Oxidative Stability of Restructured Beef Roasts As Affected by Cooking Temperature

Restructured beef roasts (2.5 kg) were cooked in a water bath at 70, 85, and l00°C to an internal temperature of 65°C, then stored at 4°C for 0 and 3 days. Storage increased (p ≤ 0.05) oxidation; after 3 days storage, roasts cooked at higher temperatures had higher (p ≤ 0.05) TBA values. Sensory panelists detected more (p ≤ 0.05) warmedover flavor (WOF) due to storage; however, after 3 days there was less (p ≤ 0.05) WOF in samples cooked at 70°C than in samples cooked at 85 or 100°C. Interaction (p ≤ 0.05) between cooking temperature and storage indicated oxidation proceeded more rapidly with higher cooking temperatures during refrigerated storage. Cook yield decreased as cooking temperature increased and expressible moisture was lower (p ≤ 0.05) at 100°C than at 70°C.     

LIPID OXIDATION IN MUTTON: SPECIES-RELATED AND WARMED-OVER FLAVORS

Effects of lipid oxidation in cooked mutton on species-related flavor and warmed-over flavor (WOF) intensities were studied using various additive treatments and post-cooking storage (versus no additive/no storage) as means to produce samples of varied lipid oxidation. Ground mutton was treated with 200 ppm sodium nitrite, 0.5% sodium tripolyphosphate, 0.05% sodium ascorbate, 3% sodium lactate, 0.002% propyl gallate, or water only (control), cooked to 74C, and aerobically stored at 4C for 0, 2, or 4 days. Nitrite-treated samples showed the least lipid oxidation as determined by the 2-thiobarbituric acid reactive substances (TBARS) and had more intense species-related (muttony) flavor than all other treated samples. Some samples exhibited high TBARS after 4 days but were still rated "slight" for WOF intensity, probably due to the strong species-related flavor that could have made WOF less perceivable. Accordingly, correlations, although statistically significant, were low between TBARS and WOF intensity or between species flavor intensity and WOF intensity.     

Sensory and chemical analysis of cooked porcine meat patties in relation to warmed-over flavour and pre-slaughter stress

Two independent sensory profiles were carried out to evaluate warmed-over flavour (WOF) development in cooked, chill-stored and reheated pork patties. The patties were derived from the Musculus semimembranosus of animals subjected to different pre-slaughter stress treatments. All patties were stored in oxygen permeable bags at 4°C for 0, 1, 2, 3 and 5 days to facilitate WOF development. In addition, thiobarbituric acid reactive substances (TBARS), conjugated dienes, pH, water content, total lipids and the fatty acid compositions of phosphatidyl choline (PC), phosphatidyl ethanolamine (PE) and total lipids, were measured in the cooked meat patties. A data analytical strategy involving Analysis of Variance-Partial Least Squares Regression (ANOVA-PLSR), to determine relationships between the design variables (WOF and pre-slaughter stress) and the sensory-chemical data, and PLSR to elucidate predictive links between the sensory and chemical data was utilised. WOF was found to involve the development of lipid oxidation derived nuance off-flavour and odour notes, e.g. rancid-like flavour and linseed oil-like odour, in association with a concurrent decrease in cooked pork meat-like flavour. The reduction in "meatiness", over the initial days, 0-2 of WOF development was attributed to the degradation of both, unstable sulfur-containing amino acids in meat proteins and sulfur-containing "meaty" aroma compounds. Whereas, at the later days, 3-5 of WOF development the "meaty" loss was ascribed to perceptual masking by lipid oxidation products. TBARS and conjugated dienes were found to be significant (P<0.05) predictors of the sensory terms related to the lipid oxidation aspect of WOF. Whilst the polyunsaturated fatty acid (PUFAs) contents of PE, PC and the total lipids were found to decrease with WOF development, reflecting their loss in lipid oxidation reactions. The sensory variation related to pre-slaughter stress appeared to be distinct from WOF variation and was described by a sour to sweet taste continuum. However, interactions were noted that indicated increasing pre-slaughter stress resulted in a decreased sensory perception of WOF. Moreover, pH and water content were found to significantly (P<0.05) predict the sensory effects resulting from pre-slaughter stress.     

Monitoring of warmed-over flavour in pork using the electronic nose - correlation to sensory attributes and secondary lipid oxidation products

Sensory analysis of meatballs was carried out to monitor the warmed-over flavour (WOF) development in cooked, cold-stored (at 4 °C for 0, 2 and 4 days) and reheated meatballs derived from M. longissimus dorsi (LD) and M. semimembranosus (SM) of pigs fed a standard diet supplemented with either 3% of rapeseed oil or 3% of palm oil. This was performed in combination with measurement of volatile compounds using a solid-state-based gas sensor array system (electronic nose) and gas chromatography/mass spectrometry together with measurement of thiobarbitoric acid reactive substances (TBARS). Subsequently, to elucidate the relations and predictability between the obtained data, the gas sensor responses were correlated with chemical (volatile and non-volatile secondary lipid oxidation products) and sensory data (flavour and odour attributes), using partial least squares regression modelling (PLSR). The TBARS, hexanal, pentanal, pentanol and nonanal all correlated to the sensory attributes associated to WOF formation. Moreover, the responses from eight of the MOS (metal oxide semiconductor) sensors within the electronic nose proved to be significantly related to WOF characteristics detected by both sensory and chemical analysis, while six of the MOSFET (metal oxide semiconductor field effect transistor) sensors were related to freshly cooked meat attributes determined by sensory analysis. The obtained results show the potential of the present gas sensor technology to monitor WOF formation in pork.     

A comparison of warmed-over flavour in pork by sensory analysis, GC/MS and the electronic nose

Pork muscle samples (M. longissimus dorsi and M. psoas major) were obtained from pigs given one of 4 dietary treatments, (i) control diet, (ii) supplemental iron (300 mg iron (II) sulphate/kg feed), (iii) supplemental vitamin E (200 mg dl-α-tocopheryl acetate/kg of feed) and (iv) supplemental vitamin E+supplemental iron. Warmed-over flavour (WOF) was evaluated by a trained sensory panel (n=8) for the four treatments cooked and refrigerated at 4?°C for up to 5 days. Gas chromatography mass spectrometry (GC/MS) and Electronic nose analysis was performed on a subset of the full design which included samples of M. longissimus dorsi, treatments (ii) and (iii) and M. psoas major with treatment (i) for 0 days of WOF development. Day 5 of WOF development was included in the subset and represented by samples of M. longissimus dorsi, treatment (iv) and M. psoas major, treatments (ii) and (iii). Bi-linear modeling was used to determine the correlation of GC/MS and electronic nose data to sensory data. Also, the reproducibility and reliability of electronic nose data was evaluated by repeating the analysis of samples in a different laboratory and with a time difference of approximately 11 months. Mean-centring was used to normalise the data from these two different electronic noise data sets. GC/MS data correlated to sensory data with specific compounds (e.g., pentanal, 2-pentylfuran, octanal, nonanal, 1-octen-3-ol and hexanal), proving to be good indices of oxidation in cooked samples of M. longissimus dorsi and M. psoas major. Electronic nose data correlated to sensory data and separated the sensory variation. The reproducibility of this data was high with the second set of samples being predictive of the first set.     

Determination of the Freshness of Beef Strip Loins (M. longissimus lumborum) Using Electronic Nose

A beef strip loins (Musculus longissimus lumborum) freshness determination method utilizing electronic nose (e-nose) was investigated in this paper. Fresh beef strip loins samples were stored at 4°C continuously for 10 days. Total viable count (TVC) index, total volatile basic nitrogen (TVB-N) index, and e-nose responses to beef strip loins samples were measured every day. TVC and TVB-N index rose with the increase of storage time. Principal component analysis (PCA) only partially discriminated beef samples under different storage days. Stochastic resonance (SR) signal-to-noise ratio (SNR) spectrum discriminated all beef samples successfully. Beef strip loins freshness discrimination model was developed using SR SNR maximums (SNRmax) linear fitting regression. The proposed method forecasted beef freshness with high accuracy. It is holds promise in meat freshness determination applications.     

Monitoring of warmed-over flavour in pork using the electronic nose – correlation to sensory attributes and secondary lipid oxidation products

Sensory analysis of meatballs was carried out to monitor the warmed-over flavour (WOF) development in cooked, cold-stored (at 4 °C for 0, 2 and 4 days) and reheated meatballs derived from M. longissimus dorsi (LD) and M. semimembranosus (SM) of pigs fed a standard diet supplemented with either 3% of rapeseed oil or 3% of palm oil. This was performed in combination with measurement of volatile compounds using a solid-state-based gas sensor array system (electronic nose) and gas chromatography/mass spectrometry together with measurement of thiobarbitoric acid reactive substances (TBARS). Subsequently, to elucidate the relations and predictability between the obtained data, the gas sensor responses were correlated with chemical (volatile and non-volatile secondary lipid oxidation products) and sensory data (flavour and odour attributes), using partial least squares regression modelling (PLSR). The TBARS, hexanal, pentanal, pentanol and nonanal all correlated to the sensory attributes associated to WOF formation. Moreover, the responses from eight of the MOS (metal oxide semiconductor) sensors within the electronic nose proved to be significantly related to WOF characteristics detected by both sensory and chemical analysis, while six of the MOSFET (metal oxide semiconductor field effect transistor) sensors were related to freshly cooked meat attributes determined by sensory analysis. The obtained results show the potential of the present gas sensor technology to monitor WOF formation in pork.     

无损检测光动力杀菌鲜切苹果气味及糖度

目的利用电子鼻及高光谱成像无损检测技术评价光动力杀菌对鲜切苹果气味及糖度的影响。方法通过电子鼻,基于雷达图、负荷加载(loadings)和主成分分析(principal components analysis,PCA)评价光动力处理鲜切苹果风味变化。卷积平滑(Savitzkye-Golay,S-G)和多元散射矫正(multiplicative signal correction,MSC)预处理高光谱数据,以偏最小二乘法建立糖度数学模型。结果鲜切苹果贮藏8 d后挥发性物质增加,其中2、8号传感器在区分其香气成分中起关键作用,结果显示光动力处理对鲜切苹果气味影响较小。高光谱S-G模型拟合效果较好,预测均方根误差为0.5320,相关系数r为0.8452,且光动力处理有助于维持其贮藏前期可溶性糖分含量。结论电子鼻及高光谱技术可以无损检测鲜切果蔬品质,可为光动力处理作为新型非热杀菌技术在鲜切果蔬保鲜的应用提供理论参考。     

Potent odorants formed by lipid peroxidation as indicators of the warmed-over flavour (WOF) of cooked meat

Hexanal (I), 1-octen-3-one (II), (E,E)-2,4-nonadienal (III), (E,E)-2,4-decadienal (IV) andtrans-4,5-epoxy-(E)-2-decenal (V) were quantified in cooked meat (beef, pork, chicken) in which the warmed-over flavour (WOF) was observed after storage for 2 days at 4°C. Odour activity values of the compounds on the basis of odour threshold values in water revealed that compounds I and V contributed most strongly to WOF. During the storage, free iron but not metmyoglobin catalysed the increase of compounds I, II, IV and V in models containing the lipids of beef meat.     

Chemical and Instrumental Analyses of Warmed-Over Flavor in Beef

Raw, freshly cooked, stored and recooked beef muscle samples were assessed by chemical, instrumental and sensory methods of analyses for flavor quality, with particular emphasis on warmed-over flavor (WOF). The character notes used by a trained sensory panel to describe WOF were cardboardy, rancid, stale, and metallic. Samples analyzed by direct gas chromatography utilizing either packed or fused silica capillary columns showed that compounds usually associated with lipid oxidation reactions could be used as marker compounds to follow the development of WOF. Of the many compounds that appeared to be markers, hexanal and 2,3-octanedione as well as total volatiles showed a highly significant degree of correlation when compared to sensory scores and 2-thiobar bituric acid (TBA) numbers. Many of the volatile compounds that were identified in WOF meat samples were also found in the distillates prepared for the TBA reaction.     

基于气味指纹预测养殖大黄鱼贮藏过程中的品质变化

在模拟市场环境冰鲜贮藏条件下,采用电子鼻对大黄鱼不同贮藏时间的挥发性气味及相关指标变化进行分析。以室温贮藏作对照,对电子鼻数据进行主成分分析与最小线性回归分析,并与挥发性盐基氮、三甲胺及菌落总数进行最小线性回归分析,建立大黄鱼在冰鲜贮藏条件下品质变化的预测曲线。结果表明：冰鲜和室温保存的大黄鱼挥发性盐基氮、三甲胺与菌落总数值均随着贮藏时间的延长而增多;电子鼻能很好地区分冰鲜和室温贮藏的大黄鱼随时间的气味变化;基于电子鼻最小线性回归分析拟合的气味信号值与该贮藏条件下的菌落总数、挥发性盐基氮、三甲胺相关系数,冰鲜贮藏条件下分别为0.9884、0.9889和0.9648,室温分别为0.9878、0.9915和0.9924。     

氧化牛油对天然牛肉调味基料的赋香效果

以冷冻牛骨肉末为原料,采用热—压浸提、调控酶解、美拉德反应集成技术制备牛肉调味基料,研究脂肪适度氧化对牛肉调味基料的赋香效果。在美拉德反应阶段添加不同程度的氧化牛油,采用电子鼻、电子舌结合气—质联用仪分析牛肉调味基料的风味。结果表明:与酶氧化牛油相比,热氧化牛油对牛肉调味基料的特征香气贡献作用略大;氧化时间2h时,热氧化和酶氧化对体系特征牛肉香气贡献作用最大,其特征醛类物质含量分别占到总风味物质的5.57%和4.16%。     

超高压处理协同低温贮藏对卤牛肉品质的影响

为了探究不同处理技术对卤牛肉品质的影响,以卤牛肉为原料,研究4 ℃贮藏、超高压处理、超高压结合4 ℃处理后对卤牛肉品质的影响。以常温贮藏为对照组,4 ℃贮藏、超高压处理、超高压结合4 ℃为处理组,为卤牛肉新型保鲜方式提供参考。结果表明:与对照组相比,4 ℃贮藏、超高压处理、超高压结合4 ℃处理后的卤牛肉的感官评分均高于对照组。贮藏16 d后,处理组的质构、挥发性盐基氮（TVB-N）、pH、TBA等指标的变化趋势均慢于对照组,其中超高压结合4 ℃处理组TVB-N值为15.254 mg/kg,TBA值仅增大5%,菌落总数为1.78 lg CFU/g,而常温对照组第8 d已达到5.21 lg CFU/g。通过电子鼻分析,超高压结合4 ℃处理组气味未发生明显变化, 各项指标在贮藏16 d后仍接近0 d,与其他处理组相比,超高压结合4 ℃处理可以更好的延长卤牛肉的贮藏期。综合可知,超高压结合4 ℃处理组为贮藏卤牛肉的最优前处理方法。     

Discrimination of Chicken Seasonings and Beef Seasonings Using Electronic Nose and Sensory Evaluation

This study examines the feasibility of electronic nose as a method to discriminate chicken and beef seasonings and to predict sensory attributes. Sensory evaluation showed that 8 chicken seasonings and 4 beef seasonings could be well discriminated and classified based on 8 sensory attributes. The sensory attributes including chicken/beef, gamey, garlic, spicy, onion, soy sauce, retention, and overall aroma intensity were generated by a trained evaluation panel. Principal component analysis (PCA), discriminant factor analysis (DFA), and cluster analysis (CA) combined with electronic nose were used to discriminate seasoning samples based on the difference of the sensor response signals of chicken and beef seasonings. The correlation between sensory attributes and electronic nose sensors signal was established using partial least squares regression (PLSR) method. The results showed that the seasoning samples were all correctly classified by the electronic nose combined with PCA, DFA, and CA. The electronic nose gave good prediction results for all the sensory attributes with correlation coefficient (r) higher than 0.8. The work indicated that electronic nose is an effective method for discriminating different seasonings and predicting sensory attributes.     

冷水浸泡和沸水漂烫预处理对牛肉挥发性成分的影响

采用电子鼻技术、同时蒸馏萃取和气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）法研 究2 种预处理方式（冷水浸泡2 h和沸水漂烫40 s）对牛肉挥发性风味成分的影响。电子鼻分析结果表明,2 种预处 理方式牛肉的气味有明显差异。GC-MS测定结果表明：冷水浸泡2 h和沸水漂烫40 s的牛肉中分别鉴定出35、39 种 挥发性成分,2 种预处理方式牛肉中共鉴定出48 种挥发性成分,其中共有成分26 种,且2 种预处理方式牛肉中的挥 发性成分种类和含量有较大差异。冷水浸泡能更多地保留牛肉风味物质中的醛类物质,使牛肉的脂香味浓郁,香味 成分更丰富,因此预处理温度是造成牛肉风味差异的主要因素。     

葡萄冷藏时间对贮后货架期芳香物质的影响

为明确冷藏时间对葡萄贮后货架期芳香物质的影响,以‘无核寒香蜜’葡萄为试材,运用顶空固相微萃取-气相色谱-质谱（head space solid-phase microextraction and gas chromatography mass spectrometry,HS-SPME-GCMS）联用技术检测冷藏15、45 d出库后常温货架期间（0、3、6 d）挥发性成分的变化,并采用电子鼻对不同冷藏期（15、30、45、60 d）出库后常温货架的果实进行判别分析。结果表明,葡萄的挥发性成分主要由酯类、醛类和醇类组成,主要挥发性成分为乙酸乙酯、青叶醛、正己醇、叶醇、香茅醇。冷藏45 d后常温货架期间酯类和醇类物质的相对含量均低于冷藏15 d同期果实,醛类物质则较高。电子鼻结果表明,通过线性判别分析可以有效区分不同冷藏期的葡萄,贮后货架期间,除冷藏15 d出库后0、3 d货架重叠外,其余冷藏期货架期间均互不重叠,即随着贮后常温货架的延长,葡萄中挥发性成分变化较大,电子鼻区分效果越加明显;负荷加载分析分析得出,W1W（硫化氢、萜烯类）、W1S（芳香成分）、W2S（乙醇）传感器对挥发性气味的贡献较大,与HS-SPME-GC-MS分析相佐证。因此,HS-SPME-GC-MS结合电子鼻对葡萄冷藏时间及贮后货架期的芳香物质判别具有可行性。     

Electronic nose analysis of volatile compounds from poultry meat samples,fresh and after refrigerated storage

Electronic nose technology has previously been applied to the assessment of the quality of red meats, pork and fish, but not poultry products. In the present study the ability of the electronic nose to assess the microbiological quality of raw poultry meat as a function of storage time and temperature was investigated. Four types of chicken pieces (boneless breast with and without skin, wings and thighs) were stored for up to 2 days at 13 °C (the maximum allowable temperature in poultry processing environments) or for up to 5 days at 4 °C (refrigeration temperature for raw poultry products prior to shipping or further processing). Saline rinses of meat samples were serially diluted in tryptic soy broth to 10^?10. The rinses and their associated serial dilutions were analysed on an electronic nose with 12 metal oxide sensors in order to determine the specificity and sensitivity respectively of the assay. Principal component analysis (PCA) maps of the data confirmed that the electronic nose could differentiate volatile compounds associated with individual types of meat samples properly stored at 4 °C from those maintained at processing temperature, 13 °C, for a comparable time, even as early as day 1 of storage. Differences in headspace gases from any type of meat sample stored at one temperature could also be determined with increased storage time. However, data from samples stored at 4 °C clustered more tightly in PCA maps than those associated with samples maintained at 13 °C, indicating a greater diversity in volatile compounds at the higher temperature. We have shown herein that the electronic nose can detect changes in the volatile compounds associated with chicken meat based on product storage time and temperature; the technology can assess length of sample storage as well as deviation from refrigeration temperature. Published in 2002 for SCI by John Wiley & Sons, Ltd.     

By-products from herbs essential oil production as ingredient in marinade for turkey thighs

Herb decoctions—the aqueous extract of rosemary, sage and thyme, left as by-product after steam distillation of essential oils, were investigated as a source of antioxidants in marinades for turkey thigh meat. Lipid oxidation after marinating, cooking and chill storage (warmed over flavour, WOF) was assessed by thiobarbituric acid-reactive substances (TBARS), GC-MS and sensory judgement on marinated and untreated meat. Results showed that marinating with herb decoctions, which exerted antioxidant activity (free radical scavenging), was an effective means of retarding lipid oxidation in raw and cooked meat. Meat from the rosemary marinade had the lowest TBARS values and volatile levels, while the control samples showed the highest values throughout the marinating, cooking and storage period. Oxidative changes in meat marinated with thyme and sage were significantly more advanced than in meat marinated with rosemary decoction. The partial least squares regression (PLS-R) showed that control samples were strongly related to the oxidation variables (volatiles, TBARS, rancidity) while the marinated meat had high scores for spicy and acidic odour and flavour. Results indicated that antioxidants contained in herb decoction, could be exploited in marinades to prevent rancidity in stored, heat-treated turkey meat products.     

基于GC-IMS和电子鼻技术分析贮酒容器对凤香型白酒香气成分的影响

为研究贮酒容器对凤香型白酒香气成分的影响,采用电子鼻与气相色谱离子迁移谱(gas chromatography-ion mobility spectrometry,GC-IMS)技术对不同容器贮存的凤香型白酒风味物质及理化指标——乙醇体积分数、总酸、总酯、可溶性固形物质量浓度及pH值进行分析和比较,以期为凤香型白酒贮存...