Determination of ethanol,volatile fatty acids,lactic and succinic acids in fermentation liquids by gas chromatography

A rapid and simple quantitative method was developed to determine, by gas chromatography, the concentrations in fermentation liquids of ethanol, the C₂-C₆ volatile fatty acids, and lactic and succinic acids. Aqueous samples were acidified with 250μlml^?1 metaphosphoric acid (5:1 ratio), centrifuged, and injected directly on to a column containing a porous aromatic polymer (Chromosorb 101) maintained at 200°C in a gas chromatograph fitted with a flame ionisation detector. It was unnecessary to purify samples further before injection, although distillation and ion-exchange methods were examined. Derivatisation of lactic and succinic acids before injection was not necessary, but the lowest level of detection of these two relatively non-volatile acids was about four times greater than that for the volatile fatty acids. The method described was suitable for the analysis of rumen fluid, methane digester fluid, silage extracts and other anaerobic fermentation fluids. The relative retention times are given for 23 organic acids and six other fermentation end-products.     

Effects of abomasal infusions of fatty acids and 1-carbon donors on apparent fatty acid digestibility and incorporation into milk fat in cows

Our primary objective was to determine the effects of the abomasal infusion of 16-carbon (16C) and 22-carbon (22C) fatty acids (FA) on apparent FA digestibility, plasma FA concentrations, and their incorporation into milk fat in cows. Our secondary objective was to study the effects of 1-carbon donors choline and l-serine on these variables. Five rumen-cannulated Holstein cows (214 ± 4.9 d in milk; 3.2 ± 1.1 parity) were enrolled in a 5 × 5 Latin square experiment with experimental periods lasting 6 d. Abomasal infusates consisted of (1) palmitic acid (PA; 98% 16:0 of total fat), (2) PA + choline chloride (PA+CC; 50 g/d of choline chloride), (3) PA + l-serine (PA+S; 170 g/d of l-serine), (4) behenic acid (BA; 92% 22:0 of total fat), and (5) docosahexaenoic acid algal oil (DHA; 47.5% DHA of total fat). Emulsions were formulated to provide 301 g/d of total FA and were balanced to provide a minimum of 40 and 19 g/d of 16:0 and glycerol, respectively, to match the content found in the infused algal oil. Apparent digestibility of FA was highest in DHA, intermediate in PA, and lowest in BA. Digestibility of 16C FA was lowest in BA and highest in PA. The digestibility of 22C FA was highest in DHA relative to BA (99 vs. 58%), whereas 1-carbon donors had no effect on 22C FA digestibility. Plasma 16C FA concentrations were greatest with PA treatment, and 22C FA concentrations were ~3-fold greater in DHA-treated cows relative to all other treatments. Milk fat 16:0 content was highest in PA relative to BA and DHA (e.g., 37 vs. 27% in PA and DHA), whereas the milk yield of 16:0 was higher in PA relative to DHA (i.e., 454 vs. 235 g/d). Similarly, milk 22:0 content and yield were ~10-fold higher in BA relative to all other treatments, whereas DHA treatment resulted in higher content and yield of 22:6 in milk fat relative to all other treatments (41- and 38-fold higher, respectively). Consequently, the content of FA >16C (i.e., preformed) was higher in milk fat from cows infused with BA and DHA relative to PA. De novo FA content in milk did not differ between PA, PA+CC, and PA+S (~16% of milk fat) but was higher in BA and DHA treatments (19 and 21%, respectively). We conclude that FA carbon chain length and degree of saturation affected FA digestibility and availability for absorption as well as their incorporation into milk fat. The abomasal infusion of choline chloride and l-serine did not modify these variables relative to infusing palmitic acid alone.     

Short communication: Eicosatrienoic acid and docosatrienoic acid do not promote vaccenic acid accumulation in mixed ruminal cultures

Previous research found that docosahexaenoic acid (C22:6n-3) was a component of fish oil that promotes trans-C18:1 accumulation in ruminal cultures when incubated with linoleic acid. The objective of this study was to determine if eicosatrienoic acid (C20:3n-3) and docosatrienoic acid (C22:3n-3), n-3 fatty acids in fish oil, promote accumulation of trans-C18:1, vaccenic acid (VA) in particular, using cultures of mixed ruminal microorganisms. Treatments consisted of control, control plus 5 mg of C20:3n-3 (ETA), control plus 5 mg of C22:3n-3 (DTA), control plus 15 mg of linoleic acid (LA), control plus 5 mg of C20:3n-3 and 15 mg of linoleic acid (ETALA), and control plus 5 mg of C22:3n-3 and 15 mg of linoleic acid (DTALA). Treatments were incubated in triplicate in 125-mL flasks, and 5 mL of culture contents was taken at 0 and 24 h for fatty acid analysis by gas-liquid chromatography. After 24 h of incubation, the concentrations of trans-C18:1 (0.87, 0.88, and 0.99 mg/culture), and VA (0.52, 0.56, and 0.62 mg/culture) were similar for the control, ETA, and DTA cultures, respectively. The concentrations of trans-C18:1 (5.51, 5.41, and 5.36 mg/culture), and VA (4.78, 4.62, and 4.59 mg/culture) were also similar between LA, ETALA, and DTALA cultures, respectively. These data suggest that C20:3n-3 and C22:3n-3 are not the active components in fish oil that promote VA accumulation when incubated with linoleic acid.     

奶粉脂肪酸与乳制品风味关系研究

用气质（GC—MS）联用色谱分析了11个商业奶粉样品的脂肪酸组成以及含量,每个样品均检测到了28种脂肪酸,在表现奶粉风味的4个呈味脂肪酸,也即辛酸、己酸、壬酸和葵酸中只检测到了辛酸和葵酸。辛酸和葵酸含量在进口奶粉中普遍高于国产奶粉。国产奶粉中辛酸和葵酸的含量以2号最好,3号其次。亚油酸含量在国产奶粉中普遍高于进口奶粉。     

气相色谱法同时快速测定食品中丙酸、山梨酸、苯甲酸及脱氢乙酸

通过液液萃取净化样品研究,建立了食品中丙酸、山梨酸、苯甲酸、脱氢乙酸及其盐含量气相色谱同时快速测定方法,适用于固体非酯(脂)类食品的检测。结果表明:丙酸的回收率在85.1%~91.3%之间,其余3种防腐剂的回收率均在95.2%~99.4%之间;实验室内变异系数(CV,n=6)最大值≤4.7%,4种防腐剂检出限均在0.002 g/kg以下。4种目标物在有杂质干扰时,可用不同的极性毛细管柱做进一步的确认。本方法具有适用范围广、检测效率高、重现性好、准确度高、检出限低的特点,推广应用对我国食品安全的监督检验具有重要的意义。     

花生四烯酸、二十二碳六烯酸和二十碳五烯酸 在炎症中的作用概述

心脑血管疾病、肿瘤、糖尿病、神经系统疾病、自身免疫等疾病严重危害着人类的生命和健康,并消耗着大量医疗资源。事实上,很多疾病发生和发展的背后都伴随着炎症反应,炎症是众多疾病的病理基础,甚至是导致这些疾病的诱因。炎症本身是机体的防御性反应,但过度的炎症反应和长期慢性炎症会损害机体的稳态。炎症的调节和控制由炎症介质介导,花生四烯酸(arachidonic acid,AA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和二十碳五烯酸(eicosapentaenoic acid,EPA)等长链多不饱和脂肪酸(10ng-chain polyunsaturated fatty acids,LC-PUFAs)的衍生物是一类重要的调控炎症的介质。炎性细胞间的交流和细胞内信号传递与LC-PUFAs有关。AA经环氧酶和脂氧合酶合成的类二十烷酸主要起促炎作用,但有的也有抗炎作用。DHA和EPA在体内起抗炎作用,由它们合成的消退素(resolvins,Rvs)和保护素(protectin,PD)是重要的抗炎活性物质。DHA和EPA还可以干扰炎性细胞内信号传导途径来抑制炎症反应。本文从炎症与疾病的关系、LC-PUFAs的衍生物及其促炎和抗炎机制等方面综述了AA、DHA和EPA在炎症中的作用。     

Growth of Aeromonas hydrophila K144 as Affected by Organic Acids

The influence of different acids on the aerobic growth kinetics of Aeromonas hydrophila was studied in BHI broth with 0.5 and 2.0% NaCl incubated at 5 and 19°C. Growth curve data were analyzed by the Gompertz equation and a nonlinear regression program; generation and lag times were calculated from the Gompertz parameters. Type of acid, pH, NaCl level and temperature influenced lag and generation times. The organic acids (acetic, lactic, citric and tartaric) inhibited growth at higher pH values than inorganic acids (HCl and H₂SO₄). The high NaCl level interacted with type of acid and pH to restrict growth of the organism at the lower temperature of incubation. Acetic and lactic acids were effective in controlling the growth of A. hydrophila and could readily be combined with low holding temperature to render foods free of the organism.     

酸味酿造产品中三酸比例评析

酸味酿造产品中乳酸、醋酸、丁酸共存,但比例不同形成的酸味特征也不同。控制不同的环境条件,创造出不同的微生物区系,形成不同的三酸比例,才能形成不同的产品风格。该文对常见的酸味酿造产品中微生物区系的变化及三酸含量进行了分析。     

Anti-obesity effects of conjugated linoleic acid, docosahexaenoic acid, and eicosapentaenoic acid

Obesity has become a prevailing epidemic throughout the globe. Effective therapies for obesity become attracting. Food components with beneficial effects on "weight loss" have caught increasing attentions. Conjugated linoleic acid (CLA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) belong to different families of polyunsaturated fatty acids (PUFA). However, they have similar effects on alleviating obesity and/or preventing from obesity. They influence the balance between energy intake and expenditure; and reduce body weight and/or fat deposition in animal models, but show little effect in healthy human subjects. They inhibit key enzymes responsible for lipid synthesis, such as fatty acid synthase and stearoyl-CoA desaturase-1, enhance lipid oxidation and thermogenesis, and prevent free fatty acids from entering adipocytes for lipogenesis. PUFA also exert suppressive effects on several key factors involved in adipocyte differentiation and fat storage. Despite their similar effects and shared mechanisms, they display differences in the regulation of lipid metabolism. Moreover, DHA and EPA exhibit "anti-obesity" effect as well as improving insulin sensitivity, while CLA induces insulin resistance and fatty liver in most cases. A deeper and more detailed investigation into the complex network of anti-obesity regulatory pathways by different PUFA will improve our understanding of the mechanisms of body weight control and reduce the prevalence of obesity.     

杂多酸催化合成辛酸蔗糖酯

以蔗糖、辛酸为原料,杂多酸为催化剂合成辛酸蔗糖酯。用L16(45)正交设计优化实验,高效液相色谱法分析反应液组成。考察了催化剂种类和用量、反应温度、原料配比、反应时间等因素对辛酸蔗糖酯产率的影响,发现以二甲基亚砜为溶剂、蔗糖与辛酸摩尔比1∶9、磷钨酸用量为蔗糖质量的2.0%、110℃反应时间6h,蔗糖转化率达60%,产物产要是二酯。动力学研究发现,蔗糖反应级数为一级,反应表观速率常数为0.0059min-1(90℃)、0.0117min-1(110℃),反应表观活化能Ea=39.57kJ/mol。     

气相色谱法同时测定保健食品中的5种 不饱和脂肪酸

目的建立气相色谱法同时测定保健食品中亚油酸、α-亚麻酸、二十碳五烯酸(eicosapentaenoic acid,EPA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和二十二碳五烯酸(docosapentaenoic acid,DPA)的含量。方法样品先采用氢氧化钾甲醇溶液进行皂化处理,再用三氟化硼甲醇溶液甲酯化,经HP-FFAP色谱柱(30m×0.53 mm,1.0μm)分离测定。结果 EPA甲酯、DHA甲酯、DPA甲酯、亚油酸甲酯、α-亚麻酸甲酯分别在0.03927~1.178、0.04200~1.260、0.03449~1.035、0.08368~1.255、0.08482~4.241 mg/mL的浓度范围内线性关系良好,相关系数r均大于0.999;检出限分别为0.0039、0.0042、0.0034、0.0042、0.0042 mg/mL;加标回收率在91.1%~109.3%之间,相对标准偏差均小于5%。结论该方法操作简单快捷,适用于保健食品中亚油酸、α-亚麻酸、EPA、DPA和DHA的测定。     

Determination of short chain volatile fatty acids in silages from artichoke and orange by‐products by capillary gas chromatography

A simple, rapid and sensitive capillary gas chromatographic method was investigated to determine volatile fatty acids (VFA) in juice from silage made from artichoke and orange byproducts. The procedure uses a capillary column fused‐silica, 30 m×0.25 mm×0.25 mm ID and coated with FFAP‐TR. Centrifuged samples can be injected directly after lowering the pH to 1 and using a simple deproteinisation method. No adsorption, tailing or ghost phenomena occured. Separate analyses of VFA are quick and reliable. The average duration of an analyses is 7 min. The concentration, not only of the major acids, such as acetic acid, but also of the minor fermentation products such as butyric acid can be determined. The retention times of the products of fermentation and the extraction reagents were sufficiently different to avoid interference problems. © 1999 Society of Chemical Industry     

烤烟中草酸、苹果酸和柠檬酸含量的分析研究

以云南、四川、河南、重庆4个烟区云烟85、K326和红大3个品种的B2L、C2L、X2L等级烟叶为材料,采用GC法测定了169个烤烟烟叶样品中草酸、苹果酸和柠檬酸的含量,并对不同产地、品种、等级和部位烤烟烟叶的多元有机酸含量进行了统计分析,结果表明:①同一地区、K326和云烟85的相同等级烤烟烟叶中草酸、苹果酸和柠檬酸含量均没有显著差异;红大和云烟85的苹果酸含量没有显著差异,而红大的草酸和柠檬酸含量均高于云烟85;②不同地区、相同品种和等级的烤烟叶中,草酸含量均没有显著性差异;苹果酸、柠檬酸含量差异显著,含量的变化趋势为:河南重庆云南和四川;③同一地区和品种、不同部位的烤烟叶中,草酸含量均为上部明显高于中部和下部,而中部和下部相当;苹果酸含量在3个部位均有较大差别,依次为:上部中部下部;柠檬酸含量下部最高,中部与上部无显著差异。     

Grazing cows are more efficient than zero-grazed and grass silage-fed cows in milk rumenic acid production

Six rumen-cannulated Holstein cows in early lactation were assigned to 3 treatments: grazing (G), zero-grazing (ZG), and grass silage (GS) harvested from the same perennial rye grass sward in a 3 × 3 Latin square design with three 21-d periods. The objectives of this study were to investigate the underlying mechanisms for the reported elevation in milk rumenic acid (RA) concentration associated with G compared with ZG and GS, and to identify the important variables contributing to the milk RA response. Grazing animals were offered 20 kg of dry matter/cow per day; indoor animals were offered ad libitum grass or silage. A concentrate at a rate of 3 kg/d was also offered to all cows. Rumen, plasma, and milk samples were collected in the third week of each period. Data were analyzed by the MIXED procedure of SAS. Dry matter intakes were less for GS with no difference between G and ZG. Milk yield was greater for G than for ZG or GS. Milk fat and protein contents were less for GS with no difference between G and ZG. The combined intake (g/d) of linoleic and linolenic (18:3n-3) acids was different across the treatments (G: 433; ZG: 327; and GS: 164). Rumen pH was less for G with no difference between ZG and GS. Concentrations of volatile fatty acids and ammonia nitrogen in rumens were not different across the treatments. Wet rumen fill was less for G with no difference between ZG and GS. Vaccenic acid concentrations were different across the treatments in rumen (G: 12.30%, ZG: 9.31%, and GS: 4.21%); plasma (G: 2.18%, ZG: 1.47%, and GS: 0.66%) and milk (G: 4.73%, ZG: 3.49%, and GS: 0.99%). Milk RA concentrations were greater for G (2.07%) than for ZG (1.38%) and GS (0.54%). Milk desaturase index based on the ratio cis-9-14:1/14:0 was not different across the treatments. Milk RA yield per 100 g of linoleic acid and linolenic acid intake (efficiency) was 2.23, 1.50, and 0.62 g in G, ZG, and GS, respectively, suggesting that G cows were more efficient than ZG and GS cows in milk RA production. Stepwise regression analysis of a group of variables revealed that plasma vaccenic acid accounted for 95% of the variation in milk RA production. Milk desaturase index did not enter into the model. Overall findings suggest that substrate intake influenced milk RA production but it was not the only factor involved. There were differences in efficiency of milk RA production, which appears to depend on the factors regulating ruminal vaccenic acid production and its supply to the mammary tissue.     

Analysis of pomegranate seed oil for the presence of jacaric acid

BACKGROUND: Pomegranate seed oil is predominantly composed of triglycerides containing unsaturated fatty acids, including high levels of conjugated linolenic acids (CLnAs). The major CLnA component, punicic acid, is known to possess biological activity. Consequently, it is desirable to obtain a detailed characterisation of pomegranate seed oil fatty acid profiles, including molecules potentially co‐eluting with punicic acid, such as jacaric acid. RESULTS: Conjugated fatty acid profiles of a commercial sample of cold pressed pomegranate seed oil were characterised in detail by both gas chromatography of methyl esters and by ¹³C NMR spectroscopy. The methylation procedures were found to be critical for determination of accurate fatty acid profiles. GC analysis was unable to resolve jacaric acid from punicic acid, the major fatty acid present in pomegranate seed oil. To establish the presence or absence of jacaric acid, ¹³C NMR was employed. CONCLUSION: This is the first study to investigate pomegranate seed oil for the presence of jacaric acid. Punicic acid, eleostearic acid, and catalpic acid were confirmed by ¹³C NMR, but jacaric acid was not found. Thus, we have shown that punicic acid levels may be accurately measured by gas chromatography alone in pomegranate seed oil. Copyright © 2009 Society of Chemical Industry     

高效液相色谱法检测白酒中四种有机酸的方法研究

该研究建立了高效液相色谱（HPLC）法同时测定白酒中乳酸、乙酸、丁酸和己酸的方法,同时,研究了白酒样品中不同乙醇体积分数对四种有机酸保留时间的影响。结果表明,该方法测定四种有机酸在8～430 mg/L范围内线性关系良好（R2＞0.999）,精密度试验结果相对标准偏差（RSD）＜1.6%,加标回收率在97.24%～104.40%之间。丁酸和己酸的保留时间不受乙醇体积分数的影响,乳酸和乙酸的保留时间在乙醇体积分数＜3%时影响较小,与标样保留时间的差值在0.1 min以内。采用该方法对三种不同香型的白酒样品进行检测,能准确测定出酒样中四种有机酸的差异,并与其香型风格特点及实际情况相符,证明该方法可用于实际生产中白酒四种有机酸的检测。     

磁化处理对脂肪酸精馏过程的影响

在不同磁感应强度的磁场中,研究了磁化处理对脂肪酸精馏过程的影响。研究结果表明,磁场对脂肪酸的精馏过程有一定的影响,脂肪酸经磁化处理后,油酸的含量提高0.41%～0.64%,收率提高0.30%～0.47%;亚油酸的含量提高0.46%～0.69%,收率提高0.37%～0.54%;硬脂酸的含量提高0.44%～0.62%,收率提高0.34%～0.48%。由此可见,磁化处理有利于脂肪酸精馏过程的进行。     

硫酸水解法去除谷氨酸母液中的焦谷氨酸

焦谷氨酸没有鲜味,是谷氨酸产品中的无效成分,其安全性尚无定论.控制谷氨酸浓度为16 g/dL,焦谷氨酸的浓度为3.2 g/dL,实验研究了水解温度、硫酸加入量、水解时间等因素对降低谷氨酸母液中焦谷氨酸含量的影响.在保证谷氨酸回收率的基础上,确定出使焦谷氨酸含量达到1％及以下的最优水解组合:水解温度(95±5)℃、浓硫酸加入量(30％,V/V)、水解时间(2 h).在上述实验中,焦谷氨酸的初始含量均为20％.通过改变初始焦谷氨酸含量为20％～35％,最优水解组合下,水解后焦谷氨酸含量为0.96％～1.0％,仍可达到1％以下.     

内蒙古地区蓖麻材料种子中脂肪酸组成的测定及分析

采用索氏提取法、毛细管气相色谱法,首次对内蒙古地区8个品种、4个品系共12个蓖麻材料种子中的粗脂肪含量、脂肪酸组成进行测定,用IMB SPSS Statistics 19软件对数据进行分析,为内蒙古地区蓖麻高油品质育种研究及化工原料的选择提供参考数据。试验结果表明:12个蓖麻材料的种子百粒质量、种仁百粒质量、种仁率、百粒种子中粗脂肪含量、种子中粗脂肪含量、种仁中粗脂肪含量差异均达到极显著水平;蓖麻油酸是蓖麻粗脂肪的主要成分;12个材料的粗脂肪中8种脂肪酸含量、种子中8种脂肪酸含量差异均达极显著水平;基于种子中粗脂肪含量和种子中8种脂肪酸含量进行聚类的结果不相同,基于种子中8种脂肪酸含量和种子中蓖麻油酸含量进行聚类的结果基本一致。对种子中粗脂肪含量和8种脂肪酸含量进行线性回归分析,从回归方程可以看出,种子中的粗脂肪含量与硬脂酸、花生酸、亚油酸、蓖麻油酸含量呈正相关,与棕榈酸、油酸、亚麻酸、花生一烯酸含量呈负相关。     

Sorbic,benzoic and propionic acids in fishery products: a survey of the South Korean market

This study was conducted to provide basic data as part of a project to distinguish naturally occurring organic acids from added preservatives. Accordingly, we investigated naturally occurring levels of sorbic, benzoic and propionic acids in fish and their processed commodities. The levels of sorbic, benzoic and propionic acids in 265 fish and their processed commodities were determined by high-performance liquid chromatography–photodiode detection array (HPLC-PDA) of sorbic and benzoic acids and gas chromatography-mass spectrometry (GC/MS) of propionic acid. For propionic acid, GC-MS was used because of its high sensitivity and selectivity in complicated matrix samples. Propionic acid was detected in 36.6% of fish samples and 50.4% of processed fish commodities. In contrast, benzoic acid was detected in 5.6% of fish samples, and sorbic acid was not detected in any sample. According to the Korean Food and Drug Administration (KFDA), fishery products and salted fish may only contain sorbic acid in amounts up to 2.0 g kg^?1 and 1.0 g kg^?1, respectively. The results of the monitoring in this study can be considered violations of KFDA regulations (total 124; benzoic acid 8, propionic acid 116). However, it is difficult to distinguish naturally generated organic acids and artificially added preservatives in fishery products. Therefore, further studies are needed to extend the database for distinction of naturally generated organic acids and added preservatives.