Relationship of changes in quality attributes and protein solubility of ground beef under pasteurization conditions

Quality changes in chicken livers during cooking

Raw chicken livers are often contaminated with Campylobacter and Salmonella. Cooking is considered the last defense of pathogen control for meals containing chicken livers. However, consumers' preference for pink color and a creamy texture as desired attributes in preparing liver pâté may lead to inadequate cooking, thereby increasing the risk of foodborne illness. This study aimed to investigate the effects of different cooking conditions (60-90°C, 0-65 min) on quality changes in frozen and fresh chicken livers and develop cooking recommendations to produce safe liver products with desired qualities. Frozen storage reduced the water holding capacity of raw chicken livers and led to more cooking loss (reduction in the weight of liver pieces during cooking) and area shrinkage after heating. The cooking loss and area shrinkage increased with increasing heating time and temperature, following the first-order fractional model. Compared with fresh livers, the shear resistance for cutting through the cooked livers increased after heating at 73.9°C to 90°C and decreased at 60°C, whereas the livers heated at 70°C had shear resistance (~4.5 N/g) similar to the fresh liver, regardless of the heating times used in this study. Heating resulted in color changes in livers, shifting from red hue (0°) toward yellow hue (90°), as characterized by the increased hue angles after heating. Cooking livers to an internal temperature of 70°C to 73.9°C and hold for 101 to 26 s is recommended for food processing plants or restaurants to prepare ready-to-eat meals containing chicken livers to achieve microbial safety with respect to Salmonella and provide cooked livers with desired texture and pink color.

Effect of Glazing with Different Materials on the Quality of Tuna During Frozen Storage

This study investigated and determined the changes in various qualities of tuna samples that were glazed with rosmarinic acid, a bamboo leaf antioxidant, and sodium lactate and stored at −18 °C for 180 days. The water-holding capacity, cooking loss, color, texture, protein content, and total volatile basic nitrogen (TVB-N) were monitored, to study the effect of tuna glazed with different materials on the quality every 30 days. Low-field nuclear magnetic resonance (LF-NMR) was used to measure the water distribution of tuna in this paper. The results showed that the quality of unglazed tuna decreased significantly after 180 days of frozen storage. During frozen storage, the hardness and a* values of RG (glazed with the rosmarinic acid group), SG (glazed with the sodium lactate group), and CG (glazed with the composite of rosmarinic acid, sodium lactate, and the antioxidant of bamboo leaf) tuna decreased slowly, while the malondialdehyde (MDA) value of AG (glazed with the antioxidant of bamboo leaf group) tuna increased slowly. After 180 days of frozen storage, CG tuna had the highest protein content and the lowest TVB-N value, which may have been due to the synergistic effect of glazing materials. The tuna with CG also had the best freshness and quality after frozen storage. Considering the results, a composite of rosemary (0.3%), sodium lactate (3.4%), and antioxidants of bamboo leaves (0.12%) is the best material for glazing tuna.

Formation of Nϵ-Carboxymethyllysine and Nϵ-Carboxyethyllysine in Prepared Chicken Breast by Pan Frying

The objective of this work was to investigate the effects of pan frying on the formation of two typical advanced glycation end products (AGEs) named N^ϵ-carboxymethyllysine (CML) and N^ϵ-carboxyethyllysine (CEL) in prepared chicken breast. The marinated chicken breast was pan fried for 1 to 6 min, and then protein, fat, moisture, carbonyl, sulfhydryl, thiobarbituric acid reactive substances, chroma (a*, b*, L*), absorbance at 294 and 420 nm, and AGE (CEL) levels were measured once a minute. Pearson's correlation was determined and indicated that moisture was significantly negatively correlated with Maillard reaction and AGEs (P < 0.05), fat and protein contents were significantly positively correlated with AGEs (P < 0.05), and a* values were positively correlated with Maillard reaction and CEL (P < 0.05). Protein and lipid oxidation played an important role on the correlation of AGEs. In conclusion, Maillard reaction and oxidation reaction are two important factors affecting AGE formation.

Creatine Monohydrate and Guanidinoacetic Acid Supplementation Affects the Growth Performance, Meat Quality, and Creatine Metabolism of Finishing Pigs

This study aimed to investigate the effects of creatine monohydrate (CMH) and guanidinoacetic acid (GAA) supplementation on the growth performance, meat quality, and creatine metabolism of finishing pigs. The pigs were randomly allocated to three treatment groups: the control group, CMH group, and GAA group. In comparison to the control group, CMH treatment increased average daily feed intake and GAA treatment increased average daily feed intake and average daily gain of pigs. In addition, CMH and GAA treatment increased pH_45 min, myofibrillar protein solubility, and calpain 1 mRNA expression level and decreased the drip loss and shear force value in longissimus dorsi or semitendinosus muscle. Moreover, CMH and GAA supplementation increased the concentrations of creatine and phosphocreatine and the mRNA expressions of guanidinoacetate N-methyltransferase and creatine transporter in longissimus dorsi muscle, semitendinosus muscle, liver, or kidneys and decreased the mRNA expressions of arginine:glycine amidinotransferase in kidneys. In conclusion, CMH and GAA supplementation could improve the growth performance and meat quality and alter creatine metabolism of finishing pigs.

Effects of Different Selenium Sources on Growth Performance, Antioxidant Capacity and Meat Quality of Local Chinese Subei Chickens

Despite increasing evidence indicating the essential involvement of selenium (Se) on growth performance, antioxidant capacity, and meat quality of commercial broilers, the effects of different Se sources on local Chinese Subei chickens is unclear. A total of 360 50-day-old male chickens were individually weighed and randomly allocated to four treatment groups. Chickens in each of the four groups were fed diets supplemented with 0.3 mg Se/kg as sodium Se (SS), Se-enriched yeast (SY), selenomethionine (Met-Se), or nano red element Se (Nano-Se) for 40 days. At the end of the experiment, one bird of approximately average weight from each cage was selected and slaughtered, and blood and breast muscles samples were collected. The results showed that there was no significant difference in feed intake, body weight gain, or feed to gain ratio among treatments (P > 0.05). Dietary SY, Met-Se, and Nano-Se supplementation increased the activity of glutathione peroxidase in serum and breast muscles and decreased the concentration of malondialdehyde in serum and carbonyl in breast muscles compared with the SS group (P < 0.05). Moreover, SY, Met-Se, and Nano-Se supplementation increased pH_45min, total protein solubility, and myofibrillar protein solubility, as well as decreased the shear force value compared with the SS group (P < 0.05). In addition, birds in the SY and Met-Se groups exhibited lower cooking loss compared with the SS group (P < 0.05). In conclusion, organic Se and Nano-Se supplementation resulted in an improvement of antioxidant capacity and meat quality in local Chinese Subei chickens relative to inorganic Se.