The distribution of 4-hydroxy-hexenal and 4-hydroxy-nonenal in different vegetable oils and their formation from fatty acid methyl esters

The formation of 4-hydroxy-hexenal (HHE) and 4-hydroxy-nonenal (HNE) in eight vegetable oils was investigated at 180 °C. HHE was only detectable in soybean (SBO), rapeseed (RO) and linseed oils (LO). HNE was measured in all tested oils, but was found mainly in corn (CO), sunflower (SO) and soybean oil (SBO). Oil-dependent formation of HHE/HNE was remarkably observed. Furthermore, different fatty acid methyl esters in tricaprylin, as model oil systems, were constructed to demonstrate their characteristic contribution to HHE/HNE formation. As expected, HHE and HNE originated from the oxidative degradation of methyl linolenate (MLN) and methyl linoleate (ML) respectively. Whereas low concentrations of MLN (<5.0%) and ML (<1.0%) produced no detectable HHE/HNE. The results suggested MLN/ML could induce both HHE/HNE formation and pro-oxidation at higher concentrations. Unexpectedly, methyl stearate and methyl oleate slightly promoted HHE/HNE formation, which might be attributed to free radical transfer mechanisms during thermal oxidation.     

不同腌制工艺对鸡胸肉品质的影响

为了选择适合企业生产实际和安全高效的肉品腌制工艺,本文以鸡胸肉为原料,分别以高压技术（150MPa）、真空技术（-86kPa）以及常压技术三种不同的腌制方法,对比研究了三种腌制工艺中鸡胸肉相关的品质指标特性。真空腌制（-86kPa）条件下鸡胸肉的保水性、挥发性盐基氮、过氧化物值、盐溶蛋白以及亚硝酸含量等指标相对其他组最优。真空腌制技术相对于常压技术,提高了腌制效率以及改善腌制品品质,较高压腌制技术也更安全,操作更方便。     

Preservation of chicken breast meat treated with thyme and balm essential oils

The present study evaluated the effects of thyme and balm essential oils on the 3-wk storage of fresh chicken breast meat at 4 °C. Thyme and, to a lesser extent, balm essential oils reduced DPPH (2,2-diphenyl-1-picrylhydrazyl) radical formation in the meat (25% to 30% and 20%, respectively). Treatment with the 2 essential oils also limited lipid peroxidation and the deterioration of sarcoplasmic proteins, helping to preserve the meat even after 2 wk of storage. Thyme and balm essential oils decreased the natural microflora present in the meat; total microbial content decreased down to 50% in comparison to the control samples. In addition, a clear effect on lactic acid bacterial growth was recorded. Balm essential oil significantly limited the growth of Salmonella sp., whereas thyme essential oil effectively inhibited the growth of Escherichia coli. Our data demonstrate that these 2 essential oils effectively reduced deteriorative processes in chicken meat and extended the shelf life of this fresh product. Practical Application: The essential oils of thyme and balm can protect the chicken meat from decomposition during the storage time.     

Effect of refrigerated and frozen storage on the survival of Campylobacter jejuni in cooked chicken meat breast

This experimental work aimed to examine the survivability of Campylobacter jejuni in cooked chicken breast under several conditions: storage for 1, 3, and 7 d at refrigerated temperatures (4 °C) and for 20 d at frozen temperatures (-18 °C). In addition, storage at ambient temperature (26 to 28 °C) was involved. Chicken samples were inoculated with a mixed culture of C. jejuni strains (ATCC: 29428 and 33219) of known concentrations (50 and 500 CFU/g). Bacterial cells were recovered and enumerated using standard procedure (Preston method). Bacteria were not detected in the majority of samples stored at ambient temperature. Refrigeration reduced survivals in 95, 90, and 77.5% for samples inoculated with 500 CFU/g and kept for 1, 3, and 7 d, respectively. The maximum reduction reached 1 log(10) cycle for all refrigeration durations. It was observed that bacteria died in 17.5% of samples kept for 7 d at 4 °C. However, survivors in samples inoculated with 50 CFU/g were not detected in 50, 65, and 55% of samples kept for 1, 3, and 7 d, respectively. Freezing rendered survivors not detectable in 70% of samples inoculated with 50 CFU/g, while survived viable counts were reduced in 92.5% of samples inoculated with 500 CFU/g. These findings suggested that C. jejuni could be killed or just sublethally injured with or without reduction in viable counts under the investigated storage temperatures, which may indicate the ability of this bacterium to survive in chicken meat stored under refrigerated and frozen conditions.     

Effects of slightly acidic low concentration electrolyzed water on microbiological, physicochemical, and sensory quality of fresh chicken breast meat

Anticmicrobial effect of slightly acidic low concentration electrolyzed water (SlALcEW) and strong acidic electrolyzed water (StAEW) on fresh chicken breast meat was evaluated in this study. Meat samples each of 10 ± 0.2 g in weight and 2.5 × 2.5 cm2 in size were experimentally inoculated with Listeria monocytogenes (ATCC 19115) and Salmonella Typhimurium (ATCC 14028) and subjected to dipping treatment (22 ± 2 °C for 10 min) with SlALcEW and StAEW. Shelf-life study was conducted for inoculated and noninoculated meat samples treated with SlALcEW and StAEW at storage temperatures of 5, 15, and 25 °C. Dipping treatment with electrolyzed water significantly (P < 0.05) reduced the background and inoculated pathogens compared to untreated controls. The reduction of 1.5 to 2.3 log CFU/g was achieved by SlALcEW and StAEW against background flora, L. monocytogenes and Salmonella Typhimurium. There was no significant difference (P > 0.05) between the SlALcEW and StAEW treatments efficacy. Comparing treated samples to untreated controls showed that SlALcEW and StAEW treatments extended the shelf life of chicken meat at different temperatures with marginal changes of sensory quality. Although SlALcEW and StAEW treatments showed similar antimicrobial effects but SlALcEW was more beneficial in practical application for its semineutral pH and low chlorine content. PRACTICAL APPLICATION: Food safety issues have led to development of new sanitizers to eliminate spoilage and pathogenic organisms in food. This study provides the foundation for further application of slightly acidic low concentration electrolyzed water (SlALcEW) as a sanitizing agent in meat industry. SlALcEW can be produced on site on demand and no chemicals are necessary except NaCl solution. It does not leave any residue in food due to low chlorine concentration and it is safe to handle for its semineutral pH.     

Effect of marinating ingredients on temperature-induced denaturation of hemoglobin and its relation to red blood spot formation in cooked chicken breast

Red blood spot (RBS) commonly found in cooked chicken breast has caused severe economic loss as it is perceived as a sign of undercooked product. The objectives of this study were to investigate the cause of RBS as related to common ingredients used in marination, based on both chicken breast and isolated chicken hemoglobin (Hb) models. The effect of sodium chloride (NaCl), sodium tripolyphosphate (STPP), and glucose on thermal denaturation of Hb was investigated along with the extent of RBS formation in cooked marinated chicken breast. After vacuum tumbling for 65 min and subsequent storage at 4 °C for 20 hr, STPP and glucose were not absorbed into the center of chicken breast. However, Na⁺ was absorbed after 12 hr storage. The denaturation temperature (T_d) of isolated chicken Hb decreased to 65.8 °C in the presence of 1.5 M NaCl, while that of the control was 69.4 °C. STPP at pH 9 decreased T_d of Hb to 61.4 °C. The alkaline pH induced by STPP destabilized the Hb structure. RBSs were observed at 100% incidence when cooked to core temperatures of 50 and 70 °C for 1 min. RBSs were completely eliminated at core temperature of 85 °C. The ingredients used during marination appeared to have a minimal effect on RBS formation due to their limited absorption into the chicken breast. The cooking temperature is a major factor governing RBSs, as it directly affects the denaturation of Hb.     

Effect of ripening with Penicillium roqueforti on texture,microstructure, water distribution and volatiles of chicken breast meat

In this study, the influence of ripening with Penicillium roqueforti on texture, microstructure, protein structure, water mobility and volatile flavour compounds of chicken breast meat was investigated. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) images showed that the granule formed and chicken myofibril fractured after ripening. Reduction in α-helix and increases in β-sheet structure content accompanied by decrease in hardness and springiness and increase in gumminess were found in ripened chicken breast meat. Low field nuclear magnetic resonance (LF-NMR) revealed that increasing intra-myofibrillar water and decreasing extra-myofibrillar water resulted in the higher water-holding capacity after ripening with P. roqueforti. In addition, chicken breast meat ripened with P. roqueforti contained more volatile flavour compounds, in particular aldehydes.     

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).     

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.     

Combined effect of oregano essential oil and modified atmosphere packaging on shelf-life extension of fresh chicken breast meat, stored at 4 degrees C

The combined effect of oregano essential oil (0.1% and 1% w/w) and modified atmosphere packaging (MAP) (30% CO2/70% N2 and 70% CO2/30% N2) on shelf-life extension of fresh chicken meat stored at 4 degrees C was investigated. The parameters that were monitored were: microbiological (TVC, Pseudomonas spp., lactic acid bacteria (LAB), yeasts, Brochothrix thermosphacta and Enterobacteriaceae), physico-chemical (pH, TBA, color) and sensory (odor and taste) attributes. Microbial populations were reduced by 1-5 log cfu/g for a given sampling day, with the more pronounced effect being achieved by the combination of MAP and oregano essential oil. TBA values for all treatments remained lower than 1 mg malondialdehyde (MDA) kg(-1) throughout the 25-day storage period. pH values varied between 6.4 (day 0) and 5.9 (day 25). The values of the color parameters L*, a* and b* were not considerably affected by oregano oil or by MAP. Finally, sensory analysis showed that oregano oil at a concentration of 1% imparted a very strong taste to the product for which reason these lots of samples were not scored. On the basis of sensory evaluation a shelf-life extension of breast chicken meat by ca. 3-4 days for samples containing 0.1% oregano oil, 2-3 days for samples under MAP and 5-6 days for samples under MAP containing 0.1% of oregano oil was attained. Thus oregano oil and MAP exhibited an additive preservation effect.     

Understanding the difference of 4-hydroxyhexenal and 4-hydroxynonenal formation in various vegetable oils during thermal processes by kinetic and thermodynamic study

The formation of two toxic aldehydes, 4-hydroxyhexenal (HHE) and 4-hydroxynonenal (HNE) were monitored in five vegetable oils during thermal processing (100–200 °C) with the results modelled. HHE was only determined in rapeseed and linseed oil, while HNE was determined in all tested oils and the contents varied significantly depending on the oil type. For HHE/HNE-detected oils, the evolution during heating was well described by the pseudo-first-order kinetic model. The equilibrium contents of HHE/HNE increased and the duration until equilibrium decreased as a function of temperature. The calculated reaction rate constants followed the Arrhenius law. The formation rate of HHE/HNE was remarkably oil-dependent, which was also in accordance with the calculated kinetic and thermodynamic parameters. Accordingly, the above results can contribute to a prediction of HHE/HNE formation in different vegetable oils during thermal processing, especially the temperature/time required during frying, which is generally higher than 100 °C and 6 h., respectively.     

Contents of biologically active polyamines in chicken meat,liver, heart and skin after slaughter and their changes during meat storage and cooking

Dietary polyamines, putrescine, spermidine (SPD) and spermine (SPM), participate in an array of important physiological roles, including tumour growth. Thus, reliable information on polyamine content in foods has been needed. We therefore determined polyamine contents in chilled chicken meat and giblets (n = 20) and skin (n = 10) 24 h after slaughter. The polyamines were determined, after extraction with perchloric acid, as dansyl derivatives, using an HPLC method. Mean SPD values were 4.8, 10.2, 11.4, 48.7 and 12.1 mg kg⁻¹ and SPM values were 36.8, 38.0, 24.3, 133 and 82.7 mg kg⁻¹ in breast, thigh, skin, liver and heart, respectively. Significant statistical correlations between SPD and SPM contents were observed in breast, thigh, skin and liver, whereas correlations were insignificant in heart. An increase of SPD and SPM was apparent in breasts and thighs stored at −18 °C for 6 months; however, it was significant only for SPM in thighs. The losses of both SPD and SPM were statistically insignificant during storage of aerobically packaged breasts up to 9 days at +2 °C. A significant decrease of SPM to about 60% of the initial contents was observed in both vacuum-packaged and in modified atmosphere (20% CO₂ and 80% O₂)-stored breasts on day 21 at +2 °C. For both SPD and SPM, roasting, grilling and frying of fresh breasts caused losses of about 40–60% of the initial contents (higher than boiling and stewing). Similarly, losses of SPM, due to roasting of breasts frozen for 3 or 6 months, were higher than those caused by stewing. Putrescine was detected only sporadically and at levels close to the detection limit of 1.0 mg kg⁻¹ (fresh matter).     

木质化鸡胸肉发生率统计及其肉糜功能特性研究

本研究对肉鸡屠宰企业日常生产过程中的木质化鸡胸肉发生率进行统计,并测定其品质指标及肉糜凝胶的保水性、质构特性,比较其与正常肉凝胶微观结构及蛋白质二级结构含量差异。实验测得木质化鸡胸肉发生率为18.33%。与正常肉相比,木质化鸡胸肉宰后24 h的p H显著升高（p<0.05）,但L^*值无显著差异（p>0.05）。与正常肉肉糜相比,木质化鸡肉肉糜蒸煮得率低,离心损失大,肉糜凝胶质构指标降低（p<0.05）。微观结构显示,木质化鸡胸肉凝胶结构中空隙较多且形成大量聚集状凝胶基质。与正常肉凝胶相比,木质化鸡肉凝胶α-螺旋含量显著升高,β-折叠与β-转角含量显著降低（p<0.05）。结果表明,木质化鸡胸肉在肉鸡屠宰加工企业日常生产过程中发生率较高,且降低鸡肉功能特性。      

Improved gelation functionalities of myofibrillar protein from pale,soft and exudative chicken breast meat by nonenzymatic glycation with glucosamine

The potential of nonenzymatic glycation of myofibrillar proteins (MPs) to improve the gelation functionalities of pale, soft and exudative (PSE‐like) chicken breast meat was investigated. MP suspensions (4 mg mL^?1) obtained from both normal and PSE‐like chicken breast meat were mixed with glucosamine at a ratio of 1:6 (protein : glucosamine) in phosphate‐buffered saline (0.6 m KCl, 20 mm K₂HPO₄/KH₂PO₄, 0.02% NaN₃ and pH 7.5) and incubated at 37 °C for 12 h. Untreated normal and PSE‐like MP suspensions maintained at 4 °C were used as positive and negative controls, respectively. The glycation treatment increased the surface hydrophobicity but decreased the reactive sulfhydryl contents compared to those of the control (P < 0.05), indicating that the tertiary conformation of the protein changed. Correspondingly, these glycated samples also exhibited significant improvements in gel strength and the water‐holding capacity (P < 0.05). Conclusively, nonenzymatic glycation is a potential technique to improve the properties and offer a means for effective use of PSE‐like meat.     

Effects of vitamin E and fish oil inclusion in broiler diets on meat fatty acid composition and on the flavour of a composite sample of breast meat

BACKGROUND: Enriching poultry meat with long‐chain n‐3 polyunsaturated fatty acids (LC n‐3 PUFA) can increase low population intakes of LC n‐3 PUFA, but fishy taints can spoil reheated meat. This experiment determined the effect of different amounts of LC n‐3 PUFA and vitamin E in the broiler diet on the fatty acid composition and sensory characteristics of the breast meat. Ross 308 broilers (120) were randomly allocated to one of five treatments from 21 to 42 days of age. Diets contained (g kg^?1) 0, 9 or 18 LC n‐3 PUFA (0LC, 9LC, 18LC), and 100, 150 or 200 mg LD ‐α‐tocopherol acetate kg^?1 (E). The five diets were 0LC100E, 9LC100E, 18LC100E, 18LC150E, 18LC200E, with four pens per diet, except 18LC100E (eight pens). Breast meat was analysed for fatty acids (uncooked) and sensory analysis by R‐index (reheated). RESULTS: LC n‐3 PUFA content (mg kg^?1 meat) was 514 (0LC100E) and 2236 (9LC and 18LC). Compared with 0LC100E, meat from 18LC100E and 18LC150E tasted significantly different, while 23% of panellists detected fishy taints in 9LC100E and 18LC200E. CONCLUSION: Chicken meat can be enriched with nutritionally meaningful amounts of LC n‐3 PUFA, but > 100 mg dl‐α‐tocopherol acetate kg^?1 broiler diet is needed to protect reheated meat from oxidative deterioration. Copyright © 2010 Society of Chemical Industry     

A 2-step cooking method of searing and hot water pasteurization to maximize the safety of refrigerated, vacuum packaged, chicken breast meat

ABSTRACT:  Americans consume almost 40 kg per capita of chicken each year. Increasing consumption of chicken surpassed pork in 1982 and beef in 1992. The objectives of this study were to examine the effectiveness of a novel, 2-step cooking method of grilling, slicing, vacuum packaging, and hot water pasteurization to inhibit the growth of Listeria monocytogenes in chicken breast meat. Because this study required the use of pilot plant scale pasteurization equipment, Listeria innocua M1, a nonpathogen with slightly greater heat resistance than L. monocytogenes , was used as a surrogate. We first examined the lethal effects of grilling on a boneless skinless chicken breast to mimic cross-contaminated, surface-inoculated Listeria . Searing produced a mean reduction of 2.5 log CFU/g of Listeria and a moisture loss of only 7% (w/w). A 2nd experiment studied the lethal effect of pasteurization of the sliced seared chicken breast. L. innocua M1 inoculated between the slices mimiced contamination in deep muscle. Pasteurization in a 71 °C bath (final internal temperature of 66 °C) gave an additional 2.3 log CFU/g reduction. L. innocua M1 did not show significant regrowth during a wk of refrigerated storage. The combined 2-step cooking method of searing and pasteurization gave a combined 4.8 log reduction in LI M1. In parallel tests a non- Listeria indicator, Corynebacterium glutamicum , inoculated between sliced, seared chicken, showed a 3 log reduction after pasteurization for 10 min in a 71 °C bath compared to 2.3 log reduction of Listeria . Corynebacterium regrowth occurred much faster than did L. innocua M1.     

Addition of tea catechins and vitamin C on sensory evaluation, colour and lipid stability during chilled storage in cooked or raw beef and chicken patties

The effects of addition of tea catechins (TC) and vitamin C (VC) on sensory evaluation, colour and lipid stability in cooked or raw beef and chicken meat patties during refrigerated storage were studied. Fresh beef striploin and chicken breast muscles were minced, following removal of external fat and connective tissue. Following mincing, beef and chicken were assigned to one of the following five treatments: control (meat treated with no antioxidant); TC200, meat plus 200 mg TC/kg muscle; TC400, meat plus 400 mg TC/kg muscle; VC200, meat plus 200 mg VC/kg muscle, VC400, meat plus 400 mg VC/kg muscle. Sodium chloride (1%) was added to all samples. Patties (125 g portions), formed from the above-treated minced meat, were oven cooked, cooled, and packaged in 30% CO₂:70% N₂. Fresh raw beef and chicken patties were packaged in 80% O₂:20% CO₂. All samples were stored for up to 7 days under fluorescent lighting at 4 °C. Sensory parameters (colour, flavour, taste, tenderness and overall acceptability) were evaluated on cooked beef and chicken patties after 1, 3 and 6 days of storage. Surface colour (Hunter L, a and b values), and lipid oxidation (2-thiobarbituric acid reactive substances) were measured on days 1, 3 and 6 of storage for cooked meats and on days 2 and 7 for raw beef and chicken. Tea catechins addition (200 or 400 mg/kg) to minced meat caused (P < 0.05) discolouration in cooked beef and chicken meat patties and significantly reduced (P < 0.001) lipid oxidation in cooked or raw beef patties compared to the control. Beef, either raw or cooked, was more susceptible (P < 0.01) to oxidation compared to chicken. Raw meat stored in high oxygen conditions was more susceptible to lipid oxidation than cooked meat stored in anaerobic conditions. Tea catechins treatments (TC200 and TC400) inhibited (P < 0.05) lipid oxidation in raw beef to a greater extent than vitamin C treatments (VC200 and VC400). These results indicate that tea catechins are potent natural antioxidants and exhibit greater antioxidant efficacy compared to vitamin C.     

Ready-to-use single tube quadruplex PCR for differential identification of mutton,chicken, pork and beef in processed meat samples

ABSTRACT

A reliable and sensitive identification method is required to tackle food adulteration mainly in meat production. We developed a dry reagent based ready-to-use single tube quadruplex PCR assay for accurate identification of chicken, mutton, beef and pork. The assay was found to be specific and reproducible. Thermo-stability studies of lyophilized PCR master mix were conducted at different temperature and time intervals, which revealed significant stability for 75 days at 4°C and for 60 days at 25°C. The developed assay was shown to be sensitive down to 16 pg DNA per reaction and the detection limit was found to be 0.01% (w/w) of each species. Furthermore, this method has been applied to the analysis of 68 commercial meat products and the results indicated that nine samples contained non-declared meat components. This dry reagent-based quadruplex PCR assay can be utilized to monitor various processed food products and also to maintain quality control in food industries mainly in the resource-limited settings.     

Effect of rosemary on lipid oxidation in pressure-processed,minced chicken breast during refrigerated storage and subsequent heat treatment

The protective effect of rosemary (Rosmarinus officinalis L.) against lipid oxidation and tocopherol degradation in minced, pressure-processed chicken breast with 0.5% salt added was investigated during chill storage for 9 days and/or subsequent heat treatment by measurement of head-space hexanal and pentanal together with thiobarbituric acid reactive substances (TBARS) and α- and γ-tocopherol. High-pressure processing at 600 MPa for 10 min led to a significant increase in secondary lipid oxidation products in minced chicken breast without rosemary, when compared to chicken breast with rosemary added. During subsequent chill storage, the level of secondary lipid oxidation products decreased slightly. For samples heated after pressure treatment and chill storage to mimic cooking, levels of secondary lipid oxidation products were higher than for the uncooked samples and rosemary was very efficient in preventing the oxidative process also during cooking, while the length of the chill storage period prior to cooking had little effect. Higher levels of α- and γ-tocopherol were found in all samples with rosemary compared to samples without rosemary, indicating that rosemary also protects tocopherols against degradation in pressurized chicken breast during chill storage and/or subsequent heat treatment.     

Development of breast muscle and meat quality in Arbor Acres broilers, Jingxing 100 crossbred chickens and Beijing fatty chickens

The objective of this experiment was to examine development of breast muscle and myofiber of M. pectoralis superficialis in three chicken breeds. Commercial broiler chickens (Arbor Acres broilers, AA), crossbred chickens (Jingxing 100 crossbred chickens, JXC) and Chinese native chickens (Beijing fatty chickens, BJF) were grown up to 98d to estimate myofiber density, and size (area, and diameter of myofibers) in P. superficialis. At 42, 56, 70, 84, and 98d of age, Pectoralis muscle was used to evaluate breast muscle weight, breast yield, and tenderness (shear force value). Results indicate that commercial broilers have higher breast weight, and higher shear force value than crossbred chickens and Chinese native chickens, that may be due to an increased myofiber diameter and area in Pectoralis muscle. It is suggested that histological properties of myofibers play an important role in increasing the shear force value of meat.