Effect of processing on buckwheat phenolics and antioxidant activity

The effect of processing on functional compounds in buckwheat was investigated. Extractions of buckwheat flour were carried out before and after roasting or extrusion. Folin–Ciocalteu assays indicated that processing did not cause any change in total phenolic content in buckwheat flour. Roasted (200 °C, 10 min) dark buckwheat flour exhibited an increase in non-polar compounds as well as polar compounds whereas extrusion exhibited increase only in polar compounds. Antioxidant activity test (DPPH) showed that roasting at 200 °C for 10 min decreased the antioxidant activity slightly whereas extrusion (170 °C) did not cause any change. The results suggest that processing conditions can be optimized to retain the health promoting compounds in buckwheat products.     

Phenolic composition,antioxidant and acetylcholinesterase inhibitory activities of Sclerocarya birrea and Harpephyllum caffrum (Anacardiaceae) extracts

Total phenolic content, proanthocyanidins, gallotannins, flavonoids, and antioxidant activities of Sclerocarya birrea and Harpephyllum caffrum methanolic extracts were evaluated using in vitro assays. S. birrea young stem extract contained the highest levels of total phenolic content (14.15 ± 0.03 mg GAE/g), flavonoids (1.21 ± 0.01 mg CE/g) and gallotannins (0.24 ± 0.00 mg GAE/g). H. caffrum stem bark extract had the highest content of proanthocyanidins (1.47%). The EC₅₀ values of the extracts in the DPPH free radical scavenging assay ranged from 4.26 to 6.92 μg/ml, compared to 6.86 μg/ml for ascorbic acid. A dose-dependent linear curve was obtained for all extracts in the ferric-reducing power assay. Dichloromethane and methanol extracts exhibited dose-dependent acetylcholinesterase inhibitory activity. Similarly, all extracts exhibited high antioxidant activity comparable to butylated hydroxytoluene based on the rate of β-carotene bleaching (84.1–93.9%). The two Anacardiaceae species provide a source of natural antioxidants and acetylcholinesterase inhibitors, and may be beneficial to the health of consumers.     

Antioxidative potential of cashew phenolics in food and biological model systems as affected by roasting

The effect of different roasting conditions on antioxidant capacity of phenolics of cashew nuts and their testa was evaluated using several food and biological model systems. Total phenolic content (TPC) of cashew extracts was determined and accelerated oxidative stability of stripped corn oil in the presence of cashew extracts evaluated. In addition, the antioxidant activity of the extracts was assessed in a β-carotene-linoleate and a cooked comminuted pork model system. Inhibition of oxidation of human low density lipoprotein (LDL) cholesterol and stand breaking of supercoiled deoxyribonucleic acid (DNA) was also investigated. The TPC ranged from 5 to 791 mg gallic acid equivalents/g crude extract. In general, whole cashew nuts and testa extracts demonstrated stronger antioxidant activity than that of the cashew kernel. The inhibition percentage of LDL cholesterol oxidation, as evaluated by conjugated dines formation, of cashew kernels was higher than that of testa and was 69% at the end of 24 h incubation. Extracts of roasted cashew nut showed considerable antioxidative efficiency in model systems employed in this study, however, the effect was not significantly (P ? 0.05) different from that of their raw counterparts, except for the accelerated oxidative stability assay. The results suggest that whole cashew nut and testa extracts could be used as a potential source of natural antioxidants in certain food applications and for disease risk reduction.     

Evaluation of the antioxidant activity of three microalgal species for use as dietary supplements and in the preservation of foods

The antioxidant activity of the microalgal ethanolic extracts of Porphyridium cruentum, Phaeodactylum tricornutum and Chlorella vulgaris was determined by means of the β-carotene–linoleate model system. The results show that the activity of C. vulgaris extract was higher than those obtained for the other microalgal extracts tested and for the synthetics BHA (butylated hydroxyanisole), and BHT (butylated hydroxytoluene). In addition, the major constituents present in the ethanolic extracts of the three microalgae species were analyzed by means of GC and GC–mass spectrometry. The results showed that the tested microalgae may be an important source of natural antioxidants, as an alternative to higher plants or the production by chemical synthesis.     

Screening of the antioxidant potentials of six Salvia species from Turkey

This study was designed to examine the in vitro antioxidant activities of the methanol extracts of six Salvia species [Salvia caespitosa Montbret & Aucher ex Bentham (ENDEMIC), Salvia hypargeia Fisch. & Mey. (ENDEMIC), Salvia euphratica subsp. euphratica Montbret & Aucher ex Bentham (ENDEMIC), Salvia sclarea L., Salvia candidissima subsp. candidissima Montbret & Aucher ex Bentham and Salvia aethiopis L.] from Turkey. The extracts were screened for their possible antioxidant activities by two complementary test systems, namely DPPH free radical-scavenging and β-carotene/linoleic acid systems. Non-polar subfractions of the methanol extracts of Salvia species studied did not show any antioxidant activity in both test systems. In the first case, the most active plant was S. euphratica subsp. euphratica, an endemic species, with an IC₅₀ value of 20.7 ± 1.22 μg/ml, followed by S. sclarea (IC₅₀ = 23.4 ± 0.97 μg/ml) among the polar subfractions. In the β-carotene/linoleic acid test system, polar extract of S. hypargeia was superior to the polar extracts of other Salvia species studied (69.2% ± 1.90%). This activity was followed by S. sclarea with 63.5% ± 4.24% inhibition rate. The inhibition rate of the synthetic antioxidant, buthylated hydroxytoluene (BHT), was also determined to be 96%. Since the polar extracts of Salvia species dealt with here exhibited excellent antioxidant activities when compared to BHT, it seems possible to keep perishable fat-containing food longer by direct addition of an extract of sage.     

Effect of muscle and post-mortem rate of pH and temperature fall on antioxidant enzyme activities in beef

The aim of this study was to investigate the effect of muscle, inner and outer Musculus biceps femoris (IBF and OBF respectively) and Musculus longissimus dorsi (LD), on the post-mortem rate of pH and temperature fall, and the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) during simulated retail display. At day 0 of display (2 days post-mortem), the CAT and GSH-Px activities were lower in IBF than in OBF and LD (P < 0.001), and the SOD activity was lower in OBF compared to IBF and LD (P < 0.001). At day 10 of display, SOD and CAT activities had decreased in all three muscles compared to day 0 (P < 0.001), whereas the GSH-Px activity did increase with time of display. Across muscles, there were significant relationships between temperature fall, colour, lipid and colour stability and antioxidant enzyme activities.     

The antioxidant activity of selected cruciferous vegetables subjected to aquathermal processing

Kale (Brassica oleracea var. Acephala), broccoli (Brassica oleracea var. botrytis italica), Brussels sprouts (Brassica oleracea L. var. gemmifera) and green and white cauliflower (Brassica oleracea var. botrytis) were used to determine their contents of antioxidising agents: vitamin C, carotenoids and polyphenols. The examined vegetables were found to contain between 40.6 and 107 mg/100 g FW of vitamin C, from 0.04 to 2.7 mg/100 g FW of carotenoids, and from 144 to 773 mg/100 g FW of polyphenols. Cauliflower was found to contain the smallest amount of these compounds and kale the largest. The antioxidant activity of the vegetables was determined on the basis of their ability to extinguish the ABTS free radical. The aquathermal processes to which the vegetables were subsequently subjected reduced their antioxidant activity, mainly due to escape of vitamin C and polyphenols into the water environment. These losses were largest in the case of leafy or highly fragmented vegetables.     

Isolation and evaluation of the radical-scavenging activity of the antioxidants in the leaves of an edible plant, Mallotus japonicus

The antioxidative properties of a hot water extract of the leaves of Mallotus japonicus were evaluated. The extract had a high phenolic content and strong antioxidative activity, compared with green tea, rooibos tea, and red wine. Six phenolic compounds were isolated as antioxidative components by HPLC. They were identified as mallotinic acid, mallotusinic acid, corilagin, geraniin, rutin, and ellagic acid. These antioxidative compounds were subjected to DPPH radical-scavenging, superoxide radical-scavenging, and hydroxyl radical-scavenging assays, and compared with other antioxidative compounds. Four of the compounds, mallotinic acid, mallotusinic acid, corilagin and geraniin, exhibited much stronger antioxidative activity than gallic acid, rutin, ellagic acid, quercetin, and chlorogenic acid, and were as active as epigallocatechin gallate (EGCG), a strong antioxidant in green tea. Mallotus japonicus leaves are an excellent source of strong natural antioxidative materials.     

Antioxidant activity of Knipholone anthrone

Knipholone anthrone (KA), isolated from an Ethiopian medicinal plant, Kniphofia foliosa, Hochst (Asphodelaceae) has been shown to display a potent antiprotozoal activity and a relatively little cytotoxic effect on mammalin cells. In the present study, the antioxidant potential of KA was assessed using a variety of in vitro assay models. KA displayed a concentration-dependant scavenging effect against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. The IC₅₀ values obtained for KA and the positive control (−)-epicatechin (EC) in the DPPH assay were 22 ± 1.5 and 8.7 ± 0.9 μM (mean ± SEM; n = 3 separate experiments), respectively. KA displayed a better activity than EC in scavenging superoxide anions and preventing deoxyribose degradation by hydroxyl radicals. KA appeared to form a complex with Fe²⁺, displayed a concentration-dependant reducing power, and also protected (at concentrations of 4.4 μM and above) isolated DNA from damage induced by Fenton reaction-generated hydroxyl radicals.     

楮头红的抗氧化活性研究

分别用纯水、60%乙醇和无水乙醇三种溶剂对楮头红进行提取,检测了三种提取物中的总黄酮含量及其抗氧化活性。结果表明纯水、60%乙醇和无水乙醇三种溶剂提取物中的总黄酮含量分别为0.081、0.311、0.217mg/mL,三种提取物都具有较好的抗氧化能力,其中以黄酮含量最高的60%乙醇提取物的总抗氧化、抑制羟基自由基和超氧阴离子自由基活力最强,三种提取成分的抗氧化活性及对自由基的抑制能力在1～7g/L的浓度范围内呈量效关系,且与总还原力测定结果呈正对应关系。      

加工方式对全谷物抗氧化活性影响研究进展

全谷物中富含多酚、花青素、植酸、γ-谷维素、烷基间苯二酚等多种生理活性物质,其抗氧化能力备受关注。全谷物品种多样,加工方式不尽相同,不同的加工方式对全谷物抗氧化活性的影响也不同。本文就近年来国内外有关不同加工方式对全谷物中抗氧化活性影响的研究进行综述,为全谷物加工的深入研究及合理消费提供参考。      

挤压加工对小米多酚及抗氧化活性的影响研究

研究了挤压加工温度、螺杆转数、物料含水量变化对小米中多酚类物质含量、存在形式和抗氧化功能性质的影响,并分析了总酚、黄酮含量与抗氧化能力之间的相关性以及挤压前后的变化。结果表明,挤压温度、螺杆转数、物料含水量变化对小米中多酚类物质含量、存在形式以及抗氧化功能存在显著性影响,其中游离黄酮含量受温度影响较小,螺杆转数的变化对结合酚含量的影响不显著;小米中总酚、黄酮含量与抗氧化能力之间具有显著的相关性(p<0.01)。总体而言,挤压加工有利于保留小米中的多酚类物质,是一种有效的加工方式。      

辣椒素对茶油的抗氧化与清除超氧阴离子自由基活性研究

研究了辣椒素对高温强化处理的油茶籽油的抗氧化性能及对O-2·的清除能力.添加抗氧化剂的油茶籽油在（60±2）℃恒温下强化处理后,用碘量法来测定过氧化值（POV）评判抗氧化性能.通过改良邻苯三酚自氧化法测定辣椒素清除自由基能力.样品经10d的60℃加热处理后,未添加抗氧化剂的POV值达到32.16 mmol/kg,添加质量分数0.10％辣椒素的POV值为17.03 mmol/kg.在相同浓度下,辣椒素的对油茶籽油的抗氧化效果介于同BHT与VE之间.当辣椒素的物质的量浓度为0.006 0 mmol/mL时,对O-2·自由基的清除率达到80.75％,此时维生素E为81.12％而BHT为77.15％.辣椒素具有较强的清除O-2·自由基的能力.     

Effect of steam treatment on soluble phenolic content and antioxidant activity of the Chaga mushroom (Inonotus obliquus)

The effect of steam treatment on free phenolic acids in Chaga mushrooms (Inonotus obliquus) was investigated. Untreated and steam-treated (120 °C, 3 h) samples of I. obliquus were extracted with organic solvents and free phenolic acid-containing fractions were isolated. Free phenolic acids were determined by LC/PDA (liquid chromatography/photodiode array), ESI LC/MS (electrospray ionisation liquid chromatography/mass spectrometry), and GC/MS (gas chromatography/mass spectrometry). After the steam treatment, the soluble phenolic content determined by modified Folin–Ciocalteu method was increased and antioxidant activity was enhanced, as confirmed by a DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity assay. The amounts of vanillic acid, protocatechuic acid, syringic acid, and 2,5-dihydroxyterephthalic acid were increased significantly as the result of the steam treatment, suggesting that the liberation of low molecular weight free phenolics was enhanced by the steaming process. Consequently, the radical scavenging activity was also significantly enhanced by free phenolics produced using this method.     

Acetyl cholinesterase inhibitory,antioxidant and cytotoxic activity of three dietary medicinal plants

Three medicinal plants namely Trigonellafoenum-graecum, Glycinemax and Sesamumindicum were evaluated for invitro acetyl cholinesterase inhibitory activity. These plants have been selected based on their use as memory enhancing as well as their nutrient value. These plants have been consumed as nutritious food and are believed to play an important role in health-promoting. The results were expressed as IC₅₀ and the percent of inhibition of acetylcholinesterase (AchE) activity. Diphenyl picrylhydrazil (DPPH) assay and beta-carotene bleaching method were used for antioxidant studies and brine shrimp lethality test (BSL) was used for cytotoxicity assay. The obtained results showed that the G.max extract has inhibited AChE activity strongly in a dose-dependent manner (IC₅₀ = 4.69 mg/mL). The most inhibition of AChE activity was due to G.max extract (68.4%). This extract was also able to scavenge DPPH radical with IC₅₀ = 454.3 μg/mL. The G.max extract has shown the least cytotoxicity (IC₅₀ value of 1112.6 μg/mL) in BSL assay. T.foenum-graecum and S.indicum also exhibited noticeable AchE inhibition.