Antioxidant capacity,total phenolics,glucosinolates and colour parameters of rapeseed cultivars

The antioxidant capacity of twenty nine rapeseed varieties was determined by using ferric reducing antioxidant power (FRAP) and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) methods. Mean FRAP (3190–6326 μmol Trolox/100 g) and DPPH (3194–6346 μmol Trolox/100 g) values for methanolic extracts of rapeseed cultivars did not differ significantly. Moreover, the total content of phenolics (756–1324 mg sinapic acid/100 g), glucosinolates (4.2–87.5 μmol/g, respectively), erucic acid (0.0–56.1%) and colour parameters of the studied rapeseed cultivars were analysed. Antioxidant capacity determined by FRAP and DPPH methods correlated significantly with total phenolic content (TPC) in rapeseed cultivars (r = 0.9332, 0.9339, p < 0.001). Also, significant, inverse correlations were found between antioxidant capacity, total phenolics and luminosity (L^∗) or red colour intensity (a^∗) of rapeseed cultivars. Principal component analysis (PCA) allowed the rapeseed varieties to be differentiated based on their antioxidant capacities, total amounts of phenolics, glucosinolates, erucic acid and colour parameters.     

Changes in antioxidant capacity,isoflavone profile,phenolic and vitamin contents in soymilk during extended fermentation

In this study, the influence of lactic acid bacteria fermentation on the antioxidant capacity, phenolic compounds and vitamins profile of soymilk with different final fermentation pH values (pH 4.55, 4.15 and 3.85) was examined. Fermented soymilk (FSM) with a final pH of 3.85 exhibited relatively higher antioxidant capacity than samples terminated at pH 4.55 or 4.15, as shown from results of Folin–Ciocalteu assay (57.3–63.8 mg GAE/100 mL FSM), DPPH-radical scavenging efficiency (30.0–36.5%) and ferricyanide reducing power (1.13–1.58 mg AAE/100 mL FSM). Among all products, Lactobacillus rhamnosus WQ2-fermented soymilk showed the highest antioxidant level among the four Lactobacillus species, while Lactobacillus acidophilus CSCC 2400 possessed the best ability to deglycosylate isoflavone glucoside (IG), reducing IG concentration by 60.8%. Four vitamins, three phenolic acids, one flavanol, and six isoflavones were detected in fermented and non-fermented soymilk by HPLC-DAD. The contents of antioxidant compounds in FSM were closely related to reducing power and anti-radical ability. In addition, antioxidant capacity was highly correlated with proteolytic activity. This study also demonstrated the potential of extended fermentation to enhance the overall health-promoting property of the products.     

Assessment of in vitro antioxidant capacity of the seed coat and the cotyledon of legumes in relation to their phenolic contents

Methanolic extracts of the seed coat and the cotyledon of two varieties of lentils (Lens culinaris L.) and two varieties of dark peas (Pisum sativum L.), were analysed for their antioxidant capacities (EC₅₀), in the form of free radical-scavenging activities. Huge differences have been observed in the antioxidant capacity in the seed coat and the cotyledon in both legumes. The seed coat, in which are located, principally, phenolic compounds with flavonoid structures, presents higher antioxidant activity than the cotyledon in lentils and peas, showing differences in both species but not very large differences between varieties. An analysis of principal components was applied to the results in order to relate the antioxidant capacity of these legumes with their phenolic composition previously established by the authors.     

Evaluation of antioxidant capacity and aroma quality of anthograin liqueur

Moderate consumption of wine, beer, whisky or liqueur is known to be beneficial for improving health because of the radical scavenging action of antioxidants present in them. Thus, antioxidant and aroma properties of anthograin liqueur made from purple wheat grain were evaluated for the added-value processing purpose of that grain. Anthograin liqueur showed the highest 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging activity, total phenolic content (TPC) and oxygen radical absorbance capacity (ORAC) in comparison with three control samples Canadian iceberg vodka (CIV), Hiram walker special old rye whisky (HWSORW) and Wiser’s De Luxe Canadian whisky (WDLCW). Only anthograin liqueur contained anthocyanins and its total anthocyanin content (TAC) was 81 mg/l. In lipid-soluble phase, TPC and ORAC were 241.1 and 998.6 mg/l for anthograin liqueur, 40.0 and 93.6 mg/l d for WDLCW, 23.1 and 63.6 mg/l for HWSORW, and 1.1 and 12.4 mg/l for CIV, respectively. In water-soluble phase, TPC and ORAC were 685.5 and 1467.7 mg/l for anthograin liqueur, 29.0 and 96.0 mg/l for WDLCW, 36.4 and 99.2 mg/l for HWSORW, and 2.0 and 42.8 mg/l for CIV, respectively. Eight types of phenolic acids in anthograin liqueur, four types of phenolic acids in WDLCW and three types of phenolic acids in HWSORW were found and no phenolic acid was detectable in CIV. Total phenolic acids in anthograin liqueur, WDLCW and HWSORW were 28.8, 10.3 and 5.7 mg/l, respectively. Similarity in aroma quality was found between anthograin liqueur and CIV by using the electronic nose. Purple wheat grain may have potential as a novel material for liqueur brewing.     

Evaluation of antioxidant capacity and total phenolic content of different fractions of selected microalgae

In order to identify new sources of safe and inexpensive antioxidants, the antioxidant capacity and total phenolic content of different fractions of 23 microalgae were evaluated, using Trolox equivalent antioxidant capacity assay and the Folin–Ciocalteu method, respectively. The microalgae were extracted using hexane, ethyl acetate and water by a three-step sequential extraction procedure. Most of these microalgae were evaluated for the first time for their antioxidant activities. It was found that the microalgae Synechococcus sp. FACHB 283, Chlamydomonas nivalis and Nostoc ellipsosporum CCAP 1453/17 possessed the highest antioxidant capacities and thus could be potential rich sources of natural antioxidants. In addition, the correlation coefficients between the antioxidant capacities and the phenolic contents were very small in hexane (R² = 0.0075), ethyl acetate (R² = 0.5851) and water (R² = 0.3599) fractions. Thus, phenolic compounds were not a major contributor to the antioxidant capacities of these microalgae. This was very different from many other plant species like fruits, vegetables and medicinal plants. The microalgae could contain different antioxidant compounds from other plants.     

Vitamin C,vitamin A,phenolic compounds and total antioxidant capacity of new fruit juice and skim milk mixture beverages marketed in Spain

The growing interest in new functional foods with special characteristics and health properties has led to the development of new beverages based on fruit juice–skim milk mixtures. The proliferation of ready-to-drink beverages has caused the market to focus its interest on these products. Commercial conventionally pasteurized or sterilized beverages based on a mixture of fruit juice and skim milk were evaluated nutritionally for their concentrations of vitamin C, vitamin A and phenolic compounds and their total antioxidant capacity, taking the influence of physicochemical parameters into account. The main contribution to the total antioxidant capacity (TEAC, trolox equivalent antioxidant capacity) was provided by vitamin C, followed by phenolic compounds, in accordance with a mathematical equation obtained from the data: TEAC = −0.184 + 0.009 ∗ [vitamin A] + 0.011 ∗ [phenolic compounds] + 0.058 ∗ [vitamin C]. The R-squared value was 86.88%. Citrus fruits, such as lemons or oranges, were the fruits associated with the greatest antioxidant capacity in the samples analysed.     

Antioxidant capacities and total phenolic contents of 62 fruits

In order to supply new information on the antioxidant function of selected fruits for nutritionists and the general public, antioxidant activities and total phenolic contents of 62 fruits were evaluated using ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays as well as the Folin–Ciocalteu method, respectively. The correlations between the FRAP value and the TEAC value as well as total phenolic content were also assessed. The results showed that different fruits had diverse antioxidant capacities and the variation was very large, and seven fruits, Chinese date, pomegranate, guava, sweetsop, persimmon, Chinese wampee and plum, possessed the highest antioxidant capacities and total phenolic contents among tested fruits, and could be important dietary sources of natural antioxidants for prevention of diseases caused by oxidative stress.     

A study of the antioxidant capacity of oak wood used in wine ageing and the correlation with polyphenol composition

The antioxidant capacity of oak wood used in the ageing of wine was studied by four different methods: measurement of scavenging capacity against a given radical (ABTS, DPPH), oxygen radical absorbance capacity (ORAC) and the ferric reducing antioxidant power (FRAP). Although the four methods tested gave comparable results for the antioxidant capacity measured in oak wood extracts, the ORAC method gave results with some differences compared to the other methods. Non-toasted oak wood samples displayed more antioxidant power than toasted ones due to differences in the polyphenol composition. A correlation analysis revealed that ellagitannins were the compounds mainly responsible for the antioxidant capacity of oak wood. Some phenolic acids, mainly gallic acid, also showed a significant correlation with antioxidant capacity.     

Natural antioxidants and antioxidant capacity of Brassica vegetables: A review

Dietary antioxidants, such as water-soluble vitamin C and phenolic compounds, as well as lipid-soluble vitamin E and carotenoids, present in vegetables contribute both to the first and second defense lines against oxidative stress. As a result, they protect cells against oxidative damage, and may therefore prevent chronic diseases, such as cancer, cardiovascular disease, and diabetes. Brassica vegetables, which include different genus of cabbage, broccoli, cauliflower, Brussels sprouts, and kale, are consumed all over the world. This review focuses on the content, composition, and antioxidant capacity both lipid- and water-soluble antioxidants in raw Brassica vegetables. The effects of post-harvest storage, industrial processing, and different cooking methods on stability of bioactive components and antioxidant activity also are discussed.     

Antioxidant capacity and phenolic composition of different woods used in cooperage

This study has investigated the antioxidant capacity of different woods used in cooperage and the effect of the botanical species of wood on this capacity. Quercus robur and Castanea sativa were the species with the highest antioxidant capacity, due to their relatively high content of phenolic compounds. However, the phenolic content of Prunus avium samples was very low, also reflected in its antioxidant capacity. All measurements of antioxidant capacity were consistent with the content and composition of the phenolic compounds detected in the wood samples. The major contributors to the antioxidant capacity were identified as phenolic acids, including gallic, protocatechuic, p-coumaric and ellagic acid and all the ellagitannins, due to their characteristic structure.     

Total phenolic contents and antioxidant activity of corn tassel extracts

Ground corn tassels, a by-product of corn, were used as a source of phenolic compounds. Water, ethanol, methanol, acetone, hexane, chloroform, butanol, petroleum ether and methylene chloride were evaluated as different polarity solvents to extract these phenolic compounds. Ethanol exhibited the highest extraction ability for such phenolic compounds, followed by methanol and water, where the total phenols were 0.1575%, 0.1125% and 0.0737%, respectively. Antioxidant activity of corn tassels ranged from 83.0% to 85.2%, 69.9% to 83.7%, 69.8% to 80.4%, 22.2% to 49.1% and 14.8% to 19.3% radical scavenging activity (% RSA) for ethanol, methanol, acetone, butanol and water extracts, respectively. The ethanolic extract of the corn tassels was successfully utilised to retard the oxidation of sunflower oil and the obtained induction period values were comparable to those of tert-butylhydroquinone (TBHQ).     

Microwave-assisted extraction of phenolics with maximal antioxidant activities in tomatoes

Microwave-assisted extraction (MAE) was investigated for extraction of phenolic compounds from tomato with maximised antioxidant activities using response surface methodology (RSM) coupled with a central composite design, and in vitro antioxidant assays (FRAP and ORAC). MAE was more efficient for greater antioxidant activities and higher total phenolic contents than solvent extraction. The optimal MAE processing parameters were 96.5 °C, 2.06 min, 66.2% ethanol for FRAP, and 96.5 °C, 1.66 min, 61.1% ethanol for ORAC. The models were successfully applied to 20 tomato cultivars, whose total phenolic contents (TPC) and indexes (TPI) were 489.30–997.45 mg gallic acid equivalent/100 g dry weight (DW) and 281.34–468.52 mg/100 g DW, respectively. Eight phenolic compounds were identified. Individual phenolics were 6.10–42.73 mg/100 g DW. The FRAP, but not the ORAC value showed good correlation with the TPC or TPI. The methodologies developed and the knowledge acquired in this study will provide useful information to tomato breeders and food processors.     

High hydrostatic pressure effect on chemical composition,color, phenolic acids and antioxidant capacity of Cape gooseberry pulp (Physalis peruviana L.)

The aim of this study was to evaluate the effects of high hydrostatic pressure (HHP) at 300, 400 and 500 MPa/1, 3 and 5 min on nutritional and antioxidant properties of Cape gooseberry pulp after immediate application and after 60 days of storage. Proximal analysis, color, phenolic acids content and antioxidant capacity were determined. When analyzing the immediate effect of different treatments, a clear influence of HHP was observed in all the components of the proximal analysis. Regarding color, none of the three chromatic parameters showed significant differences with control leading to a minimum ΔE at 300 MPa/3 min. Changes in bound and free phenolic acids were evidenced after treatments. The maximum levels of TPC as well as antioxidant capacity were observed at 500 MPa/5 min. By the end of storage, all treated samples discolored leading to ΔE = 14.9 at 500 MPa/5 min. The profile of free and bound phenolic acids presented differences compared to Day 0. The antioxidant capacity by means of ORAC increased for treatments above 300 MPa/5 min indicating the effectiveness of these treatments for the production of functional products based on gooseberry pulp. For treatments above 400 MPa/3 min, molds and yeasts were not detected.     

Optimisation of extraction conditions for recovering carotenoids and antioxidant capacity from Gac peel using response surface methodology

The peel of Gac fruit is regarded as waste product in the processing of Gac although it contains high level of carotenoids and possesses a significant antioxidant capacity. This study optimised the extraction yields of carotenoids and antioxidant capacity from Gac peel. Different organic solvents were examined to determine the most suitable solvent for the extraction. The extraction conditions including time, temperature and solvent–solid ratio were then optimised for maximising extraction yields of carotenoids and antioxidant capacity from Gac peel using response surface methodology. Ethyl acetate was identified as the most suitable solvent. The optimal extraction time, temperature and solvent–solid ratio were 150 min, 40.7 °C and 80 mL g^?1, respectively. The carotenoid extraction yield and the antioxidant capacity extraction yield were 271 mg/100 g DW and 737 μm TE/100 g DW, respectively. Thus, the extraction using ethyl acetate with the ratio of 80:1 (mL solvent per g Gac peel) for 150 min at 40.7 °C is suggested for recovering carotenoids and antioxidant capacity from Gac peel.     

Changes in physio-biochemical metabolism,phenolics and antioxidant capacity of different Chinese pea varieties during germination

In this study, changes in physiological and biochemical metabolism, phenolics and antioxidant capacity of six different Chinese pea varieties during germination were investigated. Results showed that germination had a positive effect on the physiological indexes and bioactive substances of pea. The bud length, root length, fresh weight and respiration rate of pea sprouts increased with germination time. The content of free and bound phenolics in germinated peas increased significantly. Meanwhile, activated phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H) and 4-coumaric acid coenzyme A ligase (4CL) led to the accumulation of phenolics. Antioxidant capacity of pea sprouts increased with the extension of germination time. From the perspective of principal component analysis, compared with the other five varieties, Longwan 7 can be distinguished by free phenolic content in the later stage of germination. The result provides a new perspective for further development of pea as a functional food for human consumption.     

The increase in antioxidant capacity after wounding depends on the type of fruit or vegetable tissue

Wounding of fresh produce may elicit an increase in antioxidant capacity associated with wound-induced phenolic compounds. However, there have been no reports on the wounding response of different types of fresh produce. Changes in antioxidant capacity, total soluble phenolics, ascorbic acid, total carotenoids and total anthocyanins were evaluated after wounding in zucchini, white and red cabbage, iceberg lettuce, celery, carrot, parsnips, red radish, sweetpotato and potatoes. Phenolic changes ranged from a 26% decrease to an increase up to 191%, while antioxidant capacity changes ranged from a 51% decrease to an increase up to 442%. Reduced ascorbic acid decreased up to 82%, whereas the changes in anthocyanins and carotenoids were less evident. In general, the wound response was dependent on the type of tissue and influenced by the initial levels of reduced ascorbic acid and phenolic compounds. Wounding may increase the antioxidant content towards the development of selected healthier fresh-cut produce.     

Effect of peptide–phenolic interaction on the antioxidant capacity of walnut protein hydrolysates

Walnut antioxidant peptides and phenolic compounds (POHs) commonly coexist in walnut protein hydrolysates (WPHs). However, the peptide–phenolic interaction and its effects on antioxidant activities of WPHs remain unknown. Fluorescence and dynamic light scattering were used to study the peptide–phenolic interaction in WPH‐POH mixtures (W‐P) with different POH/WPH ratios; antioxidant abilities of POH only solution, WPH only solution and W‐P were measured with three assays: DPPH radical scavenging, Fe²⁺ chelation and linoleic acid peroxidation inhibition. Results showed that initially POHs bonded to hydrophobic sites of peptides; subsequently, when POH/WPH ratio exceeded 1:120 (w/w), POHs changed the conformation and average particle size of peptides. Their interaction could at most increase WPHs’ capability in scavenging DPPH radical (44.9%), chelating Fe²⁺ (36.1%) and inhibiting linoleic acid oxidation (87.5%) at the POH/WPH ratio (w/w) point of 1:12. This research offered a guidance in the production of WPHs with high functionality.     

Antioxidant capacity,phenolics and isoflavones in soybean by-products

This study aimed to determine proximate composition, antioxidant capacity, total phenolic content, isoflavones and free phenolic compounds in soy by-products. High carbohydrate and protein contents were found in grade A soymilk powder (GASP) compared to grade B soymilk powder (GBSP) and soy husk powder (SHP). Ash, moisture and total dietary fibre contents were reported to be the highest in soy husk, while GBSP had the highest fat content. Antioxidant capacity as assessed using β-carotene bleaching assay was in the order of SHP ≈ GBSP > GASP, and the ranking order of the Trolox Equivalent Antioxidant Capacity (TEAC) value was GASP ≈ GBSP > SHP, while the Ferric Reducing Antioxidant Power (FRAP) value was GASP > GBSP > SHP. The total phenolic content was in the range of 62.44–103.86 mg GAE/100 g wet weight, and the major phenolic compounds in free form were ferulic, vanilic as well as gallic acids. Acid hydrolysis increased the amount of total extractable isoflavone in all soy samples.