Effect of germination on vitamin C,phenolic compounds and antioxidant activity in flaxseed (Linum usitatissimum L.)

Flaxseed (Linum usitatissimum L.) is well known for its health benefits and chemical composition. This study aimed to evaluate the dynamic changes caused by germination in vitamin C, phenolic compounds and antioxidant activities of flaxseed. It was observed that eight‐day germination of flaxseed sprouts caused increases in phytochemical contents, that is 22.1‐fold increase in vitamin C, 2.67‐fold increase in phenolics and 5.48‐fold increase in flavonoid contents as compare to initial concentration in flaxseeds on dry weight basis. The stimulation was also noted in the three identified phenolic acid ingredients including caffeic acid, p‐coumaric acid and ferulic acid. Similarly, the total PSC and ORAC values of flax sprouts at day 8 increased by 3‐ to 4‐folds compared to nongerminated flaxseeds. It is revealed that comparatively, 8‐day germination of flax sprouts leads to a significant increase in vitamin C, phenolic constituents and total antioxidant activities than those of flaxseeds.     

Effect of dehydration on phenolic compounds and antioxidant activity of blackcurrant (Ribes nigrum L.) pomace

This study examined the effect of dehydration on the phenolic compounds and antioxidant activity of blackcurrant (Ribes nigrum L.) pomaces (DBP) subjected to hot air oven drying (HOD), industrial rotary drying (IRD) and freeze drying (FD). Temperature and residence time were evaluated for HOD, whereas air-on and air-off temperature, ratio of drum rotor speed to air speed and particle size were evaluated for IRD. The highest total anthocyanins (ATC) and flavonols (FLV) were obtained in particle size of> 5.0 mm using IRD at 475°C/97°C (air-on/air-off) and higher ratio of drum rotor speed to air speed. Smaller size particles were found susceptible to degradation due to high temperature and retention time applied in IRD, resulting in loss of phenolic compounds in DBP, and thus, HOD was deemed more suitable. Overall, drying method selection and parameters of operation are key in preserving the concentrations of individual HCA and FLV in DBP.     

啤酒花多酚提取物体内外抗氧化活性研究

从酿造废酒花（Humulus lupulus L.）中提取制备一种高纯度（总多酚含量为88.7%）的酒花多酚提取物（hop polyphenol extract,HPE）,测定其酚类组成成分与体内外抗氧化活性。结果表明：HPE中55%以上的多酚物质是原花青素,28%以上的多酚物质是黄酮苷类。在体外,HPE能有效清除活性氧自由基,显著抑制Cu2+-VC诱导的DNA氧化断裂损伤。在体内,口服200～800 mg/kg（以体质量计）多酚剂量的HPE可显著抑制因溴代苯诱导的小鼠肝脏超氧化物歧化酶和谷胱甘肽过氧化物酶活性的降低,也可降低溴代苯氧化应激小鼠肝脏的硫代巴比妥酸产物含量。结论：膳食摄入HPE可提供体内外抗氧化损伤的保护作用,酒花多酚的体内外抗氧化效果均优于同质量浓度的绿茶多酚。     

Antioxidant activity and polyphenol contents in Brazilian green propolis extracts prepared with the use of ethanol and water as solvents in different pH values

Propolis is a natural product with a variable and complex chemical composition associated with its high concentration on polyphenolic compounds. The effect of pH variation (2.0, 3.0, 4.3, 6.0 and 8.0) during aqueous and ethanolic propolis extraction was studied for up to 10 days. Total phenols and flavonoids contents were measured for the extracts by spectrophotometric assays. Antioxidant activity was measured by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and ferric thiocyanate (FTC) methods. The best time of extraction was up to 5 days for all samples. Basic aqueous extracts (pH 8.0) resulted in a higher concentration of compounds than the extract without pH modification, reaching an increase of 160% in flavonoids and 25% in phenols. Ethanolic extracts with pH variation resulted in an extract with 50% less polyphenols and 6% less flavonoids than extract without pH modification. The antioxidant activity was highest for ethanolic extract at pH 4.3 and aqueous extract at pH 8.0 – almost 90% and 45%, respectively, in DPPH method – and was related to the level of polyphenols by Pearson's correlations.     

Antiproliferative and antioxidant activities of Turkish pomegranate (Punica granatum L.) accessions

The objective of this study was to assess antioxidant and antiproliferative activities of four different Turkish pomegranate varieties (Hatay, Hicaz, Adana and Antalya) using an in vitro HepG2 cancer cell model. All the pomegranate extracts employed in this study significantly diminish the proliferation of HepG2 cells in a dose‐dependent manner. The total phenolic acid, anthocyanin and flavonoid contents for each of the four varieties were determined. The Hatay pomegranate variety had the highest total phenolic acid (337.4 ± 2.34 mg/100 g) and flavonoid (58.42 ± 2.25 mg/100 g) contents of the pomegranates examined. Antioxidant activities of the pomegranates were determined using DPPH and ABTS radical scavenging assays. The lack of correlation between colour index value and antioxidant–antiproliferative activities suggested that phenolic acids and flavonoids are predominant compounds influencing pomegranate's bioactivity rather than anthocyanins. Individual phenolic acids found in Hatay pomegranates were determined, using an HPLC system, as gallic acid being the most predominant phenolic compound.     

Supercritical CO2 extraction of Chilean hop (Humulus lupulus) ecotypes

Hops (Humulus lupulus L) have very stringent requirements of diurnal light hours during flowering. Thus, the beer industry is permanently assessing new agricultural land to grow hops, southern Chile being an excellent candidate for their introduction. Supercritical carbon dioxide extraction procedures were implemented to assess Chilean hop ecotypes. Based on results of a preliminary study with commercial samples (cv Nugget), 200 bar and 40 °C were selected as extraction conditions. Very limited increases in extraction rate were observed when applying pressures >200 bar; such pressures did not speed up the extraction of α‐acids (bitter flavor principles), but rather increased the co‐extraction of undesirable compounds (hard resins and chlorophyll pigments). On the other hand, the effects of retrograde condensation phenomena were just starting to subside at 200 bar, and thermal damage of samples could increase at >40 °C. Ground cone samples of five local hop ecotypes, originating from Osorno, La Junta, Coyhaique and Elizalde Lake, were subsequently tested. Osorno exhibited a higher yield (65 g kg^?1 oleoresin/substrate) than other Chilean ecotypes. Moreover, Osorno extract had a light yellowish color, as well as a higher content of bitter flavors (157 g kg^?1 α‐acid/extract) and 1.5–7.1 times more representative aroma compounds than extracts of the other ecotypes. However, all these indicators were very low compared with the commercial Nugget sample (134 g kg^?1 oleoresin/substrate, 383 g kg^?1 α‐acid/extract, 14 times more aroma compounds than Osorno ecotype). Copyright © 2003 Society of Chemical Industry     

Antimicrobial and antioxidant activity of crude onion (Allium cepa,L.) extracts

Antioxidant and antimicrobial activity of the ethyl acetate and water subfractions of methanolic extracts of three Spanish onion varieties were assayed. Flavonoids were mainly present in ethyl acetate subfraction being 34.92 ± 0.75, 7.95 ± 0.16, 0.38 ± 0.01 μmol of rutin eq. g^?1 D.W. and its antioxidant capacity was 74.86 ± 1.77, 24.59 ± 0.67, 4.55 ± 0.44 μmol Trolox g^?1 D.W. of Grano de Oro, Fuentes de Ebro and Calçot de Valls varieties, respectively. The antimicrobial activity of flavonol standards and onion extracts was evaluated against some food spoiler microorganisms. Quercetin and kaempferol were inhibitory against gram positive bacteria such as Bacillus cereus, Staphylococcus aureus, Microcroccus luteus and Listeria monocytogenes. Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa were less sensible to the antimicrobial effect of both flavonol standards and Candida albicans was totally resistant. Among the onion extracts tested only ethyl acetate subfraction showed antimicrobial inhibition.     

Broad spectrum anti-infective potential of xanthohumol from hop (Humulus lupulus L.) in comparison with activities of other hop constituents and xanthohumol metabolites

This review summarizes the capacity of xanthohumol (XN) in comparison with additional hop constituents and metabolites to act as an antiinfective agent against microorganisms including bacteria, viruses, fungi and malarial protozoa. XN was shown to inhibit the Gram-positive bacteria Staphylococcus aureus and Streptococcus mutans. Antiviral activity was demonstrated against bovine viral diarrhea virus, cytomegalovirus, herpes simplex virus type 1 and 2 and human immunodeficiency virus 1. Inhibition of two Trichophyton spp. was indicative of antifungal activity. Finally, XN potently inhibited the replication of Plasmodium falciparum, the causative agent of malaria. This effect was linked to the inhibition of glutathione-mediated degradation and detoxification of haemin, a by-product of the parasitic digestion of haemoglobin. Overall, these activities further contribute to the broad spectrum of biological effects observed with XN.     

Determination of the botanical origin of hops (Humulus lupulus L.) using different analytical techniques in combination with statistical methods

Beer flavour and aroma depend mostly on the hop variety used in the brewing process. For this reason it is of crucial importance for brewers to be certain about the botanical origin of the hop variety. Metabolic fingerprinting is one of the approaches that can be used for determination of the botanical origin of many agricultural and food products. The aim of the current work was to differentiate between the five most important hop varieties in Slovenia. Gas chromatography, high‐performance liquid chromatography (HPLC) and Fourier transform infrared spectroscopy were carried out in combination with three different chemometric methods – principal component analysis, regularized discriminant analysis and hierarchical clustering – on 121 hop samples. The chemometric classification of the hop varieties was obtained with nearly 100% success. The best results were obtained with GC and HPLC data, within one year of harvesting. Copyright © 2016 The Institute of Brewing & Distilling     

Bioactive compounds and antioxidant potential of mango peel extract

Bioactive compounds such as polyphenols, carotenoids and anthocyanins present in fruits and vegetables are receiving increased attention because of their potential antioxidant activity. Consumption of such antioxidants offers health benefits including protection against cardiovascular diseases and cancer. Mango peel is a major byproduct obtained during the processing of mango products such as mango pulp and amchur. In the present study, the antioxidant activity of mango peel extracts was examined. Polyphenol, anthocyanin and carotenoid contents in acetone extract of peels were determined. Ripe peels contained higher amount of anthocyanins and carotenoids compared to raw peels while raw mango peel had high polyphenol content. Antioxidant activity of ripe and raw mango peels extracted in acetone was determined using different antioxidant systems such as reducing power activity, DPPH free radical scavenging activity, iron induced lipid peroxidation of liver microsomes and soybean lipoxygenase inhibition. The IC₅₀ values were found to be in the range of 1.39–5.24 μg of gallic acid equivalents. Thus, the mango peel extract exhibited good antioxidant activity in different systems and thus may be used in nutraceutical and functional foods.     

Analysis of supercritical carbon dioxide extracts from cones and leaves of a Humulus lupulus L cultivar

Extracts obtained by supercritical carbon dioxide extraction of cones and leaves of hop (Humulus lupulus L) at different combinations of temperature and pressure were analysed for their α- and β-acids and volatiles, using HPLC and GC respectively. The yield and composition of the mixtures of bitter compounds from the cones were largely influenced by the temperature and pressure applied during the extraction. Bitter compounds could not be detected in the extracts from the leaves. The most important volatile components identified were β-myrcene, β-caryophyllene and α-humulene. The extraction parameters also influenced the composition of the mixture of volatiles from the cones and leaves, 40°C and 20.0 MPa being optimum for the extraction of both bitter compounds and volatiles, which are thought to be important for the aroma of beer.     

Effect of agitated bed drying on the retention of phenolic compounds,anthocyanins and antioxidant activity of roselle (Hibiscus sabdariffa L.)

An agitated fluidised bed dryer was employed to dry lixiviated roselle (Hibiscus sabdariffa L.) calyxes. The effects of operational drying variables on the chemical attributes such as the retention of monomeric anthocyanins (MA), phenolic compounds, polymeric colour, antioxidant activity and drying rate were analysed. Drying curves showed only decreasing falling rate period. To determine the kinetic parameters, the drying data were fitted to a Page's model, based on the moisture content ratio vs. the drying time; the k values ranged from 1.58 × 10^?5 to 6.28 × 10^?2 s^?1. The different drying conditions showed significant differences in the chemical parameters. When processing wet feeds, as lixiviated roselle calyxes, the mechanical assisted fluidisation can be considered as an innovative concept.     

Radiation-induced enhancement of antioxidant activity in extracts of rosemary (Rosmarinus officinalis L.)

Dry rosemary leaf powder was subjected to 30 kGy of gamma ray irradiation, followed by solvent extraction with methanol, ethanol or water. The antioxidant activity of the extracts was assessed using the DPPH radical-scavenging method and the reducing power test. EC₅₀ values, using the radical-scavenging method, indicate a 22% increase in the antioxidant activity of ethanol and water extracts as a result of irradiation treatment. EC₅₀ values in the reducing power test show an increase of 45% and 28% for the ethanol and water extracts, respectively. The antioxidant activity of methanol extracts of irradiated rosemary remained the same as in the controls in both types of test. A high correlation was found between the EC₅₀ values obtained in the DPPH radical test and those from the reducing power test. Total phenolic content (Folin–Denis test) increased by 35% in the water extracts as a result of irradiation but remained the same in the methanol and ethanol extracts. The methanol extract showed the highest antioxidant activity and the highest amount of total phenolic compounds. Radiation reduced the good correlation between antioxidant activity and total phenolic content.     

Bioactive compounds,in vitro antioxidant capacity and Maillard reaction products of raw,boiled and fried garlic (Allium sativum L.)

Garlic is used in many dishes but some of its bioactive compounds are lost when exposed to heat. This study evaluated bioactive compounds, antioxidant activity and Maillard reaction products of raw (RG), boiled (BG) and fried garlic (FG). Total phenolic compounds, flavonoids, allicin and phytosterol were quantified as well as dietary fibres and mineral content. Antioxidant activities of RG, BG and FG were evaluated by oxygen radical absorbance capacity (ORAC), oxidation of β‐carotene/linoleic acid and Rancimat methods. The main results were the following: thermal processing of RG decreased both bioactive compounds and antioxidant capacity, boiling was found to be less aggressive than frying, and strong correlations were obtained between total phenolic compounds and the antioxidant assays. However, phytosterol content was higher in FG than in RG and BG and higher temperatures increased the formation of Maillard reaction products. It was concluded that RG and BG should be preferred for human consumption as they present higher antioxidant capacity.     

Bioactive compounds and in vitro antioxidant activities of peel,flesh and seed powder of kiwi fruit

The aim of this work was to assess the bioactive compounds and antioxidant potential of powder obtained by the lyophilisation of the peel, flesh and seeds of kiwi fruit. Eight typical varieties of kiwi fruit in Shaanxi, China, were selected, and the pH value, content of Vc, total polyphenols, and flavonoids of different parts of the kiwi fruit were analysed. The content of phenols was determined by HPLC. The results revealed that phenolic compounds, such as protocatechuic acid, chlorogenic acid, caffeic acid, rutin, p‐hydroxybenzoic acid and quercetin, were rich in different parts of kiwi fruit and highest in the peel. The Vc content was highest in the flesh. The antioxidant activities show the same trend as the total polyphenol content. The kiwi fruit peel and seed can be used to reduce agro‐industrial waste and are promising ingredients for use in the enrichment of products providing dietary fibre, bioactive compounds and antioxidant action.     

The effect of simulated digestion on the composition of phenolic compounds and antioxidant activities in lychee pulp of different cultivars

Simulated gastric fluid (SGF) and intestinal fluid (SIF) digestion were used to evaluate the effects of digestion on the composition of phenolic compounds and antioxidant capacities of the pulp of six lychee cultivars. Caffeic acid, ferulic acid, procyanidin B2, epicatechin, A-type procyanidin trimer, procyanidin A2, quercetin-3-rutinose-7-rhamnoside, rutin and isoquercitrin were quantified using HPLC-DAD. Lychee pulp had high concentrations of procyanidin B2 (0.30~15.53 mg g⁻¹), procyanidin A2 (0.29~0.52 mg g⁻¹) and quercetin-3-rutinose-7-rhamnoside (0.16~0.45 mg g⁻¹). SGF and SIF Digestion, which significantly decreased the concentration of procyanidin B2, epicatechin and quercetin-3-rutinose-7-rhamnoside. But observably increased the concentration of procyanidin A2. Compared with deionized water treatment (DW), the total phenolic content (TPC) and total flavonoid content (TFC) of different lychee pulps significantly increased after SGF and SIF digestion. After SGF digestion, the ferric ion reducing antioxidant power (FRAP) of lychee pulps increased while the ABTS+ free radical scavenging ability (ABTS) had a slight decline. This shows that simulated digestion improves the bioactive component and antioxidant activity of different varieties of lychee pulp.     

Optimisation of microwave‐assisted extraction of phenolic compounds from broccoli and its antioxidant activity

The effect of independent variables of microwave‐assisted extraction (MAE), extraction temperature (50–90 °C), microwave power (100–200 W), solvent concentration (methanol/water, 50–90%, v/v) and extraction time (1–27 min) on total phenolics and flavonoids contents as well as antioxidant activity of broccoli extracts was investigated. Response surface methodology was successfully applied for optimisation and the high correlation of the mathematical model indicated that a quadratic polynomial model could be used for optimisation of investigated responses. Considering the maximum amount of extracted total phenolics, total flavonoids and antioxidant activity expressed as ORAC value, the optimal conditions for all three investigated responses were obtained (temperature ?71.11 °C; microwave power ?167.03 W; solvent concentration ?75.95%; and extraction time 16.34 min), which is in agreement with optimal conditions obtained for each investigated responses. The development of simultaneously MAE methods for total phenolics, total flavonoids and antioxidant activity of broccoli extracts might simplify assessment of broccoli as valuables source of antioxidants.