Antioxidant activity,anthocyanins, and phenolics of rabbiteye blueberry (Vaccinium ashei) by-products as affected by fermentation

Basic blueberry processing includes juice processing or winemaking. By-products obtained from the juice and wine industry can be a source of new value-added products such as phenolic antioxidant supplements or ingredients for food processing. The phenolic compositions of products and by-products (pomaces) depend mainly on processing techniques such as duration of skin contact, crushing, pressing, and others. The present study was to evaluate the effects of fermentation type on retention of total anthocyanins, total phenolics, and antioxidant activity of blueberry by-products. Total phenolics (TPH), total anthocyanins (ACY), antioxidant activities (β-carotene bleaching assay and ferric thiocyanate assay), and antiradical activity (DPPH radical-scavenging assay) of rabbiteye blueberry (Vaccinium ashei) by-products (juice, wine, and vinegar pomaces) were determined. The wine pomace (WP) had higher TPH, antioxidant activities and antiradical activity. Vinegar pomace (VP) had the lowest ACY, TPH, antiradical activity, and antioxidant activities. The results indicate that the antioxidant and antiradical activities of blueberry by-products were not significantly affected by the wine making process. Acetification significantly decreased TPH, ACY, antioxidant activities, and antiradical activity. However, VP still maintained an important phenolics concentration and antioxidant activity.     

Comparison of anthocyanins and phenolics in organically and conventionally grown blueberries in selected cultivars

Consumption of berries has become popular among health-conscious consumers due to the high levels of valuable antioxidants, such as anthocyanins, and phenolic compounds in berries. Four Rabbiteye blueberry cultivars (i.e., Powderblue, Climax, Tifblue, and Woodward) grown organically and conventionally were compared regarding their chemical profiles and antioxidant capacity in terms of total phenolic content (TPC), total anthocyanin content (TAC) and ORAC activity. Regardless of the high TPC, TAC and ORAC in both organically and conventionally grown blueberries, not all the organic berries showed significantly higher TPC, TAC and ORAC than the conventional berries. The chemical profiles (i.e., the free phenolic compounds and anthocyanins) were determined with aid of HPLC-MS, by which 13 individual anthocyanins and seven free phenolics were identified. This study demonstrated the subtle differences of bioactive phytochemicals between the organically and conventionally grown berries.     

Anthocyanins and other polyphenolics in American elderberry (Sambucus canadensis) and European elderberry (S. nigra) cultivars

BACKGROUND: Ten genotypes representing two elderberry species, Sambucus canadensis L. (eight genotypes) and S. nigra L. (two genotypes), were examined for their anthocyanins (ACY), total phenolics (TP),°Brix, titratable acidity (TA), and pH over two growing seasons. RESULTS: Overall, fruit generally had higher ACY, TP, ACY/TP,°Brix, and pH in 2005 than 2004. All samples of S. canadensis had similar anthocyanin profiles to one another, but were distinctly different from S. nigra. Both species had cyanidin‐based anthocyanins as major pigments. Previously unreported anthocyanins were identified in some samples in this study. Trace levels of delphinidin 3‐rutinoside were present in all elderberry samples except cv. ‘Korsør’. Also, petunidin 3‐rutinoside was detected in cvs ‘Adams 2’, ‘Johns’, ‘Scotia’, ‘York’, and ‘Netzer’ (S. canadensis). The identified polyphenolics of both species were mainly composed of cinnamic acids and flavonol glycosides. The major polyphenolic compounds present in S. canadensis were neochlorogenic acid, chlorogenic acid, rutin, and isorhamnetin 3‐rutinoside, while chlorogenic acid and rutin were found to be major polyphenolic compounds in S. nigra. CONCLUSION: Sufficient variability was seen among these genotypes to suggest that a successful breeding program could be carried out to improve levels of the various compounds evaluated in this study. Copyright © 2007 Society of Chemical Industry     

Biochemical Characterization of Dovyalis hebecarpa Fruits: A Source of Anthocyanins with High Antioxidant Capacity

Dovyalis hebecarpa, which is also known as the Ceylon gooseberry, is an attractive exotic purple berry that is produced in the southwest of Brazil with high yields. Current literature lacks information about the nutritional composition and antioxidant capacity of this fruit. As such, this work aimed to evaluate and compare the proximate composition, phytochemical content, and antioxidant capacity of D. hebecarpa over two seasons through the application of a range of different methods, including FRAP, ABTS, and ORAC assays. The proximate composition and biometric parameters were monitored for quality purposes. The results significantly changed between seasons in accordance with variations in rain incidence and average temperatures. The Ceylon gooseberry contained a similar or higher content of anthocyanins (ACY) than other berries commonly consumed in human diet. These ACY were identified at higher levels in the fruit's skin (284 to 351 mg of cyanidin‐3‐glucoside equivalents/100 g of fresh weight [FW]) than in its pulp (49 to 69 mg/100 g of FW). The use of an ORAC assay identified higher antioxidant activity (145 μmol of Trolox equivalents [TE]/g in the skins and 179 μmol of TE/g in the pulp on a FW basis) than all other methods used to determine antioxidant activity. Thus, D. hebecarpa is a rich source of ACY that demonstrates high antioxidant activity against the peroxyl radicals formed in ORAC assay conditions.     

PRODUCT DEVELOPMENT AND NUTRACEUTICAL ANALYSIS TO ENHANCE THE VALUE OF DRIED FRUIT

ABSTRACT

Value‐added fruit products suitable for production by small‐scale farmers and processors were developed and evaluated. Apples, blueberries, peaches and strawberries from local growers were processed into a dried fruit product. The total phenolics, total anthocyanins and oxygen radical absorbing capacity (ORAC) were determined. Drying the fruit concentrated total phenolics, total anthocyanins and ORAC levels as compared to fresh fruit. The nutraceutical components of the blueberries, peaches and strawberries of the local dried fruit were higher than those of commercial dried fruit purchased at a natural food store. The dried fruit from both the local and commercial fruits was used to create a fruit pie filling for consumer evaluation. Consumer acceptance of fruit pie filling from dried fruit grown locally and dried commercial fruits was evaluated using a 9‐point verbal hedonic scale and a 5‐point Just About Right scale. In terms of consumer evaluation, the pie fillings made from local dried fruits were either better or at parity with those from commercial products. In addition to the nutraceutical benefits, the pie fillings were consumer acceptable products that could represent an avenue for small‐scale farmers to add value to surplus fruit.

PRACTICAL APPLICATIONS

Complete utilization of fruit crops is a key component to the success of small farm operations. Excess fruit crops can be dried (or processed in other manners) and used to create many value‐added products. Increased consumer awareness of healthy food products provides a niche market for these fruit products. In this research, the nutraceutical benefits of fresh and dried apples, blueberries, peaches and strawberries were investigated and the consumer overall acceptance of a pie filling produced from these dried fruit was shown.

     

The influence of organic/integrated production on the content of phenolic compounds in apple leaves and fruits in four different varieties over a 2‐year period

BACKGROUND: Phenolics in fruit may be influenced by the fruit type, cultivation conditions of a plant, climatic conditions, growing season, storage conditions, and industrial processing. The aim of this study was to compare single phenolic compounds, total phenolics and antioxidant capacity of four varieties of apple grown under organic and integrated conditions over a 2‐year period. RESULTS: Several different phenolic compounds belonging to the groups of hydroxycinnamic acids, flavanols, dihydrochalcones, flavonols and anthocyanins were quantified. The levels of all analysed groups of phenolics were higher (not always significantly) in the organically grown apple leaves and fruit than in the leaves or apples from integrated production. Leaves from organic trees had 10–20% higher content levels of total phenols than the leaves from trees in the integrated growing system. In both years, organic production affected the increase in the antioxidant activity of apple peel. Organic apples have higher total phenolic content than the integrated grown ones. CONCLUSION: Cultivation type had an important influence on the polyphenolic level and antioxidant capacity of the apple fruits and leaves. Apples from organic production showed a higher content of hydroxycinnamic acids, flavanols, dihydrochalcones, quercetins and total phenolics than apples from integrated cultivation. Copyright © 2010 Society of Chemical Industry     

Genotype and growing season influence blueberry antioxidant capacity and other quality attributes

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.     

Selected bioactivities of Vaccinium berries and other fruit crops in relation to their phenolic contents

Antioxidant activity, urinary tract protective activity, and cardioprotective anti‐platelet effects are among the bioactivities associated with dietary phenolics. These bioactivities were measured in vitro in fruit extracts from seven Vaccinium species and five non‐Vaccinium species to determine their relationship to total phenolic content and to anthocyanin and proanthocyanidin content. Berries belonging to the genus Vaccinium were particularly high in antioxidant activity and urinary tract protective anti‐adhesion activity, while anti‐platelet activity varied among species. There was a positive relationship between antioxidant activity (using the oxygen radical absorbing capacity (ORAC) assay) and both the total phenolic (R² = 0.76) and anthocyanin content (R² = 0.43) of the fruit, although there was no relationship between ORAC and proanthocyanidin content. There were no relationships between anti‐adhesion activity and total phenolic content, anthocyanin content, or proanthocyanidin content. Likewise, no relationships were observed between anti‐platelet activity and total phenolic content, anthocyanin content, or proanthocyanidin content. These results suggest that while antioxidant properties are characteristic of all fruit phenolics, in vitro anti‐adhesion and anti‐platelet bioactivities may be due to less abundant phenolic subgroups. Copyright © 2007 Crown in the right of Canada and Society of Chemical Industry     

Fruit quality and bioactive compounds relevant to human health of sweet cherry (Prunus avium L.) cultivars grown in Italy

The fruit quality characteristics, phenolic compounds and antioxidant capacities of 24 sweet cherry (Prunus avium L.) cultivars grown on the mountainsides of the Etna volcano (Sicily, Italy) were evaluated. High-performance liquid chromatographic methods were used to identify and quantify sugars, organic acids and phenolics. A total of seven phenolic compounds were characterised as hydroxycinnamic acid derivatives (neochlorogenic acid, p-coumaroylquinic acid and chlorogenic acid) and anthocyanins (cyanidin 3-glucoside, cyanidin 3-rutinoside, pelargonidin 3-rutinoside and peonidin 3-rutinoside). The total anthocyanin content ranged from 6.21 to 94.20 mg cyanidin 3-glucoside equivalents/100 g fresh weight (FW), while the total phenol content ranged from 84.96 to 162.21 mg gallic acid equivalents/100 g FW. The oxygen radical absorbance capacity (ORAC) assay indicated that fruit of all genotypes possessed considerable antioxidant activity. The high level of phenolic compounds and antioxidant capacity of some sweet cherry fruits implied that they might be sources of bioactive compounds that are relevant to human health.     

Phenolic Compounds and Antioxidant Capacities of 10 Common Edible Flowers from China

The free and bound phenolic compounds in 10 common Chinese edible flowers were investigated using reversed phase high‐performance liquid chromatography. Their antioxidant capacities were evaluated using 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical‐scavenging activity, 2,2'‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulphonic acid) (ABTS) radical‐scavenging activity, oxygen radical absorption capacity (ORAC), ferric reducing antioxidant power (FRAP), and cellular antioxidant activity (CAA). Free factions were more prominent in phenolic content and antioxidant capacity than bound fractions. Paeonia suffruticosa and Flos lonicerae showed the highest total phenolic content (TPC) 235.5 mg chlorogenic acid equivalents/g of dry weight and total flavonoid content 89.38 mg rutin equivalents/g of dry weight. The major phenolic compounds identified were gallic acid, chlorogenic acid, and rutin. P. suffruticosa had the highest antioxidant capacity in the DPPH, ABTS, and ORAC assays, which were 1028, 2065, 990 μmol Trolox equivalents/g of dry weight, respectively, whereas Rosa chinensis had the highest FRAP value (2645 μmol Fe²⁺ equivalents /g of dry weight). The P. suffruticosa soluble phenolics had the highest CAA, with the median effective dose (EC₅₀) 26.7 and 153 μmol quercetin equivalents/100 g of dry weight in the phosphate buffered saline (PBS) and no PBS wash protocol, respectively. TPC was strongly correlated with antioxidant capacity (R = 0.8443 to 0.9978, P < 0.01), which indicated that phenolics were the major contributors to the antioxidant activity of the selected edible flowers.     

Analysis of Phenolic Composition of Noble Muscadine (Vitis rotundifolia) by HPLC‐MS and the Relationship to Its Antioxidant Capacity

Abstract: Phenolic compounds and anthocyanins in muscadines have attracted much attention due to their diverse biological activities. With bioassays of antioxidant activities in terms of total phenolic content (TPC), total anthocyanin content (TAC), total procyanidin content (TPA), oxygen radical absorbance capacity (ORAC), and ferric reducing antioxidant power (FRAP) of different parts of the Noble muscadine, the butanol (BuOH) extract of the muscadine skin showed the highest TPC (317.91 ± 1.83 mg GAE/100 g FW), which might be ascribed to its high TAC of 227.06 ± 1.29 mg/100 g fresh weight (FW). The ethyl acetate (EtOAc) extract of the muscadine seed contained the highest TPA (55.30 ± 0.63 mg CE/100 g FW). Correlation analyses demonstrated a significant linear relationship of TPC and TAC compared to their ORAC and FRAP values within the range of R² from 0.9283 to 0.9936, which suggested that phenolics and anthocyanins in the extracts contributed significantly to their antioxidant potential. Nineteen individual phenolics and 5 anthocyanins were identified by HPLC‐MS, which indicated different chemical profiles of anthocyanins and other phenolics in the muscadine extracts. Practical Application: The paper has provided rich information of bioactive phytochemical profiles in different solvent extracts and their correlation with the antioxidant activity in the muscadine that is a very special regional fruit in U.S. Its high content of phenolic compounds demonstrates that muscadine could be beneficial to human health.     

Effects of refrigerated storage and processing technologies on the bioactive compounds and antioxidant capacities of ‘Marion’ and ‘Evergreen’ blackberries

The effects of refrigerated storage at 2 °C and 95% RH and processing treatments on the bioactive compounds and antioxidant capacities of ‘Marion’ and ‘Evergreen’ blackberries were investigated. During refrigerated storage, total phenolics (TPC), total monomeric anthocyanins (ACY), and radical scavenging activity (RSA) fluctuated in ‘Marion’, but TPC and ACY continuously declined in ‘Evergreen’. Oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) decreased by 20% and increased by 19% in ‘Evergreen’, respectively after 7-d refrigerated storage, while no changes (P > 0.05) in ‘Marion’ were observed. Compared with frozen samples, freeze-dried ‘Evergreen’ had higher TPC (21%), ACY (5.5%), and RSA (14%), while hot-air dried “Marion” had lower ACY (56%), ORAC (37%), and FRAP (27%) and hot-air dried ‘Evergreen’ had lower TPC (37%), ACY (84%), and RSA (13%). ORAC and FRAP in canned ‘Marion’ was 21-61% lower than that of frozen samples. Jam also had lower TPC and ACY (67-84%), RSA (˜80%), and ORAC and FRAP (65-77%) values than frozen ones in both varieties (P < 0.05). The 6-mo post-process room storage had little effect on the bioactive compounds of frozen and freeze dried samples, but reduced ACY in hot-air dried, canned, and jam samples, and antioxidant capacities of all samples (P < 0.05).     

Antioxidant Capacity of Fruit Extracts of Blackberry (Rubus sp.) Produced in Different Climatic Regions

A range of blackberry genotypes harvested in different seasons and regions in Mexico (Michoacan) and in the United States (Pacific Northwest) were collected to determine their antioxidant capacity using oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays. Total acidity, ascorbic acid, soluble solids, total phenols, and total anthocyanins, as well as the correlation between all these parameters, were determined for all treatments. Total acidity ranged from 4.22% in wild blackberry from Patzcuaro, Mexico, to 1.02% in ‘Evergreen’ from Woodburn, Oreg. These treatments were also the outliers in terms of ascorbic acid content. Cultivar ‘Brazos’ did not exhibit any significant differences in acidity or ascorbic acid as a consequence of the geographic origin or harvest season. The highest concentration of soluble solids was recorded for ‘Evergreen’ from Woodburn and relatively low soluble solids levels were recorded for all the Mexican treatments. Wild blackberry from Patzcuaro exhibited the highest values for ORAC, FRAP, total phenolic and anthocyanin content. Other relatively high antioxidant capacity values were detected for ‘Marion’ and ‘Evergreen’, both produced in Oregon. Different cultivars grown in the same region/season consistently showed differences in antioxidant capacity. There was little effect of harvest season on phenolic levels. We conclude that levels of total acidity, ascorbic acid, soluble solids, antioxidant capacity, and polyphenols mainly depended on the genotype and not on the climate or the season. ORAC and FRAP values were both highly correlated with each other, and with total phenols and anthocyanin content.     

Antioxidant activity and antimicrobial properties of phenolic extracts from acerola (Malpighia emarginata DC) fruit

The antioxidant activity and antimicrobial property of phenolic extracts from acerola (Malpighia emarginata DC) fruit were assessed. The contribution of ascorbic acid and phenolic compounds in the total antioxidant capacity of the extracts was also evaluated. The extracts showed high total phenolic values and possessed high antioxidant activity as expressed by 2,2′‐diphenylpicrylhydrazyl (DPPH) and oxygen radical absorbance capacity assays (ORAC). The ascorbic acid content ranged from 405 to 1744 mg/100 g of fruit on a fresh weight basis. The antioxidant capacity of the phenolic fractions was in the following order: anthocyanins<phenolic acids<flavonoids. The phenolic fractions contributed 7.1–36.5% of the antioxidant activity expressed by ORAC, whereas the contribution of ascorbic accounted for 18–39% of the total activity. Selected extracts from the flavonoids fraction showed some activity against Staphylococcus aureus.     

Changes in strawberry phenolics, anthocyanins, and antioxidant capacity in response to high oxygen treatments

Changes in fruit quality, decay, phenolic and anthocyanin content, and antioxidant capacity of strawberries (Fragaria × ananassa Duch. cv. Allstar) stored under air and high oxygen atmospheres at 5 °C were investigated. Freshly harvested strawberries were placed in jars and ventilated continuously with air or with 40, 60, 80, or 100 kPa O₂ at 5 °C for up to 14 days. Samples were taken initially, and after 3, 7, 10 and 14 days of storage. While fruit quality parameters such as titratable acidity, total soluble solids and surface color were only slightly affected by differing levels of O₂, the higher oxygen concentration treatments significantly reduced decay. Oxygen concentrations higher than 60 kPa also promoted increases in ORAC values, total phenolics and total anthocyanins as well as individual phenolic compounds analysed by HPLC during the initial 7 days of storage. However, this effect diminished with prolonged storage. No significant differences in ORAC values, total phenolics, total anthocyanins, or the individual phenolic compounds were observed among the high O₂ and air-stored fruits after 14 days of storage. These results indicate that high oxygen treatments exert the most effects on fruit quality and antioxidant capacity of strawberry fruit in the first 7 days of storage.     

Effects of Food Processing on Blueberry Antiproliferation and Antioxidant Activity

Cultivated highbush (Vaccinium corymbosum L.) and wild lowbush (Vaccinium angustifolium Ait.) blueberries are excellent sources of phytochemicals that are believed to have significant biological activity. The objective of this study was to determine whether incorporation of blueberries into food products affects their phenolic content or antioxidant and antiproliferation activity. Several blueberry fruit‐containing products including fresh, individually quick frozen (IQF), freeze‐dried, spray‐dried, heat‐dried, cooked, juice concentrate, pie filling, and jam were fractionated to remove sugars and isolate groups of phytochemicals based on solubility. The fractions were analyzed for total phenolics and assayed for ferric reducing antioxidant power (FRAP) antioxidant activity, 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity, and hepa‐1c1c7 antiproliferative activities. For both cultivated and wild berries, fresh and IQF berries had the highest total phenols, antioxidant activity, and antiproliferation activity. Whole freeze‐dried wild blueberries also retained significant antiproliferative activity in 2 fractions eluted with acetone (fraction 4, 4% of control cell growth at 20 (μg/mL) and 50% aqueous acetone (fraction 5, 69% of control cell growth at 20 (μg/mL) and ranked close to the activities recorded for fresh (30% of control cell growth at 20 (μg/mL for fraction 5) and IQF whole fruit (27% of control cell growth at 20 (μg/mL for fraction 5). Products that were heat‐processed retained most of the antioxidant activity and total phenolics found in unprocessed whole fruit. However, the heat‐treated products lacked or had diminished antiproliferation activity, suggesting that although products may be high in phenolic compounds and antioxidant activity, some forms of bioactivity may be compromised by harsh processing methods.     

Characterization of Red Raspberry (Rubus idaeus L.) Genotypes for Their Physicochemical Properties

ABSTRACT:  The worldwide tendency for growing more small fruits, including raspberries, shows permanent increase because this group of fruits has a relatively higher content of bioactive nutrients. To study the health benefits of red raspberry fruits, 11 preselected wild-grown and 1 well-known cultivar, Heritage, were evaluated for some of their physicochemical properties such as fruit weight, total antioxidant capacity (measured by β-carotene bleaching and FRAP assays), total phenolics, ascorbic acid, soluble solid content (SSC), and acidity. Fruit weight, SSC, and ascorbic acid contents were between 1.47 and 2.32 g, 10.87% and 13.60%, and 21 and 36 mg/100 g, respectively. Antioxidant activity and total phenolic content varied among genotypes and the ERZ5 genotype had the highest antioxidant capacity as ascertained by both methods. This genotype also had the highest total phenolic (2031 μg GAE/g FW) content. There are linear relationships between antioxidant capacities and total phenols. The present study demonstrates the potential of certain wild genotypes, notably ERZ5, for improving the nutritional value through germplasm enhancement programs.     

Increase of antioxidant capacity of the lowbush blueberry (Vaccinium angustifolium) during fermentation by a novel bacterium from the fruit microflora

Members of the genus Vaccinium, such as blueberry and cranberry, are known to be excellent sources of antioxidant phenolic compounds, for example anthocyanins, flavonols and phenolic acids. The fruit also provides a natural habitat for numerous microorganisms. Interaction between the fruit and the microflora might affect the antioxidant phenolic compounds. The aim of this study was to investigate the effects on phenolic content and antioxidant capacity of wild blueberry fermented by a newly identified bacterium isolated from blueberry‐fruit surface microflora, Serratia vaccinii. Increase in the antioxidant capacity following fermentation of blueberries by the novel bacterium, as determined with the 2,2′‐diphenyl‐1‐picrylhydrazyl method, was attributed not only to an increase in total phenolics, but also to a change in the phenolic profile, as demonstrated by the production of gallic acid and of a novel compound of phenolic or phenylpropanoic structure. Copyright © 2005 Society of Chemical Industry     

Effect of baking on dietary fibre and phenolics of muffins incorporated with apple skin powder

Apple fruit skin, a rich source of dietary fibre and phenolics, is a by-product of apple processing. The effect of baking on the dietary fibre, phenolics, and total antioxidant capacity was investigated using a model system of muffins incorporated with dried apple skin powder (ASP) as a value-added food ingredient. The blanched, dehydrated, and ground ASP contained approximately 41% total dietary fibre and oxygen radical absorption capacity (ORAC) of 52 mg Trolox equivalents g⁻¹ dry weight. The total dietary fibre content, total phenolic content, and total antioxidant capacity of muffins were positively correlated to the amount of ASP incorporated into muffins. The mean percent recovery of quercetin glycosides, catechins, chlorogenic acid, phloridzin, and cyanidin galactoside after baking were 61%, 57%, 53%, 44%, and 20%.     

Effect of Heat Treatment on Antioxidant Capacity and Flavor Volatiles of Mead

ABSTRACT: The objective of this study was to evaluate the effects of heat processing on the antioxidant capacity of mead (honey wine). Soy and buckwheat honey musts were subjected to 2 heat treatments and fermented into wine. Total phenolic concentration was determined. High-performance liquid chromatography (HPLC) phenolic profiling was performed on the methanol fraction of Amberlite extraction. Antioxidant capacity was evaluated using the oxygen radical absorbance capacity (ORAC) assay. Changes in volatile components were evaluated by headspace-solid phase microextraction/gas chromatography-mass spectrometry (H-SPME/GC-MS). ORAC values of experimental meads (3.62 m M Trolox equivalent) were comparable to those of commercial white wine (3.66 m M Trolox equivalent). No significant difference in antioxidant capacity due to heat treatment or honey type was observed. There was no difference in total phenolics between heat treatments in buckwheat mead; however, soy mead made from high-heated must had significantly greater phenolic concentration than the gently heated mead (α= 0.05). Linear regression analysis indicated a strong positive correlation between total phenolic concentration and antioxidant capacity by ORAC ( r = 0.9077; P < 0.0001). HPLC analysis of phenolic profiles in the methanol fractions of Amberlite extraction of the meads indicated significantly higher levels of certain phenolics as a result of the high-heat process in buckwheat mead, but not in soy mead. Differences in volatile components that potentially impact flavor were noted between high and low heat treatments. Results of this study suggest dramatic heat treatments that are often avoided because their flavor impact in mead production have the potential to alter the antioxidant capacity of mead by changing phenolic profiles.