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  • Author or Editor: Luis Cisneros-Zevallos x
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Pecans nuts from `Kanza' and `Desirable' cultivars were irradiated with 0, 1.5, and 3.0 kGy using electron beam (E-beam) irradiation and stored under accelerated conditions (40 °C and 55% to 60% RH). Antioxidant capacity (AC), phenolic (TP) and condensed tannin (CT) content, HPLC phenolic profile, tocopherol content, peroxide value (PV), and fatty acid profile were evaluated in kernels after 0, 7, 21, 55, and 134 days of storage. Irradiation had no detrimental effects in AC and TP; however, variation was found throughout storage. Tocopherol content of 1.5 and 3.0 kGy kernels decreased after irradiation, but no further decrease was observed thereafter. Irradiated `Desirable' samples had greater PV than controls, while `Kanza' 1.5 kGy samples had increased PV only after 134 days of storage. No change in fatty acid composition was detected for any cultivar. Color modification induced by storage included a decrease in lightness and yellowness and an initial increase of redness followed by a decrease after 98 days of storage. No differences in phenolic profile were observed after irradiation. Compounds identified by HPLC in hydrolyzed extracts were gallic and ellagic acid, catechin, and epicatechin. In general, beside the decrease in tocopherol content, no detrimental effects were found in antioxidant composition caused by irradiation treatments. While a faster oxidation rate was seen in irradiated kernels for `Desirable' cultivar, no other quality attribute was affected by E-beam irradiation.

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The objective of this study was to evaluate kernels of different pecan (Carya illinoinensis) cultivars for their antioxidant profile and their contribution to nutritional and quality attributes. Kernels were analyzed for their antioxidant capacity (AC), phenolic, tannin, and vitamin C content. Fatty acid (FA) composition and phenolic profile were determined using, respectively, gas and liquid chromatographic techniques. AC was measured using one spectrophotometrical [2,2-diphenyl-1-picrylhydrazyl (DPPH)] and one fluorescence method [oxygen radical absorbance capacity (ORAC)]. Phenolic and tannin content were determined using spectrophotometrical assays. Ascorbic and dehydroascorbic acid were determined using a HPLC. Both AC methodologies gave similar results with marked differences between cultivars. `Desirable' had an antioxidant capacity of 47,747 μg·g-1 TEq/DW with DPPH method followed closely by `Cheyenne' (36,192 μg·g-1 TEq/DW) and, with smaller amounts, by `Cape Fear' and `Pawnee' (16,540 and 13,705 μg·g-1 TEq/DW, respectively). Total phenolic content showed a similar trend, but `Pawnee' showed a higher phenolic content than `Cape Fear'. The FA composition varied between cultivars. This phenolic profile jointly with FA composition and other compositional characteristics will provide the quality and nutritional attributes of each specific cultivar. Furthermore, the high antioxidant profile of pecans suggests that bioactive and anticancer properties should also be evaluated. Results from the present research can be used as an additional tool to evaluate pecan cultivars and help create new guidelines for breeding programs to select “healthier” pecans.

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Stone fruits contain a range of phenolic compounds and carotenoids which have been implicated in improving human health. The objective of this study was to characterize the phytochemicals and antioxidant activity (AOA) exhibited in peaches and plums. Twenty-two peach varieties and fifty-three plum varieties with different flesh and skin color collected from fields in California, Georgia, and Texas were analyzed for their antioxidant content and AOA. Total phenolics, anthocyanins, carotenoids were analyzed spectrophotometrically. AOA was evaluated by DPPH. Anthocyanin and phenolic contents were higher in red-flesh than in white/yellow-flesh peaches. Carotenoid content was higher in yellow-flesh [2-3 mg β-carotene/100 g fw (fresh weight)] than in white or red-flesh peaches (0.01-1.8 mg β-carotene/100 g fw). AOA was about 2-fold higher in red-flesh varieties than in white/yellow-flesh varieties. Among the peaches, the AOA was well correlated with both phenolic and anthocyanin content. Among the plums, the anthocyanin content increased with the red color intensity. Although the plums varied widely in phenolic content, the red/purple-flesh plums generally had higher phenolic content (400-500 mg chlorogenic acid/100 g fw) than the other plums. Carotenoid content in plums was similar for all varieties (0.2-2 mg β-carotene/100 g fw). AOA was higher in red/purple-flesh varieties; however, it was well correlated only with the phenolic content in light colored flesh plums. These results suggest that red-flesh peach varieties have a greater potential health benefit based on antioxidant content and AOA as compared to the white/yellow-flesh varieties. Although this trend is not clear over all the plum varieties; the red/purple-flesh plums usually have higher antioxidant content and AOA.

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Nineteen peach [Prunus persica (L.) Batsch] genotypes and 45 plum (Prunus salicina Erhr. and hybrids) genotypes with different flesh and skin color were analyzed for their antioxidant content and activity. Anthocyanin content, phenolic content, and antioxidant activity were higher in red-flesh than in light-colored flesh peaches. Carotenoid content was higher in yellow-flesh peaches than in light-colored ones. Red-flesh plums generally had higher anthocyanin and phenolic contents than the other plums but not necessarily greater antioxidant capacity. The total phenolic content had the most consistent and highest correlation with antioxidant activity, indicating that it is more important in determining the antioxidant activity of peaches and plums than are the anthocyanin or carotenoid contents. In general, the wide range of phytochemical content and antioxidant activity found indicates that the genetic variability present can be used to develop cultivars with enhanced health benefits.

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