Antioxidant activity of lettuce extract (Lactuca sativa) and synergism with added phenolic antioxidants

Combined antioxidative effects of lettuce extract and α-tocopherol, quercetin or ascorbic acid (AA) were investigated for peroxidation of l-α–phosphatidylcholine liposomes with oxidation initiated by lipophilic or by hydrophilic azo-initiators. Lettuce extract had a clear antioxidative effect as evidenced by a lag phase for formation of conjugated dienes, and α-tocopherol and especially quercetin acted synergistically in prolongation of the lag phase both following initiation in the lipid phase and in the aqueous phase. Combination of AA with lettuce extract showed in contrast a lag phase that was similar to that observed for AA alone. Storage of lettuce extract for 24 h at refrigerator or room temperatures resulted in a decreasing lag phase with increasing storage time for both storage temperatures, an effect not counteracted by addition of quercetin or α-tocopherol. Heating of lettuce extract for 10 min at 80 °C did not affect the lag phase and heating of lettuce extract resulted in an increasing synergism for added quercetin and α-tocopherol indicating that thermal inhibition of polyphenoloxidase (PPO) increases antioxidant potential and interaction.     

The effect of Pulsed Electric Field as a pre-treatment step in Ultrasound Assisted Extraction of phenolic compounds from fresh rosemary and thyme by-products

Emerging extraction techniques, including pulsed electric field (PEF) and ultrasound (US), are attracting considerable interest in the recovery of bioactives. Though, limited work has focused on PEF application as pre-treatment for US assisted extraction to enhance the release of phenolics from herbs. Hence, the present study investigated the use of an optimized PEF pre-treatment to enhance the recovery of phenolics from fresh rosemary and thyme by-products in a subsequent US assisted extraction step. Total phenolic content (TPC), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) were assessed as an index of extraction efficacy. Qualitative and quantitative analyses were performed through liquid chromatography-mass spectrometry analyses to evaluate the influence of the methods on individual phenolic compounds and the formation of potential derivatives. The results indicated that in a number of cases PEF pre-treatment enhanced (p < 0.05) the recovery of phenolic compounds and antioxidant capacity compared to US individually.     

Incorporation of by-products of rosemary and thyme in the diet of ewes: effect on the fatty acid profile of lamb

The present study measured changes in fatty acid composition of lamb meat from sheep fed plant by-products (rosemary- and thyme-distilled leaves) during pregnancy and lactation. For that, thirty-six pregnant Segureña ewes were employed per experiment (2 experiments in total: A with distilled rosemary leaf—DRL—and B with distilled thyme leaf—DTL) and were randomly assigned into three homogeneous groups. Sheep in the control group (C _R: control DRL experiment; C _T: control DTL experiment) were given a basal diet (BD). The experimental diets of the other two groups were modified by substituting 10 and 20 % of the BD by DRL (R ₁, R ₂) in experiment A and with 10 and 20 % of the BD by DTL (T ₁, T ₂) in experiment B. Moisture, fat, protein content, fatty acid profile, and pH of the fresh lamb meat were analysed. Pearson’s correlations were made between fatty acid profile and rancid odour (RO), TBARS of fresh lamb meat at day 21 of storage. The incorporation of thyme- and rosemary-distilled leaves in the diet of pregnant and lactating ewes caused a significant increase (P < 0.05) in the levels of polyunsaturated fatty acid (PUFA), unsaturated fatty acids (UFA), and a significant decrease in the percentage of saturated fatty acid (SFA) saturation index (S/P), atherogenic (AI), and thrombogenic (TI) indices in lamb meat. In general, this effect was more pronounced with a diet of 20 % DRL. High positive correlations were found between rancid odour and SFA (except C _18:0 and C _20:0) and monounsaturated fat (MUFA); on the contrary, a negative correlation was shown between PUFA content and RO, TBARS. Thus, adding by-products of rosemary and thyme to the diet of ewes significantly improved fatty acid profile of lamb meat.     

Synergistic antioxidant and antibacterial activity of rosemary plus butylated derivatives

Antioxidant and antibacterial activity of a methanol rosemary extract (RE) containing 30% carnosic acid (CA), 16% carnosol (COH) and 5% rosmarinic acid (RA) was studied in vitro alone and in combination with the antioxidant food additives butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). The antioxidant efficiency of the extract, CA, and RA, was determined by a kinetic analysis of the 2,2-diphenyl-2-picrylhydrazyl hydrate radical (DPPH·) scavenging activity. RE showed two different rate slopes in the reduction of DPPH· vs. time curve, which correlated with the distinct behaviours of RA and CA; pure RA reached the plateau more rapidly than CA. A synergistic antioxidant effect between RE and BHT was demonstrated by isobolographic analysis and a synergistic interaction of RE with BHA to inhibit Escherichia coli and Staphylococcus aureus growth was observed. Therefore, rosemary not only enhances the antioxidant efficiency of BHA and BHT, but also the antibacterial effect of BHA; allowing a decrease from 4.4 to17 folds in the amounts of the synthetic compounds used.     

Antioxidant activity and dietary fibre in durum wheat bran by-products

Milling of wheat generates by-products, which can be used to improve the technological performance and/or to integrate foods with healthy compounds. The aim of this paper was to select fractions of durum wheat bran having different functional and nutritional characteristics. Wheat bran by-products were obtained by an industrial milling process. Beside the single fractions, two commercial products Bran & Brain 50 and 70, obtained by blending some of the durum wheat fractions were also studied. All samples were investigated for water holding capacity, soluble and insoluble dietary fibre content and for their antioxidant activity. The soluble fibre content of the durum wheat by-product ranged between 0.9% and 4.1%; while that of insoluble fibre between 21% and 64%. B&B 70 has a TDF content of 61%, while B&B 50 has 42%. The water holding capacity of each fraction is strictly related to the amount of insoluble fibre and to the granulometry of the by-products. Cooking-extrusion process does not affect the amount of soluble fibre; by contrast, a significant increase of the insoluble fibre was detected. The antioxidant activity is higher for the internal bran fraction and it increases in fractions having reduced granulometry. The antioxidant activity of some durum wheat by-product fractions is comparable to that of widespread fruits and fresh vegetables, likely due to the presence of fibre-bound phenol compounds. The high fibre content and antioxidant activity of durum wheat bran by-products can be of particular interest for their use in cereal-based products.     

迷迭香天然抗氧化剂的应用研究

以核桃油为实验基油,研究了迷迭香天然抗氧化剂的应用。通过抗氧化实验、储藏实验和烹调实验,比较了迷迭香抗氧化剂和TBHQ的抗氧化效果。结果表明,迷迭香抗氧化剂具有较佳的抗氧化效果,在核桃油中随着迷迭香抗氧化剂添加量的增大抗氧化效果依次增强,0.02%迷迭香抗氧化剂与0.02% TBHQ有相似的抗氧化能力,可对核桃油酸败和反式脂肪酸形成起到延缓作用。     

Antioxidant activity of spice extracts in a liposome system and in cooked pork patties and the possible mode of action

Three experiments were conducted to assess the antioxidant efficacy of spice extracts in cooked meat. In experiment 1, antioxidant activity of 13 common spice extracts was screened in a liposome system. Six of the extracts (clove, rosemary, cassia bark, liquorice, nutmeg, and round cardamom), identified to have the greatest total phenolic contents, were strongly inhibitory of TBARS formation. In experiment 2, 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, ferric-reducing power, and metal chelation of these six spice extracts were evaluated. Clove exhibited the greatest reducing power, and all had strong DPPH scavenging activity. In experiment 3, clove, rosemary, and cassia bark extracts were further tested for in situ antioxidant efficacy. Cooked pork patties containing these spice extracts had markedly reduced TBARS formation and off-flavour scores but a more stable red colour, during storage. The results demonstrated strong potential of spice extracts as natural antioxidants in cooked pork products.     

叶黄素-花青素脂质体的制备及其体外抗氧化活性研究

采用分段乳化结合超声薄膜法制备氧化性更强、更稳定的叶黄素–花青素脂质体。结果表明:叶黄素的乳化最佳HLB值为10.9,选用的复合表面活性剂双乙酰酒石酸单甘油酯和辛奎酸甘油酯为42∶58。叶黄素与花青素在60℃,p H 9,膜材用量为7.9%的条件下,超声乳化47 min,包封率可达38%;体外抗氧化实验(ABTS自由基、DPPH自由基和OH·清除实验)表明叶黄素和花青素具有协同抗氧化作用。     

Influences of added surfactants on the water solubility and antibacterial activity of rosemary extract

Food Science and Biotechnology - Rosemary extract (RE) has significant antioxidant and antibacterial properties; however, the application of RE to areas with an aqueous solution is limited due to...     

Antioxidant and antilisterial activity of olive oil,cocoa and rosemary extract polyphenols

Antibacterial and antioxidant activity of polyphenols from olive oil, cocoa, and rosemary extract was tested. Antimicrobial activity against Listeria strains was assessed using broth dilution and time-kill curve methods. The 2,2-diphenyl-2-picrylhydracyl hydrate (DPPH) radical scavenging method, Folin–Ciocalteu method, and high performance liquid chromatography (HPLC) were used for phenolics identification and determination of antioxidants level. Antibacterial and antioxidant activity of main pure phenolic compounds, such as hydroxytyrosol in olive oil, epicatechin in cocoa and carnosic acid in rosemary was each compared with their extracts.     

迷迭香的抗氧化活性及对藻油氧化稳定性影响的研究

在对迷迭香的DPPH自由基清除能力和还原力与合成抗氧化剂BHT对比研究的基础上,采用Schaal烘箱法,以POV(过氧化值)、TBA(丙二醛值)和DHA含量为氧化稳定性指标,研究了迷迭香在藻油中的抗氧化作用,并探究了增效剂对迷迭香的协同增效作用。结果表明:DPPH自由基清除能力和还原力依次为迷迭香粉BHT迷迭香精油;迷迭香粉和迷迭香精油对藻油都具有较强的保护作用,抗氧化能力依次为0.02%迷迭香粉0.02%BHT0.02%迷迭香精油0.02%VE;0.02%迷迭香粉与0.01%VC棕榈酸酯在藻油中有很强的增效作用。     

Changes of liposome and antioxidant activity in immature rice during seed development

For the past several decades, only a few studies were conducted on the change in immature rice liposomes during seed development. To evaluate and compare the lipid material of different degrees of developing rice grains, this paper focused on fresh rice seeds from only one most popular species of Dasan divided into five growth periods. The lipid components of fresh rice, especially γ-oryzanol and fatty acids equipped with extremely beneficial phytonutrients, were investigated. The results illustrated that the level of extracted liposome increased gradually along with the development of rice and in the third stage of development, the level of liposome achieved maximum. And then, instead of increasing, it was decreased at later stages of development. Moreover, the antioxidant activity of fresh edible rice (FER) was also evaluated by DPPH and ABTS assay. It was shown that FER has the higher antioxidant activity than the ripened rice seed on lipids, which will improve FER using on the functional foods and help provide certainly theoretical basis in food processing industry.     

In vitro antioxidant activity and phenolic profiles of tropical fruit by-products

Peel and seeds of red-skinned passion fruit, mango, longan, rambutan, white-flesh and red-flesh dragon fruit were screened for their in vitro antioxidant activity, and determination of a detailed profile of phenolic compounds. Rambutan peel and mango seed extracts exhibited the highest total phenolic content and antioxidant activities (DPPH, ABTS and FRAP values). By using UPLC-QTOF-MS/MS analysis, the profiles of soluble and bound phenolics in the fruit by-products were obtained. Ellagic acid, geraniin, quercetin hexoside, gallic and galloyshikimic acid were predominant in rambutan peel, whereas, mangiferin, ellagic acid and galloy(di)glucoside were the major phenolic compounds in mango seed. Main phenolic compounds in longan peel were ellagic acid, galloyldiglucoside, and gallic acid, while in dragon fruit peel this was isorhamnetin glycoside, isorhamnetin glucorhamoside. Meanwhile, rutin and quercetin hexoside were predominant in passion fruit peel. These findings contribute significantly to the database of phenolic profiles of by-products of tropical fruits.     

蜂胶脂质体制备工艺优化及抗氧化活性分析

[目的]提高蜂胶的水溶性及其生物利用率,扩大蜂胶在食品行业的应用范围。[方法]以胆固醇、大豆卵磷脂为壁材,蜂胶为芯材,利用薄膜分散法制备蜂胶脂质体。以包封率为检验指标,通过单因素试验及响应面分析法优化得到蜂胶脂质体的最佳制备工艺,并对其抗氧化活性进行分析评价。[结果]蜂胶脂质体的最优制备工艺为大豆卵磷脂用量2.5 g/100 mL,大豆卵磷脂与胆固醇质量比10.3∶1,蜂胶与胆固醇质量比3.8∶1,蜂胶脂质体的包封率可达93.09%。该法所得蜂胶脂质体在体积分数为50 μL/mL时,对DPPH自由基、ABTS⁺自由基、羟自由基清除率分别达88.58%,61.13%,86.02%。[结论]试验制备的蜂胶脂质体包封率高,水溶性好,且具有良好的抗氧化能力。