Comparison of phenolic acids in organically and conventionally grown pac choi (Brassica rapa L. chinensis)

BACKGROUND: Field and greenhouse studies were performed to investigate whether organic production methods influenced levels of phenolic acid compounds in pac choi (Brassica rapa L. chinensis cv. Mei Qing Choi) compared with conventional cultivation. RESULTS: In the field experiment, organic fertilisation (compost + fish emulsion) resulted in significantly higher phenolic concentrations compared with conventional fertilisation (NPK + CaNO₃) under both high tunnel and open field environments. Increased phenolics were accompanied by a significant reduction in plant fresh weight and dry weight, probably due to nitrogen deficiency. However, the elevated level of phenolics in organically grown pac choi could also have been due to confounding effects of nitrogen availability, insect attack and pesticide application. A follow‐up greenhouse experiment further demonstrated a significant increase in phenolic compounds and a reduction in yield with organic fertiliser (vermicompost + fish fertiliser) relative to conventional treatment (slow release inorganic fertiliser). Preventive insecticide application did not affect the phenolic levels in pac choi under either organic or conventional fertilisation. CONCLUSION: Given that higher phenolic content in pac choi was associated with low nitrogen availability and considerable yield reduction, research is needed to determine the extent to which phenolic compounds may differ in organic and conventional pac choi when nutrient levels are adjusted to produce comparable yields. Additional study is also warranted to determine the extent to which insect attack might contribute to elevated phenolic content in organic pac choi. Copyright © 2009 Society of Chemical Industry     

Antioxidant capacity of leafy vegetables as affected by high tunnel environment,fertilisation and growth stage

BACKGROUND: This study was conducted to evaluate the influences of protected environment, organic fertilisation and growth stage on the oxygen radical absorbance capacity (ORAC) values of leafy vegetables. RESULTS: In a first experiment, pac choi grown in high tunnels had significantly lower ORAC than field‐grown plants. Organic fertiliser markedly increased the antioxidant capacity of pac choi compared with conventional treatment, especially in the open field. However, both open field and organic production resulted in significantly lower yield and more severe leaf damage due to insect attack. In a second study, spinach showed the highest ORAC, followed by pac choi, red leaf lettuce and romaine lettuce. A significant decline in ORAC under high tunnel production was observed only in spinach. In contrast to the first trial, organic fertilisation did not cause an increase in antioxidant capacity of the leafy vegetables. The ORAC values of spinach from the open field and pac choi from high tunnels were significantly higher when harvested at the mature head stage than at the baby size stage. CONCLUSION: Further studies will help to elucidate effects of genotype, growth stage, and production environment on antioxidant capacities of vegetables and may lead to recommended practices to maximise antioxidant capacity of vegetable crops. Copyright © 2007 Society of Chemical Industry     

不同品种甜瓜的关键香气成分鉴定及感官特性形成分析

该研究首先利用气相色谱-质谱-嗅闻技术（Gas Chromatography-Mass Spectrometry-Olfactometry,GC-MS-O）结合香气活力值（Odor Activity Value,OAV）从伽师瓜、黄河蜜瓜、西州密25号和西州密17号中分别鉴定出9、16、12和10种关键香气物质,其中的乙酸乙酯、乙酸丁酯和乙酸苄酯等7种香气物质是我国厚皮甜瓜主要的特征香气成分;采用定量描述分析确定了甜瓜的果香、瓜香、甜香、青香、花香和麝香-烘烤香6个感官特性并给出了相应的感官得分;利用聚类热图法分析了4种甜瓜中关键香气物质种类和含量的差异性;偏最小二乘回归法（Partial Least Squares Regression,PLSR）分析了甜瓜香气感官特性形成的原因。结果表明乙酸乙酯与甜瓜麝香-烘烤香感官属性形成相关;2-甲基丁基乙酸酯和乙酸丁酯与甜瓜果香感官属性形成相关;乙酸苄酯、异戊醛、(E,Z)-3,6-壬二烯-1-醇、硫代乙酸甲酯、(Z)-6-壬烯-1-醇和3-甲基丁酸乙酯与甜瓜的花香和瓜香感官属性形成呈显著相关性。该研究为我国厚皮甜瓜风味香气的改良以及其感官质...     

Phytochemical phenolics in organically grown vegetables

Fruit and vegetable intake is inversely correlated with risks for several chronic diseases in humans. Phytochemicals, and in particular, phenolic compounds, present in plant foods may be partly responsible for these health benefits through a variety of mechanisms. Since environmental factors play a role in a plant's production of secondary metabolites, it was hypothesized that an organic agricultural production system would increase phenolic levels. Cultivars of leaf lettuce, collards, and pac choi were grown either on organically certified plots or on adjacent conventional plots. Nine prominent phenolic agents were quantified by HPLC, including phenolic acids (e. g. caffeic acid and gallic acid) and aglycone or glycoside flavonoids (e. g. apigenin, kaempferol, luteolin, and quercetin). Statistically, we did not find significant higher levels of phenolic agents in lettuce and collard samples grown organically. The total phenolic content of organic pac choi samples as measured by the Folin-Ciocalteu assay, however, was significantly higher than conventional samples (p < 0.01), and seemed to be associated with a greater attack the plants in organic plots by flea beetles. These results indicated that although organic production method alone did not enhance biosynthesis of phytochemicals in lettuce and collards, the organic system provided an increased opportunity for insect attack, resulting in a higher level of total phenolic agents in pac choi.     

乳酸菌协同发酵对饼干风味的影响及应用

本文基于消费者喜好酸度的探究,考察乳酸菌协同发酵对饼干风味特性的影响。经消费者对不同pH值面团制备的乳酸菌协同发酵饼干的喜好度评价显示,当发酵面团p H值为4.35~4.20时具有较高的消费者喜好度评分。采用21株乳酸菌发酵制备饼干,观察其对产品风味的影响。经感官描述性分析发现,坚果味、水果味(气味和滋味)、乳品酸味和甜味的强度与消费者喜好度呈正相关;而丁酸味、苦味和酵母味风味强度则与喜好度呈负相关。不同乳酸菌制备的发酵饼干中风味物质的种类和含量均具有差异。酯类、羰基类及烃类化合物的含量与消费者喜好度呈正相关;而有机酸及醚类物质种类及含量的不同是决定产品风味差异及喜好度评分不同的主要因素之一。结果表明,乳酸乳球菌XX3发酵制得的饼干具有较好的感官风味品质,其果香风味强度及酯类物质含量显著高于其他组饼干。     

基于E-nose、HS-SPME-GC-MS和GC-IMS检测三种草莓鲜榨汁的香气

不同草莓品种鲜榨汁风味存在较大区别,风味特征会直接影响草莓鲜榨汁消费者接受度和经济价值。本研究以妙香3号草莓、红颜草莓和黔莓2号草莓为研究对象,利用电子鼻(Electronic nose, E-nose)、顶空固相微萃取-气相色谱-质谱联用(Headspace Solid Phase Micro Extraction-Gas Chromatography-Mass Spectrometry, HS-SPME-GC-MS)和气相色谱-离子迁移谱(Gas Chromatography-Ion Mobility Spectrometry, GC-IMS)对三种草莓鲜榨汁的挥发性风味物质进行定性和定量分析。结果表明,三种草莓鲜榨汁中挥发性风味物质含量和种类有明显差别。电子鼻可以有效区分三种草莓鲜榨汁;HS-SPME-GC-MS检测出89种挥发性风味物质,包括55种酯类、9种醛类、7种醇类、13种酮类和5种酸类。其中22种挥发性风味物质是三种草莓鲜榨汁共有的,包括11种酯类、4种醛类、芳樟醇、5种酮类及壬酸。妙香3号鲜榨汁中5-己基二氢-2(3H)-呋喃酮含量较高,红颜草莓鲜榨汁中乙酸己酯和(Z...     

Comparison of the Volatile Constituents from Rabbiteye Blueberries (Vaccinium ashei) During Ripening

GLC-MS analyses of steam distillates prepared from Delite, Tifblue, and Woodard cultivars of rabbiteye blueberries at three stages of maturity showed qualitative and quantitative differences in their organic constituents. Fifty-one compounds, consisting of aldehydes, ketones, alcohols, aromatic hydrocarbons, terpenes, esters, and three methyl substituted indanones (the latter tentative) were identified and compared. Most compounds with molecular weights of 100 - 200 amu appeared to increase with maturity and indicate potential use as indices of quality. Terpenes, C6 unsaturated aldehydes, and unsaturated alcohols were the predominant types of compounds identified in the distillates. Synthetic mixtures of lina- 1001, trans-2-hexenal, trans-2-hexenol, cis-3-hexen-1-ol and geraniol possessed typical fruity aromas reminiscent of fresh blueberry odorflavor as determined by informal sensory evaluations.     

二、三倍体虹鳟肌肉感官品质差异的对比分析

为研究二倍体虹鳟和三倍体虹鳟感官品质差异,分析同一亲本、同一养殖条件下二、三倍体虹鳟肉色、肉质和风味物质的组成及含量的差异。结果表明：在肉色方面,二倍体虹鳟肌肉黄色值显著大于三倍体虹鳟（P＜0.05）,亮度值和红色值无显著差异;在肉质方面,三倍体虹鳟肌肉弹性和咀嚼性显著高于二倍体虹鳟（P＜0.05）,持水力和pH值等无显著差异;在滋味物质方面,三倍体虹鳟肌肉滋味组成相对二倍体虹鳟较为丰富,有鲜、咸、苦和甜等味道;在挥发性物质组成方面,二、三倍体虹鳟肌肉挥发性物质均由77 种化合物组成,气味活度值较大的特征性气味物质主要有1-辛烯-3-醇、己醛、辛醛、壬醛和(E)-2-壬烯醛,整体呈现青草味、脂肪味及水果香味,三倍体虹鳟肌肉中总特征性气味物质的气味活度值显著高于二倍体虹鳟（P＜0.05）。本研究表明二、三倍体虹鳟具有不同的感官品质特征。     

GC-O结合OAV鉴定陇南初榨橄榄油关键香气成分

选取甘肃陇南代表性品种莱星和鄂植8号初榨橄榄油及消费口碑良好的特级混合初榨橄榄油为研究对象,通过气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）检测比较3 种初榨橄榄油的挥发性物质组成,同时采用气相色谱-嗅闻（gas chromatography-olfactometry,GC-O）技术筛选其香气活性物质,最后结合香气活性值（odor activity value,OAV）分析各呈香组成对橄榄油香气轮廓呈现的贡献性,从而鉴定出3 种橄榄油各自的关键香气成分。结果表明：采用GC-MS在莱星、特级混合及鄂植8号初榨橄榄油中各检测出35、30 种及25 种挥发性成分,其中己醇、3-己烯-1-醇、(E)-2-己烯-1-醇和(E)-2-己烯醛的含量丰富。采用GC-O在3 种初榨橄榄油中各筛选出13、15 种和12 种香气活性成分,包含具有青草特征的C6化合物、呈现油脂香气的庚醛和(E,E)-2,4-癸二烯醛以及表现其他气味信息的香气物质。OAV分析发现3 个样品各有12、13 种及11 种关键香气成分（OAV≥1）,以1-辛烯-3-醇、芳樟醇、(E)-2-己烯醛和(E,E)-2,4-癸二烯醛为代表的OAV较高,对初榨橄榄油呈香品质具有重要作用。本研究筛选出3 种初榨橄榄油的关键香气成分,结果可为提升初榨橄榄油风味品质提供理论基础。     

浒苔挥发性风味成分分析

采用顶空固相微萃取-气质联用法对新鲜肠浒苔的挥发性风味成分进行测定,并加以感官评定分析比较风味物质组成。结果表明：浒苔的主要特征性风味物质是顺-3-十七烯,该物质在新鲜肠浒苔中含量高达59.54%,其次是棕榈醛、(E,E)-2,4-庚二烯醛、β-紫罗兰酮、壬醛、反式-2-己烯醛、2,4-戊二烯醛以及反,反-2,4-癸二烯醛等。     

Volatile composition of pomegranates from 9 Spanish cultivars using headspace solid phase microextraction

Fruits of 9 Spanish pomegranate cultivars were analyzed for quality parameters, volatile composition, and sensory profile. Volatile compounds were extracted using headspace solid phase micro-extraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS) and flame ionization detector (GC-FID). Twenty-one compounds were found in the headspace of fresh pomegranate juices, including aldehydes, monoterpenes, and alcohols. The most abundant compounds were hexanal, limonene, trans-2-hexenal, and cis-3-hexenol. Fruits from the cultivars Mollar Elche(ME) ME14, ME1, and ME2 presented the highest values of overall liking by the consumer panel; however, their total volatiles concentration were low compared to the other pomegranate cultivars and their color intensity was intermediate. Overall consumer liking of pomegranate juices was mainly associated with the presence of monoterpenes (α-terpineol); however, high aldehydes (trans-2-hexenal) concentrations were correlated with poor overall consumer liking. Fruits from sour-sweet cultivars (PTO7 and ADO4) could improve the quality of ME pomegranate juices due to their intense color, high monoterpenes concentrations, and their moderate sourness. Practical Application: The information provided in this study proves that sour-sweet pomegranate fruits can be used in the manufacturing of pomegranate juices and will improve the sensory quality and the volatile composition of this product.     

基于主成分分析法的安溪铁观音香气质量评价模型的构建

从4个季节(每个季节两个等级)共8个安溪铁观音茶样中提取并分离出74种香气组分。通过主成分分析法鉴定出安溪铁观音中的主要特征香气成分,它们分别是：橙花叔醇、法呢烯、吲哚、苯乙醇、反-2-己烯醛、壬醛、苯乙醛、亚油酸甲酯、亚麻酸甲酯、棕榈酸甲酯、顺-己酸-3-己烯酯、苯甲酸-3-己烯-1-醇酯、辛酸-2-苯乙酯、5-正丁基-δ-戊内酯、顺式茉莉酮、法尼基丙酮、棕榈酸、香叶基芳樟醇异构体。利用主成分分析法,基于综合评价函数F＝β1F1＋β2F2＋…＋βkFk构建了安溪铁观音香气质量的评价模型,以不同特征值的方差贡献率βi(i＝1,2,…,k)为加权系数,利用所建立的模型计算各样本得分,然后进行排序评价各个茶样的香气质量。通过感官评价法进一步对模型评价结果进行了检验,结果显示两种方法具有很好的一致性,表明所建立的方法是可行的。