酚类物质的结构与性质及其与葡萄及葡萄酒的关系

酚类物质是一类大而复杂的化合物。葡萄与葡萄酒中常见的酚类物质可分为类黄酮和非类黄酮两大类，它们是葡萄中重要的次生代谢产物，与葡萄的抗病性、采后生理、贮存、保鲜等密切相关。葡萄酒中的酚类物质来自于葡萄果实、果梗、酵母代谢以及橡木桶，参与形成葡萄酒的味道、骨架、结构和颜色等，对红葡萄酒的特征和质量尤其重要。     

云南主产区夏黑果皮营养成分及抗氧化活性研究

以云南4个葡萄主产区的夏黑果皮为原料,对其营养成分及抗氧化活性进行了分析。以DPPH、ABTS+自由基清除能力和还原能力评价了四个地区果皮多酚提取物的抗氧化活性。结果发现:同一品种的四个样品,因其生长环境不同,营养成分及组成存在明显差异。葡萄皮中脂质的不饱和脂肪酸含量较高,单糖含量为葡萄糖>阿拉伯糖、半乳糖醛酸、半乳糖。葡萄皮中的原花青素、多酚含量存在显著性差异,酚酸组成中芦丁和儿茶素含量较高。果皮多酚提取物表现较好的抗氧化活性,其在三种抗氧化体系中的IC50值分别在13.34¹4.86μg/m L、9.15¹0.64μg/m L和32.63³4.24μg/m L之间。      

八种葡萄籽油中主要脂肪酸的检测与分析

为了定性探究不同用途的葡萄籽主要脂肪酸含量的差异,为葡萄籽提油时的品种选择提供理论依据。以三种不同用途的八种葡萄籽为原料,采用超临界CO2流体萃取设备及气相色谱法,检测其主要脂肪酸百分含量。结果表明:鲜食品种中,凤凰和京玉的硬脂酸含量均高于巨峰。白色酿造中,霞多丽油酸含量高于小芒森。红色酿造中,三个品种的硬脂酸、亚麻酸含量有明显不同。不同用途的葡萄籽,均有一些脂肪酸百分含量存在差异。这显示出,对葡萄籽进行提油时,品种差异会造成葡萄籽油成分的明显差异。     

Effects of different osmo‐dehydrofreezing treatments on the volatile compounds,phenolic compounds and physicochemical properties in mango (Mangifera indica L.)

The influences of different osmotic solution pretreatments (sucrose, glucose and maltose with concentration of 45%) on the volatile compounds, phenolic compounds and other physicochemical parameters in frozen mangoes were studied. Volatile and phenolic compounds were measured using SPME/GC‐MS and HPLC method, respectively. The results revealed that compared with untreated frozen mango, some volatile compounds (e.g. alcohols, aldehydes and some terpenes and esters) increased significantly and there were more compounds identified in osmo‐dehydrofrozen samples. These changes positively affected mango aroma and resulted in higher sensory scores for osmo‐dehydrofrozen samples. In addition, data on phenolic compounds showed that dehydrofrozen samples pretreated in glucose and sucrose had higher ρ‐hydroxybenzoic acid and quercetin contents, respectively, while samples pretreated in maltose showed higher ρ‐coumaric acid and sinapic acid contents compared with untreated frozen samples. The current work indicates that osmo‐dehydrofreezing can improve the retention of phenolic and aromatic compounds in frozen mango.     

Effect of duration and level of supplementation of diets of lactating dairy cows with selenized yeast on selenium concentrations in milk and blood after the withdrawal of supplementation

Cows’ milk containing elevated concentrations of Se provides a rich nutritional source of this essential element for meeting daily nutritional requirements or providing health benefits in humans with low immune function or at risk of cancer. An experiment involving either 2 or 6 wk of dietary supplementation with Se yeast (with the yeast supplying about 30, 40, and 60 mg of Se/d for cows supplemented for 2 wk, and about 20, 30, 40, and 60 mg of Se/d for cows supplemented for 6 wk), and 21 wk of monitoring of Se status after the withdrawal of supplementation, was undertaken between September 2008 and April 2009 using 35 multiparous Holstein-Friesian cows. Using milk and blood Se concentrations as surrogates, the research examined the time taken for Se build-up in tissue due to supplementation of lactating dairy cows with Se yeast to dissipate back to normal levels. At the end of Se supplementation, a significant relationship was found between milk Se concentration and Se intake, whereby milk Se concentration had increased by 4.5 μg of Se/kg of milk for each mg of Se eaten per day, but no effect of duration of supplementation on this relationship was observed. At the same time, both Se intake and duration of supplementation affected blood Se concentration; it increased by 3.6 μg of Se/kg of blood for each mg of Se eaten per day, and was 86 μg of Se/kg higher after 6 wk compared with 2 wk of supplementation. After the withdrawal of Se supplementation, milk Se concentrations responded quickly to the change in the quantity of Se consumed, and again, duration of supplementation had no effect on the response, but any effect that Se intake had on milk Se had completely dissipated by 4 wk. In contrast to milk, blood Se concentrations continued to be affected by both amount and duration of Se supplementation for at least 4 mo after the withdrawal of supplementation, although by 5 mo the effects of the previous supplementation treatments had virtually disappeared. The slow decline in blood Se concentrations after the withdrawal of supplementation would most likely be due to the protracted clearance of Se from the various tissues that had accumulated Se during supplementation and the rate of erythrocyte turnover. When undertaking an on-farm Se enhancement program to generate milk for the manufacture of Se-enriched milk products, post-supplementation milk Se concentrations are unlikely to create any problems at the milk factory beyond 4 wk, but the high residual blood/tissue Se concentrations that take considerably more time to dissipate may provide the potential for possible unintended consequences at the food chain/farm environment level.     

Grape and wine analysis - enhancing the power of spectroscopy with chemometrics.

Spectroscopic techniques offer the potential to simplify and reduce analytical times for a range of grape and wine analytes. It is this aspect, together with the ability to simultaneously measure several analytes, which was the impetus for developing spectroscopic methods. The Australian Wine Research Institute (AWRI) has long used spectroscopic analysis of wines in the ultraviolet (UV) and visible (Vis) wavelengths, and since 1998 has been investigating applications of spectroscopic techniques in the near infrared (NIR) and mid-infrared (MIR) wavelength regions of the electromagnetic spectrum for the rapid analysis and quality control of both grapes and wine by the Australian wine industry. This paper reviews the use of several spectroscopic techniques, including NIR, MIR, and Vis, combined with chemometrics, to assess grape and wine composition in the Australian wine industry. The achievements, current research, and proposed further applications of different spectroscopic techniques are discussed in studies into the assessments of red grape composition and of fungal diseases in grapes, monitoring phenolic compounds during red wine fermentations, quality grading of red, white and fortified wine styles, monitoring wine distillation processes, and yeast strain classification.     

Selenium Content of Venison, Squirrel, and Beef Purchased or Produced in Ohio, a Low Selenium Region of the United States

ABSTRACT: The selenium (Se) content (AOAC fluorometric method) of: 1) raw and cooked venison, squirrel, and beef from a low selenium region of the United States and 2) nonregion-raised beef was assessed and compared by region, species, and gender. For both raw and cooked meats, the Se content of venison was not different from region-raised beef (p > .05), and their contents were generally less than squirrel, which was less than nonregion-raised beef (p < .05). Gender and age did not influence Se content of the meats. Field-dressed weight did not affect Se content of deer, and antler size did not impact Se content of meat from male deer.     

Reactions with phenolic substances can induce changes in some physico-chemical properties and activities of bromelain – the consequences for supplementary food products

Bromelain was allowed to react with phenolic compounds. The activity and selected physico‐chemical properties of the resulting derivatives were characterized. In vitro experiments showed that the proteolytic activity of bromelain was inhibited. Bromelain also serves as a food protein, because food stuffs based on pineapple contain relatively high concentrations of bromelain. In vitro digestion of bromelain derivatives with the main proteolytic enzymes of the gastrointestinal tract was also adversely affected. A covalent attachment of the phenolic compounds was identified at the tryptophan, free amino (lysines and N‐terminal) and thiol groups of bromelain. A decrease in solubility of the derivatives was observed. The isoelectric point was shifted to lower pH values and high molecular weight fractions were identified. All effects observed depended on the reactivity of the phenolic substances. Two supplementary food products containing both bromelain and quercetin were also tested in terms of their proteolytic activity and digestibility.     

Edible coating materials—their properties and use in the fortification of rice with folic acid

This study investigated the technical feasibility of adding folic acid on to rice and coating with edible polymers. The coating solutions were cast into film and their properties were investigated. A concentrated premix of rice was prepared in a rotating coating pan by spraying first with folic acid solution, and then with polymer solutions and drying. The fortified rice premixes were evaluated for washing and cooking losses. The loss of folic acid in washing was lowest in rice premixes coated with ethyl cellulose followed by pectin, composite mixtures of locust bean and other coating materials with highest loss in gum arabic coated rice. No edible polymer could satisfactorily retain folic acid during boiling in excess water. Edible polymers failed to mask the yellow color of folic acid and additional masking agent was needed. The premixes had a higher water uptake ratio than raw milled rice had. Triangle tests did not show any significant difference (=0.05) between the sensory qualities of cooked fortified rice and raw milled rice.     

Antioxidant activity and polyphenol contents in Brazilian green propolis extracts prepared with the use of ethanol and water as solvents in different pH values

Propolis is a natural product with a variable and complex chemical composition associated with its high concentration on polyphenolic compounds. The effect of pH variation (2.0, 3.0, 4.3, 6.0 and 8.0) during aqueous and ethanolic propolis extraction was studied for up to 10 days. Total phenols and flavonoids contents were measured for the extracts by spectrophotometric assays. Antioxidant activity was measured by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and ferric thiocyanate (FTC) methods. The best time of extraction was up to 5 days for all samples. Basic aqueous extracts (pH 8.0) resulted in a higher concentration of compounds than the extract without pH modification, reaching an increase of 160% in flavonoids and 25% in phenols. Ethanolic extracts with pH variation resulted in an extract with 50% less polyphenols and 6% less flavonoids than extract without pH modification. The antioxidant activity was highest for ethanolic extract at pH 4.3 and aqueous extract at pH 8.0 – almost 90% and 45%, respectively, in DPPH method – and was related to the level of polyphenols by Pearson's correlations.     

Identification of the major yeasts isolated from high moisture corn and corn silages in the United States using genetic and biochemical methods

The objective of this study was to identify species of yeasts in samples of high moisture corn (HMC) and corn silage (CS) collected from farms throughout the United States. Samples were plated and colonies were isolated for identification using DNA analysis. Randomly selected colonies were also identified by fatty acid methyl esters (FAME) and by physiological substrate profiling (ID 32C). For CS, Candida ethanolica, Saccharomyces bulderi, Pichia anomala, Kazachstania unispora, and Saccharomyces cerevisiae were the predominant yeasts. Pichia anomala, Issatchenkia orientalis, S. cerevisiae, and Pichia fermentans were the prevalent species in HMC. The 3 identification methods were in agreement at the species level for 16.6% of the isolates and showed no agreement for 25.7%. Agreement in species identification between ID 32C and DNA analysis, FAME and ID 32C, and FAME and DNA analysis was 41.1, 14.4, and 2.2%, respectively. Pichia anomala and I. orientalis were able to grow on lactic acid, whereas S. cerevisiae metabolized sugars (galactose, sucrose, and glucose) but failed to use lactic acid. The yeast diversity in CS and HMC varied due to type of feed and location. Differences in species assignments were seen among methods, but identification using substrate profiling generally corresponded with that based on DNA analysis. These findings provide information about the species that may be expected in silages, and this knowledge may lead to interventions that control unwanted yeasts.     

Reactions of chlorogenic acid and quercetin with a soy protein isolate--influence on the in vivo food protein quality in rats

Plant phenolic compounds are known to interact with proteins producing changes in the food (e. g., biological value (BV), color, taste). Therefore, the in vivo relevance, especially, of covalent phenol-protein reactions on protein quality was studied in a rat bioassay. The rats were fed protein derivatives at a 10% protein level. Soy proteins were derivatized with chlorogenic acid and quercetin (derivatization levels: 0.056 and 0.28 mmol phenolic compound/gram protein). Analysis of nitrogen in diets, urine, and fecal samples as well as the distribution of amino acids were determined. Depending on the degree of derivatization, the rats fed with soy-protein derivatives showed an increased excretion of fecal and urinary nitrogen. As a result, true nitrogen digestibility, BV, and net protein utilization were adversely affected. Protein digestibility corrected amino acid score was decreased for lysine, tryptophan, and sulfur containing amino acids.     

Factors associated with occurrence and recovery of nonambulatory dairy cows in the United States

The primary objective of this study was to compare characteristics of US dairy operations that had one or more nonambulatory cows (unable to rise for any period of time) (cases) with operations that had no nonambulatory cows (controls) during 2004. A secondary objective was to describe factors associated with recovery of the last nonambulatory cow on the operation during 2004. Case dairy operations (n = 1,822) more often fed a total mixed ration [odds ratio (OR) = 2.0; confidence interval (CI): 1.1-3.4], produced more than 9,090 kg of milk (OR = 2.8; CI: 1.8-4.5), and were more likely to be of medium to large herd size (100 or more head of adult cows, O  = 3.7; CI: 2.2-6.2) compared with control dairies (n = 151). Compared with operations where the predominant flooring surface on which lactating cows stood or walked in winter was pasture, operations where pasture was not the predominant surface were at increased risk of having nonambulatory cows (OR = 4.7; CI: 2.2-10.2). Cows nonambulatory for less than 24 h were more likely to recover compared with cows nonambulatory for 24 h or more (OR = 3.0; CI: 2.0-4.4). Cows that received calcium, phosphorus, or potassium while non-ambulatory were more likely to recover (OR = 3.6; CI: 2.1-6.1) than cattle that did not receive these treatments. Cattle that were not repositioned periodically were more likely to recover (OR = 2.1; CI: 1.4-3.1), as were cattle that were not treated by a veterinarian before becoming nonambulatory (OR = 1.9; CI: 1.1-3.3). These findings are consistent with prolonged recumbency and prior history of health issues, respectively. Nonambulatory cattle with hypocalcemia were more likely to recover (OR = 6.0; CI: 3.4-10.7) compared with nonambulatory cows with all other causes of a nonambulatory condition (analyzed collectively as a single variable but including cancer, clinical mastitis, digestive conditions, metabolic imbalances, neurological problems, respiratory disease, other, unknown). The results of this study reveal that the majority of US dairy operations have at least one nonambulatory dairy cow over the course of a year. Additionally, individual animal factors associated with being nonambulatory may lead to improved identification and treatment of animals that are nonambulatory for a prolonged period. From the perspective of recovery, considering euthanasia is appropriate for cows that have been nonambulatory for more than 24 h.     

Analysis of fumonisin contamination and the presence of Fusarium in wheat with kernel black point disease in the United States

The ability of the fungus Fusarium proliferatum to cause kernel black point disease in wheat was previously established, but natural contamination of black point wheat with both F. proliferatum and fumonisin mycotoxins has not been studied in the United States. Low levels of fumonisins were detected in nine of 43 wheat samples with kernel black point disease that were obtained from across the United States. A subset of samples was contaminated with F. proliferatum as well as with F. fujikuroi, F. nygamai, F. thapsinum and F. verticillioides, species closely related to F. proliferatum and morphologically similar to it in that they produce chains of asexual spores, or conidia. Nevertheless, of conidial chain-forming fusaria isolated from symptomatic wheat, F. proliferatum dominated. In greenhouse tests, isolates of F. proliferatum and the other species recovered from wheat samples were able to cause symptoms of kernel black point and, in some cases, low levels of fumonisin contamination of wheat. These data add to the understanding of the risk of fumonisin contamination of wheat and the potential for Fusarium species to cause kernel black point disease and fumonisin contamination of wheat. Further, the results of this study indicate that while US-grown wheat can sporadically be contaminated by fumonisins, the natural contamination levels seem to be low. The observations made provide evidence that fumonisins are not likely to be a factor contributing to the ability of Fusarium to cause kernel black point disease.     

HPLC-ICP-MS在线联用分析食品中无机硒和硒氨基酸的形态

以亚硒酸盐（Se（Ⅳ））、硒酸盐（Se（Ⅵ））、硒胱氨酸（Se Cys₂）、硒蛋氨酸（Se Met）、甲基硒代半胱氨酸（Me Se Cys）和硒代乙硫氨酸（Se Et）为硒形态的目标分析物,采用Dionex Ion Pac AS11色谱柱（250 mm×4.0 mm）为分离柱,通过优化流动相的p H、浓度、甲醇含量、流速和色谱柱的柱温等因素对六种目标硒形态分离及不同提取方法对目标分析物提取效率的影响,建立了高效液相色谱-电感耦合等离子体质谱（HPLC-ICP-MS）在线联用同时测定食品中无机硒和硒氨基酸的分析方法。Me Se Cys、Se Met、Se Et、Se（Ⅳ）、Se Cys₂和Se（Ⅵ）的检出限分别为0.25、0.20、0.35、0.15、0.30、0.15μg Se/L;Me Se Cys和Se Cys₂的线性范围为2.0²500μg Se/L,Se（Ⅳ）和Se（Ⅵ）线性范围为1.2¹200μg Se/L,Se Met和Se Et的线性范围分别是1.5¹500μg Se/L和2.2²200μg Se/L,各硒形态的线性相关系数均不少于0.9997。将该方法应用于食品中硒形态的分析,其加标回收的回收率为80.8%¹06.7%,相对标准偏差（RSDs,n=3）为4.7%⁹.6%。方法具有操作简单、方便快速、灵敏度高和环境友好等优点,可满足食品中硒形态定量分析。      

基于美国药典委EMA数据库的全球经济利益驱动型掺假和食品欺诈分析

目的 分析全球范围内经济利益驱动型掺假(EMA)和食品欺诈信息,为建立符合我国国情的EMA数据库提供借鉴。方法 搜集美国药典委(USP)食品欺诈数据库的EMA信息,对1980-2018年在全球范围发生的4102条食品掺假事件作归类和统计分析。结果 掺假分为替代或稀释、人工增强、非法添加物、标签作假和产地作假等6个类型;EMA信息来源主要为学术文献(59.5%)、媒体报道(31.0%)和监管抽查(5.7%);欺诈事件发生率地区排名前三位为印度、中国、美国;按我国食品分类标准28类分析,食用油脂、乳制品、肉制品、酒类、调味品、饮料和蜂产品等7类产品占所有掺假食品类别的90%以上;牛奶、橄榄油和蜂蜜高居掺假食品产品前三,分别占13.1%、7.8%和6.9%;水产品、果品和蔬菜以及制品、饮料作物高居掺假农产品产品前四,分别占54.6%、11.0%、8.0%和7.6%;稀释或替代是最主要的掺假方式;目前最常用的掺假检测方法为高效液相色谱法和质谱法。结论 EMA是全球性的严重食品安全问题,EMA数据库是预防控制食品安全风险的重要技术支撑。     

Risk factors associated with bulk tank standard plate count,bulk tank coliform count,and the presence of Staphylococcus aureus on organic and conventional dairy farms in the United States

The purpose of this study was to assess the association of bulk tank milk standard plate counts, bulk tank coliform counts (CC), and the presence of Staphylococcus aureus in bulk tank milk with various management and farm characteristics on organic and conventional dairy farms throughout New York, Wisconsin, and Oregon. Data from size-matched organic farms (n = 192), conventional nongrazing farms (n = 64), and conventional grazing farms (n = 36) were collected at a single visit for each farm. Of the 292 farms visited, 290 bulk tank milk samples were collected. Statistical models were created using data from all herds in the study, as well as exclusively for the organic subset of herds. Because of incomplete data, 267 of 290 herds were analyzed for total herd modeling, and 173 of 190 organic herds were analyzed for the organic herd modeling. Overall, more bulk tanks from organic farms had Staph. aureus cultured from them (62% of organic herds, 42% conventional nongrazing herds, and 43% of conventional grazing herds), whereas fewer organic herds had a high CC, defined as ≥50 cfu/mL, than conventional farms in the study. A high standard plate count (×1,000 cfu/mL) was associated with decreased body condition score of adult cows and decreased milk production in both models. Several variables were significant only in the model created using all herds or only in organic herds. The presence of Staph. aureus in the bulk tank milk was associated with fewer people treating mastitis, increased age of housing, and a higher percentage of cows with 3 or fewer teats in both the organic and total herd models. The Staph. aureus total herd model also showed a relationship with fewer first-lactation animals, higher hock scores, and less use of automatic takeoffs at milking. High bulk tank CC was related to feeding a total mixed ration and using natural service in nonlactating heifers in both models. Overall, attentive management and use of outside resources were useful with regard to CC on organic farms. In all models except the organic CC model, we observed an association with the average reported somatic cell count from 3 mo before the herd visit, indicating that many of the regularly tested milk quality parameters are interconnected. In conclusion, we found that conventional and organic farms are similar in regard to overall herd management, but each grazing system faces unique challenges when managing milk quality.