after 15 min. A standard curve was prepared using different concentrations of catechin. The flavonoid content is expressed as milligrams catechin equivalents per 100 g DW. Determination of total antioxidant activity (TAA). Total antioxidant activity (by
Ambani R. Mudau, Puffy Soundy, Hintsa T. Araya and Fhatuwani N. Mudau
Gregory M. Peck, Preston K. Andrews, John P. Reganold and John K. Fellman
Located on a 20-ha commercial apple (Malus domestica Borkh.) orchard in the Yakima Valley, Washington, a 1.7-ha study area was planted with apple trees in 1994 in a randomized complete block design with four replications of three treatments: organic (ORG), conventional (CON), and integrated (INT). Soil classification, rootstock, cultivar, plant age, and all other conditions except management were the same on all plots. In years 9 (2002) and 10 (2003) of this study, we compared the orchard productivity and fruit quality of `Galaxy Gala' apples. Measurements of crop yield, yield efficiency, crop load, average fruit weight, tree growth, color grades, and weight distributions of marketable fruit, percentages of unmarketable fruit, classifications of unmarketable fruit, as well as leaf, fruit, and soil mineral concentrations, were used to evaluate orchard productivity. Apple fruit quality was assessed at harvest and after refrigerated (0 to 1 °C) storage for three months in regular atmosphere (ambient oxygen levels) and for three and six months in controlled atmosphere (1.5% to 2% oxygen). Fruit internal ethylene concentrations and evolution, fruit respiration, flesh firmness, soluble solids concentration (SSC), titratable acidity (TA), purgeable volatile production, sensory panels, and total antioxidant activity (TAA) were used to evaluate fruit quality. ORG crop yields were two-thirds of the CON and about half of the INT yields in 2002, but about one-third greater than either system in 2003. High ORG yields in 2003 resulted in smaller ORG fruit. Inconsistent ORG yields were probably the result of several factors, including unsatisfactory crop load management, higher pest and weed pressures, lower leaf and fruit tissue nitrogen, and deficient leaf tissue zinc concentrations. Despite production difficulties, ORG apples had 6 to 10 N higher flesh firmness than CON, and 4 to 7 N higher than INT apples, for similar-sized fruit. Consumer panels tended to rate ORG and INT apples to have equal or better overall acceptability, firmness, and texture than CON apples. Neither laboratory measurements nor sensory evaluations detected differences in SSC, TA, or the SSC to TA ratio. Consumers were unable to discern the higher concentrations of flavor volatiles found in CON apples. For a 200 g fruit, ORG apples contained 10% to 15% more TAA than CON apples and 8% to 25% more TAA than INT apples. Across most parameters measured in this study, the CON and INT farm management systems were more similar to each other than either was to the ORG system. The production challenges associated with low-input organic apple farming systems are discussed. Despite limited technologies and products for organic apple production, the ORG apples in our study showed improvements in some fruit quality attributes that could aid their marketability.
Ambani R. Mudau, Puffy Soundy, Hintsa T. Araya and Fhatuwani N. Mudau
for 12 d. Data points indicate mean se . Total antioxidant activity. Total antioxidant activity decreased in all treatments; however, the baby spinach stored under MA showed better activity when compared with those stored in a normal air. During
Ambani R. Mudau, Mpumelelo M. Nkomo, Puffy Soundy, Hintsa T. Araya, Wonder Ngezimana and Fhatuwani N. Mudau
compounds decreased gradually in samples stored at 4 °C. However, samples stored at 22 °C decreased rapidly after 4 d of storage as shown in Fig. 1D . Both total antioxidant activities and vitamin C content showed similar trends, with the content remaining
Mudau N. Fhatuwani and Makunga P. Nokwanda
recorded were soluble sugars (sucrose, glucose, and fructose), starch (amylopectin and amylase), total polyphenol content, TFC, total antioxidant activities (DPPH = 2,2-diphenyl-2-picrylhydrazyl and FRAP), and TTCs. The quality of bush tea from the
Cristian Moya, Eduardo Oyanedel, Gabriela Verdugo, M. Fernanda Flores, Miguel Urrestarazu and Juan E. Álvaro
total antioxidant activity by ferric reducing ability plasma (FRAP) analyses using 25 g homogenized with 25 mL of methanol 80% (v/v) in HCl at 1% and incubating for 2 h at 24 °C. The extracts were filtered using a 120 mm paper filter (Whatman, Maidstone
Dipayan Sarkar, Prasanta C. Bhowmik, Young-In-Kwon and Kalidas Shetty
-VIS spectrophotometer (Genesys; Milton Roy, Rochester, NY). ABTS [2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)] cation radical and antioxidant activity assay. The total antioxidant activity of turfgrass leaf extract was measured by the ABTS + radical
Itani Tshivhandekano, Fhatuwani Nixwell Mudau and Thilivhali Emmanuel Tshikalange
. The method described by Du Toit et al. (2001) was used to determine the total antioxidant activity of bush tea leaf and twig extracts. Vitamin C was used as the standard. The plant extract (2 mg) was dissolved in 200 µL ethanol to yield a stock
Peter J. Mes* and James R. Myers
Tomato lines carrying the genes Aft, atv, Abg, hp-1, and an as yet undetermined gene from the introgression line LA2099 have been combined to produce fruit with elevated anthocyanin content. The antioxidant activity of juice made from anthocyanin-expressing tomatoes was compared to juices made from tomatoes with varied carotenoid content. The contribution of anthocyanin to the total antioxidant activity of the whole fruit in current material is small, but with potential for significant improvement. The increase in flavonoids in the elevated anthocyanin lines has increased water-soluble antioxidant activity of the fruit in vitro.
Lavanya Reddivari*, Anna L. Hale, Douglas C. Scheuring and J. Creighton Miller Jr.
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.