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.     

RP-HPLC法同时测定糕点中安赛蜜、苯甲酸、山梨酸、糖精钠和脱氢乙酸

建立反相高效液相色谱法(RP-HPLC同时测定糕点中安赛蜜、苯甲酸、山梨酸、糖精钠和脱氢乙酸。该方法糕点样品经处理后,采用SunFire C185μ4.6 mmmm反相色谱柱,流动相为甲醇:磷酸盐缓冲液(pH6.7=793等度洗脱,流速为1.0 mL/min检测波长230 nm柱温为30℃进样量为20μ。线性范围0.2 mg/L120 mg/L检出限0.4 mg/kg1.0 mg/kg加标回收率为87.7%105.3%相对标准偏差小于5%。结果表明,该方法操作简便、结果可靠,可用于同时检测糕点中安赛蜜、苯甲酸、山梨酸、糖精钠和脱氢乙酸。     

无铬酸、氢氟酸、硝酸的新型不锈钢抛光工艺

不锈钢抛光工艺，传统配方多有铬酸、氢氟酸、硝酸等毒害较大物质，对环境污染较大，同时采用高温酸洗，去除氧化皮等，使成本增加。本文介绍不锈钢的粗抛、细抛、精抛是将酸洗、化抛、电抛融为一体的不锈钢抛光组合工艺，不仅显著地降低了环境污染，还确保了不锈钢光亮如镜的靓兰色泽，这在生产实践中得到验证。     

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。     

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。     

气相色谱法测定鱼油中的二十碳五烯酸、 二十二碳六烯酸和二十二碳五烯酸

目的通过优化鱼油中二十碳五烯酸(eicosapentaenoic acid,EPA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和二十二碳五烯酸(docosapentaenoic acid,DPA)的测定条件,建立鱼油中EPA、DHA和DPA气相色谱定量检测分析方法。方法采用正己烷处理样品,经色谱柱(Agilent,Elite-WAX,30 m×0.25 mm,0.25μm)分离鱼油中的EPA、DHA、DPA甲酯标准品,并进行定量检测。结果 EPA浓度在0.36~3.6 mg/m L、DHA浓度在0.37~3.7 mg/m L、DPA浓度在0.16~1.62 mg/m L的范围内与峰面积的线性良好,相关系数r0.999。在80%、100%、120%添加水平下,EPA、DHA和DPA的检出限分别为0.01%、0.03%、0.009%,EPA、DHA和DPA的回收率分别为96.2%、96.4%、95.7%。结论气相色谱法灵敏度高、准确、重现性好,适用于鱼油中EPA、DHA和DPA的含量测定。     

Photostabilization of ascorbic acid with citric acid, tartaric acid and boric acid in cream formulations

This study involves the evaluation of the effect of certain stabilizers, that is, citric acid (CT), tartaric acid (TA) and boric acid (BA) on the degradation of ascorbic acid (AH(2) ) in oil-in-water cream formulations exposed to the UV light and stored in the dark. The apparent first-order rate constants (0.34-0.95 × 10(-3) min(-1) in light, 0.38-1.24 × 10(-2) day(-1) in dark) for the degradation reactions in the presence of the stabilizers have been determined. These rate constants have been used to derive the second-order rate constants (0.26-1.45 × 10(-2) M(-1) min(-1) in light, 3.75-8.50 × 10(-3) M(-1) day(-1) in dark) for the interaction of AH(2) and the individual stabilizers. These stabilizers are effective in causing the inhibition of the rate of degradation of AH(2) both in the light and in the dark. The inhibitory effect of the stabilizers is in the order of CT > TA > BA. The rate of degradation of AH(2) in the presence of these stabilizers in the light is about 120 times higher than that in the dark. This could be explained on the basis of the deactivation of AH(2) -excited triplet state by CT and TA and by the inhibition of AH(2) degradation through complex formation with BA. AH(2) leads to the formation of dehydroascorbic acid (A) by chemical and photooxidation in cream formulations.     

Simultaneous determination of dehydroacetic acid,benzoic acid,sorbic acid,methylparaben and ethylparaben in foods by high-performance liquid chromatography

In this study, an analytical method was established and validated to determine the preservatives such as dehydroacetic acid, benzoic acid, sorbic acid, methylparaben and ethylparaben. The level of preservatives was measured by solvent extraction method adding purification process with carrez reagent and by high-performance liquid chromatography (HPLC). The developed analytical method was successfully applied to determine the concentration of preservatives in various food samples including jam, cheese and soy sauce, displaying high accuracy (recoveries between 87.8% and 110%) and precision (%RSD less than 5.92% and 7.72% for intra-day and inter-day, respectively). To verify the applicability of the improved test method, selected 13 food items and collected 521 samples were monitored. As a result, all the cases met the Korea standard guidelines. Consequently, this study is expected to contribute to the safety management of preservatives for domestic distribution and imported food.

     

Determination of mycophenolic acid, penicillic acid, patulin, sterigmatocystin, and aflatoxins in cheese.

A method has been developed for detection of aflatoxins, mycophenolic acid, patulin, penicillic acid, and sterigmatocystin in cheese. It is based on selective extraction with a mixture of equal volumes of 5% sodium chloride, methanol, and aceton, precipitation of caseins at -25 C, defatting with hexane, and removal of extraneous matter by transfer of mycotoxins to chloroform and ethyl acetate. The extract is purified further by column chromatography. Mycotoxins are quantitated on thin layer chromatograms by fluorescence comparisons. Mycophenolic acid, patulin, and penicillic acid are visualized with diethylamine. The limits of detection in cheese are about 20 micrograms/kg for mycophenolic acid, patulin, and sterigmatocystin, 30 microgram/kg for pencillic acid, and 1 microgram/kg for aflatoxins B1 and M1.     

富硒豆豉中安赛蜜、苯甲酸、山梨酸、糖精钠、 脱氢乙酸的测定

目的建立高效液相色谱法同时测定富硒豆豉中安赛蜜、苯甲酸、山梨酸、糖精钠和脱氢乙酸的分析方法。方法样品经过沉淀剂沉淀蛋白后过滤,使用C_(18)反向色谱柱(pH1.5～9.0)分离,用甲醇-乙酸铵溶液作为流动相进行洗脱,经高效液相色谱紫外检测器和二极管阵列检测器检测,检测波长为230 nm。结果 5种添加剂具有良好的线性关系,相关系数均大于0.9990,检出限为1.0～2.0mg/kg。应用该方法检测富硒豆豉的加标回收率为90.2%～101.1%,相对标准偏差小于2.0%。结论本研究建立的方法有效可行,结果可靠,适用于富硒豆豉中5种添加剂的检测。     

超高效液相色谱法同时测定饮料中的山梨酸、苯甲酸、脱氢乙酸、糖精钠和安赛蜜

目的建立用超高效液相色谱法(ultra performance liquid chromatography,UPLC)同时测定饮料中的山梨酸、苯甲酸、脱氢乙酸、糖精钠和安赛蜜的分析方法。方法样品中山梨酸、苯甲酸、脱氢乙酸、糖精钠和安赛蜜用水提取,经BEH C_(18)柱(2.1 mm×100 mm,1.7μm)分离,在波长225 nm处检测。结果此方法的线性范围是5~100μg/mL,回收率为95.5%~100.2%,相对标准偏差(relative standard deviation,RSD)为1.0%~3.1%。结论此方法简便快速,准确可靠,灵敏度高,可用于同时检测饮料中的山梨酸、苯甲酸、脱氢乙酸、糖精钠和安赛蜜。     

毛细管区带电泳法测定食品中山梨酸、苯甲酸和糖精的含量

采用毛细管区带电泳(CZE),以10mmol/L硼砂和0.1%草酸(pH8.26)为缓冲液,分离电压20kV,检测波长230nm,压差进样时间10s,以焦性没食子酸为内标,在7min内分离和测定了食品中山梨酸、苯甲酸和糖精的含量。线性范围:山梨酸4～640mg/L、苯甲酸4～640mg/L、糖精4～1000mg/L;样品加标回收率在95.0%～98.4%,相对标准偏差(RSD)均小于4%。方法简便、快速、准确。     

高效液相色谱法同时测定食品中安赛蜜、苯甲酸、山梨酸、糖精钠以及脱氢乙酸

建立食品中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸等甜味剂和防腐剂的高效液相色谱测定法。方法采用C18(5um,4.6mm×150mmi.d)反相色谱柱,流动相:v(甲醇)∶v(0.02moL/L乙酸铵溶液)=(5∶95),流速1.0mL/min,检测波长230nm,柱温30℃,进样量5μL。样品的检出限1.5～4.4mg/kg,线性范围1～10mg/L,加标回收率95.5%～103.6%,相对标准偏差为0.95%～2.81%(n=6)。该法具有样品预处理简单,灵敏度高,分析时间短等优点,可用于食品样品的直接测定。     

Role of peroxyacetic acid, octanoic acid, malic acid, and potassium lactate on the microbiological and instrumental color characteristics of ground beef

Abstract: This study evaluated the effects of peroxyacetic acid (PAA), malic acid (MA), octanoic acid (OA), and potassium lactate (KL) followed by mixing with trisodium phosphate (TSP) and an ultra‐chilled CO₂ snow shower on microbial counts of Escherichia coli (EC), coliform (CF), aerobic plate count (APC), and Salmonella Typhimurium (ST) on inoculated beef trimmings and the instrumental color attributes of the resultant ground beef. Beef trimmings inoculated with EC and ST were treated with either 0.02% PAA; 2% MA; 0.04% OA; or 2% KL, followed by mixing with 10% TSP and rapid chilling with CO₂ snow shower. Treated trimmings were then ground, packaged, displayed under simulated retail conditions, and sampled on days 1, 2, 3, 5, and 7 for microbial counts and instrumental color characteristics. PAA, MA, OA, and KL reduced (P < 0.05) the microbial counts of EC, CF, APC, and ST during display. Among treatments, OA was most effective on EC, CF, ST, and APC during retail display. Chilling beef trimmings with CO₂ improved instrumental color characteristics of the produced ground beef but made little difference in reducing microbial counts during display. During retail display, ground beef produced from beef trimmings treated with antimicrobials tended to maintain redness, myoglobin redox form stability (630 nm/580 nm), and overall instrumental color characteristics. Practical Application: This research provides a practical and cost‐effective decontamination technology for beef processors that can be immediately implemented in the ground beef production chain. Using antimicrobial intervention coupled with rapid chilling could benefit the meat industry by preserving the quality attributes of ground beef during retail display under aerobic packaging environment.     

甘蓝型油菜籽粒油酸、亚油酸、亚麻酸和蛋白质含量变异及相关性分析

对现有种质资源进行分析,有利于甘蓝型油菜品质育种亲本选配及种质创新。本研究对312份甘蓝型油菜种质资源进行近红外光谱检测,通过相关性分析和聚类分析探究油菜籽粒中油酸、亚油酸、亚麻酸和蛋白质含量及它们间的相关性。结果表明：油酸含量与亚油酸及蛋白质含量呈极显著负相关,亚油酸含量与蛋白质含量呈极显著正相关;在阈值为2时,可将312份种质资源划分为6个类群,其中第Ⅱ类群适于选育高油酸亲本,第Ⅲ类群适于选育高亚麻酸亲本,第Ⅳ、Ⅵ类群适于选育高亚油酸、高蛋白亲本。     

高效液相色谱法测定山楂制品中的苯甲酸、山梨酸和糖精钠

对液相色谱法测定山楂片中苯甲酸、山梨酸、糖精钠进行了方法优化,对色谱条件进行了调整,采用ODS—Cl8型(150 mm×4.6 mm,5μm)色谱柱,流动相甲醇—0.02 mol/L乙酸铵(体积比5∶95),流速为1.0 mL/min,采用紫外检测器,检测波长为230 nm。方法测定结果的相对标准偏差小于2%(n=4),平均回收率大于90%,该法满足实验要求。     

HPLC检测白桦脂酸、齐墩果酸和熊果酸方法的建立

建立了一种简单、快速可同时检测白桦脂酸、齐墩果酸和熊果酸的高效液相色谱法,色谱条件为Kromasil C_(18)(5μm,4.6×250mm)色谱柱,流动相为甲醇∶水=91∶9(磷酸调pH为3.0),流速0.6mL/min,柱温为室温,检测波长为210nm,进样量20μL,紫外检测器;三种三萜酸线性关系良好,R~2均在0.9998以上,最低检出限为0.21~0.26μg/mL,定量限为0.71~0.87μg/mL,加标回收率在96.43%~101.33%之间且精密度、稳定性和重复性良好。     

毛细管气相色谱法同时测定果汁中山梨酸、苯甲酸、脱氢乙酸

目的建立同时快速测定果汁中山梨酸、苯甲酸、脱氢乙酸的毛细管气相色谱法。方法果汁样品经液-液萃取后,样品中山梨酸、苯甲酸、脱氢乙酸经过毛细管柱分离,气相色谱FID检测器进行检测。结果本方法在10 min内可完成定性和定量检测,方法的线性范围为100～500 mg/L,线性相关系数都大于0.999,3种添加剂的测定结果的相对标准偏差(n=7)都小于3%,山梨酸、苯甲酸、脱氢乙酸在100、300、600 mg/L添加水平的回收率为89.9%～108.9%。结论该方法快速、灵敏、性价比高,适合测定果汁中山梨酸、苯甲酸、脱氢乙酸的测定。     

Changes of lactose, lactic acid, and acetic acid contents in Serra cheese during ripening

 Changes in the quantities of lactose, lactic acid and acetic acid in Serra cheese were monitored using a triplicate two-way factorial design over a ripening period of 35 days (sampling at 0, 7, 21 and 35 days) throughout the cheesemaking season (sampling in November, February and June). The amount of lactose in total solids of cheese (TS) decreased slowly from 6.17% to 0.21% (w/w_TS) as ripening time elapsed. As a result of sugar metabolism, the lactic acid content increased from 0.07% at day 0 to 2.10% (w/w_TS) by 35 days, whereas the acetic acid content increased from 0.00% to 0.24% (w/w_TS) during the first week. The lactose content was statistically correlated with the lactic acid content but not with the acetic acid content. Received: 18 November 1996     

HPLC法测定熟肉制品中苯甲酸、山梨酸和脱氢乙酸的含量

建立HPLC法测定熟肉制品中苯甲酸、山梨酸和脱氢乙酸含量的方法。色谱柱为Thermo Acclaim TM C18(250 mm×4.6 mm,5μm);流动相:甲醇-0.02 mol/L乙酸铵溶液(7:93,v/v);流速:1.0m L/min;检测波长:230 nm;柱温:35℃。结果表明,该方法具有良好的精密度与稳定性,苯甲酸、山梨酸和脱氢乙酸分别在1.17~27.96、1.11~26.63、1.08~25.89μg/m L范围内线性良好,其平均回收率分别为90.4%、94.4%、86.8%。实验结果表明该方法简便、结果准确、重现性好,适用于熟肉制品中苯甲酸、山梨酸及脱氢乙酸的含量测定,为熟肉制品中添加剂的检测奠定了基础。