The Effect of Local Cooking Methods on Polycyclic Aromatic Hydrocarbons (PAHs) Contents in Beef,Goat Meat,and Pork as Potential Sources of Human Exposure in Kisumu City,Kenya

Roasted meat is known to be a major source of human exposure to PAHs. The contribution of direct-heat charcoal-roasted, electric- oven grilled, and shallow-pan fried meat to human exposure in Kisumu City was not known although the three modes of cooking meat are very prevalent. This study analyzed the concentrations of the PAHs in raw beef, goat meat, and pork, investigated the effect of direct-heat charcoal roasting, electric-oven grilling, and shallow-pan frying on these concentrations, and compared their concentration levels with international standards for foods in order to assess the potential risks to consumers. Samples were taken from three popular meat-roasting hotels within Kisumu City, Kenya. Extraction of PAHs was done using liquid-liquid partition after saponification with alcoholic potassium hydroxide followed by clean-up on a silica gel column and final analysis by gas chromatography-mass spectrometry (GC-MS). Roasting and shallow-pan frying introduced new PAHs and significantly (P ≤ 0.05) increased the concentrations of those existing in raw meat. Direct-heat charcoal roast beef had 5 new PAHs and a total mean PAH content of 17.88 μg/kg, compared with a mean of 1.39 μg/kg for raw beef, with the potent dibenz(a,h)anthracene also being detected. Direct-heat charcoal roasted goat meat had three new PAHs and a total mean PAH content of 4.77 μg/kg, compared with a mean of 2.13 μg/kg in raw meat, with the potent benzo(a)pyrene concentration being 8.84% of the total mean PAH. Fried pork had 7 new PAHs and a total mean PAH content of 3.47 μg/kg, compared with a mean total of 0.17 μg/kg, detected in the raw meat. Roast beef had the highest individual PAH concentration (5.03 μg/kg) and highest total PAHs concentration (17.88 μg/kg), both being higher than acceptable EU limits. The PAHs from local raw and cooked meat were characterized and quantified for the first time in Kisumu City and the study therefore provided the needed baseline data on PAHs in raw and cooked meat.     

肉味香精前体物的制备技术研究

本文研究了以天然动植物资源(猪骨素、辛香料等)为主要原料,不同条件对酶解和美拉德反应肉味香精前体物的影响,确定了相对优化的胰蛋白酶水解猪骨素的最佳工艺条件和美拉德反应的基础配方。     

Effect of grass vs. concentrate feeding on the fatty acid profile of different fat depots in lambs

The aim of this study was to produce high‐quality meat from lambs under different feeding conditions, as measured by the accumulation of n‐3 fatty acids and conjugated linoleic acids (CLA) in muscle and subcutaneous fat. In total, 13 male crossbred lambs (Black Head×Gotland), each at 24 kg live weight, were divided into two feeding groups. Lambs were kept either on pasture (pasture grazing, n = 6) or in the stable (concentrate feeding, n = 7). The linolenic acid (C18:3n‐3) contained in the grass was absorbed and deposited into the different lipid classes of muscle and subcutaneous fat. The proportion of total n‐3 fatty acids in the different lipids of grazing lambs was significantly (p = 0.05) higher compared to that in concentrate‐fed lambs. The n‐6/n‐3 ratio (mean ± SEM) in muscle of grazing lambs was 1.2 ± 0.09 in contrast to 2.3 ± 0.09 (p = 0.05) of the animals kept in the stable. In subcutaneous fat, this ratio was 0.9 ± 0.2 in lambs kept on pasture versus 3.5 ± 0.2 (p = 0.05) after indoor keeping. The relative concentration of C18:1trans‐11 in total muscle lipids, phospholipids, triacylglycerols and subcutaneous fat was significantly increased by grass feeding compared to concentrate feeding. Significant influences of feeding were shown for saturated fatty acids. In concentrate‐fed lambs, a lower content of saturated fatty acids was detected. The proportion of CLAcis‐9,trans‐11 (1.9 ± 0.2% vs. 1.1 ± 0.1% in muscle, 2.5 ± 0.2% vs. 1.4 ± 0.2% in subcutaneous fat, 0.7 ± 0.04% vs. 0.4 ± 0.04% in phospholipids) in lambs was significantly (p = 0.05) higher after grazing than after concentrate feeding, respectively.     

Devolatilization of wood and wastes in fluidized bed

Experiments were carried out in a laboratory fluidized bed (FB) to characterize the devolatilization behavior of wood and various wastes at temperatures applicable to FB gasification and combustion, i.e. 750-900 °C. The fuels tested were pellets made of wood, meat and bone meal, and compost (from municipal solid wastes), as well as dried granulates of sewage sludge (DSS). Determination of yields of char, condensate and light gas, as well as the composition of the gas and the time of devolatilization during the pyrolysis of single fuel batches was made. A simple model was developed to analyze the mode of conversion of a single wood pellet and DSS granulate, giving insight on the controlling mechanisms during devolatilization. The devolatilization kinetics of DSS was determined by tests using fine granulates. The model was successfully applied to simulate the conversion of large DSS granulates and wood pellets under the whole range of temperatures analyzed.     

Trans-10 18:1 in ruminant meats: A review

Trans (t) fatty acids (TFA) from partially hydrogenated vegetable oils (i.e., industrial trans) have been phased out of foods in many countries due to their promotion of cardiovascular disease. This leaves ruminant-derived foods as the main source of TFA. Unlike industrial TFA where catalytic hydrogenation yields a broad distribution of isomers, ruminant TFA are enzymatically derived and can result in enrichment of specific isomers. Comparisons between industrial and ruminant TFA have often exonerated ruminant TFA due to their lack or at times positive effects on health. At extremes, however, ruminant-sourced foods can have either high levels of t10- or t11-18:1, and when considering enriched sources, t10-18:1 has properties similar to industrial TFA, whereas t11-18:1 can be converted to an isomer of conjugated linoleic acid (cis(c)9,t11-conjugated linoleic acid), both of which have potential positive health effects. Increased t10-18:1 in meat-producing ruminants has not been associated with negative effects on live animal production or meat quality. As such, reducing t10-18:1 has not been of immediate concern to ruminant meat producers, as there have been no economic consequences for its enrichment; nevertheless at high levels, it can compromise the nutritional quality of beef and lamb. In anticipation that regulations regarding TFA may focus more on t10-18:1 in beef and lamb, the present review will cover its production, analysis, biological effects, strategies for manipulation, and regulatory policy.     

Lamb Meat Quality Assessment by Support Vector Machines

The correct assessment of meat quality (i.e., to fulfill the consumer’s needs) is crucial element within the meat industry. Although there are several factors that affect the perception of taste, tenderness is considered the most important characteristic. In this paper, a Feature Selection procedure, based on a Sensitivity Analysis, is combined with a Support Vector Machine, in order to predict lamb meat tenderness. This real-world problem is defined in terms of two difficult regression tasks, by modeling objective (e.g. Warner–Bratzler Shear force) and subjective (e.g. human taste panel) measurements. In both cases, the proposed solution is competitive when compared with other neural (e.g. Multilayer Perceptron) and Multiple Regression approaches.     

聚类分析在猪肉品质评定中的应用

本文采用多元统计学上聚类分析法对53头猪的肉质性状进行了综合分析,结果认为:聚类分析用来区分正常肉和劣质肉PSE(Pale苍白,Soft柔软,Exudative渗水)是一种比较准确而合理的方法,计算机的广泛应用,使这种方法简便易行。