Measurement of meat color using a computer vision system

The limits of the colorimeter and a technique of image analysis in evaluating the color of beef, pork, and chicken were investigated. The Minolta CR-400 colorimeter and a computer vision system (CVS) were employed to measure colorimetric characteristics. To evaluate the chromatic fidelity of the image of the sample displayed on the monitor, a similarity test was carried out using a trained panel. The panelists found the digital images of the samples visualized on the monitor very similar to the actual ones (P < 0.001). During the first similarity test the panelists observed at the same time both the actual meat sample and the sample image on the monitor in order to evaluate the similarity between them (test A). Moreover, the panelists were asked to evaluate the similarity between two colors, both generated by the software Adobe Photoshop CS3 one using the L*, a* and b* values read by the colorimeter and the other obtained using the CVS (test B); which of the two colors was more similar to the sample visualized on the monitor was also assessed (test C). The panelists found the digital images very similar to the actual samples (P < 0.001). As to the similarity (test B) between the CVS- and colorimeter-based colors the panelists found significant differences between them (P < 0.001). Test C showed that the color of the sample on the monitor was more similar to the CVS generated color than to the colorimeter generated color. The differences between the values of the L*, a*, b*, hue angle and chroma obtained with the CVS and the colorimeter were statistically significant (P < 0.05–0.001). These results showed that the colorimeter did not generate coordinates corresponding to the true color of meat. Instead, the CVS method seemed to give valid measurements that reproduced a color very similar to the real one.     

Quality control of Toxoplasma gondii in meat packages: standardization of an ELISA test and its use for detection in rabbit meat cuts

Toxoplasma gondii causes severe disease both to man and livestock and its detection in meat after slaughtering requires PCR or biological tests. Meat packages contain retained exudate that could be used for serology due to its blood content. Similar studies reported false negative assays in those tests. We standardized an anti-T. gondii IgG ELISA in muscle juices from experimentally infected rabbits, with blood content determination by cyanhemoglobin spectrophotometry. IgG titers and immunoblotting profiles were similar in blood, serum or meat juice, after blood content correction. These assays were adequate regardless of the storage time up to 120 days or freeze-thaw cycles, without false negative results. We also found 1.35% (1/74) positive sample in commercial Brazilian rabbit meat cuts, by this assay. The blood content determination shows ELISA of meat juice may be useful for quality control for toxoplasmosis monitoring.     

果胶酶澄清菠萝汁最佳工艺研究

用果胶酶对菠萝浆进行酶解及最佳澄清工艺条件试验。单因素试验研究了果胶酶用量、酶解温度和酶解时间分别对菠萝汁透光率、可溶性固形物、出汁率、果胶含量的影响。在此基础上,通过二次正交旋转回归试验,得出了酶解条件的回归方程,确定了果胶酶对菠萝汁澄清的最佳工艺条件为果胶酶用量为80mg/kg、温度25℃、时间为60min。     

Substrate utilization during incubation in meat juice medium of psychrotolerant clostridia associated with blown pack spoilage

Several new species of psychrophilic or psychrotolerant clostridia have been identified in recent years. Some of these may be involved in ‘blown pack’ spoilage (BPS) of vacuum packaged beef. Organisms that cause BPS must produce large volumes of gas while utilizing substrates available in raw meat. Therefore, Clostridium algoriphilum, Clostridium algidixylanolyticum, Clostridium bowmanii, Clostridium frigoris, Clostridium frigidicarnis, Clostridium gasigenes, Clostridium lacusfryxellense, Clostridium psychrophilum, Clostridium tagluense and Clostridium vincentii were grown in meat juice medium (MJM), and changes in substrate concentrations were monitored to assess the potential for gas production by each organism. All 10 species were able to grow exponentially on glucose with simultaneous hydrolysis of glycogen, reaching maximum values for absorbance at 600 nm of 0.3–1.90. All ceased growing when glucose and glycogen were still detectable in the growth medium. C. frigidicarnis utilized most of the amino acids available in MJM and reduced the concentration of total amino acids by 10 mM. The other 9 species caused little or no reduction in amino acid concentrations. C. algidixylanolyticum and C. frigidicarnis utilized glucose, glycogen and lactate simultaneously during growth and after growth ceased. C. algoriphilum and C. frigoris commenced utilization of lactate, while continuing utilization of glucose and glycogen, only after growth ceased, but utilization of lactate by C. algoriphilum was weak. C. psychrophilum ceased utilization of glucose and glycogen but initiated weak utilization of lactate after growth ceased. The other 5 species did not utilize any substrate after growth ceased. The utilization of glucose, glycogen and relatively large amounts of lactate by C. algidixylanolyticum, C. frigoris, and C. frigidicarnis after growth ceased indicates that these organisms have the potential to cause BPS. The other 7 species appear to lack such potential.     

响应面法优化紫薯汁糖化工艺研究

以紫薯液化汁为原料,采用单因素试验对紫薯汁的糖化工艺进行研究,并通过响应面法优化得到紫薯汁糖化最佳工艺参数。结果表明,各因素对紫薯液化汁糖化的影响大小依次为时间、糖化酶添加量、温度和pH值。并得到紫薯汁糖化最佳工艺参数:温度60℃、pH值4.5、糖化酶添加量1.0%、糖化酶作用时间2.0 h。在此条件下,紫薯汁总糖含量为38.691 g/L。     

Prospects for new technology of meat processing in Japan

This review starts by introducing the history and underlying culture of meat production and consumption in Japan since early times, and the effects of social change on these parameters. Meat processing in Japan is described, and certain other related papers are also introduced. Automatic machines for meat cutting have been developed by the Japanese food industry and are currently being used throughout the world, particularly in Europe. Soft meat products specially produced for the elderly, along with diet meat products low in salt and calorie content for middle aged persons have recently gone into production. The intensification of color formation of meat using naturally occurring materials, and tenderization of sausage casing are discussed.     

利用果胶酶澄清西番莲果汁的工艺研究

通过单因素试验分析探讨了果胶酶的种类、添加量、pH、温度和时间对西番莲果汁澄清效果的影响,确定最佳的澄清工艺参数。     

Determination of added fat in meat paste using microwave and millimetre wave techniques

By evaluating the sensitivity of measurement parameters such as dielectric constant and microwave loss to fat content, several microwave and millimetre methods were compared to identify optimal frequency measurement bands. The results showed that the optimum frequency range lay between 8 and 20GHz where these parameters vary linearly, by up to a factor of 8, as fat is increased to 50% volume. A narrowband waveguide sensor cell was designed and constructed for this optimum range. The imaginary part (ε') of the complex permittivity demonstrated a better measurements resolution for determining fat content than the real part (ε'). The waveguide method has excellent repeatability as indicated by low relative standard deviation (RSD<4.88%). Temperature and sample density had minimal impact on the accuracy, repeatability and robustness of the final measurement system. A method of mixtures model for complex permittivity was shown to be a useful predictor of fat content.     

生姜汁在鹅腿肉嫩化中的应用研究

以剪切力为指标研究生姜汁对鹅腿肉的嫩化效果,通过单因素实验对生姜汁浓度、pH、处理温度进行了研究,并且进一步通过正交实验选择出最佳嫩化工艺。结果表明:生姜汁对鹅腿肉的嫩化效果十分显著(P<0.01),生姜汁对鹅腿肉嫩化的最佳工艺条件是:生姜汁浓度6%、pH6.0、处理温度为50℃。     

胡萝卜制汁常规工艺的改进

通过胡萝卜制汁常规工艺的改进,确定一种新的胡萝卜制汁工艺方法：即对未去皮胡萝卜进行低温（65℃）,长时间（70min）蒸汽保温处理。改进工艺后胡萝卜出汁率提高了20％。     

Determination of the boar taint compound skatole in meat juice by means of stable isotope dilution analysis-direct immersion-solid phase microextraction-gas chromatography/mass spectrometry

A novel SIDA-DI-SPME-GC/MS procedure for the quantitation of skatole in pork meat juice was developed and validated as a substitute for back fat sample analysis. System suitability was evaluated by determining the correlation between skatole concentrations in a subset of 38 paired meat juice and back fat samples selected from 90 fattened boars. High correlation was observed between both matrices and conclusions about the partitioning of skatole as well as of androstenone between fat and lean compartments in vivo were drawn.     

Relationships between biochemical characteristics and meat quality of Longissimus thoracis and Semimembranosus muscles in five porcine lines

Five porcine genetic lines which represent a high proportion of European pig production were fully characterized for meat quality parameters and muscle biochemical characteristics (Longissimus thoracis, LT, and Semimembranosus, SM). The line characterisation was based on 100 animals each representing Large White, Landrace, Duroc, Piétrain (Halothane negative) and Meishan (a Meishan/Large White crossbred line) prevalent genetic backgrounds. Different meat quality parameters (pH 45min, pH ultimate, electrical conductivity, and colour measurements), as well as muscle water holding capacity, muscle metabolic and contractile traits, fibre type, size and frequencies were measured and their relationships studied. The main differences in the LT were found between the Meishan and Piétrain genetic lines, in relation to the muscle fibre size (larger in Piétrain). The Duroc line was characterized by the muscle oxidative traits and the Landrace by the high percentage of fast glycolytic fibres. In SM, Duroc and Piétrain were distinguished from Landrace and Meishan according to the metabolic and contractile characteristics of this muscle. Large White tended to lie between the other breeds for many of the traits. The measured muscle characteristics were related to differences in drip loss and marbling values and could thereby influence the eating quality of pork. Overall the results show differences between the genetic lines for a number of muscle traits which could have impact on consumer appeal and eating quality. The present findings should serve to emphasise the importance of including eating quality as a trait in breed selection.     

高压均质技术在果汁加工中的应用

果汁产品感官、营养品质提升及其安全性保障是其加工领域近年来亟待解决的关键难题和研究热点,而非热加工技术在杀菌的同时能最大限度地保留果汁原汁原味,其有望替代热加工技术.其中,高压均质技术从一种传统的均质化工艺逐渐发展成为非热加工技术而备受关注.基于前期的研究成果,该文从高压均质技术的发展历史和设备原理出发,对高压均质处理...     

超高压技术在鲜榨桃汁加工中的应用

以鲜榨桃汁为原料,分别研究了热处理对其多酚氧化酶(PPO)、过氧化物酶(POD)的灭酶效果影响和超高压对其微生物的灭菌效果影响。结果显示:PPO、POD相对残存酶活随着热处理温度和时间的增加而减小,PPO对热处理的耐受性明显高于POD,最适灭酶条件为75℃1min;菌落总数、霉酵总数和乳酸菌数均随着超高压处理压力和时间的增加而减少,霉菌和酵母菌对超高压的耐受能力明显差于细菌,最适灭菌条件为600MPa10min;按以上最适条件生产的桃汁在1个月贮藏期内达到商业无菌。     

中国果蔬汁加工技术发展新趋势

简要介绍了中国果蔬汁加工新技术，如酶技术、膜技术、中温灌装技术等，并对这些技术的应用现状、存在问题及未来发展趋势进行了分析。     

Mitochondrial respiratory activity in porcine longissimus muscle fibers of different pig genetics in relation to their meat quality

The pig genetics of Duroc, Pietrain (MHS homozygote negative, PiNN), Pietrain (MHS homozygote positive, PiPP) and a F2-Duroc-Pietrain cross-breed were analyzed. The animals had comparable (P > 0.05) carcass weights, but the PiPP pigs had higher carcass yield and lean meat values (P < 0.05). Considering the meat quality characteristics, the PiPP showed a faster pH drop and higher electrical conductivity, drip loss, shear force as well as lightness and redness values (P < 0.05). The PiPP animals had less slow-twitch-oxidative (STO) and more fast-twitch-glycolytic (FTG) muscle fibers, whereas the results of the Duroc animals were converse (P < 0.05). The STO and FTG fibers of the PiPP animals were larger than those of the other genetics (P < 0.05). The analysis of the mitochondrial respiratory activity (MRA) using permeabilized longissimus muscle fibers resulted in no differences between the pig genetics before and immediately after slaughter. During chilling the MRA decreased in all pigs but to a higher extent in the PiPP pigs (P < 0.05).     

膜分离技术在菠萝汁澄清中的应用研究

采用超滤膜和微滤膜对菠萝汁进行膜分离澄清实验,研究了不同操作参数(如压力、温度和时间)对膜分离效率及膜的清洗的影响,并对膜分离效果进行评价。结果表明,膜分离菠萝汁的最佳工作条件为:操作压力为0.06MPa,温度45℃;PVDF微滤膜的抗污染能力比PS超滤膜强,清洗后膜透水速率的恢复率达到了97.8%;膜分离可基本保留菠萝汁中的营养成分,有效去除果汁中的大分子物质、微生物和部分色素,大大改善了菠萝汁的外观品质和微生物指标。     

Optimising operating conditions in ultrafiltration fouling of pomegranate juice by response surface methodology

The resistance‐in‐series model was used to analyse flux behaviour, which involved the resistances of membrane itself, the fouling and solute concentration polarisation. Response surface methodology was used to establish the relationships between operating parameters and ultrafiltration (UF) efficiency and thus to determine optimal conditions. Experiments were performed according to Box–Behnken design by changing the levels of three parameters, namely transmembrane pressure, feed flow rate and temperature. The fitted mathematical models allowed us to plot isoresponse curves. It was shown that the resistance due to solute concentration polarisation (R_cp) dominated the flux decline (40–74%). The fouling resistance (R_f) varied from 12 to 46%. To optimise simultaneously the three responses studied (R_f, R_cp and permeate limit flux), we applied the desirability function approach which allowed us to determine the best acceptable compromise. The selected UF conditions of the compromise were as follows: three bars, 0.95 L min^?1 and 30 °C. Optimal values of R_f, R_cp and permeate limit flux were equal to 18%, 72% and 19 L h^?1 m^?2, respectively.     

Prediction of lamb meat eating quality in two divergent breeds using various live animal and carcass measurements

This study investigated how accurately taste panel sensory assessments of meat eating quality (MEQ) could be predicted in two divergent lamb breeds, using predictors measured in live animals (weights, subjective conformation assessments, ultrasound, computed tomography (CT) and video image analysis measurements) and carcasses (weights, MLC fat and conformation classes, pH, temperature, carcass dimensions and cross-sectional tissue dimensions), individually and in optimal combinations. Grilled muscle samples from the pelvic limb (semimembranosus) and loin (Longissimus lumborum) of 120 Texel (TEX) and 112 Scottish Blackface (SBF) lambs were assessed by a trained taste panel for texture, juiciness, flavour, abnormal flavour and overall liking. Residual correlations (adjusted for fixed effects, age and sire) between MEQ and predictor traits were low to moderate in size (<±0.42). MEQ traits predicted best by single measurements were loin flavour and overall liking for TEX (using fat area in a CT scan or subcutaneous fat depth measured post-mortem), and for SBF were leg texture (using carcass weight or temperature) and juiciness (using CT fat area or shoulder conformation score). Combining live animal and carcass measurements increased MEQ prediction accuracies, compared with using either set alone, to explain >40% of residual variation in several MEQ traits, with the highest adjusted R² values for leg juiciness in TEX (0.53) and leg texture in SBF (0.59). The most useful predictors of MEQ depended on breed, with measurements of fatness generally more important in the lean breed and carcass size and muscling more important in the fatter breed.     

3，5-二硝基水杨酸法测定蔗汁中还原糖含量的研究

采用3,5-二硝基水杨酸法（DNS）测定蔗汁的还原糖含量。探讨了测量波长、DNS试剂用量、加热时间、放置时间对测定结果的影响。与目前分析所用的兰-艾农法、奥夫奈尔法比较,该方法操作简便,准确性较高,其线性方程为：Y=14．778x-0．6262,R2=0．9994,检出限为0．005mg／mL,加标回收率为99％～103％。用本法测定各种蔗汁的还原糖含量,获得满意的结果。