The aglycone, or free quercetin, and total quercetin content of 75 cultivars and selections was analyzed by reverse-phase high-performance liquid chromatography. Quercetin glycosides were hydrolyzed into aglycones. Total quercetin content in yellow, pink, and red onions varied from 54 to 286 mg·kg-1 fresh weight in different onion entries grown during 1992. White onions contained trace amounts of total quercetin. Free quercetin content in all the onions was low (< 0.4 mg·kg-1) except in `20272-G' (12.5 mg·kg-1 fresh weight). Bulbs stored at 5, 24, and 30C and controlled atmosphere (CA) for 0,1,2,3,4, and 5 months showed a most marked change in total quercetin content at 24C compared to other treatments, with a rise in mid-storage followed by a drop. Storage at 5 and 30C also demonstrated a similar change. However, total quercetin content did not vary significantly in bulbs stored at CA for 5 months. We conclude that genetic and storage factors affect quercetin content on onions.
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.
Eight individual potatoes, exhibiting a wide range of quality characteristics, were cloned at the Texas A&M Vegetable Improvement Center, College Station, Tex., in order to produce a large number of slips for field trials. Leaf photosynthetic light response for six of these clonal selections was determined during a greenhouse experiment conducted at the Texas A&M Univ. Agricultural Research and Extension Center at Overton, Tex. Photosynthesis data were fit to a rectangular hyperbola in order to estimate light saturated leaf photosynthetic rate (Amax), quantum efficiency (QE), and dark respiration rate (Rd). Significant differences (P ≥ 0.05) were detected in all three of these parameter estimates among the six clonal selections. Parameter estimates ranged from 23.4 to 28.8 μmol (CO2) m-2·s-1, 0.056 to 0.071 mol (CO2)/mol (photons), and –0.9 to –2.0 μmol (CO2) m-2·s-1 for Amax, QE, and Rd, respectively. However, these differences were not clearly related to quality characteristics determined for these clones in field trials.
Habanero peppers have become increasingly popular in the United States for supplying unique flavors and high levels of pungency. As consumption of this product increases, development of improved cultivars with elevated phytochemicals will likely result in additional demand from consumers. This study evaluated fruit size, capsaicinoid, and flavonoid concentrations in six Habanero (Capsicum chinense) genotypes grown at three different Texas locations: College Station, Uvalde, and Weslaco. Five of these Habanero experimental hybrids (H1-red, H2-orange, H3-orange, H5-dark orange, and H6-yellow) were developed at Texas A&M University with genetic improvement in numerous traits of interest, and Kukulkan F1 (Kuk-orange) was included as a commercial control. In general, H1-red had the largest fruits in these locations. Capsaicin and dihydrocapsaicin (DHC) concentrations were highest in Kuk-orange followed closely by H5-dark orange and were lowest in H6-yellow. Fruit at Weslaco was larger and contained more capsaicin and DHC than those produced in Uvalde or College Station. Although flavonoid contents were variable and low in all genotypes and locations, H3-orange showed the most stability for use in future crossing schemes to compete against Kuk-orange for this characteristic. Our results suggest that variation in phytochemicals in fruit tissue of Habanero genotypes can be exploited by selecting in an appropriate environment.