Characterization of Chicken By-products by Mean of Proximate and Nutritional Compositions chicken by-products;vitamin;mineral;amino acid;fatty acid contents; Though a great amount of chicken by-products are consumed everyday in many countries worldwide, however, no attention has been paid to the investigation of nutritional composition of these by-products. In the present work, the basic information regarding the aspects of nutritional composition of chicken by-products such as; liver, gizzard, heart, lung, crop, small intestines, cecum and duodenum was studied. Our results revealed that the approximate composition range (minimum to maximum) of these by-products was found as such: moisture 76.68-83.23%; fat 0.81-4.53%, protein 10.96-17.70% and calories 983.20-1,426.0 cal/g tissue, in which liver and gizzard had the highest protein content. Liver had higher (p<0.05) vitamin A, B1, B2, B3, B5 and B6 contents in comparison to other remaining byproducts. Total saturated fatty acids (SFA), unsaturated fatty acids (UFA), polyunsaturated fatty acids (PUFA) levels ranged between the by-products from 31.82% to 43.96%, 56.04% to 68.19%, and 18.27% to 32.05%, respectively. Remarkably, all of by-products showed desirable PUFA/SFA ratios. Furthermore, all of chicken by-products, especially liver, contained higher levels of trace elements (e.g., Fe, Mn and Zn) in comparison with those from muscle tissues published in literature. Overall, the study indicated that most of chicken byproducts examined are good sources of essential nutrients and these obtained results will be the useful information to consumers and meat processors.

Objective: Pork belly is considered as the most commercially important and preferable primal cut by consumers worldwide. Thus, this study was conducted to determine the effects of fat levels on the meat quality characteristics of pork bellies.Methods: Seventy-eight growing-finishing pigs collected from different commercial pig farms were slaughtered and used in the present study. After slaughter 24 h, bellies were fabricated according to the Korean Pork Cutting Specification, and immediately sampled for analysis of their fat content. Based on the fat levels, the bellies were segregated into three different groups: low fat (LF, fat ≤20%, n = 15), medium fat (MF, fat 21% to 30%, n = 30), and high fat (HF, fat ≥31%, n = 33). The bellies were then analyzed for meat quality traits, fatty acids, flavor compounds and eating quality properties.Results: The HF group had lower moisture and cooking loss levels compared to the other groups (p<0.05). The LF group presented higher proportions of polyunsaturated fatty acids compared to the other groups (p<0.05). The LF group showed higher amounts of the Maillard reaction-derived flavor compounds (e.g., 2,5-dimethyl pyrazine, 2-ethyl-3,5-dimethyl, and 4-methylthiazole) associated with meaty and roasty flavors whereas, the HF group showed higher amounts of oleic acid- derived compounds (e.g., nonanal and octanal) associated with the fatty and oily flavors. Interestingly, significantly higher scores for all the eating quality attributes (flavor, juiciness, tenderness, and overall acceptance) were found in the HF group compared to those in the LF or MF group (p<0.05).Conclusion: The high-fat bellies (fat ≥31%) had a better technological quality and eating quality compared to the low-fat bellies (fat ≤20%). Thus, increasing the fat content may improve the technological quality and eating quality traits of pork bellies, however, this increase may also result in more trimmed loss due to excessively deposited body fat.

The present work aimed at evaluating the effects of carcass quality grade on the quality characteristics of pork meat according to Korean carcass quality grade system. Pork carcasses with varying in quality grades (QG): 1+ (QG1+, n=10), 1 (QG1, n=10) and 2 (QG2, n=10), were used to evaluate the relationship between carcass quality grade and meat quality. The meat quality traits, fatty acid profiles, flavor compounds and sensory qualities were measured on the longissimus dorsi muscle samples of these carcasses. Pork meat of higher quality grade (GQ1+) presented significantly higher fat content (5.43%), C18:2n-6 level (19.03%) and total unsaturated fatty acids (UFA) content (62.72%). Also, the QG1+ meat was significantly higher in levels of classes of flavor compounds such as aldehydes, alcohols and hydrocarbons in comparison to those of the meat samples from the lower GQ groups. The sensory evaluation results (flavor, juiciness, tenderness and acceptability scores) of QG1+ meat was significantly higher than the QG1 and QG2 meats. The pork with lower QG (i.e., QG2) was found positively correlated to redness (r=0.987), C18:1n-9 level (r=1.000) but negatively correlated to the fat content (r=-0.949), and flavor (r=-0.870), juiciness (r=-0.861), tenderness (r=-0.862) and acceptability (r=-0.815) scores. The pork with higher quality grade had higher fat content, total unsaturated fatty acids and better eating quality, thus producing pork with higher quality grades should be considered in order to satisfy the consumer's expectation.

The present study aimed at investigating the effects of dry- and wet-aging methods on flavor compounds and sensory properties of low fat Hanwoo beef muscles. All the beef samples were obtained from 2-grade carcasses of Hanwoo cows. The beef samples used in the dry- and wet-aging methods were prepared in the forms of quarter beef (bone-in) and cuts (boneless), respectively. The dry-aging was carried out at 2°C-4°C and humidity of 65%-85%, while the wet-aging was done at 1°C for 0, 20, 40, and 60 d. At each aging time, three muscles: longissmus thoracis (LT), glutaeusmedus (GM) and semimembranosus (SM) were taken from the corresponding quarters and cuts, and used for the flavor compounds and sensory analyses. Results showed that both aging methods significantly increased the concentrations of flavor compounds and total amount of all classes of the flavor compounds as the aging time increased (p<0.05). In the dry-aging method, the GM and SM muscles presented significantly higher total amounts of pyrazines and sulfur-containing compounds compared to the LT muscle (p<0.05). Both the aging methods improved the eating quality attributes, indicating by increased scores of sensorial attributes with increased aging time for all the muscles studied (p<0.05). However, compared to the wet-aging, the dry-aging method resulted in significantly higher scores of tenderness and flavor for the GM and SM muscles after 40 to 60 d. Thus, postmortem aging, especially the dry-aging method could be used to improve eating quality attributes (tenderness and flavor) of low fat beef muscles such as GM and SM.