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  • Author or Editor: Lavanya Reddivari x
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Antioxidants have been widely reported to play an important role in disease prevention. In addition to preventing cancer, stroke, heart diseases, and inflammation, they are also involved in immune surveillance. Since the per capita consumption of potatoes in the U.S. is about 137 lb, even moderate levels of antioxidants in this most important vegetable crop probably have an important human health benefit. About 75% to 80% of antioxidant activity in specialty potatoes is due to phenolics and carotenoids. The objectives of this investigation were to evaluate antioxidant activity and total phenolic and carotenoid content of specialty potato selections from the Texas Potato Variety Development Program, and to identify candidate compounds for cancer cell culture investigations. Potato tubers were also used to identify and quantify individual phenolics and carotenoids. Some 320 specialty selections were screened for antioxidant activity (AA), total phenolic content (TP) and carotenoid content (CC) using DPPH (2,2-Diphenyl-1-picrylhydrazyl), FCR (Folin-Ciocalteu Reagent) and colorimetric assays, respectively. After the initial screening, the top 10% were used for analysis of individual phenolics and carotenoids using HPLC. Wide variability for antioxidant activity, phenolic content, and carotenoid content was found among specialty potato selections, providing evidence for genetic control of theses traits. The specialty selection CO112F2-2P/P (purple flesh, purple skin) had the highest AA (832 μg trolox equivalents/g fw), TP (1553 μg chlorogenic acid equivalents/g fw) and CC (590 μg lutein equivalents/100 g fw). Chlorogenic acid (55% to 60%), caffeic acid (≈5%), gallic acid (18% to 20%), and catechin (18% to 20%) were found to be the most prevalent phenolic acids, and lutein and zeaxanthin were the most prominent carotenoids contributing to antioxidant activity. Gallic acid was identified as the candidate compound for use in cancer cell culture investigations.

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Orange juice is an important source of bioactive compounds like flavonoids and the main human dietary source of antioxidant compounds in developed countries. Citrus flavonoids possess chemo-preventive and anti-inflammatory properties as well as the ability to lower cholesterol and modulate the immune function. In this study, we examined flavonoid content of “concentrated” (n = 12) and “Not-From Concentrate (NFC)” (n = 14) commercial orange juices by an HPLC method to investigate the brand to brand differences and differences within the brand (various types). Correlation between flavanonoid content (mg) and price per unit volume was also evaluated. Significant (P = 0.05) differences among the brands were observed in the flavanoid content of both NFC and concentrated orange juices. Total flavonoid content was significantly higher in concentrated juices compared to the NFC juices. However, higher content of didymin was found in NFC juices. Within the brand, no significant differences in the total flavonoid content were observed in juice types containing antioxidant vitamins compared to the juice types devoid of these vitamins. Price did not correlate with the total flavonoid content for either NFC (r = 0.057) or concentrated (r = -0.49) orange juices. Hesperidin was the major flavonoid and followed by narirutin and didymin. Their content (mg/100 mL) in concentrated and NFC juices ranged between 18-55 (Hesperidin); 3-8 (narirutin); and 1-2.5 (didymin), respectively. This study provides valuable information on flavonoid composition of orange juices commonly available in the US market.

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In recent years, much emphasis has been placed on functional/antioxidant properties of various fruits and vegetables and their contribution to human health. Since average per capita consumption of potatoes in the United States is about 137 pounds, even moderate levels of antioxidants could be viewed as an important human health benefit. Variation in antioxidant activity has not been extensively investigated for colored potatoes (specialty selections). Therefore, the objective of this study was to evaluate antioxidant activity of specialty selections from the Texas Potato Variety Development Program and identify elite lines to use in breeding for improvement of this trait. Potato tubers were also assessed for their outer appearance, skin color, flesh color, spoilage and yield characteristics. Specialty potato selections (320 lines) were screened for total antioxidant activity using the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay. After an initial screening, the top 10 % of selections were reevaluated in the following year. Significant (P ≤ 0.01) differences were found among selections and, for some selections, differences were found between seasons. Total antioxidant activity ranged from 27 μg/gfw to 832 μg/gfw. The specialty selection CO112F2-2 (purple flesh) had the highest antioxidant activity (832 μg/gfw) irrespective of season. In most cases, purple flesh selections produced the highest antioxidant activity, probably due to the presence of anthocyanins, followed by yellow selections.

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