SPME/GC-MS Characterization and Comparison of Volatiles of Eleven Varieties of Turkish Cheeses

In this study, the volatile aroma profiles of a variety of economically important cheeses for the Turkish dairy sector were characterized. A total of 75 samples belonging to 11 Turkish cheese varieties, including Civil, Canak, Dil, Divle Tulum, Ezine, Hellim, Malatya, Mihalic, Orgu, Urfa, and Van Otlu, were comparatively studied for their volatile profiles. One hundred and twelve volatile compounds were identified in the cheeses by solid-phase microextraction combined with gas chromatography-mass spectrometry and the results are discussed based on their chemical classes (31 esters, 7 acids, 18 ketones, 3 aldehydes, 24 alcohols, 10 terpenes, and 19 miscellaneous compounds). Esters, ketones, and alcohols were the most abundant classes identified and were highly dependent on the variety of cheese. Principal component analysis was applied to aid the interpretation of the gas chromatography-mass spectrometry data and to distinguish the cheeses. Divle Tulum cheese had high levels of aldehydes, ketones, and alcohols and separated from all the other cheeses, and the cheeses including Dil, Hellim, Malatya, Orgu, and Urfa grouped together. The last group of cheeses had low levels of volatiles stemming probably from the restricting effect of scalding or cooking that are employed in the manufacture of these cheeses and on the biochemical and/or microbial activity. Civil, Ezine, and Mihalic cheeses had somewhat different aroma profiles, but they were closely located near the cheeses including Dil, Urfa, Orgu, etc. The results suggest that each variety of cheese had different volatiles profile and that the manufacturing technique as well as ripening conditions of the cheeses played a major role on the individual volatile profiles.     

Free fatty acids quantification in dairy products

Free fatty acids (FFA) in dairy products have experienced a resurgence of interest in recent years due to their associated health benefits, flavour potential and antimicrobial activity, as a direct cause of hydrolytic rancidity, and also because of the importance of accurate determination for quality, research and legislative purposes. Gas chromatographic analysis remains the technique of choice for FFA analysis; however, little advancements in method development have occurred over the last twenty years. The purpose of this review is to provide an overview of the methodology used to quantify FFA in dairy products by gas chromatography since its inception, to highlight some of the challenges experienced, to suggest aspects that could be improved to increase accuracy and throughput and reduce labour costs and solvent usage and to widen applications.     

Primary and Secondary Proteolysis in Eleven Turkish Cheese Varieties

Levels of proteolysis of 75 samples belonging to 11 Turkish cheese varieties, including Civil, Canak, Dil, Divle Tulum, Ezine, Hellim, Malatya, Mihalic, Orgu, Urfa, and Van Otlu, were comparatively studied. The cheeses were mainly produced using traditional methods; however, some varieties were industrially produced. Chemical composition and the levels of soluble nitrogen fractions of the cheeses varied depending on the cheese variety. Gel electrophoresis of the cheeses showed that the samples presented different gel patterns with α_s1-casein being extensively degraded in many cheeses; whereas the hydrolysis of α_s1-casein in Malatya and Hellim was observed to be limited. Peptide profiles by RP-HPLC of the water-soluble fractions were largely different for many of the samples, but some similarities were visualized. Multivariate analysis of the RP-HPLC data grouped the cheeses according to their peptide profiles. The results suggested that each variety of cheese had different levels of proteolysis. The manufacturing technique and ripening conditions employed have played a determinative role on the proteolytic patterns of the cheeses analyzed.     

六种鳞鲀亚目鱼肌肉脂肪酸分析和比较

从广东湛江市场收集到6种鳞鲀亚目鱼：丝背细鳞鲀、圆斑疣鳞鲀、双棘三刺鲀、中华单角鲀、黄鳍马面鲀、单角革鲀,采用国家标准方法测定组织中的水分和粗脂肪,经毛细管气相色谱法测定了肌肉中的24种脂肪酸组分,分析和比较了其饱和脂肪酸（SFA）、单不饱和脂肪酸（MUFA）和多不饱和脂肪酸（PUFA）的含量,结果显示,6种鳞鲀亚目的鱼体含水量67.2%~72.9%,粗脂肪占干重1.05%~1.42%,肌肉饱和脂肪酸含量为34.21%~43.45%,单不饱和脂肪酸含量为11.84%~19.43%,多不饱和脂肪酸含量为34.39%~48.86%。6种鳞鲀亚目鱼有较高含量的多不饱和脂肪酸,其ω-3系脂肪酸高于ω-6系脂肪酸,ω-3/ω-6为1.0~4.7,具有较高的脂肪酸营养价值,其中圆斑疣鳞鲀和黄鳍马面鲀的ω-3/ω-6分别为3.3和4.7。6种鳞鲀亚目鱼均具有较高的EPA（二十碳五烯酸）+DHA（二十二碳六烯酸）,含量为17.20%~37.49%,按鱼中肌肉的EPA+DHA含量,黄鳍马面鲀（37.49%）>圆斑疣鳞鲀（30.29%）>中华单角鲀（25.73%）>丝背细鳞鲀（23.82%）>双棘三刺鲀（18.82%）>单角革鲀（17.20%）,其中黄鳍马面鲀EPA+DHA高达37.49%±2.67%,具有较高的食用价值和医用价值。     

Comparison of Cheeses Made from Milk Having Normal and High Oleic Fatty Acid Compositions

Calcium salts of high‐oleic sunflower oil (> 86% oleic acid) were prepared and fed at 0% and 7.5% of diet dry matter weight to 8 Holstein cows in early‐ to mid‐lactation in a cross‐over experimental design. Oleic acid content of milk fat increased from 26% to over 40% and cholesterol‐raising saturates were reduced from 41% to 33%. Latin American white cheese, queso blanco, was produced from modified and normal milk. No differences in firmness were found between cheeses using penetration‐compression testing with an Instron machine. Sensory difference tests indicated no significant differences between cheeses. Latin American white cheeses made with high oleic milk are similar to traditional cheese.     

卤猪肉加工过程中游离脂肪酸、游离氨基酸及核苷酸变化分析

利用气相色谱质谱联用和高效液相色谱法检测分析了卤猪肉加工过程中游离脂肪酸、游离氨基酸及核苷酸的变化。结果表明,在加工过程中,总游离脂肪酸有效峰面积呈下降趋势,饱和脂肪酸也呈现下降的变化趋势,不饱和脂肪酸含量先增加后减少,在高温煮制1 h时达到最大值。总游离氨基酸的含量在卤猪肉加工过程中变化明显,在原料肉中总游离氨基酸含量为244.39 mg/100 g,其它样品中含量都显著(p0.05)高于原料肉,在二次煮制完成后达到最大值,为349.32 mg/100 g。谷氨酸在成品中的含量达到119.02mg/100 g,占总游离氨基酸的34.12%。呈味核苷酸检测结果显示,在加工过程中5'-IMP和5'-GMP的含量呈现下降趋势。由于加热导致核苷酸热降解,其降解产物肌苷的含量呈现上升趋势,在成品中检测到其含量显著(p0.05)高于原料肉中的含量。本研究结果为改进卤猪肉的生产工艺、提高产品品质提供了理论参考。     

Fatty Acid Composition and Trans Fatty Acids in Crisps and Cakes in Turkey's Markets

In this study, trans fatty acid and fatty acid composition of 57 crisps and 50 cakes sold in the markets in Turkey were determined. C 18:1, oleic acid, was the major fatty acid in all crisps and cake samples. The percentages of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) ranged between 27.98–46.57, 35.73–47.57, and 9.86–35.90 g/100 g fatty acids in crisps and 35.41–54.03, 25.89–44.87, and 10.52–26.97 g/100 g fatty acids in cakes, respectively. Total trans fatty acids ranged from 0.02 to 1.35 g/100 g fatty acids in crisps and 0.00 to 5.05 g/100 g fatty acids in cakes, respectively.     

11种品牌玉米油脂肪酸及异构体的主成分分析

对市售的11种品牌玉米油开展了脂肪酸(包括脂肪酸及其异构体)组成与含量的调查研究。采用气相色谱技术,结合主成分分析法,分析了不同品牌玉米油中脂肪酸的差异性和相关性。结果表明,11种品牌玉米油中共鉴定出19种脂肪酸,包括7种饱和脂肪酸,5种不饱和脂肪酸,6种反式脂肪酸(TFAs)和1种共轭亚油酸(t,t-CLAs),平均含量分别为14.18×10~(-2) g/g,80.32×10~(-2) g/g,1.47×10~(-2) g/g和0.23×10~(-2) g/g;其中,亚油酸(C18:2-9c12c)、油酸(C18:1-9c)和棕榈酸(C16:0)依次是玉米油中含量最多的3种脂肪酸;不同品牌玉米油中脂肪酸含量存在显著性差异(p0.05)。主成分分析揭示了不同品牌玉米油在脂肪酸含量上的相似性、差异性及脂肪酸之间相关程度,TFAs和CLAs正相关程度高。本研究为评价市售玉米油脂肪酸品质特征提供了较为全面的数据支撑。     

驼、牛、羊乳中脂肪酸含量的比较分析

采用气相色谱法对驼、牛、羊乳3 种乳中脂肪酸（fatty acids,FA）种类及含量进行比较。结果表明,3 种乳脂肪酸种类和含量差异显著。驼乳检测出33 种脂肪酸,棕榈酸相对含量最高（（23.73±2.17）%）;驼乳的多不饱和脂肪酸（polyunsaturated fatty acids,PUFA）相对含量（（4.09±0.54）%）显著高于牛乳和羊乳;牛乳中检测出29 种脂肪酸,棕榈酸相对含量最高（（27.44±2.45）%）;羊乳检测出34 种脂肪酸,且油酸相对含量最高（（30.89±3.57）%）。3 种乳中羊乳单不饱和脂肪酸（monounsaturated fatty acids,MUFA）含量最高（（35.26±3.86）%）。此外,结合主成分分析和相关性分析方法,对驼乳的脂肪酸含量进行进一步分析,结果显示,驼乳的饱和脂肪酸（saturated fatty acids,SFA）∶MUFA∶PUFA为1∶0.60∶0.08,驼乳更接近联合国粮食及农业组织/世界卫生组织推荐SFA∶MUFA∶PUFA为1∶1∶1。PUFA与短链脂肪酸（short-chain fatty acids,SCFA）、长链脂肪酸（long-chain fatty acids,LCFA）呈负相关,与n-6 FA相关性最大（0.978）;SCFA与LCFA呈正相关,n-6 FA与n-3 FA呈正相关。     

鳗鱼肝脏和骨中脂肪酸测定及比较

利用有机溶剂法对鳗鱼肝脏和骨中所含油脂进行提取,比较研究提取鳗鱼肝油和骨油的感官表现、理化指标及其所含脂肪酸成分的差异。结果表明:提取鳗鱼骨油比肝油的感官评价好,但二者均达到鱼油标准SC/T350 2—20 00《鱼油》中精制鱼油一级标准。相比较而言,提取鳗鱼肝油较鳗鱼骨油饱和脂肪酸含量少(分别为24.3%和34.9%),二者单不饱和脂肪酸含量接近(分别为48.0%和49.6%),鳗鱼肝油较鳗鱼骨油多不饱和脂肪酸含量多(分别为12.1%和3.3%),特别是EPA含量(分别为1.90%和0.6%)和DHA的含量高得多(分别为9.0%和1.6%),未定性脂肪酸含量鳗鱼肝油也略高于鳗鱼骨油(分别为15.7%和12.1%)。因此,从脂肪酸种类和含量来看,鳗鱼肝油较鳗鱼骨油营养价值更高、品质更好。     

发酵液中脂肪酸及乳酸的气相色谱分析

本文采用四甲基氢氧化铵中和羧酸,生成的羧酸盐在非质子偶极溶剂一二甲基乙酰胺中,室温下与碘甲烷发生亲核取代反应生成各酸对应的甲酯。甲酯衍生物在15％的邻苯二甲酸二壬酯与5％的吐温-80混合固定相上获得满意分离。用本法测定发酵液中一元脂肪酸及乳酸含量,平均回收率在90％以上。     

Short-Chain Fatty Acid Formation during Thermoxidation and Frying

Formation and evolution of the short-chain fatty acids originated by oxidation and remaining bound to the parent triglyceride, specifically heptanoate and octanoate, were studied during thermoxidation of palm olein, conventional sunflower oil and high-oleic sunflower oil at 180°C, as well as in real used frying oils of unknown history collected by Food Inspection Services. Fatty acids were quantified by gas–liquid chromatography following transesterification of samples and using methyl nonanoate and methyl heptadecanoate as internal standards. Alteration level was determined through analyses of polar compounds and polar fatty acids. Results showed high correlation coefficients between short-chain fatty acids and polar compounds or polar fatty acids, thus suggesting that quantification of short-chain fatty acids is a good indication of the total alteration level in used frying oils.     

Effect of Commercial Starter Cultures on the Fatty Acid Composition of Pastirma (Turkish Dry Meat Product)

ABSTRACT: The effects of different commercial starter cultures on fatty acid composition of the pastirma (Turkish dry meat product) were investigated. It was observed that using commercial starter cultures ( Staphylococcus carnosus, Staphylococcus carnosus + Lactobocillus pentosus, Staphylococcusxylosus + Lactobacillus sakei ) in the manufacturing of pastirma had significant effects on fatty acid composition (P < 0.01). However; effect of each starter culture on fatty acid composition was different. Most of the change in fatty acid composition occured during drying steps in pastirma manufacturing. TBA values of pastirma samples produced with starters were lower than those of the control group.     

广式香肠烘烤过程中游离脂肪酸的变化研究

利用气相色谱对广式香肠中游离脂肪酸 (freefattyacid ,FFA)组分进行色谱分析。广式香肠游离脂肪酸中主要是十六碳和十八碳的脂肪酸 ,其中 ,不饱和脂肪酸占的比例较大。烘烤过程中广式香肠FFA组成发生变化 ,不饱和脂肪酸的质量分数由 53%升至 6 0 % ,饱和脂肪酸的质量分数则由 4 7%降为 4 0 % ;烘烤过程中FFA含量逐渐增加 ,由未烘时的 7 12 9mg/g干重上升为 52h时的 13 74 6mg/ g(干重 ) ,成品中FFA含量达干重质量的 1%以上。各游离脂肪酸组分含量增加的程度不同 ,增加的速率为 :亚油酸 >油酸 >棕榈油酸 >硬脂酸 >棕榈酸     

内蒙古放牧和舍饲绵羊肉的脂肪酸特征

内蒙古盛产天然放牧牛羊肉,规模化舍饲也在农区和禁牧地区迅速发展,但不同饲养方式绵羊肉的脂肪酸特征缺乏系统评价。从内蒙古东北部、东中部和西部3 个典型纯牧业和农牧业区的7 个旗县采集草原放牧绵羊肉109 份和舍饲绵羊肉30 份,采用气相色谱法测定脂肪酸并进行主成分分析（principal component analysis,PCA）和描述性统计。结果表明：对各旗县绵羊肉样按放牧和舍饲2 种饲养方式或地域聚类进行PCA,呼伦贝尔和锡林郭勒草原放牧肉样聚集在一起,巴彦淖尔农区舍饲肉单独聚类,放牧和舍饲同地域内各旗县和品种聚类均未能分离;股二头肌和羊肥尾多数脂肪酸含量存在差异,但放牧和舍饲肉样间特征脂肪酸有一致性;羊肥尾脂肪酸对2 种饲养方式的区分效果比股二头肌好;放牧肉n-3多不饱和脂肪酸（polyunsaturated fatty acid,PUFA）、α-C18:3 n-3（α-亚麻酸）、C14:1和C14:0含量显著高于舍饲肉,放牧股二头肌和羊肥尾n-3 PUFA含量为舍饲的6.0 倍和4.2 倍,而α-亚麻酸含量为舍饲的4.6 倍和3.9 倍,舍饲绵羊肉n-6 PUFA、反式脂肪酸和C18:2 n-6c（亚油酸）、C18:1 n-9t（反式油酸）含量显著高于放牧肉。     

煎炸油在煎炸过程中脂肪酸组成的变化

以大豆油、棉籽油、棕榈液油和氢化油作为煎炸油,分别进行薯条和鸡翅的煎炸实验。结果表明：在煎炸过程中,各种煎炸油的脂肪酸含量均会发生一定的变化。采用C18:2/C16:0比值变化作为研究煎炸油脂肪劣变的指标,氢化油煎炸过程中C18:2/C16:0比值减少的程度最小(P＜0.05),证明其煎炸过程中脂肪酸的稳定性最好。但对于反式脂肪酸含量变化来说,均没有显著增加(P＞0.05),其中氢化油的反式脂肪酸含量从煎炸前的10.39%降低到煎炸后的6.66%,变化显著(P＜0.05),不过高反式脂肪酸含量的煎炸油在煎炸后其反式脂肪酸含量还保持在较高水平。     

绿豆胚芽中脂肪酸组成和维生素E的分析

利用气相色谱对绿豆胚芽中脂肪酸组成进行了测定,结果表明绿豆胚芽油中脂肪酸主要由棕榈酸和不饱和酸组成,其中棕榈酸占２５．１４％、油酸占９．７４％、亚油酸占４２．２２％、亚麻酸占１６．９７％,与一般食用油脂相比较,绿豆胚芽油中亚麻酸含量明显高于常用油脂的亚麻酸含量。同时利用高效液相色谱法测定了ＶＥ的含量,流动相选用甲醇∶水（９８∶２,Ｖ／Ｖ）,流速０．６ｍｌ／ｍｉｎ,检测波长２９２ｎｍ,在ＺｏｒｂａｘＣ１８柱上测定了ＶＥ的含量,ＶＥ的平均含量为２３１ｍｇ／１００ｇ胚芽油,ＶＥ的回收率为９２．００％～１０２．００％,相对标准偏差为４．３３％。     

驴骨、驴皮与阿胶中脂肪酸组成的比较

为探求阿胶、驴骨胶在脂肪酸组成方面的差异性,利用气相色谱法初步构建了驴骨、驴皮与阿胶中总脂肪酸成分的指纹图谱,并对阿胶、驴皮中特异性脂肪酸亚油酸、γ-亚麻酸的含量进行了比较研究。结果表明,驴皮、阿胶总脂肪酸的气相色谱指纹图谱具有较高相似性,除阿胶中含有植物油成分-花生酸(29.00)外,其它脂肪酸成分完全吻合;与驴皮、阿胶相比,驴骨的气相色谱指纹图谱则表现出一定的差异性,除缺少亚油酸(28.19)、γ-亚麻酸(29.50)外,驴骨中还含有多种特异性脂肪酸:羊脂酸(11.04)、十五烷酸(22.50)、11,14-二十碳二烯酸(30.95)。同时,作为特异性脂肪酸,亚油酸、γ-亚麻酸在驴皮(12.90%、1.10%)和阿胶(45.25%、5.48%)中具有较高的含量。综上所述,通过构建驴骨、驴皮与阿胶中总脂肪酸成分的指纹图谱以及阿胶中亚油酸、γ-亚麻酸含量测定可以为阿胶质量控制提供参考。