wines was r = 0.94. Individual phenolic compounds (gallic acid, catechin, myricetin, quercetin, caffeic acid, rutin, epicatechin, cyanidin, malvidin-3-glucoside) contributed to the antioxidant activity. The correlation coefficient for the compounds ranged from r = 0.92 to r = 0.38 in descending order.

In red wine, Ghiselli et al. (1998) reported the anthocyanin fraction to be the most effective fraction against both hydroxyl and peroxyl radicals, in vitro inhi-bition of LDL oxidation and platelet aggregation, compared with the phenolic acids and 3-glucuronide fraction and with the catechin and quercetin-3-glucoside fraction of the wines. The high efficiency of the anthocyanin fraction was explained both by its high concentration and by its antioxidant molar effi-ciency calculated as mM Trolox equivalents/mM phenolic concentration. The molar antioxidant efficiency was 0.6 for the anthocyanin fraction, 0.22 for the phenolic acid fraction and 0.12 for the catechin fraction. Gardner et al. (1999), also studying red wine, similarly concluded that it is unlikely that quercetin and myricetin are the main cause of the health benefits assumed to arise from moderate consumption of red wine. The flavonols accounted for only 2% of total phenolic content and for less than 1.5% of the total antioxidant capacity in the red wine. Also, Saint-Cricq de Gaulejac et al. (1999) concluded that the anthocyanin fraction showed high free radical activity compared with the other tannic fractions when using an enzymatic method (hypoxanthin–xanthin oxidase) for determination of free radical scavenger activities.

Total antioxidant activities in 13 typical Italian wines were determined with an average of 12.3 µM Trolox equivalents for red wines and 1.6 µM for white wines (Simonetti et al., 1997). The values correlated well with total phenols (r = 0.9902) and flavanols (r = 0.9270) and clearly demonstrated that red wine polyphenols are significant in vitro antioxidants. The antioxidant capacity of 16 red wines from several countries was tested using electron spin resonance (ESR) spectroscopy (Burns et al., 2000). The antioxidant activity ranged from 4.13 × 10²¹ to 9.29 × 10²¹ number of Fremy’s radicals reduced by 1 L of wine. The antioxidant capacity was associated with the phenolic content of the wines, determined either by Folin-Ciocalteau or by summation of the individual phenolics determined by HPLC or by spectroscopy. Total phenolics as measured by the Folin-Ciocalteau method ranged from 6.47 to 18.6 mM GAE per liter. The anthocyanin levels ranged from 101.5 to 325.7 µM. There were substantial differences in the proportion of polymeric pig-ments in the wines.

The development of free radical scavenging capacity as determined by the DPPH method was studied during aging of selected red Spanish wines (Larrauri et al.,

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1999). The antiradical efficiency increased during aging up to a certain time, then leveled off. The main polyphenolics identified were tannic acid, oenin and gallic acid. The changes were explained as a gradual transition from monomeric antho-cyanins to oligomers to polymeric pigments. The polyphenols were characterized as slow reacting compared with other antioxidants analyzed by this method.

3.6.2.3 Juices

Wang and Lin (2000) measured antioxidant activity (ORAC) and total phenolic and anthocyanin contents of juice from thornless blackberry, strawberry and red and black raspberry fruits and found linear relationships between ORAC and total phenolics and between ORAC and anthocyanins of ripe fruits. The ORAC values are presented in Table 3.6. Calculated on a wet weight basis, black raspberries and blackberries were the best sources for antioxidants. However, when calculated on a dry weight basis, strawberries had the highest ORAC activities, followed by black-berries, black raspberries and red raspberries. Where comparisons can be made, the ORAC values of the juices were comparable to those obtained by extraction with organic solvents (Wang et al., 1996; Prior et al., 1998; Kalt et al., 1999a). Wang et al. (1996) reported increases in ORAC values of 12.4 to 15.4 for strawberry when the pulp remaining after juice production was extracted and added. The correspond-ing increases were 4.0 to 7.4 ORAC values for red grapes and 2.9 to 4.5 for white grapes. The antioxidant activity increased most in the red grapes, where the poly-phenols are strongly incorporated into the skin.

ORAC values during ripening of fruits have also been reported (Wang and Lin, 2000). Blackberry, black raspberry and strawberry revealed the highest ORAC values during their green stages, while the ripe fruits had the highest ORAC values in red raspberries. With all species, the pink stage of ripening had the lowest ORAC values.

The antioxidant activities of red and white commercial grape juices have been studied using in vitro inhibition of the copper-catalyzed oxidation of human LDL (Frankel et al., 1998). The correlation between total phenols, expressed as GAE, and relative percent of inhibition of LDL oxidation was r = 0.99. In red Concord grape juices, the antioxidant activity was related to the anthocyanin levels. In the white grape juice, the antioxidant activity was associated with the levels of hydrox-ycinnamates (caffeic acid) and flavanols (catechin). When compared at the same level of total phenolics (10 µM GAE), the antioxidant activities of the grape juices were comparable to the antioxidant activities of red wine (Frankel et al., 1995).

Laplaud et al. (1997) found protective action of copper-mediated LDL oxidation in aqueous V. myrtillus extracts. On a molar base, the extracts were more efficient than ascorbic acid and BHT in inhibiting LDL oxidation.

Spray-dried elderberry juice with high amounts of anthocyanin glucosides caused prolongation of the lag phase of copper induced oxidation of human LDL, while the maximum oxidation rate remained unchanged (Abuja et al., 1998). For peroxyl-radical-driven LDL oxidation, however, both prolongation of lag time and reduction of maximum oxidation rate occurred. When the extract was added after LDL oxidation was initiated, the elderberry extract demonstrated a pro-oxidative action. The pro-oxidative effect was more pronounced the longer the LDL oxidation was allowed to proceed before the extract was added.

Flavonoids from Berries and Grapes 115

Miller and Rice-Evans (1997) studied total antioxidant activity (TAA) and reduc-tion in vitamin C during storage of black currant drinks containing 16.7% and 25%

black currant extract. The anthocyanin fraction of the black currant drinks contrib-uted only partly to the TAA values, and the authors concluded that there may be additional antioxidants present in the black currant drinks. The black currant drinks demonstrated vitamin C sparing ability.