Comparison of nutritional and nutraceutical properties in cultivated fruits of Fragaria vesca L. produced in Italy

Individual sugars, organic acids, total polyphenols, vitamin C and antiradical activity (as measured by DPPH method) were quantified in cultivated Fragaria vesca berries, comparing different varieties (Regina delle Valli, Alpine, Sara and Valitutto) and different environments with regard to altitude. Cultivar effect mainly influenced the concentration of total polyphenols and antiradical activity which are strongly correlated (R² = 0.91; P = 0.001); conversely, altitude seemed to exert an influence in sugar and organic acid composition. The comparison of the general quality of the most diffused cultivar of F. vesca (Regina delle Valli and Alpine) evidenced that both cultivars have the same nutritional properties, whereas Regina delle Valli is better than Alpine from the point of view of total polyphenolic content (716 vs 471 mg catechin/100 g fresh weight) and radical scavenging activity (301 vs 219 ml DPPH solution/100 g fresh weight), thus resulting more attractive from the health protecting attributes point of view. F. vesca berries showed also a concentration of sugars, citric acid, malic acid and total polyphenols much higher than those reported in literature for Fragaria x ananassa.     

Linking chemical reactivity and protein precipitation to structural characteristics of foliar tannins

Tannins influence ecosystem function by affecting decomposition rates, nutrient cycling, and herbivory. To determine the role of tannins in ecological processes, it is important to quantify their abundance and understand how structural properties affect reactivity. In this study, purified tannins from the foliage of nine species growing in the pygmy forest of the northern California coast were examined for chemical reactivity, protein precipitation capacity (PPC), and structural characteristics (¹³C NMR). Reactivity of purified tannins varied among species 1.5-fold for the Folin total phenol assay, and 7-fold and 3-fold, respectively, for the acid butanol and vanillin condensed tannin assays. There was about a 5-fold difference in PPC. Variation in chemical reactivity and PPC can be largely explained by differences in structural characteristics of the tannins determined by ¹³C NMR. In particular, the condensed versus hydrolyzable tannin content, as well as the hydroxylation pattern of the B-ring and stereochemistry at the C-2–C-3 position appear to influence reactivity. Due to the large differences in chemical reactivity among species, it is necessary to use a well-characterized purified tannin from the species of interest to convert assay values to concentrations. Our results suggest that structural characteristics of tannins play an important role in regulating their reactivity in ecological processes.     

温度对软包装葡萄酒总酚和氧化褐变的影响

在不同温度条件下对红葡萄酒进行储存实验,运用福林-酚比色法测定不同温度条件下葡萄酒中总酚含量,同时检测葡萄酒褐变度的变化规律,研究分析温度对红葡萄酒氧化褐变及其氧化褐变速率的影响。研究发现,温度越高,葡萄酒总酚减少越快,氧化褐变度也越大。研究将为红葡萄酒储存和包装研究提供理论基础。     

迷迭香脂溶性抗氧化剂总酚测定及其稳定性研究

以没食子酸为对照品,建立了基于福林-酚(Folin-Ciocalteu)试剂显色法(F-C法)定量检测超临界二氧化碳萃取的脂溶性迷迭香抗氧化剂中总酚的方法,进一步考察了上述抗氧化剂及其在不同溶剂中的总酚含量的存放稳定性.结果表明:上述所建立的方法用于枪测脂溶性迷迭香抗氧化剂中总酚的含量稳定可靠;上述抗氧化剂室温下储藏稳定性非常好,在8个月内总酚含量依然十分稳定;室温下在不同溶剂中的存放稳定性则依溶剂不同而明显不同.在四氢呋喃、甲醇、N,N-二甲基酰胺中,随着放置时间的延长,总酚含量不断下降,并且下降明显;在乙醇中,总酚含量在11天内基本维持稳定,此后随时间的延长逐渐缓慢降低;在乙腈中,即使放置长达25天,总酚含量也几乎不变,表现出极好的稳定性.     

蓝莓干红的抗氧化能力分析

采用福林-酚法测定了12种干红的总酚含量,结果表明：这12种干红的总酚含量在643．58mg／L-2570．75mg／L之间,其中蓝莓干红的总酚含量远远高于其它种类干红,蓝莓比例占的越高,总酚含量越高;采用FeCl/K3Fe（CN）。测定还原力的体系分析干红的抗氧化能力,结果表明：这12种干红的抗氧化能力都比Vc强。加有蓝莓酿制的干红抗氧化能力比BHT、BHA及单品种葡萄干红高,蓝莓添加量越大,还原能力越高,蓝莓单独酿制的蓝莓干红抗氧化能力最强。干红中总酚含量与还原能力大致成正相关,表明干红的抗氧化能力与其所含有的总酚类物质有关。     

栘[木衣]属植物多酚的含量测定与比较

以根皮苷为标样,研究Folin-Ciocalteu（FC）比色法测定栘[木衣]属3 个种的多酚含量适宜条件,进一步用此改良法测定和比较多酚含量在栘[木衣]属的3 个种的叶以及在长爪栘[木衣]的不同器官中的差异性。结果表明,FC比色法最佳测定条件为：加质量分数10%的Na2CO3溶液2.5 mL和FC显色剂0.5 mL,在55 ℃条件下反
应7 min。在1.252～15.024 μg/mL范围内,根皮苷的吸光度与其质量浓度呈良好的线性关系（R2=0.999 1）,平均加样回收率为（100.08±2.43）%;测定结果还表明,3 个物种的叶片多酚含量的差异显著,云南栘[木衣]最低12.55 g/100 g,长爪栘[木衣]最高25.35 g/100 g;长爪栘[木衣]的不同器官均含有多酚类化合物,含量差异显著（3.75～25.35 g/100 g）（P＜0.05）,由低到高为：果核＜根＜果肉＜根皮＜果皮＜茎＜叶。结论：改良后的FC比色法,用于测定栘[木衣]的多酚含量,具有快速、准确、重复性好的特点。栘[木衣]属植物的多酚含量较高,且多酚含量有明显的种间差异性及部位的差异性,栘[木衣]属的植物具有较大的开发和应用价值。     

Folin-Ciocalteu 比色法测定苹果渣中的多酚

采用超临界CO2 萃取技术从苹果渣中提取多酚,以没食子酸为标准物质,系统研究了Folin-Ciocalteu(FC)比色法测定多酚的条件,建立了Folin-Ciocalteu 比色法测定苹果渣中多酚的方法。适宜的显色条件为FC 试剂用量0.3mL、饱和碳酸钠溶液用量1.5mL、反应时间20min、反应温度25～35℃。结果表明：在1～10μg/mL 范围内,没食子酸吸光度与其质量浓度呈良好的线性关系,r ＝ 0.9994;并进行了高、中、低3 个不同加标水平的加标回收率测定实验,相应的回收率分别为99.66%、98.79%、98.20%,平均值为98.82%,RSD 为1.93%。该法测定样品快速、准确,重复性好,可应用于实际样品的测定。     

Folin-Ciocalteu法测定鱼腥草多酚的含量

目的：探索优化Folin-Ciocalteu 法测定鱼腥草中多酚含量。方法：运用不同的溶剂超声提取鱼腥草叶片,比较不同时间提取物用Folin-Ciocalteu 法测得的吸光度。并以乙醇2h 提取液为对象研究不同的碳酸钠溶液、Folin-Ciocalteu 显色剂加入量、反应温度及时间对吸光度大小及稳定性的影响。结果：甲醇提取效率最高,其次为乙醇、丙酮和水;提取时间2h;较适宜测定方法为采用0.5mL 提取液,加入2.0mL 20% 的碳酸钠缓冲液、1.5mLFolin-Ciocalteu 显色剂,蒸馏水定容至50.0mL,55℃保温1.5h,测定波长为760nm。结论：该方法比较快速、准确和稳定,适合推广。     

雪花梨梨皮多酚含量测定

采用Folin-Ciocalteu比色法测定梨皮中的多酚含量,以没食子酸为对照品,确定最佳条件为显色剂2．0mL、10％Na2CO33mL、室温反应40min,比色测定波长760nm．其线性回归方程为y=0．00931x＋0．0254,相关系数詹为0．9978。该方法具有所用试剂量少,操作方便,灵敏度高,精密度高,稳定性好等优点,适宜梨皮总多酚含量的测定,本文采用超声波提取法市售雪花梨梨皮多酚测得含量0．9906mg／g,对雪花梨的附加值开发有一定实践意义。     

Comparison of the Antioxidant Properties of Commonly Consumed Commercial Teas

The antioxidant properties of various commonly consumed commercial teas were screened and compared to check what the consumers get in commercial tea bags in the range of consume preparation conditions. It includes flavored black teas and green teas, as well as some fruit teas. Electron transfer-based assays, such as phenolic content by Folin-Ciocalteu method and cupric ion reducing antioxidant capacity (CUPRAC), were applied. Higher antioxidant activity values were obtained for green and black tea infusions in comparison to fruit teas. The correlation between FC total phenolic and CUPRAC assay for all studied teas was significant (R² = 0.871). The antioxidant power of tea infusions were also measured using cyclic voltammetry. The observed anodic waves were broadened in comparison with voltammograms of single flavonoids due to the response of several antioxidants with different oxidation potentials. The values of Trolox equivalents obtained by electrochemical approach were lower than in the CUPRAC assay; however, the increased order of the antioxidant capacity of tea infusions was the same.