Effect of irradiation, packaging, and postirradiation cooking on the thiamin content of chicken meat

The effect of irradiation with X rays or electrons, irradiation and storage temperature, and postirradiation cooking on the thiamin content of vacuum- or air-packaged minced chicken meat was examined. Samples irradiated with 3-kGy X rays (50 Gy/min) or electrons (5 kGy/min) contained less thiamin than the control specimens, but no differences between both irradiation methods were detected. The thiamin content in samples stored and/or irradiated at 5 degrees C was between 13 and 24 microg per 100-g product lower than in samples stored and/or ionized at -18 degrees C. The same difference in thiamin content was found for specimens packaged in a vacuum or air package, respectively. Vacuum packaging lead to a greater loss of drip than air-packaged samples. The biggest loss of thiamin, 31.1 and 28.0% for X rays and electron beams, respectively, was measured for vacuum-packaged specimens stored and irradiated at 5 degrees C. Compared with the cooked minced chicken breast meat, a higher thiamin content (6 to 17 microg of thiamin per 100-g product) was obtained for the raw samples. When irradiation and vacuum packaging were compared as two separate preservation techniques, the two methods had approximately the same effect on the thiamin content of the minced chicken meat. The mean temperature of the samples after cooking was 87.2 +/- 4.9 degrees C. However, significant differences in internal temperature after cooking of the samples were measured between air- and vacuum-packaged samples.     

Muscle fiber and fatty acid profiles of Mertolenga-PDO meat

The influence of phenotype and muscle type on intramuscular total lipids (ITL) neutral lipid (NL) and phospholipid (PL) compositions, cholesterol, α-tocopherol and haem iron contents were evaluated in Semitendinosus (St), Longissimus dorsi (Ld) and Supraspinatus (Ss) muscles from 39 Mertolenga young bulls. The results showed that lipid, α-tocopherol, cholesterol and haemic iron contents were not influenced by phenotype. Furthermore, the individual effect of phenotype was not a significant source of variation on ITL, NL and PL fatty acid composition. Muscle histological traits from Unicolor phenotype (n = 13) showed that Ss and Ld muscles exhibited higher proportion of type I (P < 0.001) and oxidative fibers (P < 0.001) and lower percentages of IIB fibers (P < 0.001) than St. The Ss muscle, with higher relative area occupied by oxidative fibers (P < 0.05–0.001) than Ld and St, had higher ITL (P < 0.001), NL (P < 0.001), PL (P < 0.05–0.01), α-tocopherol (P < 0.001), cholesterol (P < 0.01) and haem iron (P < 0.001) contents than its counterparts. Muscle type notably affected ITL, as a result of its influence on NL rather than in PL composition.     

反复冻融对鸡汤氨基酸和脂肪酸的影响

利用氨基酸分析仪和气相质谱联用仪(GC-MS),分析反复冻融条件下的鸡汤氨基酸和脂肪酸变化。结果表明:速冻(冻融1次)鸡汤的氨基酸总量(TAA)、必需氨基酸(EAA)和不饱和脂肪酸(UFA)呈显著增加(p0.05),而饱和脂肪酸(SFA)显著降低(p0.05)。随着反复冻融次数增加,鸡汤TAA、EAA和SFA显著性降低(p0.05),而UFA呈显著性增加(p0.05),甜味、鲜味和苦味的风味氨基酸均呈现增加后减小趋势(p0.05)。结论:表明速冻(冻融1次)和反复冻融对鸡汤品质有较大影响。     

Antioxidant effect of turmeric powder,nitrite and ascorbic acid on stored chicken mince

This investigation was carried out to evaluate the antioxidant effect of turmeric (turmeric 1000 ppm, turmeric 5000 ppm), nitrite (nitrite 200 ppm) and ascorbic acid (ascorbic acid 500 ppm) on raw minced chicken stored at 4 ± 1 °C. Physicochemical properties [pH, water activity, cooking loss, thiobarbituric acid (TBA) value, peroxide value (PV), free fatty acid (FFA)] were evaluated on 0, 2, 4 and 6th day of storage. Highly significant differences (P < 0.01) in pH, TBA value, PV and FFA value were noticed between treatments and between storage periods. TBA values were observed to be lowest for nitrite 200 ppm and then turmeric 5000 ppm, and there was no significant difference between nitrite 200 ppm and turmeric 5000 ppm, and both were superior to ascorbic acid 500 ppm and turmeric 1000 ppm. Among different treatments, PV was found to be lowest in turmeric 5000 ppm and highest in nitrite 200 ppm. FFA value was found to be lowest in turmeric 5000 ppm and highest in ascorbic acid 500 ppm among all treated samples. It can be concluded that turmeric has potential to replace synthetic antioxidants presently used in meat processing with many added advantages.     

不同包装材料密闭贮藏对花生品质影响

为了获得适合贮藏花生包装材料,探讨包装材料对花生耐贮性的影响,该文研究了4种不同的包装材料密闭贮藏花生对花生色泽、品质、发芽率、虫害和黄曲霉毒素防控效果的影响。结果表明：不同包装材料贮藏花生效果差异非常显著。铝箔袋包装花生种皮颜色在贮藏期间没有发生变化,尼龙/聚乙烯(PA/PE)薄膜袋包装花生的种皮颜色变化速度比PE膜缓慢,而PE膜比编织袋包装的变化缓慢;铝箔袋、PA/PE复合膜密闭包装贮藏18个月后,花生米品质依然保持了较好;铝箔袋密闭包装能长期保持花生发芽率;4种密闭包装方式抑制虫害繁殖作用差异显著,高通透性的编织袋包装的花生害虫侵蚀严重,而铝箔袋和PA/PE袋包装可以有效地抑制虫害的发生;铝箔袋、PA/PE复合膜包装花生米原料贮藏18个月均没有黄曲霉毒素产生,但是PA/PE复合膜包装的部分花生有明显霉菌滋生。     

反复冻融对鸡汤氨基酸和脂肪酸的影响

利用氨基酸分析仪和气相质谱联用仪（GC-MS）,分析反复冻融条件下的鸡汤氨基酸和脂肪酸变化。结果表明:速冻（冻融1次）鸡汤的氨基酸总量（TAA）、必需氨基酸（EAA）和不饱和脂肪酸（UFA）呈显著增加（p<0.05）,而饱和脂肪酸（SFA）显著降低（p<0.05）。随着反复冻融次数增加,鸡汤TAA、EAA和SFA显著性降低（p<0.05）,而UFA呈显著性增加（p<0.05）,甜味、鲜味和苦味的风味氨基酸均呈现增加后减小趋势（p<0.05）。结论:表明速冻（冻融1次）和反复冻融对鸡汤品质有较大影响。      

Influence of dietary conjugated linoleic acid on volatile profiles, color and lipid oxidation of irradiated raw chicken meat

Forty-eight, 27-week-old White Leghorn hens were fed a diet containing 0, 1.25, 2.5 or 5.0% conjugated linoleic acid (CLA) for 12 weeks. At the end of the 12-week feeding trial, hens were slaughtered, and boneless, skinless breast and leg meats were separated from carcasses. Meats were ground through 9 and 3-mm plates, and patties were prepared. Patties prepared from each dietary treatment were divided into two groups and either vacuum- or aerobic-packaged. Patties were irradiated at 0 or 3.0 kGy using a linear accelerator and stored at 4°C. Samples were analyzed for thiobarbituric acid reactive substances, volatile profiles, color and odor characteristics at 0 and 7 days of storage. Dietary CLA reduced the degree of lipid oxidation in raw chicken meat during storage. The content of hexanal and pentanal in raw chicken meat significantly decreased as dietary CLA level increased. Irradiation accelerated lipid oxidation in meat with aerobic packaging, but irradiation effect was not as significant as that of the packaging. Dietary CLA treatment improved the color stability of chicken patties. Color a*-value of irradiated raw chicken meat was higher than that of the nonirradiated meat. Dietary CLA decreased the content of polyunsaturated fatty acid and increased CLA in chicken muscles, which improved lipid and color stability and reduced volatile production in irradiated and nonirradiated raw chicken meat during storage.     

Effect of gamma-ray irradiation on the fatty acid profile of irradiated beef meat

The effect of γ-ray irradiation on the fatty acid profile of beef meat was examined at doses of 2.5, 5.0, 7.5, 10.0 and 15.0 kGy by means of ¹H NMR spectroscopy. NMR results revealed a clear trend toward an increase in the amount of saturated fatty acids and a decrease in the amount of polyunsaturated fatty acids in the triacylglycerol composition of the irradiated samples compared to the unirradiated sample with increasing the irradiation dose.     

Relation of biogenic amines to microbial and sensory changes of precooked chicken meat stored aerobically and under modified atmosphere packaging at 4 °C

The formation of biogenic amines and their correlation to microflora and sensory characteristics of a precooked chicken meat product stored aerobically and under modified atmosphere packaging (MAP) (30% CO₂, 70% N₂) was studied. Putrescine was the main amine formed both in aerobically and MA-packaged chicken samples. For the rest of the biogenic amines, including tyramine, histamine, and cadaverine, a stepwise increase was recorded throughout the 23-day storage period under the above packaging conditions. Spermidine was found in higher amounts, as compared to spermine in both aerobically and MA-packaged chicken samples at 4 °C. Formation of these amines in precooked chicken stored either aerobically or under a 30% CO₂, 70% N₂ atmosphere followed an inconsistent trend during the entire storage period at 4 °C. Agmatine, β-phenyl-ethylamine, and tryptamine were not detected in precooked chicken. Of the bacterial groups monitored, lactic acid bacteria (LAB) became the dominant bacteria after day 8 of storage under MAP while LAB were the dominant population of natural microflora of precooked chicken stored both aerobically or under MAP, reaching 7.5 and 8.0 log cfu/g, respectively, on day 23 of refrigerated storage. Enterobacteriaceae populations in chicken meat were below the detection limit (<1 log cfu/g) by pour plating throughout the 23-day storage period, irrespective of packaging conditions. Based on sensory data, after ca. 8 days for the precooked chicken meat stored aerobically and after 12 days under MAP (time to reach initial decomposition stage, score of 2) the putrescine and tyramine content of chicken samples were ca. 14–19 and 1.4 mg/kg, values that may be proposed as the limit for spoilage initiation of precooked chicken meat (respective TVC for both aerobically and MA-packaged chicken meat were ca. 6.5 log cfu/g).     

不同阻隔性的包装材料对气调包装鲜肉品质的影响

使用四种不同气体阻隔性的塑料复合包装材料进行新鲜猪肉的气调包装,然后测定猪肉品质指标的变化,确定塑料包装材料的阻隔性对鲜肉贮存品质的影响,为包装材料的精确选择提供可以量化的科学依据.     

Pork meat quality affects peptide and amino acid profiles during the ageing process

Twenty pork carcasses were classified in different pork meat qualities: red, firm and non-exudative (RFN), pale, soft and exudative (PSE), red, soft and exudative (RSE) and dark, firm and dry (DFD) meat. The content of peptides and free amino acids during the ageing process was analysed and compared within quality classes. Four peptide fractions were isolated through cation-exchange and reverse-phase chromatography. The main significant differences among qualities were obtained for peptide fractions 3 and 4. Peptide fraction 3 at 4 days and peptide fraction 4 at 2 h postmortem were higher in the ideal pork quality (RFN) than in the other quality classes. The ageing of pork meats produced a general increase in all free amino acid concentrations for the studied quality classes except for Gln, β-Ala, Taurine and Orn and the dipeptides carnosine and anserine. The DFD class showed higher increases in Lys, Ala and Met probably due to the activation of neutral aminopeptidases.     

Documentation of fatty acid profiles in lamb meat and lamb-based infant foods

Lamb meat, when used in the weaning diet of children, is presumed to have a lower allergenicity than other forms of red meat. In children with atopic dermatitis and multiple food hypersensitivities, consumption of lamb meat has also resulted in significant clinical improvements in the severity of the eczematous lesions. Lamb meat is also of special interest in infant nutrition because it provides a somewhat unique fatty acid (FA) profile that mirrors what is thought to be optimal for neonatal growth and development. However, very little is known about how the processing of fresh meat (FM) into prepared infant foods influences its FA composition. In this study, we compared the FA profile of FM from suckling lambs with those of homogenized (HO) and lyophilized (LIO) baby foods prepared primarily with lamb meat. The results show that the content of total omega-3 polyunsaturated FAs was the highest in FM (more than 3-fold) compared to commercial baby food, due to largely higher contents of α-linolenic acid (1.5-fold higher), eicosapentaenoic acid (6-fold higher), and docosahexaenoic acid (10-fold higher). Furthermore, arachidonic acid was more than 6-fold higher in FM compared to LIO and HO. Results from this study suggest the possibility of enhancing the FA profile of commercial baby food based on meat by using lamb meat, but care should be taken during processing so that important FAs are not lost. PRACTICAL APPLICATION: In this article, we have documented that meat from the suckling lamb is an interesting and potentially important source of omega-3-FAs, especially some of the long-chain polyunsaturated FAs (LC-PUFAs) that are essential for optimal neonatal growth and development. These results may have special implications to the infant food industry, in that products made using meat from suckling lambs may provide not only exceptional amounts of these FAs, but also other limiting essential nutrients such as iron. This may be especially important in regions of the world, such as Italy, where use of lamb meat as a weaning food is common during infancy.     

Instrumental meat quality of veal calves reared under three management systems and color evolution of meat stored in three packaging systems

This study evaluated the meat quality of grazing suckling calves (GR), suckling plus supplemented calves (SUP) and weaned calves finished on concentrates (FIN) and the color evolution of meat packaged in film (FILM), modified atmosphere packaging (MAP) and vacuum packaging (VAC). Intramuscular fat was quite low for all treatments and GR meat had greater percentages of PUFA and lower SFA, MUFA and n6/n3 than SUP and FIN. FIN and SUP meat had more L* and was more tender when aged than GR. GR meat was tough and dark. The packaging system was more influential on meat color than the feeding management. VAC had the lowest values of metmyoglobin when aged. MAP had the greatest L* and hue angle and the lowest redness after 13 d of aging, thus MAP was the packaging with the shortest shelf life.