核桃青皮中多酚的超高压提取工艺优化

为优化核桃青皮中多酚类物质的超高压提取工艺,以温度、压力、时间、液料比为自变量,多酚得率为响应值,进行响应面试验设计和优化,并建立预测数学模型。结果表明,超高压提取核桃青皮多酚最佳工艺为:采用超高压二次提取法,以50%乙醇—水为提取液,粉碎粒度80目,温度42℃,压力310 MPa,时间6min,液料比40∶1(V∶m),该条件下多酚得率为7.417 mg/g,获得的数学模型能够用于预测超高压提取核桃青皮多酚的过程。     

含茶多酚的壳聚糖涂膜对四季豆贮藏品质和 生理生化特性的影响

目的研究壳聚糖联合茶多酚对四季豆涂膜保鲜的可行性。方法以四季豆为实验材料,采用壳聚糖涂膜(浓度为1.5%)、壳聚糖联合茶多酚复合涂膜(1.5%壳聚糖中添加150 mg/kg茶多酚)2种保鲜方式,研究茶多酚对四季豆贮藏品质和生理生化特性的影响。结果茶多酚联合壳聚糖涂膜的四季豆在贮藏期内叶绿素、维生素C、水分含量的下降速率和纤维素含量的上升速率均低于壳聚糖涂膜组,贮藏品质较好。茶多酚联合壳聚糖涂膜的四季豆体内的过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的活力低于壳聚糖涂膜组,但二者均高于未处理组。结论涂膜处理有利于四季豆的贮藏,涂膜剂中加入茶多酚后保鲜效果更好,和壳聚糖涂膜相比可将四季豆贮藏期延长10 d,和不涂膜组相比可延长20d。     

茶叶中有效成分综合提取的研究

以绿茶为原料，采用ZJL大孔离了交换树脂和ZJX大孔吸附树脂从茶叶的浸提液中提取茶氨酸、咖啡因、茶多酚和茶多糖。通过对树脂的静态、动态吸附性能的实验研究，确定了咖啡因、茶氨酸、茶多酚及茶多糖联合分离提取的工艺。研究结果表明：该工艺能有效的从茶叶中提取咖啡因、茶氨酸和茶多酚，提取的咖啡因纯度达83．23％，提取率为1．9％，茶氨酸纯度达85．43％，提取率为0．94％，提取的茶多酚纯度达95．62％，提取率为12．35％，且茶多酚中的咖啡因含量低于0．7％，茶多糖的纯度达51％，提取率为1．1％。     

Flavonoids protecting food and beverages against light

Flavonoids, which are ubiquitously present in the plant kingdom, preserve food and beverages at the parts per million level with minor perturbation of sensory impressions. Additionally, they are safe and possibly contribute positive health effects. Flavonoids should be further exploited for the protection of food and beverages against light‐induced quality deterioration through: (1) direct absorption of photons as inner filters protecting sensitive food components; (2) deactivation of (triplet‐)excited states of sensitisers like chlorophyll and riboflavin; (3) quenching of singlet oxygen from type II photosensitisation; and (iv) scavenging of radicals formed as reaction intermediates in type I photosensitisation. For absorption of light, combinations of flavonoids, as found in natural co‐pigmentation, facilitate dissipation of photon energy to heat thus averting photodegradation. For protection against singlet oxygen and triplet sensitisers, chemical quenching gradually decreases efficiency hence the pathway to physical quenching should be optimised through product formulation. The feasibility of these protection strategies is further supported by kinetic data that are becoming available, allowing for calculation of threshold levels of flavonoids to prevent beer and dairy products from going off. On the other hand, increasing understanding of the interplay between light and matrix physicochemistry, for example the effect of aprotic microenvironments on phototautomerisation of compounds like quercetin, opens up for engineering better light‐to‐heat converting channels in processed food to eventually prevent quality loss. © 2014 Society of Chemical Industry     

茶多酚对干果类食品抗氧化作用的研究

为了延长言含油脂的干果类食品的保质期，研究了茶多酚、维生素C（Vc）对炒熟花生仁、核桃仁油脂氧化酸败的抑制作用。通过测定常温贮存两个月的样品中过氧化值（POV）的变化来检测炒熟花生仁和核桃仁油脂的氧化酸败程度。结果表明，茶多酚、Vc对炒熟花生仁和核桃仁油脂氧化酸败确实有抑制作用。     

Forage quality and tannin concentration and composition of a collection of the tropical shrub legume Flemingia macrophylla

A collection of 23 Flemingia macrophylla (Willd.) Merrill accessions of different growth habits and contrasting digestibility and one Flemingia stricta reference accession were assessed for forage quality with particular emphasis on digestibility, condensed tannin concentration and fiber content. Large differences in in vitro dry matter digestibility (IVDMD) (356 to 598 g kg^?1), content of crude protein (CP) (121 to 254 g kg^?1) and extractable condensed tannins (CT) (0 to 268 g kg^?1), protein‐binding capacity of extractable CT or astringency (1.7 to 7.9 protein‐binding entities) (PBE) and monomer composition of extractable CT were detected. IVDMD and extractable CT were negatively correlated and extractable CT was positively correlated with protein‐binding capacity. Prodelphinidin was positively and propelargonidin negatively correlated with protein‐binding capacity of extractable CT. The accessions CIAT 18438, CIAT 21083, CIAT 21090 and CIAT 22082 were superior to the most widely used accession CIAT 17403 in terms of forage quality and could be an option in production systems with acid infertile soils. In future evaluations, particular attention needs to be paid to chemical and structural features related to the composition of extractable CT and their effect on nitrogen utilization by ruminants. Copyright © 2006 Society of Chemical Industry     

冷却猪肉生产中保鲜技术的研究

为了寻求天然、安全、效果良好的冷却猪肉保鲜剂，本试验筛选了乳酸菌肽、茶多酚、壳聚糖三种天然保鲜剂，用浸泡的方式对肉块进行处理，结合真空包装技术对冷却肉的保鲜效果进行研究，并测定菌落总数、TVB—N值和pH值指标。主要以TVB—N值来判定冷却肉最终新鲜度。结果表明：3种天然保鲜剂单独使用都有一定的保鲜效果，复合试验中对照组的保质期仅为7d，壳聚糖、Nisin复合组和壳聚糖、茶多酚、Nisni复合组均可使冷却肉的保质期达到15d以上，后者对冷却肉的保鲜效果明显优于其它组，可使保质期达到21d以上。     

Açaí (Euterpe oleraceae) ‘BRS Pará’: A tropical fruit source of antioxidant dietary fiber and high antioxidant capacity oil

This article reports a study of the concentrations of dietary fiber (DF) and antioxidant capacity in fruits (pulp and oil) of a new açaí (Euterpe oleraceae) cultivar—‘BRS-Pará’, with a view to determine the possibility of using it as a source of antioxidants in functional foods or dietary supplements. Results show that ‘BRS-Pará’ açaí fruits has a high content of DF (71% dry matter) and oil (20.82%) as well as a high antioxidant capacity in both defatted matter and oil. ‘BRS-Pará’ Açaí fruits can be considered as an excellent source of antioxidant dietary fiber. Antioxidant capacity of açaí ‘BRS-Pará’ oil by DPPH assay was higher (EC₅₀ = 646.3 g/g DPPH) than extra virgin olive oil (EC₅₀ = 2057.27 g/g DPPH). These features provide açaí ‘BRS-Pará’ fruits with considerable potential for nutritional and health applications.     

The intake of dietary fiber from grape seeds modifies the antioxidant status in rat cecum

The aim of this study was to measure the antioxidant activity and polyphenolic compounds in cecum and feces of rats fed with a grape seed concentrate. The grape concentrate was rich in indigestible compounds (dietary fiber, polyphenols and other associated compounds) which presented significant antioxidant activity. Polyphenols extracted by aqueous–organic solvents (extractable polyphenols, EPs) and non‐extractable polyphenols (NEPs) exhibited high antioxidant capacity as measured by the ABTS method. High correlations were found between antioxidant capacity values and EP (r² = 0.9608) and NEP content (r² = 0.9179). EPs and NEPs exhibited considerable antioxidant activity within the large intestine. Significant antioxidant activity was also found in feces derived from excreted EPs and NEPs. The grape fiber concentrate enhanced the antioxidant status in the large intestine. The antioxidant activity in the intestinal content should be considered when assessing the effects of dietary components on bowel diseases. Copyright © 2005 Society of Chemical Industry     

红车轴草不同部位多酚提取工艺优化及抗氧化活性研究

目的：优化红车轴草多酚提取工艺,并评价其抗氧化活性。方法：采用超声波辅助提取红车轴草茎、叶和花各部位总多酚,选取多酚含量较高部位作为研究对象,采用响应面法优化红车轴草多酚提取工艺,并通过羟自由基和超氧阴离子自由基的清除效率检测总多酚的抗氧化活性。结果：红车轴草中叶的多酚含量较高,其最佳提取工艺为料液比为1∶79 （g/mL）,提取时间23 min,乙醇体积分数38%,超声功率800 W,超声温度50 ℃,此时多酚得率为2.31%,与预测值相近,相对标准偏差为2.16%（n=5）。提取物对羟自由基和超氧阴离子自由基的IC₅₀值分别为0.419,0.428 mg/mL。结论：该提取方法稳定可靠,多酚提取物具有较好的抗氧化活性。