Meat Flavor.

SUMMARY— Water-soluble, low molecular weight beef aroma precursors have been separated by column chromatography on Bio-Gel P-2, Amberlite XAD-2 and DEAE-Sephadex. Separations on the basis of gel filtration, adsorption, and anion exchange resulted in a number of fractions that developed roast beef aroma on pyrolysis, but differed in composition. Either sugar phosphates or free sugars are involved in aroma development. Tyrosine, phenylalanine, taurine and glutamic acid may be removed without affecting aroma. A number of amino acids were present in the aorma producing fractions in trace amounts, thus the requirement for their presence may be questionable. Creatine, creatinine and the purine derivatives (inosinic acid, inosine, and hypoxanthine) may also be removed without affecting aroma development.     

Water-Soluble Flavor and Odor Precursors of Meat. 3. Changes in Nucleotides, Total Nusleosides and Bases of Beef, Pork and Lamb During Heating

SUMMARY: Studies were made of the influence of heating on nucleotides and total purine nucleosides and bases of beef, pork and lamb muscle. lnosinic acid was the predominant nucleotide in all three species and it was degraded by heating. Adenylic acid increased during cooking in meat from all three species. Cytidylic, uridylic and guanylic acids were present in relatively low concentrations in meat from all three species and changed little during cooking. A rapid method for estimating total nucleotides resulted in greater variation than a specific method for measuring individual nucleotides.     

Bestimmung der Inosins?ure im Muskelgewebe

Zusammenfamung Für die Extraktion der Inosinsäure wurden optimale Bedingungen ermittelt, die chromatographische Erfassung (mit Dowex) modifiziert und die Bestimmung am Rindfleisch erprobt, wird spektrometrisch im UV durchgeführt.

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Determination of inosinic acid in muscle tissue

Summary A method for the determination of inosinic acid in muscle tissues was studied. The conditions of extraction of inosinic acid from tissues and its chromatographic separation on Dowex were described. For the determination of inosinic acid à spectrophotometric method was used. The method was tested on beef samples.

     

Water-Soluble Flavor and Odor Precursors of Meat. 5. Influence of Heating on Acid-Extractable Non-Nucleotide Chemical Constituents of Beef, Lamb and Pork

SUMMARY: Studies of the perchloric acid-extractable nitrogen, amino nitrogen, nonamino nitrogen, total carbohydrates, inorganic phosphate, free creatinine, creatine and total creatine plus creatinine of raw and heated beef, lamb and pork were made. Specific changes that occurred in the various constituents during heating are discussed. An extensive study of the influence of heating on certain chemical constituents of 80 beef samples of eight different cuts was also performed. Changes in chemical constituents during cooking of the various beef cuts were greatest in Choice clod and Good calf clod roasts, followed by round roasts and smallest changes occurred in rib steaks. Cooking caused significant increases in creatinine and decreases in amino and non-amino nitrogen, creatine and total carbohydrates. Creatine-creatinine was a better index of sensory quality than other chemical constituents studied.     

食盐腌制对油炸罗非鱼风味的影响

为探究食盐腌制对油炸罗非鱼风味的影响,本研究以蛋白质、脂肪酸、游离氨基酸以及呈味核苷酸含量为考察指标,通过感官评定结合顶空固相微萃取-气质联用(HS-SPME-GC-MS)方法分析食盐腌制对油炸罗非鱼可挥发性风味物质以及风味组分间的影响。结果表明,腌制前后的油炸罗非鱼风味变化明显,感官评价结果显示经过食盐腌制处理,油炸罗非鱼油脂味、肉香味增强,土腥味减弱;HS-SPME-GC-MS检测结果显示,食盐腌制过后油炸罗非鱼的可挥发性气味物质中1-辛烯-3-醇相对含量降至4.17%,ROAV值为5.70、(E,E)-2,4-癸二烯醛含量升为5.12%,ROAV值为100,肉香味和油脂味明显增强,土腥味明显降低;食盐腌制处理后油炸罗非鱼蛋白质与脂肪的含量显著降低(P<0.05),游离氨基酸与脂肪酸的消耗量增加,分别为38.94 mg/100 g和2.37 mg/g,且呈味氨基酸的占比与不饱和脂肪酸的含量发生显著降低(P<0.05),提供鲜味的肌苷酸(Inosinic acid,IMP)和鸟苷酸(Guanylic acid,GMP)含量显著(P<0.05)降低。实验证明食盐腌制对油炸罗非鱼的风味物质及组分影响显著(P<0.05),显著降低蛋白质和脂肪的含量,降解形成的挥发性物质显著提高,提高罗非鱼的油脂香、鲜味和肉香味,降低其土腥味和青草味,明显改善罗非鱼的品质。     

GUD1 (YDL238c) encodes Saccharomyces cerevisiae guanine deaminase, an enzyme expressed during post-diauxic growth

Purine salvage is a complex pathway allowing a correct balance between adenylic and guanylic derivatives. In this paper, we show that GUD1 (YDL238c) encodes guanine deaminase, a catabolic enzyme producing xanthine and ammonia from guanine. Importantly, Gud1p activity was higher during post-diauxic growth, suggesting that a decrease of the guanylic nucleotide pool could be required when cells shift from proliferation to quiescence.     

酱卤牛肉的质地及风味改良研究

在传统的酱卤牛肉生产制作工艺基础上,采用目前应用于肉类、鱼类等衍生产品中为提升样品质地特性的TG酶水解法,应用于酱牛肉制作前处理中,探究其对酱牛肉质地的影响,结果表明经过TG酶水解后,酱牛肉的质地得到改善。采用乳酸菌发酵法,通过前期乳酸菌发酵液对牛肉的发酵,探究其对酱牛肉风味的影响,结果表明经过乳酸菌发酵后,制作的酱牛肉风味得到明显增强。经过这两种工艺改良后的酱牛肉具有色泽均一、香味诱人、肉汁浓郁、肉质紧实有嚼劲的特点。     

Distribution of fatty acids in lipids as an aid to the identification of animal tissues. I.—Bovine,porcine, ovine and some avian species

Fat was extracted from various cuts of meat, from domestic and foreign sources. The majority of the samples were of pork, beef and lamb, but specimens from rabbit, various species of poultry, and three African ruminants, were also prepared. The fatty acid compositions of the samples were determined by gas-chromatography of their methyl esters, on polar and non-polar stationary phases. The use of such results both for the identification of the animal source of meat, and of the purity of lard samples, is discussed. It is suggested that the presence of lard in certain branched-chain fatty acids, characteristic of ruminant fat, provides evidence of adulteration with beef or mutton tallow.     

高效液相色谱法测定略阳乌鸡肌肉中的肌苷酸

以略阳乌鸡为研究对象,通过对色谱条件进行优化,建立了略阳乌鸡肌肉中肌苷酸的高效检测方法,并重点就不同前处理方法对略阳乌鸡肌肉中肌苷酸含量的影响进行研究。对样品进行冷冻干燥、脱脂和冷冻干燥脱脂处理,以0.05%磷酸三乙胺为提取溶剂提取肌肉中的肌苷酸,采用COSMOSIL Packed Column C₁₈(4.6 mm×250 mm,5μm)色谱柱,甲醇-磷酸三乙胺(体积比4∶96)为流动相进行梯度洗脱。结果显示,该方法下肌苷酸呈现良好的线性关系(R²>0.999),线性范围在12.2~97.6μg/mL;方法检测限分别为0.02、0.08μg/mL;方法精密度相对标准偏差为0.30%~4.78%;平均回收率为99%,相对标准偏差为2.71%。鲜肉样、冷冻干燥样、鲜肉去脂样、冷冻干燥去脂样的肌苷酸含量分别为0.014、0.018、0.023、0.029 g/kg。该实验建立了精确度高、重现性好的色谱方法;前处理方法采用先冷冻干燥再脱脂处理,肌苷酸的提取率高,为高效液相色谱法测定肌肉中肌苷酸含量的样品制备提供了思路。     

不同烹饪方法对牛肉挥发性风味物质的影响

为了研究不同烹饪方法(炸制、蒸制和煮制)对牛肉挥发性风味物质的影响,利用固相微萃取(solid phase microextraction,SPME)结合气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)联用技术对不同烹饪方法处理牛肉样品中挥发性风味物质进行分离鉴定....     

不同部位牛肉炖煮风味特征分析

目的：为深入了解炖煮牛肉的风味特征,对不同部位的牛肉（上脑、辣椒条、牛腩、牛臀和腱子肉）炖煮后进行全面分析。方法：采用感官评价、电子舌、快速气相电子鼻以及同时蒸馏萃取（simultaneous distillation extraction,SDE）结合气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）联用的方法对其物质构成进行定性定量分析。结果：感官评价发现牛腩香气重,肉汤味浓厚,油脂感强,肉质肥厚,炖煮口感最佳;电子舌分析发现,各样品的滋味存在明显差异;快速气相电子鼻分析发现5?种不同部位牛肉表现有明显差异的雷达图谱特征;同时SDE-GC-MS分析共检测出98?种挥发性物质,其中醛类物质最丰富,其次为醇类和酮类。腱子肉、辣椒条、牛腩、牛臀、上脑分别有44、50、20、31?种和47?种。结论：本研究结果为炖煮牛肉风味数据库的建立提供基础和理论参考。     

The evolution of lean beef: identifying lean beef in today's U.S. marketplace

Changes in cattle breeding and management coupled with extensive trimming of visible fat from retail cuts have resulted in the wide-spread availability of lean beef to U.S. consumers. Despite these changes, there is limited awareness regarding the reduced total fat content and the favorable fatty acid profile of beef. Relative to the calories it contributes, the impact of beef on the nutritional quality of the American diet via its contribution of protein and certain key micronutrients is often under appreciated. The following discussion documents the progressive reduction in fat content of U.S. beef during the past 30 years, highlights ongoing efforts to update United States Department of Agriculture nutrient data for beef, and summarizes findings from randomized controlled trials of beef and plasma lipid outcomes. Beef is a popular, nutrient-dense food and the availability of at least 29 lean cuts of beef in the U.S. marketplace can help consumers meet their cardiovascular health goals.     

青海省养殖三倍体虹鳟呈味核苷酸和挥发性风味物质的研究

本研究以国产虹鳟主产地-青海省龙羊峡、公伯峡和拉西瓦网箱养殖三倍体虹鳟为研究对象,采用高效液相色谱法检测分析呈味核苷酸物质,用顶空固相微萃取（headspace solid phase microextraction,HS-SPME）结合气相色谱-质谱联用（gas chromatgraph ymass spectrometry,GC-MS）分析挥发性化合物。结果显示:青海省养殖虹鳟鱼肉呈鲜味的肌苷酸含量为176~242 mg/100 g,其中,公伯峡和拉西瓦养殖虹鳟鱼肉肌苷酸含量显著高于龙羊峡产地组（P<0.05）;挥发性化合物共鉴定出69种,用气味活度值法（odor activity value,OVA）筛选出21种气味活性物质,其中壬醛、辛醛、2-壬烯醛、1-辛烯-3-醇和己醛对虹鳟鱼肉的气味贡献较大,主要呈青草味、油脂味、花香味和鱼腥味。公伯峡和拉西瓦养殖虹鳟鱼肉挥发性化合物含量整体较高。综上,青海省养殖三倍体虹鳟鱼肉呈味核苷酸含量较高,挥发性化合物种类丰富。拉西瓦和公伯峡养殖虹鳟风味相似,具有较高的肌苷酸含量和挥发性气味物质,龙羊峡养殖虹鳟新鲜度较高,鲜味及气味强度较低。研究结果可为养殖三倍体虹鳟鱼肉风味物质的分析和调控提供一定的理论依据。     

发酵牛肉干加工中理化特性与风味品质分析

为探究发酵牛肉干不同加工阶段理化性质和风味品质的变化,以牛臀肉为原料,接种木糖葡萄球菌和清酒乳杆菌制作发酵牛肉干,并对牛肉干在发酵前后及成品的营养成分、质构、色泽等理化特性及游离氨基酸、脂肪酸组成和挥发性风味物质对比分析。结果表明,与发酵前相比,接种复合发酵剂的牛肉干pH值、水分活度、亚硝酸盐残留量、硬度、咀嚼性均显著降低（P＜0.05）;红度值和游离氨基酸含量显著增加,且鲜味氨基酸占比最高;游离脂肪酸以棕榈酸、硬脂酸、油酸、亚油酸为主,其中油酸占比最大;发酵后牛肉检出47 种挥发性化合物,高于发酵前42 种,提高了牛肉干中醛、醇、酚、酯、酸、含氮及其他化合物的种类和相对含量。发酵牛肉干质构及色泽明显改善,游离氨基酸和脂肪酸含量增加,产品营养价值、风味品质及质量安全显著提高。     

Validation of acid washes as critical control points in hazard analysis and critical control point systems

A 2% lactic acid wash used in a large meat-processing facility was validated as an effective critical control point (CCP) in a hazard analysis and critical control point (HACCP) plan. We examined the microbial profiles of beef carcasses before the acid wash, beef carcasses immediately after the acid wash, beef carcasses 24 h after the acid wash, beef subprimal cuts from the acid-washed carcasses, and on ground beef made from acid-washed carcasses. Total mesophilic, psychrotrophic, coliforms, generic Escherichia coli, lactic acid bacteria, pseudomonads, and acid-tolerant microorganisms were enumerated on all samples. The presence of Salmonella spp. was also determined. Acid washing significantly reduced all counts except for pseudomonads that were present at very low numbers before acid washing. All other counts continued to stay significantly lower (P < 0.05) than those on pre-acid-washed carcasses throughout all processing steps. Total bacteria, coliforms, and generic E. coli enumerated on ground beef samples were more than 1 log cycle lower than those reported in the U.S. Department of Agriculture Baseline data. This study suggests that acid washes may be effective CCPs in HACCP plans and can significantly reduce the total number of microorganisms present on the carcass and during further processing.     

Decontamination of beef subprimal cuts intended for blade tenderization or moisture enhancement

The prevalence of Escherichia coli O157:H7 on beef subprimal cuts intended for mechanical tenderization was evaluated. This evaluation was followed by the assessment of five antimicrobial interventions at minimizing the risk of transferring E. coli O157:H7 to the interior of inoculated subprimal cuts during blade tenderization (BT) or moisture enhancement (ME). Prevalence of E. coli O157:H7 on 1,014 uninoculated beef subprimals collected from six packing facilities was 0.2%. Outside round pieces inoculated with E. coli O157:H7 at 10(4) CFU/100 cm2 were treated with (i) no intervention, (ii) surface trimming, (iii) hot water (82 degrees C), (iv) warm 2.5% lactic acid (55 degrees C), (v) warm 5.0% lactic acid (55 degrees C), or (vi) 2% activated lactoferrin followed by warm 5.0% lactic acid (55 degrees C) and then submitted to BT or ME. Prevalence (n=196) of internalized (BT and ME) E. coli O157:H7 was 99%. Enumeration of E. coli 0157:H7 (n=192) revealed mean surface reductions of 0.93 to 1.10 log CFU/100 cm2 for all antimicrobial interventions. E. coli O157:H7 was detected on 3 of the 76 internal BT samples and 73 of the 76 internal ME samples. Internal ME samples with no intervention had significantly higher mean E. coli O157:H7 populations than did those internal samples treated with an intervention, but there were no significant differences in E. coli O157:H7 populations among internal BT samples. Results of this study demonstrate that the incidence of E. coli O157:H7 on the surface of beef subprimal cuts is low and that interventions applied before mechanical tenderization can effectively reduce the transfer of low concentrations of E. coli O157:H7 to the interior of beef subprimal cuts.     

Microbiological status of fresh beef cuts

Fresh beef samples (n = 1,022) obtained from two processing plants in the Midwest (July to December 2003) were analyzed for levels of microbial populations (total aerobic plate count, total coliform count, and Escherichia coli count) and for the presence or absence of E. coli O157:H7 and Salmonella. A fresh beef cut sample was a 360-g composite of 6-g portions excised from the surface of 60 individual representative cuts in a production lot. Samples of fresh beef cuts yielded levels of 4.0 to 6.2, 1.1 to 1.8, and 0.8 to 1.0 log CFU/g for total aerobic plate count, total coliform count, and E. coli count, respectively. There did not appear to be substantial differences or obvious trends in bacterial populations on different cuts. These data may be useful in establishing a baseline or a benchmark of microbiological levels of contamination of beef cuts. Mean incidence rates of E. coli O157:H7 and Salmonella on raw beef cuts were 0.3 and 2.2%, respectively. Of the 1,022 samples analyzed, cuts testing positive for E. coli O157:H7 included top sirloin butt (0.9%) and butt, ball tip (2.1%) and for Salmonella included short loins (3.4%), strip loins (9.6%), rib eye roll (0.8%), shoulder clod (3.4%), and clod, top blade (1.8%). These data provide evidence of noticeable incidence of pathogens on whole muscle beef and raise the importance of such contamination on product that may be mechanically tenderized. Levels of total aerobic plate count, total coliform count, and E. coli count did not (P > or = 0.05) appear to be associated with the presence of E. coli O157:H7 and Salmonella on fresh beef cuts. E. O157:H7 was exclusively isolated from cuts derived from the sirloin area of the carcass. Salmonella was exclusively isolated from cuts derived from the chuck, rib, and loin areas of the carcass. Results of this study suggest that contamination of beef cuts may be influenced by the region of the carcass from which they are derived.     

挤压喷雾生产香菇粉工艺优化及产品理化性质

利用挤压喷雾技术生产香菇粉调味料。在单因素试验基础上进行正交试验优化挤压条件,通过对比挤压前后香菇粉的理化性质变化,研究香菇粉的使用条件、范围以及营养成分的变化规律。结果表明:最佳工艺为香菇原料初始水分含量50%、挤压温度150℃、模孔直径3 mm,此条件下制得的香菇粉香味物质I+G(I表示肌苷酸,G表示鸟苷酸)含量最高。挤压喷雾处理后的香菇粉脂肪含量下降,热性质稳定,表面更加致密光滑,粉状性质变佳且活性基团没有明显变化。挤压喷雾处理的香菇粉,在食品生产中可作为调味料和功能性添加剂使用。     

National Beef Market Basket Survey - 2006: External fat thickness measurements and separable component determinations for beef from US retail establishments

A market basket survey for beef retail cut composition at the retail level (four stores each from two chains in each city) was conducted in 11 US cities from January to March 2006. Beef cuts (n=17,495) were measured for external fat thickness with cuts from the chuck (0.05cm), round (0.05cm), and miscellaneous (0.04cm) having less (P<0.05) fat than cuts from the loin (0.11cm) and rib (0.11cm). Beef cuts (n=1327) were separated physically into separable components with round cuts having more (P<0.05) separable lean (96.63%) than chuck cuts (86.81%) and miscellaneous cuts (86.18%), which had more (P<0.05) separable lean than loin cuts (84.53%) with rib cuts (69.34%) having the lowest (P<0.05) separable lean. Chemical fat from the separable lean differed (P<0.05) between each cut category: round cuts (3.71%), miscellaneous cuts (4.99%), loin cuts (5.60%), chuck cuts (6.90%), and rib cuts (8.61%). Ground beef samples (n=235), with declared lean/fat percentages ranging from 73/27 to 96/4, had overall chemical fat values of 13.41% and moisture values of 67.42%. This survey documents the current beef retail cut and ground beef composition, which is helpful to those who need this information for various dietary and marketing purposes.     

基于脂肪酸指纹的放牧与舍饲牛肉真实性判别模型建立

为论证以脂肪酸指纹建立模型判别牛肉放牧和舍饲来源的可行性,从内蒙古优势肉牛养殖带8个旗县/区采集放牧和舍饲牛股二头肌、背最长肌和肋部皮下脂肪共91份,气相色谱法测定脂肪酸,进行主成分分析(principal component analysis,PCA)和描述性统计,并建立软独立建模分类(soft independen...