Relationships of quality indices with wooden breast myopathy severity in chicken breast meat under refrigerated storage.

1. This study investigated the relationships of quality indices with the severity of wooden breast (WB) myopathy in chicken breast meat under refrigerated storage. The physicochemical properties, water-holding capacity (WHC), microbial quality and fatty acid profiles of normal chicken breast meat samples (NOR samples, n = 63), moderate WB (MWB, n = 63) myopathy and severe WB (SWB, n = 63) myopathy (MWB and SWB samples, respectively) were evaluated immediately after sampling and after 4 and 8 d of refrigerated storage at 4°C.2. Total collagen, fat, saturated and monounsaturated fatty acid contents, redness and pH of the SWB and MWB samples were higher than the NOR samples. The SWB samples that were stored for 8 d had poor WHC, total viable counts (TVC) of higher than 7.0log colony-forming units, total volatile basic nitrogen (TVB-N) content of greater than 15 mg/100 g and a thiobarbituric acid - reactive substance level of higher than 1 mg/kg malondialdehyde.3. No significant difference was observed in the TVB-N content and TVC of the MWB and NOR samples during storage. Polyunsaturated fatty acid content was lower in the SWB and MWB samples than in the NOR samples. The SWB samples were tougher than the MWB and NOR samples after 8 d of refrigeration.4. In conclusion, the quality of chicken breast meat with SWB myopathy degraded considerably over time; thus, such meat should not be subjected to extended refrigeration for storage.

Combination of sensory evaluation with conventional physiochemical analyses to evaluate quality changes during long-term storage and estimate the shelf life of chicken eggs.

1. This study developed a comprehensive sensory evaluation system that consisted of descriptions corresponding to United States Department of Agriculture photos to evaluate overall acceptability, albumen and yolk appearances and odours. It determined physiochemical parameters of eggs stored at 7°C (7W12 and 7U12 for washed and unwashed, respectively) for 12 weeks and stored at 25°C (25W4 and 25U4 for washed and unwashed, respectively) for four weeks.2. Throughout storage, there was a general downward trend in Haugh units (HU) and yolk index and an upward trend in air cell size, weight loss and S-ovalbumin content were observed (P < 0.05). The 25W4 and 25U4 egg quality rapidly deteriorated from grade AA (HU 81.7) to grade B after two weeks (HU 46.5 and 49.6), whereas 7W12 and 7U12 eggs remained grade A after 12 weeks (HU 67.3 and 66.9). High correlations were observed between the sensory and physiochemical parameters (i.e., R2 = 0.93, 0.93, 0.88 and 0.94 for albumen appearance, yolk appearance, sensorial odour and overall acceptability, respectively, with HU in 25W4 eggs).3. Eggs stored at 25°C and classified into 'premium', 'class I', and 'class II' on the basis of their HU had estimated shelf life of 0.5, 1.5 and 2.5 weeks, while shelf lives of 4, 9 and 15 weeks were estimated for 7°C-stored premium, class I and II eggs, respectively.4. In conclusion, distinct HU requirements for eggs of different quality classes under two storage temperatures need to be established. Incorporating sensory evaluation with conventional physiochemical analyses is promising to assess and estimate egg quality changes. Further research work about the influences of different storage temperatures and possible temperature fluctuations during storage on egg quality changes is needed.

Application of principal component analysis with instrumental analysis and sensory evaluation for assessment of chicken breast meat juiciness.

1. The objectives of this study were to use principal component analysis (PCA) to analyse the variability of the three instrumental and 14 descriptive sensory properties of chicken breast meat. The meat was cooked until the internal temperature reached 85°C and further cooked for 0, 20, and 40 min. The second objective was to identify the most critical variables for assessing meat juiciness.2. Cooking loss and moisture content exhibited high correlation with sensorial moisture release and mouth feel.3. The distribution of objects on the axes of the first two principal components (PCs) enabled the identification of three groups undergoing different cooking durations. The four major PCs explained 80.0% of the total variability.4. Cooking loss, moisture content, water-holding capacity, sensorial moisture release and mouth feel were demonstrated as the most effective variables for the first two PCs. PCA with instrumental and sensory analyses proved an effective procedure for systematically and comprehensively judging chicken meat juiciness.

Influences of end-point heating temperature on the quality attributes of chicken meat.

This study aimed to evaluate the changes in physicochemical, textural and sensory characteristics of broiler (BR) and Taiwan native chicken (TNC) pectoralis muscle heated at temperatures of 50-95°C. With increasing temperature, cooking loss, collagen solubility, shear force value and hardness, of samples increased in both chicken breeds. Rapid decreases in protein solubility were observed when the meat was heated to 50°C and gradually decreased thereafter. Meat from BRs and native chickens performed differently upon heating in certain characteristics. TNC meat had longer cooking time and lower myofibrillar fragmentation index than BR meat did. TNC meat had higher collagen content, shear force values and springiness but lower collagen solubility than BR meat did. BR meat had significantly higher onset and end transition temperatures than TNC meat did. In BR meat, a sensory analysis revealed that moisture release decreased and chicken flavour increased with increasing temperature. Protein solubility, cooking loss and the texture of heated meat were highly correlated. This study scientifically assessed the performances of the two breeds of chickens with different thermal treatments; producers could utilise the information to produce poultry products with more desirable qualities.

Regulation of apoptosis by C. elegans CED-9 in the absence of the C-terminal transmembrane domain.

Bcl-2 proteins regulate apoptosis in organisms as diverse as mammals and nematodes. These proteins are often localized at mitochondria by a C-terminal transmembrane domain. Although the transmembrane domain and mitochondrial localization are centrally involved in specific cases of vertebrate Bcl-2 activity, the significance of this localization is not clear for all species. Studying the Caenorhabditis elegans Bcl-2 homolog CED-9, we found that the transmembrane domain was both necessary and sufficient for localization at mitochondrial outer membranes. Furthermore, we found that in our assays, ced-9 transgenes lacking the transmembrane domain, although somewhat less active than equivalent transgenes derived from wild-type ced-9, rescued embryonic lethality of ced-9(lf) animals and responded properly to upstream signals in controlling the fate of Pn.aap neurons. Both of these apoptotic activities were retained in a construct where CED-9 lacking the transmembrane domain was targeted to the cytosolic surface of the endoplasmic reticulum and derived organelles, suggesting that in wild-type animals, accumulation at mitochondria is not essential for CED-9 to either inhibit or promote apoptosis in C. elegans. Taken together, these data are consistent with a multimodal character of CED-9 action, with an ability to regulate apoptosis through interactions in the cytosol coexisting with additional evolutionarily conserved role(s) at the membrane.

Physical and sensory characteristics of marinated broiler drumsticks treated with lactoperoxidase system and thermal treatment.

1. The lactoperoxidase system (LPS) and thermal treatments have been shown to inactivate some micro-organisms in foods. However, further studies are needed to evaluate whether these treatments influenced the physical and sensory characteristics of treated samples. 2. A solution that contained 1% acetic acid and 3% salt with pH adjusted to 4 was developed as a standard marinade. The LPS consisting of 1 microg/ml lactoperoxidase (LP), 5.9 mM potassium thiocyanate (KSCN) and 2.5 mM hydrogen peroxide (H2O2) was added to the marinade for the LPS treatments. 3. In the thermal treatment, samples were heated with the marinade solution at 58 degrees C for 2 min and then marinated at 4 degrees C for 18 h, while the non-thermal treatments were marinated at 4 degrees C for 18 h. 4. For sensory evaluation, flavouring agents including 0.3% black pepper and 0.15% garlic powder were added to the marinade. For physical evaluation, no flavouring agents were added. 5. The results showed that combined LPS and thermal treatment did not impair the physical or sensory qualities of the samples. 6. In conclusion, marinated broiler drumsticks treated with LPS and thermal treatment had acceptable physical and sensory qualities.

Assessment of fresh pork color with color machine vision.

Currently, fresh pork color is visually evaluated using either the Japanese Pork Color Standards (JPCS) or the National Pork Producers Council Pork Quality Standards (NPPC) as a reference. Although useful, visual evaluation of meat color can vary with evaluator and may be quite expensive. In this study, three separate studies were used to compare the ability of color machine vision (CMV) and untrained panelists to evaluate pork color. Panels visually evaluated over 200 pork loin chops using either the JPCS or NPPC reference standards. Results from each panel were used to evaluate the ability of the CMV to sort pork loin chops based on the same criteria. Representative samples, typical of each color class, were used to train neural-network-based image processing software. After training, the CMV system was used to evaluate quality classes of pork samples based on color distribution. Classification by CMV was compared with the average panel score, rounded to the nearest integer. Training the CMV system using images of actual meat samples resulted in a stronger correlation to panel scores than training with either set of artificial color standards. Agreement between the CMV system and the panels was as high as 90%. Agreement between individual panelists and the integer panel average (52 to 85%) was less than that observed for CMV classification. Finally, the on-line performance of CMV using a laboratory conveyor system was simulated by repeatedly classifying 37 samples at a speed of 1 sample per second. Collectively, these results demonstrate that CMV is a rapid and repeatable means of evaluating pork color.

Effect of halothane genotype on porcine meat quality and myoglobin autoxidation.

The objective of this study was to determine effects of light (40-80 kg) or heavy (100-130 kg) slaughter weight and halothane status (positive, nn; negative, NN; and heterozygous, Nn), on meat quality. Longissimus muscle (LM) pH at 45 min (pH(45)) post-exsanguination was 6.25, 6.03, and 5.84 (different at p < 0.01) for NN, Nn, and nn genotype, respectively. At heavier weights (100-130 kg), genotype correlated (r = -0.71) with LM pH(45), 10th costae LM (TENLM) color score (r = -0.55), TENLM Hunter L(∗)-value (r = 0.47), water holding capacity (r = 0.42) and TENLM subjective firmness-wetness score (r = 0.51). Rate constants for metmyoglobin accumulation and oxymyoglobin autoxidation, indicators for fresh meat color stability, increased (p < 0.05) with decreasing pH. Color stability for NN muscle was more stable than nn muscle (p < 0.05). Electrofocusing of myoblobin revealed two bands (MW 17.10(3)) at pI 6.1 and 6.5 across genotypes. Because differences were not observed across genotypes, an observed increase (p < 0.05) in 24 hr myoglobin autoxidation rate constant (associated with increased expression of the HAL gene) are presumed dependent upon post-mortem muscle changes. These data show that changes in halothane status affect fresh pork quality and that lowered meat quality results in further color destruction due to altered chemical reactions involving myoglobin oxidation.