Lipid oxidative changes throughout the ripening of dry-cured Iberian hams with different salt contents and processing conditions

Hexanal content and TBARs were monitored in Semimembranosus and Biceps femoris muscles throughout the ripening of 46 dry-cured Iberian hams processed with different amounts of salt (6% vs. 3% w/w) and different processing systems (traditional vs. modified). Rancid odour and rancid flavour were sensorially analysed in the final product. Hams processed at higher temperatures during the drying stage, following a traditional system, showed lower values in this phase for hexanal content in both muscles (P<0.001), but TBARs showed the opposite behaviour (P<0.001 and P<0.05 for Semimembranosus and Biceps femoris, respectively). Salt content affected hexanal content of each muscle in a different way. Semimembranosus muscles from traditionally processed hams showed lower rancid flavour scores (P<0.001) while salt did not significantly affect rancid odour or aroma scores (P>0.05). Evidently the effects of salt content and processing temperature, within studied ranges, on lipid oxidation are limited. In fact, increased processing temperature, during the drying stage, does not lead to greater oxidation in dry-cured ham, in spite of the well known pro-oxidant effect of temperature.     

Influence of partial replacement of NaCl with KCl on formation of volatile compounds in Jinhua ham during processing

The influence of partial replacement of NaCl with KCl on formation of volatile compounds during Jinhua ham processing was evaluated using GC/MS system. Jinhua ham was treated with either 100% NaCl (I) or 60% NaCl and 40% KCl (II). Formation of volatile compounds increased in Jinhua hams during processing for both salt formulations, particularly at the end of the salting period. There were differences in volatile compound formation between formulations I and II after 45 days of processing. Contents of lipid-derived volatiles (hexanal) and Strecker aldehydes (2-methylbutanal and 3-methylbutanal) were higher in Jinhua hams treated with formulation II after 45 days of processing. Partial salt replacement of NaCl with KCl changed formation of volatile compounds in Jinhua hams and may have affected the flavor of finished products.     

基于电子鼻与SPME-GC-MS法分析咸鲅鱼加工过程挥发性风味成分变化

本文研究咸鲅鱼加工过程中挥发性风味成分的变化情况。采用电子鼻与固相微萃取-气质联用法(SPME-GC-MS)分别检测鲜鱼、腌制、干制4、10、24、36、48 h 7个不同阶段的风味成分变化。结果表明,腌制和干燥阶段风味变化明显。7个阶段挥发性风味成分种类数分别为27、37、53、42、47、45种以及51种。其中,成品咸鱼中三甲胺、乙二醇单丁醚、己醛、1-戊烯-3-醇、壬醛、正辛醛、庚醛、异戊醛含量较高,相对含量分别为11.05%、7.21%、6.65%、6.35%、5.69%、4.56%、3.52%和3.37%。腌制和干燥是风味产生的主要加工阶段。醛类、醇类、酮类和烃类是主要的挥发性物质的种类,其中己醛、壬醛、正辛醛、庚醛、(Z)-4-庚烯醛、苯甲醛、1-戊烯-3-醇、1-辛烯-3-醇是咸鲅鱼风味的主要成分。因此可通过控制腌制和干燥条件改善咸鲅鱼风味。     

Sensory characteristics of Iberian ham: Influence of salt content and processing conditions

Sensory characteristics of Semimembranosus and Biceps femoris muscles from 24 dry-cured Iberian hams were assessed. Hams were salted with different amounts of salt (6% and 3% w/w) and then ripened at different temperature conditions (traditional processing vs. modified processing). Hams manufactured using modified processing showed higher scores for dryness (P<0.05), hardness (P<0.05) and rancid flavour (P<0.001) in the Semimembranosus muscle than those processed in a traditional way. The Biceps femoris muscle of hams salted with 6% of salt was drier (P<0.05), harder (P<0.05) and more fibrous (P<0.01) than in hams salted with 3% salt. Salty taste was more intense in the Semimembranosus and Biceps femoris from hams with a higher level of salt (P<0.01 and P<0.001, respectively). A more intense rancidity in hams ripened in modified processing could affect the overall aroma. A decrease in salt content produces less salty hams, but the changes in texture traits should be also considered.     

Physicochemical changes throughout the ripening of dry cured hams with different salt content and processing conditions

Physicochemical characteristics of Semimembranosus and Biceps femoris muscles from 24 dry cured Iberian hams were analysed. The hams were salted with different amounts of salt (60 g kg^–1, HS, and 30 g kg^–1, LS, w/w) and then ripened at different temperatures (traditional processing, T, versus modified processing, M). The processing conditions did not significantly affect the moisture content and the chloride molality of Semimembranosus and Biceps femoris muscles (p>0.05) throughout ripening, although daily weight losses were significantly affected (p<0.01). The effect of the processing conditions on water activity was also rather limited as it was only significant at the drying stage. Colour a* values and chroma were significantly higher in Semimembranosus muscles from T hams than from M ones (p<0.01). Muscles from hams elaborated in a traditional system showed a higher number of tyrosine crystals than muscles from hams processed in a modified one, though only to a significant extent in Semimembranosus muscle (p<0.05). The salt concentration was higher in HS than in LS hams. HS hams showed higher weight losses in the salting and postsalting stages, owing to a more intense osmotic dehydration.     

米曲霉发酵罗非鱼及产物挥发性成分分析

采用米曲霉发酵罗非鱼制备腊鱼风味的咸味香精基料,初步确定发酵工艺如下:温度为37℃,接种量(米曲霉单位数/鱼肉重)为4×108cfu/g,料液比(鱼肉重/水重)为0.2(w/w),发酵时间为40h,产品具有明显腊鱼香味,无明显腥臭味,香气浓烈持久;采用聚二甲基硅氧烷/二乙烯基苯型涂层纤维萃取头(PDMS/DVB),通过固相微萃取和气质联用技术(SPME-GC-MS)分析鉴定发酵前后挥发性成分,分别鉴定出53种和75种化合物,其中发酵后产品中的醛类和醇类相对含量较高,检测到较高含量的壬醛、正己醛、辛醇、3-羟基丁酮、2-十一酮、1-辛烯-3-醇,其中壬醛、己醛和辛醇均具有特殊的脂肪气息,1-辛烯-3-醇具有明显的蘑菇和泥土味,2-十一酮具有典型牛奶香气。     

Distribution of volatile compounds in lean and subcutaneous fat tissues during processing of dry fermented sausages

The distribution of volatile compound among lean and fat tissues during processing of dry fermented sausages manufactured with either nitrite or nitrate was studied. Twelve volatile compounds were quantified by multiple headspace solid-phase microextraction (multiple HS-SPME) in combination with gas chromatography and mass selective detector (GC–MS) in the lean and fat tissues. The lean tissue contained the highest amount of volatile compounds derived from the lipid oxidation process (heptanal, octanal, nonanal, 1-octen-3-ol, 2-pentanone and 2-heptanone), amino acid degradation reactions (2 and 3-methylbutanal) and esterase activity (ethyl 3-methylbutanoate and ethyl hexanoate). However, the compounds pentanal and hexanal showed similar concentration in both tissues. Few differences were observed in the concentration of volatile compounds due to curing agents throughout the ripening stages although they disappeared after vacuum storage. In conclusion, the main tissue contributing to the flavour development in sausages is the intramuscular fat and the protein fraction. However, the fat tissue contributes to flavour perception due to the solubilization of volatile compounds in it.     

基于SPME-GC-MS和电子鼻分析方法分析薏仁饮料贮藏过程风味化合物变化

采用固相微萃取-气相色谱-质谱和电子鼻分析技术,通过相对气味活度值（relative odor activity value,ROAV）、主成分分析和聚类分析方法,对薏仁饮料保温贮藏过程中风味化合物、风味变化特征进行研究。结果表明：37?℃贮藏35?d,样品共检测出39?种主要的挥发性化合物,醛、醇、酮、烃、酯类化合物相对含量随贮藏时间延长而增加;贮藏期间ROAV不小于1的关键风味化合物有9?种,按贡献度大小依次为1-辛烯-3-醇、壬醛、3-甲基丁醛、己醛、辛醛、2-甲基丁醛、1-戊醇、辛醇、1-己醇;薏仁油脂氧化产生的醛、酮、酸和醇等挥发性化合物是薏仁饮料风味的主要成分;采用主成分分析及聚类分析能有效区分不同贮藏时间薏仁饮料,主成分分析显示样品贮藏初期和贮藏中后期的数据无重叠,其挥发性化合物存在差异,聚类分析结果将不同贮藏时间样品分为6?类,区分效果较好;通过主成分分析、ROAV和挥发性化合物相对含量变化,由此判定薏仁饮料贮藏期间品质劣变的特征性化合物为壬醛、己醛、辛醛、1-辛烯-3-醇。     

Flavor Variability and Flavor Stability of U.S.-Produced Whole Milk Powder

ABSTRACT:  Flavor variability and stability of U.S.-produced whole milk powder (WMP) are important parameters for maximizing quality and global competitiveness of this commodity. This study characterized flavor and flavor stability of domestic WMP. Freshly produced (<1 mo) WMP was collected from 4 U.S. production facilities 5 times over a 1 y period. Each sample was analyzed initially and every 2 mo for sensory profile, volatiles, color, water activity, and moisture through 12 mo storage. Selected volatiles were quantified using solid phase microextraction (SPME) with gas chromatography/mass-spectrometry: dimethyl sulfide, 2-methylbutanal, 3-methylbutanal, hexanal, 2-heptanone, heptanal, 1-octen-3-ol, octanal, 3-octen-2-one, and nonanal. Multiple linear regression with backwards elimination was applied to generate equations to predict grassy and painty flavors based on selected volatiles. All WMP were between 2% and 3% moisture and 0.11 and 0.25 water activity initially. WMP varied in initial flavor profiles with varying levels of cooked, milk fat, and sweet aromatic flavors. During storage, grassy and painty flavors developed while sweet aromatic flavor intensities decreased ( P  < 0.05). Painty and grassy flavors were confirmed by increased levels ( P  < 0.05) of lipid oxidation products such as hexanal, heptanal, and octanal. Hexanal, 2-heptanone, 1-octen-3-ol, and nonanal concentrations were best predictors of grassy flavor ( R ²= 0.38,  P  < 0.0001) while hexanal, 2-methylbutanal, 3-methylbutanal, octanal, and 3-octen-2-one concentrations were best predictors of painty flavor ( R ²= 0.61,  P  < 0.0001). These results provide baseline information to determine specific factors that can be controlled to optimize U.S. WMP flavor and flavor stability.     

Evolution of volatile aldehydes in Iberian ham matured under different processing conditions

To evaluate the influence of the Iberian ham processing conditions in the evolution of volatile aldehydes, 35 hams were processed in two plants following different conditions of relative humidity and temperature. For this, free fatty acids, peroxide values and volatile aldehydes were quantified in the hams. The highest increases in free fatty acids were noted during the drying stage in both processing plants. The drying period also revealed the greatest increase in peroxide values, where the highest values were in those hams processed at higher temperatures. The temperature during post-salting and drying had a marked influence on the formation of volatile aldehydes, being responsible for the differences in volatile compounds of matured hams.     

不同烹饪方式对干腌火腿理化、感官及风味品质的影响

熟肉制品的理化、感官和风味品质与烹饪方式密切相关,通过比较高压、微波、蒸制和煮制4 种烹饪方式对盘县火腿理化和营养特性、风味品质及感官评价的影响,筛选出最适宜盘县火腿的烹饪方法。结果表明：蒸制和煮制火腿色泽更好,pH值较高,分别为6.10和8.16,水分含量较高,分别为35.70%和35.20%,盐含量和烹饪损失率更低,分别为28.01%、5.15%和28.06%、4.99%;微波处理火腿粗脂肪和粗蛋白含量最高,分别为6.48%和55.14%;4 种烹饪方式均导致火腿中风味物质种类减少,但微波、蒸制和煮制可增加风味物质含量,特别是蒸制;聚类分析和Biplot分析同样显示出蒸制对原料火腿风味的改善作用;主成分分析结果表明,15 种特征香气成分中有7 种与蒸制火腿相关,包括2-甲基丁醛、3-甲基丁醛、己醛、壬醛、庚醛、辛醛和(E)-2-癸烯醛;感官评价结果表明,蒸制火腿的肉香属性得分最高,偏最小二乘回归相关性分析显示,这可能与其高含量的3-甲基丁醛、己醛和壬醛有关。盘县火腿最佳烹饪方式为蒸制,有助于改善其理化特性和风味品质。     

3个品牌干腌火腿皮下脂肪挥发性风味比较分析

为确定并分析各种挥发性风味活性物质对干腌火腿皮下脂肪整体风味的贡献,取金华金字火腿、宣威浦记火腿和长寿如皋火腿3 个不同年份的皮下脂肪,利用电子鼻技术和固相微萃取-气相色谱-质谱联用技术对挥发性物质进行分析。结果表明,电子鼻技术可以实现对皮下脂肪的香味轮廓进行快速区分,气相色谱-质谱联用技术共检测出皮下脂肪中的62 种挥发性风味物质,然后经相对气味活度值分析得到15 种有较大贡献的活性物质,分别为3-甲基丁醛、己醛、庚醛、辛醛、(E)-2-庚烯醛、壬醛、(Z)-2-辛烯醛、2-壬烯醛、6-壬烯醛、(Z,Z)-2,4-癸二烯醛、1-辛烯-3-酮、1-辛烯-3-醇、2-甲基丁酸乙酯、2-正戊基呋喃和2-乙基呋喃;主成分分析表明,这15 种活性物质可以实现对皮下脂肪挥发性风味的区分。     

传统加工咸鲅鱼的挥发性风味成分

为研究北方传统咸鲅鱼挥发性风味物质的变化,采用SPME-GC-MS(固相微萃取-气相色谱-质谱)和电子鼻技术研究两种市售利用传统方法制作的咸鲅鱼挥发性风味物质。对传统加工的5个阶段即鲜鱼、腌制后、干燥1 d、干燥3 d、干燥5 d的样品进行研究,分析加工过程中咸鲅鱼风味变化。电子鼻结果显示:5个加工阶段传感器对样品的响应值各不相同,2号(对氮氧化合物灵敏)传感器响应值最高,说明腌制和干燥过程咸鲅鱼风味发生变化,使得电子鼻能对不同加工阶段的样品进行区分。SPME-GC-MS结果显示:样品L1,L2,L3,L4,L5和J1,J2,J3,J4,J5中挥发性风味成分种类数分别为22,17,26,23,33种和32,29,25,36,33种。腌制和干燥阶段是咸鲅鱼风味生成的主要加工阶段,醛类和醇类构成了咸鲅鱼的主体风味,其中壬醛、己醛、庚醛、(Z)-4-庚烯醛、正辛醛、1-戊烯-3-醇、1-戊醇、(Z)-2-戊烯-1-醇、己醇、1-辛烯-3-醇、2-乙基呋喃是咸鲅鱼风味的主要成分。腌制和干燥过程是咸鲅鱼风味形成的主要过程,控制腌制和干燥条件可为咸鲅鱼工艺化生产提供理论指导。     

氧化及不同离子强度下猪肉肌原纤维蛋白结合风味物质的研究

文章研究了猪肉肌原纤维蛋白氧化导致其结构功能发生改变及氧化和不同离子条件下其结合风味物质的能力变化。实验选择了2-甲基丁醛、3-甲基丁醛、己醛、辛醛、壬醛等5种风味物质,利用顶空结合气相色谱观察肌原纤维蛋白结合风味物质的能力。结果表明：经氧化的肌原纤维蛋白二级结构及功能发生了变化。氧化处理的肌原纤维蛋白对2-甲基丁醛和壬醛有促释放的作用,对3-甲基丁醛、己醛和辛醛的作用呈2,2-偶氮二(2-甲基丙基咪)二盐酸盐(AAPH)浓度依赖性。Na+的添加促进了氧化蛋白对己醛的释放,而Na⁺、K⁺、Ca²⁺和Mg²⁺的添加促进了氧化蛋白对2-甲基丁醛、3-甲基丁醛、辛醛和壬醛的吸收。因此,在肉及肉制品的加工贮藏过程,氧化易造成蛋白结构和功能的改变,进而影响蛋白质结合风味物质的能力;另外,氯化钠在肉制品中被其它盐部分替代造成蛋白质所处的离子环境发生改变,导致蛋白质结合风味物质的能力改变,从而使肉制品风味发生改变。     

Effects of salt and temperature on proteolysis during ripening of Iberian ham

Fifty-five hams from Iberian pigs were processed using two different dry-curing techniques, traditional and modern. Salt content, non-protein nitrogen and its fractions (peptide, amino acid and volatile basic nitrogen) from Biceps femoris muscles were quantified. The existence of an overlapping effect of both temperature and salt content on the general non-protein nitrogen production was observed. The most intense proteolytic breakdown took place when higher temperatures were reached during the drying stage. The difference in salt concentration seems to contribute to generating different quantities in the non-protein nitrogen fractions. The inclusion at the end of the cellar stage of a stuffing period would permit increasing the accumulation of free amino acid in high salted hams.     

Solid-Phase Microextraction Method for the Determination of Volatile Compounds in Hydrolysates of Alaska Pollock Frame

The volatile compounds in Alaska pollock frame and Alaska pollock frame hydrolysates were analyzed by solid-phase microextraction and gas chromatography-mass spectrometry for identifying and comparing their flavor characteristics. The optimized SPME extraction conditions were 75 μm carboxen/polydimethyl siloxane fiber, adsorption time of 40 min, and extraction temperature of 65°C. Compared to Alaska pollock frame, Alaska pollock frame hydrolysates have more aromas detected and identified. Numerous volatile compounds were responsible for the overall aroma of Alaska pollock frame hydrolysates, such as 1-penten-3-ol, 2-penten-1-ol, ethyl acetate, methacrolein, 3-methylbutanal, hexanal, octanal, nonanal, 6-methyl-5-hepten-2-one, and so on. However, only a relatively small proportion showed similar composition. Although Alaska pollock frame hydrolysates was prepared by the same raw material, each Alaska pollock frame hydrolysate exhibited its individual flavor characteristics. Thus, the type of enzyme was probably one of the important factors affecting the differences of volatile compound composition and Alaska pollock frame hydrolysate flavor. Compared to other Alaska pollock frame hydrolysates, FPH5 (hydrolysates prepared by mixed enzymes for animal proteolysis) exhibited less fishy odor. It can be used as an effective approach to improve product quality.     

基于气相-离子迁移谱技术分析烤羊肉串的挥发性风味成分

为构建市售烤羊肉串特征风味指纹图谱,采用气相-离子迁移谱（gas chromatography-ion mobility spectroscopy,GC-IMS）对5家烧烤店的市售烤羊肉串风味物质进行测定与分析。结果表明:共检测鉴定出82种挥发性风味化合物,包括单体和二聚体,其中烤羊肉串样品共有的物质有:醛（戊醛、壬醛、辛醛、己醛、庚醛、异戊醛、苯甲醛、3-甲硫基丙醛）,酮（2-庚酮、2-丁酮、甲基庚烯酮、3-羟基-2-丁酮、γ-丁内酯）,醇（戊醇）和酯（乙酸乙酯）。通过构建加香辛料烤制和未加香辛料烤制的羊肉串风味指纹图谱,可明显观察不同市售烤羊肉串样品异同,羊肉串在加入香辛料烤制后甲基庚烯酮的含量降低;2-庚酮、丙酮和戊醇的含量升高;己醛、壬醛、庚醛、异戊醛、苯甲醛、3-羟基-2-丁酮的含量几乎不变,可能为羊肉串烤制后本身的特征风味物质。依据指纹图谱信息对烤羊肉串样本进行主成分分析（Principal Component Analysis,PCA）,结果显示,不同市售烤羊肉串样本特征风味具有一定的差异。综上,气相-离子迁移谱可检测烤羊肉串挥发性化合物风味成分和进行多变量分析,为烤羊肉串风味评价提供一定的理论和实际应用价值。     

加州鲈挥发性物质分析方法的建立与分析

通过对顶空固相微萃取(headspace solid phase microextraction,HS-SPME)-气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)法分析条件的优化及结合保留指数(retention index,RI)法和相对气味活度(relative odor activity value,ROAV)值对鲈鱼背部肌肉的挥发性风味物质进行萃取和分离鉴定,并以淡水鱼肉中典型的挥发性风味物质(己醛、庚醛、壬醛、癸醛、苯甲醛、1-辛烯-3醇、2,3-辛二酮)作为参照对象,以峰面积作为主要指标对HS-SPME-GC-MS分析条件进行优化。结果表明:HS-SPME-GC-MS 的较佳分析条件为鱼肉与饱和食盐水质量比7:3,萃取温度70 ℃,萃取时间40 min,解吸时间5 min,并经分析得到鲈鱼背部肌肉中含70种挥发性风味物质,主要为羰基类、醇类、烃类化合物,其相对含量分别为26.50%、7.15%、57.54%,其中己醛、庚醛、辛醛、壬醛、癸醛、2,4-癸二烯醛、1-辛烯-3-醇为新鲜鲈鱼背部肌肉中的主要挥发性风味物质。本实验方法操作简单,能够快速对鲈鱼背部肌肉中的挥发性风味物质进行萃取分析与鉴定。     

Lipolysis in dry-cured ham: Influence of salt content and processing conditions

Fatty acid composition of neutral lipids (NLs), polar lipids (PLs) and free fatty acids (FFA) from the intramuscular fat of Semimembranosus and Biceps femoris muscles was analysed in 46 Iberian dry-cured hams processed with different amounts of salt (6% high salt batch – HS vs. 3% low salt batch – LS w/w) and different processing systems (traditional – T vs. modified – M).

Total amounts of saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids in NLs decreased in similar proportions during processing of the hams as well as SFA, MUFA and PUFA in the PL fraction, whereas the amounts of SFA, MUFA and PUFA of FFAs significantly increased in Semimembranosus and Biceps femoris muscles. The amount of total fatty acids (TFA), from NLs and PLs, decreased in both muscles throughout the processing. Such a decline was more intense in HS hams than in LS ones, which could be a sign of a promoting effect of sodium chloride on lipolysis. However, the increase in FFA content throughout processing was not more intense in HS hams. Processing conditions studied in this work did not affect the changes in the fatty acid content of each fraction.     

A tentative characterization of white dry-cured hams from Teruel (Spain) by SPME-GC

Forty-six volatile compounds were identified and quantified in four parts (subcutaneous fat, and biceps femoris, semitendinosus and semimembranosus muscles) of 41 samples from Spain, France and Italy. The Univariate Brown–Forsythe test was used to determine the volatile compounds from each part of the ham that can distinguish the hams of Teruel from Iberian and white hams. Stepwise linear discriminant analysis was used in-tandem to refine the most discriminating volatile compounds. Six compounds (2-propanone, butanol, 3-methylbutanol, 3-methylbutanal, hexanal and limonene) were able to distinguish the dry-cured hams from Teruel, Iberian hams, and French and Spanish white hams simultaneously. MDS was also applied to the volatiles selected by SLDA. Information on the series of volatiles and individual compounds is also displayed.