Quantification of Almond Skin Polyphenols by Liquid Chromatography-Mass Spectrometry

ABSTRACT:  Reverse phase HPLC coupled to negative mode electrospray ionization (ESI) mass spectrometry (MS) was used to quantify 16 flavonoids and 2 phenolic acids from almond skin extracts. Calibration curves of standard compounds were run daily and daidzein was used as an internal standard. The inter-day relative standard deviation (RSD) of standard curve slopes ranged from 13% to 25% of the mean. On column (OC) limits of detection (LOD) for polyphenols ranged from 0.013 to 1.4 pmol, and flavonoid glycosides had a 7-fold greater sensitivity than aglycones. Limits of quantification were 0.043 to 2.7 pmol OC, with a mean of 0.58 pmol flavonoid OC. Mean inter-day RSD of polyphenols in almond skin extract was 6.8% with a range of 4% to 11%, and intra-day RSD was 2.4%. Liquid nitrogen (LN₂) or hot water (HW) blanching was used to facilitate removal of the almond skins prior to extraction using assisted solvent extraction (ASE) or steeping with acidified aqueous methanol. Recovery of polyphenols was greatest in HW blanched almond extracts with a mean value of 2.1 mg/g skin. ASE and steeping extracted equivalent polyphenols, although ASE of LN₂ blanched skins yielded 52% more aglycones and 23% less flavonoid glycosides. However, the extraction methods did not alter flavonoid profile of HW blanched almond skins. The recovery of polyphenolic components that were spiked into almond skins before the steeping extraction was 97% on a mass basis. This LC-MS method presents a reliable means of quantifying almond polyphenols.     

改进杏仁饼产品质量的几个措施

本文分析了传统杏仁饼生产中存在的产品加工工艺不够科学、产品微生物指标不易控制和产品营养成分不太合理这三方面的问题,在保留了传统工艺的精华上,介绍了解决这些问题的相关技术和方法,对相关产品的质量改进及新产品开发具有一定的参考价值.     

甜杏仁油品质及杏仁粕成分的分析

主要针对酶解法所得的甜杏仁毛油和精制油,对其质量指标进行了测定,并对甜杏仁毛油和精制油中的脂肪酸成分进行了分析,同时对酶解后所得的杏仁粕主要成分和氨基酸组成及含量进行了测定,得出品质较好的甜杏仁油和较优质的甜杏仁水解蛋白粕。     

茶多酚对冷藏带鱼品质及抗氧化效果的影响

以带鱼为研究对象,采用不同质量浓度（0、0.10、0.15、0.20、0.25、0.30、0.40 g/100 mL）茶多酚将带鱼片浸渍30 min后于4 ℃冷藏,每隔3 d取样测定菌落总数以及酸价、过氧化值（peroxide value,POV）、硫代巴比妥酸（thiobarbituric acid,TBA）值、三甲胺（trimethylamine,TMA）值、挥发性盐基氮（total volatile basicnitrogen,TVB-N）值等理化指标和感官评分、色差、质构分析,研究不同质量浓度茶多酚对带鱼的抗氧化效果。结果表明：带鱼的菌落总数、酸价、POV、TBA值、TMA值、TVB-N值以及颜色饱和度值都随贮藏时间延长而呈现增加的趋势,感官评分及质构测得的各项参数一直降低。经茶多酚处理过的实验组各项指标相对空白对照组变化较为缓慢,且当茶多酚质量浓度为0.20 g/100 mL时,保鲜效果最佳,能够抑制带鱼低温冷藏过程中的细菌生长,并有效减缓蛋白质、脂肪等氧化分解,不仅使带鱼货架期延长了3 d,而且使带鱼的色泽与营养在更长的保存时间内保持不变。     

食品中多酚类化合物的测定方法及其研究进展

食品中多酚类化合物主要来源于植物源性食品,人们在研究和开发食品时就不可避免的要对多酚类化合物进行分析与测定。现在应用于食品多酚类化合物的测定方法主要有高锰酸钾滴定法、光谱分析测定法、色谱分析测定法等,这是对食品中多酚类化合物分析的必要手段之一。文中主要对以上种测定方法进行了介绍和比较,为以后的研究工作者提供参考。     

杏仁皮单宁提取工艺优化及其DPPH自由基清除活性

以杏仁皮单宁得率为指标,考察了料液比、提取时间、提取温度、乙醇体积分数四个因素对杏仁皮单宁提取效果的影响。在单因素基础上,采用响应面法优化杏仁皮单宁提取工艺,并对最佳工艺下所得杏仁皮单宁的DPPH自由基清除活性进行测试。结果表明:所建立的杏仁皮单宁提取工艺模型极显著,其最优实验条件是料液比1:22 (g/mL)、提取时间89 min、提取温度70 ℃、乙醇体积分数50%,在此条件下杏仁皮单宁得率为2.13%。杏仁皮单宁浓度为250 μg/mL时对DPPH自由基的清除率达到98.65%,表明杏仁皮单宁具有较强的抗氧化活性。     

Polyphenols and antioxidant properties of almond skins: influence of industrial processing

ABSTRACT:  Almond ( Prunus dulcis [Mill.] D.A. Webb) skins have been proposed as a source of bioactive polyphenols. In this article, the phenolic composition and antioxidant activity of almond skins obtained from different processes (blanching [freeze-drying], blanching + drying, and roasting) were studied. A total of 31 phenolic compounds corresponding to flavan-3-ols (33% to 56% of the total of phenolic compounds identified), flavonol glycosides (9% to 36%), hydroxybenzoic acids and aldehydes (6% to 26%), flavonol aglycones (1.7% to 18%), flavanone glycosides (3% to 7.7%), flavanone aglycones (0.69% to 5.4%), hydroxycinnamic acids (0.65% to 2.6%), and dihydroflavonol aglycones (0% to 2.8%) were determined in the skins from 3 different varieties of almonds. The total contents of phenolic compounds identified were significantly ( P < 0.05) higher (around 2-fold) in the roasted samples than in the blanched almonds (freeze-dried). Industrial drying (oven drying) of the blanched almond skins produced an increase (< 2-fold) in the contents of phenolic compounds, although the results were only statistically significant ( P < 0.05) for some samples. The antioxidant activity (ORAC values) was higher for the roasted samples (0.803 to 1.08 mmol Trolox/g), followed by the samples subjected to blanching + drying (0.398 to 0.575 mmol Trolox/g) and then the blanched (freeze-dried) samples (0.331 to 0.451 mmol Trolox/g). Roasting is the most suitable type of industrial processing of almonds to obtain almond skin extracts with the greatest antioxidant capacity.     

Plant Polyphenols as Antioxidant and Antibacterial Agents for Shelf‐Life Extension of Meat and Meat Products: Classification,Structures, Sources,and Action Mechanisms

Oxidative processes and meat spoilage bacteria are major contributors to decreasing the shelf‐life of meat and meat products. Oxidative processes occur during processing, storage, and light exposure, lowering the nutritional and sensory value and acceptability of meat and generating toxic compounds for humans. Polyphenols inhibit oxidative processes in 3 ways: as reactive species scavengers, lipoxygenase inhibitors, and reducing agents for metmyoglobin. Thus, polyphenols are candidate antioxidants for meat and meat products. The cross‐contamination of meat with spoilage and pathogenic microorganisms can occur in production lines and result in economic losses. The ability of polyphenols to interact with bacterial cell wall components and the bacterial cell membrane can prevent and control biofilm formation, as well as inhibit microbial enzymes, interfere in protein regulation, and deprive bacterial cell enzymes of substrates and metal ions. Thus, polyphenols are candidate antimicrobial agents for use with meat and meat products. Commercially available polyphenols can decrease primary and secondary lipid peroxidation levels, inhibit lipoxygenase activity, improve meat color stability, minimize the degradation of salt‐soluble myofibrillar protein and sulfhydryl groups, and retard bacterial growth. Further studies are now needed to clarify the synergistic/antagonistic action of various polyphenols, and to identify the best polyphenol classes, concentrations, and conditions of use.     

Tannins and Human Health: A Review

Tannins (commonly referred to as tannic acid) are water-soluble polyphenols that are present in many plant foods. They have been reported to be responsible for decreases in feed intake, growth rate, feed efficiency, net metabolizable energy, and protein digestibility in experimental animals. Therefore, foods rich in tannins are considered to be of low nutritional value. However, recent findings indicate that the major effect of tannins was not due to their inhibition on food consumption or digestion but rather the decreased efficiency in converting the absorbed nutrients to new body substances. Incidences of certain cancers, such as esophageal cancer, have been reported to be related to consumption of tannins-rich foods such as betel nuts and herbal teas, suggesting that tannins might be carcinogenic. However, other reports indicated that the carcinogenic acitivity of tannins might be related to components associated with tannins rather than tannins themselves. Interestingly, many reports indicated negative association between tea consumption and incidences of cancers. Tea polyphenols and many tannin components were suggested to be anticarcinogenic. Many tannin molecules have also been shown to reduce the mutagenic activity of a number of mutagens. Many carcinogens and/or mutagens produce oxygen-free radicals for interaction with cellular macromolecules. The anticarcinogenic and antimutagenic potentials of tannins may be related to their antioxidative property, which is important in protecting cellular oxidative damage, including lipid peroxidaton. The generation of superoxide radicals was reported to be inhibited by tannins and related compounds. The antimicrobial activities of tannins are well documented. The growth of many fungi, yeasts, bacteria, and viruses was inhibited by tannins. We have also found that tannic acid and propyl gallate, but not gallic acid, were inhibitory to foodborne bacteria, aquatic bacteria, and off-flavor-producing microorganisms. Their antimicrobial properties seemed to be associated with the hydrolysis of ester linkage between gallic acid and polyols hydrolyzed after ripening of many edible fruits. Tannins in these fruits thus serve as a natural defense mechanism against microbial infections. The antimicrobial property of tannic acid can also be used in food processing to increase the shelf-life of certain foods, such as catfish fillets. Tannins have also been reported to exert other physiological effects, such as to accelerate blood clotting, reduce blood pressure, decrease the serum lipid level, produce liver necrosis, and modulate immunoresponses. The dosage and kind of tannins are critical to these effects. The aim of this review is to summarize and analyze the vast and sometimes conflicting literature on tannins and to provide as accurately as possible the needed information for assessment of the overall effects of tannins on human health.     

Diet and Health: Apple Polyphenols as Antioxidants

Abstract

Although primarily used at low moisture levels, extrusion cooking with twin‐screw extruders also applies to food mixes with 40–80% moisture. Such levels reduce or prevent viscous dissipation of energy and product expansion, but facilitate operations such as fat emulsification, sterilization, protein gelation, restructuring and shaping of comminuted meat or fish, and microcoagulation and/or fibrillation of specific protein constituents. Fibrous gelled structures are obtained from (a) defatted soy flours or concentrates; (b) wheat gluten; and (c) mixes containing 70–80% surimi plus 30–20% soy concentrate or gluten, by extrusion cooking at 50–70% moisture, at barrel temperatures above 140°C, using long cooling dies. The continuous gelled bands are highly resistant to stretching in the longitudinal direction. They display a multilayer and partly fibrous structure. An extruded crab analog with a finely fibrous texture, made from Alaska pollack surimi plus egg white and 1% starch, is already commercialized in Japan. Three main phenomena are involved in the formation of these structures: (a) protein plastification (“melting”) within the extruder, which requires a barrel temperature of 140–180°C (at 60–70% water), a residence time close to 150 s, and high shear forces; (b) stability of extrusion conditions, without surging (often difficult to achieve); (c) presence of a long cooling die, exerting essential functions: upstream pressure generation, enabling high temperature, channel filling, and extrudate continuity; progressive reduction of the mechanical and thermal energy of the food mix, permitting proper shaping, while avoiding product expansion; alignment of dispersed protein particules along the shear gradient in the narrow die channel, leading to layer and fiber formation. The restructuring of mechanically deboned meat can be achieved through extrusion cooking (40–50% water) in the presence of high levels of binders such as starch or cereal flours. Such experiments were carried out without a cooling die and without fiber formation. Emulsified and gelled cheese analogs, with textures ranging from hard blocks to soft spreads, can be obtained with a single extruder pass, starting from cheddar or from caseinate plus various fats. The extents of fat emulsification and of casein “reassociation,” and the melting ability, depend on composition and process parameters. The extrusion of fibrous products similar to mozzarella‐based string cheese is attempted. Fat substitutes with a smooth and spread‐like consistency are also prepared by thermomechanical processing of caseinate and/or whey proteins in a twin‐screw extruder at an acid or neutral pH. Shear forces and several biochemical mechanisms concur to induce the “microcoagulation” of β‐lactoglobulin as small‐size particles (<20 μm). Other potential moist extrusion processes include the coagulation of skim milk powder into an insoluble acid casein coprecipitate, the encapsulation of small molecules into protein gels, and the formation of edible thin protein films.     

玉米多酚提取工艺及其生物活性研究进展

玉米多酚是从玉米生产或加工的副产品中提取的一种生物活性成分,具有抗氧化和抑菌活性,在功能食品、保健品以及医药等领域具有潜在的应用价值,以近年来国内发表的文献为依据,总结概述了玉米多酚的提取工艺及其生物活性研究进展,并指出存在问题,展望其研究方向,为玉米多酚的深入研究及开发利用提供了参考依据.     

不同工艺制备杏仁油品质比较及相关性分析

通过对市售、溶剂提取、低温压榨3种不同杏仁油的感官品质(色泽),理化营养品质(水分及挥发物含量、脂肪酸含量、VE异构体含量、植物甾醇各组分含量)及加工品质(诱导时间、过氧化值、酸价、得率、脂肪酸比例模式)测定以及相关性分析,结果表明:3种杏仁油中,低温压榨油的加工品质最好,其诱导时间(11.68 h)最长,过氧化值(0.08 mmol/kg)和酸价(0.87 mgKOH/g)最低,且O/L值最高为2.68;此外,低温压榨油的营养品质也相对较好,其油酸质量分数(67.94%)及UFA质量分数(94.29%)皆最高。各品质指标之间相关性分析的结果表明:色泽与诱导时间呈极显著正相关;油酸与亚油酸呈极显著负相关(r=-0.914);油酸、亚油酸、MUFA、PUFA、O/L与诱导时间的相关关系均达到极显著水平。     

Diet and Health: Apple Polyphenols as Antioxidants

The traditional American rhyme says, “an apple a day keeps the doctor away.” What has made apples exceptional and appreciated for a million years? Besides their content of pectin, vitamins and minerals, they are considered to be a good source of antioxidants that scavenge and neutralize free radicals, which in turn play a role in the onset of cardiovascular diseases and cancers. Polyphenols are major antioxidants in apples, however, the antioxidants vary with the apple variety, and the post-harvest storage conditions. Further, the polyphenols are distributed differently throughout the fruit (skin or flesh). The paper reviews the present knowledge on apple polyphenols, their bioavailability and pro-health functionality.     

多酚的食物来源及生物有效性

介绍了食品中存在的多种多酚的性质及其含量;分析了农业生产、工业化生产对多酚含量的影响以及综述了目前在多酚的生物有效性方面的研究进展。     

食品中杏仁过敏原成分的检测

目的：建立检测食品中桃仁、杏仁过敏原成分的荧光PCR 方法,比较国外3 种ELISA 试剂盒效果。方法：针对杏仁Pru du1 基因设计引物及探针,建立荧光PCR 方法。利用杏仁过敏原参考物质对3 个品牌的ELISA试剂盒的回收率进行比较。结果：建立的荧光PCR 方法,具有很好的特异性;灵敏度为10mg/kg。结论：桃仁及杏仁过敏原成分荧光PCR 检测方法特异性好、灵敏度高,对食品中过敏原的检测有重要的实际意义。     

植物多酚对肉制品蛋白氧化的抑制机理及其延长货架期的应用

蛋白氧化和微生物污染是导致肉与肉制品在贮藏期间腐败变质的主要因素。植物多酚具有良好的抗氧化和抑菌活性,在肉与肉制品中添加植物多酚是防止其变质的有效方法之一。本文综述了植物多酚的种类及其对肉与肉制品蛋白质氧化和微生物污染的抑制机理;介绍了多酚以作为反应性物质清除剂、非自由基衍生物清除剂、过渡金属离子螯合剂和高铁肌红蛋白还原剂4 种方式抑制蛋白氧化,并通过与细菌细胞壁组分和细胞膜相互作用、防止和抑制生物膜形成、合成生物大分子及抑制细菌酶活性来延长肉与肉制品货架期;此外,还阐述了植物多酚在抑制肉制品氧化及微生物方面的应用,并对其研究前景进行了展望。     

几种多酚化合物抗氧化性的不同化学评价及相关性分析

利用α-脱氧核糖法、邻苯三酚自氧化法、DPPH·法、ABTS ·法、铁氰化钾还原法,对茶多酚、没食子酸、槲皮素、山奈素、芹菜素几种多酚化合物及VE(对照)的抗氧化性进行评价,并采用SAS软件对各种评价方法结果进行相关性分析.结果表明,几种多酚化合物均有一定的抗氧化能力,尤其对ABTS ·具有极强的清除能力,其中没食子酸、槲皮素、茶多酚的抗氧化能力远大于山奈素、芹菜素、VE.相关性分析表明,还原能力法分析结果与DPPH·法、ABTS ·法分析结果,具有极显著的正相关性(p<0.01);ABTS ·法分析结果与DPPH·法、α-脱氧核糖法分析结果,0-2·法分析结果与α-脱氧核糖法分析结果,具有显著的正相关性(p<0.05).     

Recent Advances in Research on Polyphenols: Effects on Microbiota,Metabolism, and Health

Polyphenols have attracted huge interest among researchers of various disciplines because of their numerous biological activities, such as antioxidative, antiinflammatory, antiapoptotic, cancer chemopreventive, anticarcinogenic, and antimicrobial properties, and their promising applications in many fields, mainly in the medical, cosmetics, dietary supplement and food industries. In this review, the latest scientific findings in the research on polyphenols interaction with the microbiome and mitochondria, their metabolism and health beneficial effects, their involvement in cognitive diseases and obesity development, as well as some innovations in their analysis, extraction methods, development of cosmetic formulations and functional food are summarized based on the papers presented at the 13th World Congress on Polyphenol Applications. Future implications of polyphenols in disease prevention and their strategic use as prophylactic measures are specifically addressed. Polyphenols may play a key role in our tomorrow´s food and nutrition to prevent many diseases.     

茶多酚的提取方法与应用进展

综述了国内外现有茶多酚的提取方法, 对溶剂法、沉淀法和树脂法各自优缺点进行了比较。并介绍了茶多酚在食品、医药和化妆品行业的应用