Shiow Y. Wang’s research while affiliated with BARC Global Central Laboratory and other places

Inhibition of α-glucosidase activity is considered an effective means for controlling diabetes by regulating glucose uptake, and blueberries have been shown to possess high levels of inhibitory activity. In the present study, we examined the variations in α-glucosidase inhibition, phenolic and anthocyanin levels, and antioxidant capacity in the peel and pulp of 16 mixed-species rabbiteye hybrids (Vaccinium ashei Reade × Vaccinium spp.), one rabbiteye cultivar (V. ashei) and two highbush hybrids (Vaccinium corymbosum). Peel tissue had, on average, about four times higher levels of α-glucosidase inhibitory activity than pulp, and exhibited significantly higher levels of all other measured activities, even though the peel comprised only a small portion of the fruit. Significant variations in the levels of antioxidant activity were observed; however, no consistent differences were observed between the hybrids with various species composition. Significant positive correlations (r≥ 0.84) were found among α-glucosidase inhibitory activity, total anthocyanin (TA) and phenolic levels, and scavenging activity against ROO∙, ∙OH, 1O2 and H2O2 radicals in the extracts from the peel and pulp. There was a high correlation observed between α-glucosidase inhibitory activity levels and ROO∙(ORAC)peel (r= 0.95). A similarly high correlation with TApeel (r= 0.93) suggests that TA would be a suitable assay proxy if a broader genotypic evaluation of blueberry genotypes is desired.

Raspberries are a delicate, high value crop with an extremely short shelf life exacerbated by postharvest decay caused by Botrytis cinerea Pers. European red raspberry (Rubus idaeus L.) is the most widely grown variety. Yellow (R. idaeus L.), black (R. occidentalis L.) and purple raspberries (R. × neglectus Peck. or R. occidentalis × idaeus hybrids) are available mainly at local markets and U-pick farms. To compare the postharvest quality of the raspberry color groups, pesticide-free fruit from cultivars and breeding selections of red, yellow, purple, and black raspberries were examined for oxygen radical absorbance capacity (ORAC), phenolics, anthocyanins, soluble solids, titratable acids, pH, color, firmness, decay and juice leakage rates, ethylene evolution and respiration. There were significant correlations between decay rate and physiochemical properties. Both decay and leakage rates were correlated with weather conditions before harvest, but each color group responded differently to different weather factors. There were no correlations between changes in color, firmness, decay or juice leakage rates. All the other color groups were less acidic than the familiar red raspberry. Yellow raspberries had the worst decay rates but the best leakage rates. Black and purple raspberries, with the highest phenolics and anthocyanins and the lowest ethylene evolution rates, resisted decay the longest, but bled soonest.

The severity of decay in strawberries stored at either 5 °C or 10 °C was significantly reduced and the shelf-life was extended by immersing fruits in chitosan solutions of 0.5, 1.0 and 1.5 g/100 mL for 5 min at 20 °C as compared to the control. Strawberries treated with chitosan also maintained better fruit quality with higher levels of phenolics, anthocyanins, flavonoids (ellagic acid, ellagic acid glucoside, p-coumaroyl glucose, quercetin 3-glucoside, quercetin 3-glucuronide, kaempferol 3-glucoside, kaempferol 3-glucuronide, cyanidin 3-glucoside, pelargonidin 3-glucoside, cyanidin 3-glucoside-succinate, and pelargonidin 3-glucoside-succinate), antioxidant enzyme activity [catalase (CAT), glutathione-peroxidase (GSH-POD), guaiacol peroxidase (G-POD), dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDAR)], and oxygen radical absorbance capacity for peroxyl radicals (ROO), hydroxyl radical radicals (OH; HOSC) and 2,2-Di (4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) than the untreated fruits. Chitosan treatments retarded the decrease of ascorbic acid (ASA) and reduced glutathione (GSH) content and β-1,3-glucanase activities compared to control. The high contents of antioxidants, antioxidant activity, ASA and GSH and high activity of β-1,3-glucanase in the treated strawberries reinforced the microbial defense mechanism of the fruit and accentuated the resistance against fungal invasion. Therefore, the application of chitosan coating could be favorable in extending shelf-life, maintaining quality and controlling decay of strawberries.

Forty‐two blueberry cultivars (thirty‐six Vaccinium ashei, three V. ashei derivative hybrids and three northern highbush standards) were evaluated for their antioxidant capacities and other fruit quality attributes over two growing seasons. Total anthocyanins, phenolic content and antioxidant capacities varied substantially among species and cultivars. ‘Early May’ (V. ashei) had the highest amounts of anthocyanins, phenolics and antioxidant capacity. Cultivars from V. ashei hybrid derivatives had lower mean antioxidant components than those from northern highbush standards or V. ashei. The antioxidant capacity, as well as total anthocyanins and phenolics, had significant cultivar × year interactions. Correlation coefficient between years for total anthocyanins, total phenolics and oxygen radical absorbance capacity were high with values of 0.86, 0.81 and 0.93, respectively. Similar interactions were observed for soluble solids content (SSC), sugar, titratable acid and organic acids among cultivars both within and across the growing seasons. Correlation coefficients between years for SSC, fructose, glucose and sucrose were 0.78, 0.71, 0.83 and 0.96, respectively. Fructose and glucose were detected as two major sugars with sucrose as a minor constituent. ‘Clara’ contained the highest amounts of SSC and sugars, while ‘Satilla’ had the lowest. In general, V. ashei cultivars had a higher mean SSC and sugar contents than did the hybrid derivatives or the northern highbush standards. Cultivars of V. ashei contained higher malic acid than citric acid, whereas in hybrid derivatives and northern highbush cultivars, citric acid was the predominant organic acid. The diversity in the amount of these fruit quality attributes and antioxidant capacities presents a great opportunity for genetic improvement of blueberries through breeding programmes. The objective of the study was to identify blueberry cultivars with high antioxidant activity and good fruit quality, so they can be used as parents for future blueberry breeding programmes to develop new cultivars with higher antioxidant activity.

This study was designed to evaluate cultivar variations in phenolic content, anthocyanin content, and antioxidant activity of peel and flesh; and to determine their potential inhibitory effects on α-glucosidase in 33 blueberry (Vaccinium species) cultivars, including 29 rabbiteye (Vaccinium ashei Reade) blueberries, two V. ashei hybrid derivatives, and two northern highbush (Vaccinium corymbosum L.). The relation of phenolic, anthocyanin, and antioxidant activity to α-glucosidase inhibition in blueberries also was investigated. It was found that peel tissue possessed higher levels of total anthocyanins (TA), total phenolics (TP), antioxidant capacity, and α-glucosidase inhibitory activity than flesh tissue in all blueberries tested. The percentage contributions of peel to whole berry on scavenging capacity against peroxyl free radicals (ROO), hydroxyl radicals (OH), hydrogen peroxide (H2O2), and singlet oxygen (1O2) radicals, were higher than those of flesh, even though the fruit contained much higher amounts of flesh than peel in terms of dry weight. Cultivars with high levels of phenolic compounds, antioxidant capacities, and α-glucosidase inhibitory activities could be selected for use in blueberry breeding programs to develop new lines with improved health benefits.

Fruit from 42 blueberry (Vaccinium spp.) cultivars, including 36 rabbiteye cultivars (Vaccinium ashei Reade), three V. ashei hybrid derivatives, and three northern highbush (Vaccinium corymbosum L.) standards were evaluated for antioxidant capacity, individual flavonoid content, and the contribution of each identified phenolic compound to total antioxidant activity. Considerable variation was found in flavonoid content, antioxidant activity, and their contribution to total antioxidant activity among cultivars. Among 42 blueberry cultivars, the rabbiteye ‘Early May’ contained the highest amount of chlorogenic acid, myricetin 3-arabinoside, quercetin derivatives, and delphinidin-, cyanidin-, petunidin-, and malvidin-basis anthocyanins. ‘Early May’ cultivar also had the highest antioxidant activity (88.2 μmol TE/g fw). ‘Owen’, ‘Bluegem’, ‘Clara’, Climax’, and ‘Centurion’ were among the other rabbiteye cultivars that also had high levels of flavonoids and antioxidant activities. In contrast, the pink-fruited V. ashei hybrid, ‘Pink Lemonade’, had the lowest content of flavonoids and lowest antioxidant activity. The mean flavonoid content and antioxidant activity of rabbiteye cultivars was higher than those among northern highbush and V. ashei hybrids. The antioxidant activity of V. ashei hybrid derivatives was derived mainly from chlorogenic acid, myricetin, and quercetin, which contributed 62.5% of total antioxidant activity, whereas anthocyanins (malvidin, petunidin, delphinidin, and cyanidin) were the main contributors to the antioxidant activity of rabbiteye cultivars (76.2%) and northern highbush standards (76.8%). Blueberry cultivars identified to have high phenolic content and high antioxidant activity could be used as parents for future blueberry breeding programmes to develop new blueberry cultivars with higher antioxidant activity and further improve human health.

The effects of cultural system and essential oil treatment on antioxidant capacities in raspberries were evaluated. Raspberries were hand-harvested from organic and conventional farms in Maryland, USA, and were treated with essential oil including carvacrol, anethole, cinnamic acid, perillaldehyde, cinnamaldehyde and linalool. Results from this study showed that raspberries grown from organic culture exhibited higher value of antioxidant capacities and individual flavonoids contents. Moreover, the organic culture also enhanced the activities of antioxidant enzymes. In addition, essential oil treatments promoted the antioxidant enzymes activities and antioxidant capacities of raspberries, and the most effective compound was perillaldehyde. In conclusion, raspberries produced from organic culture contained significantly higher antioxidant capacities than those produce from conventional culture. Postharvest essential oil treatments have positive effect on enhancing antioxidant capacities in raspberries from both organic and conventional cultures.

Fruits from forty‐two blueberry cultivars, including thirty‐six rabbiteye (Vaccinium ashei Reade), three V. ashei hybrid derivatives and three northern highbush (V. corymbosum L.) standards, were evaluated for their antioxidant activities against peroxyl free radicals (ROO˙), hydroxyl radicals (OH˙), hydrogen peroxide (H2O2), superoxide radicals () and singlet oxygen (1O2) radicals. The differences in scavenging capacities for these radicals among forty‐two selected blueberry cultivars were significant. Oxygen radical absorbance capacity values ranged from 33.8 to 118.7 μmol Trolox equivalents (TE) g fresh wt−1, 196.1 to 518.8 μmol TE g dry wt−1 and 7.1 to 22.2 μmol cm−2‐surface area. Extracts from fruit of pure rabbiteye had higher levels of scavenging capacities of oxygen species , 1O2 and H2O2 compared to V. ashei hybrid derivatives and northern highbush blueberry standards. The rabbiteye cultivars ‘Early May’ and ‘Centurion’ had the highest scavenging capacity for the reactive oxygen species, not only for ROO˙ and ˙OH, but also for , 1O2 and a strong oxidant, H2O2. In contrast, ‘Pink Lemonade’ (pink‐fruited) had the lowest ability to inhibit free radical activity of ROO˙,˙OH, 1O2, and H2O2.‘Snowflake’ had the lowest scavenging capacity for . Blueberry cultivars with high antioxidant activity and radical scavenging capacity have potential to improve human health and can possibly be used as parents for future blueberry breeding programs to develop new blueberry cultivars with higher antioxidant activity.

Fruit from 42 blueberry (Vaccinium species) cultivars, including 36 rabbiteye cultivars (Vaccinium ashei Reade), 3 V. ashei hybrid derivatives and 3 northern highbush (V. corymbosum L.) standards, were evaluated for antioxidant activities (AA), levels of antioxidant enzymes [catalase (CAT), ascorbate peroxidase (AsA-POD), glutathione reductase (GR), glutathione peroxidase (GSH-POD), superoxide dismutase (SOD), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR) and guaiacol peroxidase (G-POD)], and antioxidant nonenzyme components [ascorbic acid (ASA) and glutathione (GSH)]. The results of this study showed that cultivars had varying levels of AA, a wide range of antioxidant enzyme activities and various amounts of nonenzyme components. The correlations between AA and all of the enzyme activities or nonenzyme components were positive and high in the 42 cultivars tested in this study. The correlation (R2) values between AA and CAT, SOD, DHAR, MDAR, GSH-POD, GR, G-POD and AsA-POD were 0.91, 0.91, 0.91, 0.91, 0.90, 0.90, 0.90, and 0.90, respectively. The correlations between AA and ASA and GSH were 0.94 and 0.92, respectively. Among all 42 cultivars, ‘Early May’ had the highest activities of the AA, AsA-POD, G-POD, DHAR and MDAR and the highest amounts of ASA and GSH, whereas ‘Elliott’ had the highest levels of GR, GSH and SOD.

Fruit from forty-two blueberry (Vaccinium species) cultivars including thirty-six rabbiteye rabbiteye cultivars (Vaccinium ashei Reade), three V. ashei hybrid derivatives and three northern highbush (V. corymbosum L.) standards were evaluated for antioxidant activities (AA), levels of antioxidant enzymes [catalase (CAT), ascorbate peroxidase (AsA-POD), glutathione reductase (GR), glutathione peroxidase (GSH-POD), superoxide dismutase (SOD), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR), and guaiacol peroxidase (G-POD)], and antioxidant nonenzyme components [ascorbic acid (ASA) and glutathione (GSH)]. The results showed that cultivars had varying levels of AA, a wide range of antioxidant enzyme activities, and various amounts of nonenzyme components. The correlations between AA and all of the enzyme activities or nonenzyme components were positive and high in the forty-two cultivars tested in this study. The correlation coefficients of r values between AA and CAT, SOD, DHAR, MDAR, GSH-POD, GR, G-POD, and AsA-POD were 0.91, 0.91, 0.91, 0.91, 0.90, 0.90, 0.90, and 0.90, respectively. The correlations between AA with ASA and GSH were 0.94 and 0.92, respectively. Among all 42 cultivars, ‘Early May’ had the highest activities of the AA, AsA-POD, G-POD, DHAR, and MDAR; and the highest amounts of ASA and GSH; whereas ‘Elliott’ had highest levels of GR, GSH and SOD. The cultivars with high antioxidants and antioxidant enzyme activities could be useful in the breeding program for the development of more nutritious blueberry cultivars with improved health-promoting quality for consumers.