A solution for fillet quality: Slaughter age's effect on protein mechanism and oxidation.

Physico-chemical properties of fish flesh are reliable predictors of fillet quality and nutritional value. In our study, the age-related variations of the chemical composition, pH, water activity (aw), water holding capacity (WHC), color and texture analysis, protein thermal stability, myofibrillar fragmentation index (MFI), glycogen content, protein oxidation and protein profiles were investigated in Oncorhynchus mykiss (rainbow trout) fillet. The results revealed that protein denaturation temperatures (Tmax1 and Tmax2) decreased by 2 % and 11.6 % depending on fish age. Tmax1 and Tmax2 values in the same groups were raised 71 % at 11 months' fish and this increase was 58 % at 23 months' fish. An age-related reduction by 66.6 % and 31.25 % was noticed for protein oxidation markers sulfhydryl groups and disulfide bonds. MFI value increased by 86.6 % connected with age. The characteristics of fish meat quality are complex and are influenced by various factors that affect the degree of freshness of the product and its acceptance in the market. Taking into account the different demands of the consumer, this study has shown that age at slaughter has an impact on final product quality and that the recommended age at slaughter, taking into account market weight, positively affects meat quality.

Effect of climate change on fillet quality and shelf-life of Oncorhynchus mykiss under controlled conditions.

BACKGROUND: Temperature, which affects numerous physiological processes, has been described as the 'main ecological factor' for fish. The aim of this modeling study is to explore the impact of climate-induced temperature changes on fish fillet quality and shelf life. RESULTS: Temperature stress in rainbow trout affected ash and moisture, and inhibited myofibril fragmentation in the fillets. However, with the increase in temperature, there was a decrease in the total amount of saturated fatty acids (∑SFA) and there were significant increases in the total amount of omega 3 (∑n3) and 22:6n-3 (DHA). It was determined that temperature increase had a negative effect on color, texture, water-holding capacity, water activity, pH, lactic acid, and glycogen levels in fillets, and it had a positive effect by delaying microbial spoilage, especially in cold storage. CONCLUSION: This study suggest that the effects of climate change on product quality and shelf life in fish requires further research. It highlights knowledge gaps to guide future research in this emerging field. © 2023 Society of Chemical Industry.

Effects of animal fat replacement with almond flour on quality parameters of beef patties.

Almond is rich in vitamins, minerals, and dietary fiber and contains high fat and protein. For this reason, almond flour can be used as an additive in the production of various foods to increase nutritional value, improve texture and flavor, and produce healthier products. The purpose of this study is to determine the availability of almond flour as an animal fat replacer in the production of beef patties. For this purpose, beef patties were produced in five different formulations containing animal fat and/or almond flour, and pH, moisture content, color, and TBARS values were detected in both raw and cooked samples. In addition, cooking yield and shrinkage were calculated and fatty acid composition, texture profile, and sensory analyses were performed on cooked samples. Replacing animal fat with almond flour increased pH in raw and cooked beef patties but decreased moisture content, b* value, and TBARS in cooked samples compared to the control. While cooking yield increased in beef patties containing almond flour, shrinkage decreased. In addition, the cooking process caused decreases in L*, a*, and b* values. Using almond flour in beef patties decreased the SFAs and increased the amounts of oleic and linoleic acids. Hardness, cohesiveness, resilience, and chewiness were significantly affected by the use of almond flour (p < .01), and higher hardness and chewiness, and lower cohesiveness and resilience were determined in the samples containing almond flour compared to the control. On the other hand, the use of almond flour instead of animal fat in beef patties did not have a significant effect on the determined sensory properties (p > .05).

Investigation of textural and physicochemical changes during the manufacturing process of pastirma, a dry-cured meat product.

The changes in textural and physicochemical properties and stability of meat proteins during the production of pastirma were studied. Samples taken at different production stages (raw material, curing, first drying, second drying and final product) were analyzed. The pH decreased at the end of the curing but increased after the first and second drying. While moisture content and water activity decreased throughout the pastirma production, salt content and Thiobarbituric acid-reactive substances (TBARS) increased. Production stages affected the free fatty acids, residual nitrite content and color parameters (P < 0.01). These results showed that considerable physicochemical changes occurred in the production stages of pastirma. The denaturation temperatures for myosin and actin decreased at the end of the curing, however, no denaturation peak for myosin was observed in the later stages. Hardness, cohesiveness and chewiness increased throughout the pastirma production. Warner-Bratzler (WB) shear force increased at the end of the first drying and in the final product. These results are important in terms of obtaining the desired textural properties in the final product. Also, remarkable correlations were detected among the determined properties during the manufacturing process. The study provided considerable findings for the development of industrial pastirma production.

Volatile compounds and some physico-chemical properties of pastirma produced with different nitrate levels.

OBJECTIVE: The aim of the study was to evaluate the effects of different nitrate levels (150, 300, 450, and 600 ppm KNO3) on the volatile compounds and some other properties of pastirma. METHODS: Pastirma samples were produced under the controlled condition and analyses of volatile compounds, and thiobarbituric acid reactive substances (TBARS) as an indicator of lipid oxidation, non-protein nitrogenous matter content as an indicator of proteolysis, color and residual nitrite were carried out on the final product. The profile of volatile compounds of pastirma samples was analyzed by gas chromatography/mass spectrometry using a solid phase microextraction. RESULTS: Nitrate level had a significant effect on pH value (p<0.05) and a very significant effect on TBARS value (p<0.01). No significant differences were determined in terms of aw value, non-protein nitrogenous substance content, color and residual nitrite between pastirma groups produced by using different nitrate levels. Nitrate level had a significant (p<0.05) or a very significant (p<0.01) effect on some volatile compounds. It was determined that the amounts and counts of volatile compounds were lower in the 450 and especially 600 ppm nitrate levels than 150 and 300 ppm nitrate levels (p<0.05). While the use of 600 ppm nitrate did not cause an increase in residual nitrite levels, the use of 150 ppm nitrate did not negatively affect the color of pastirma. However, the levels of volatile compounds decreased with an increasing level of nitrate. CONCLUSION: The use of 600 ppm nitrate is not a risk in terms of residual nitrite in pastirma produced under controlled condition, however, this level is not suitable due to decrease in the amount of volatile compounds.

Curing and diffusion coefficient study in pastirma, a Turkish traditional meat product.

Changes in water activity (a(w)), moisture and salt contents and salt effective diffusion coefficients (D(eff)) of pastirma samples during the curing process were determined. At the end of the curing stage, a(w) values decreased to 0.942. The average initial moisture content of the samples decreased from 74.56% to 66.64%, depending on the curing time and the average salt content increased to 15.65 g NaCl/100 g dry matter at the end of the 48-hour curing process. Pastirma samples were assumed the geometry of endless slices, and the analytical solution of Fick's second equation was used for determination of salt D(eff) values. Salt D(eff) values were found to vary between 1.49×10(-9)-4.08×10(-9) m(2)/s.

Determination of glass transition temperature of beef and effects of various cryoprotective agents on some chemical changes.

Sucrose (2%), sorbitol (2%), mannitol (2%), gum arabic (0.15%), carrageenan (0.15%) and meat stabilizer (0.5%) were blended with ground beef and stored for 6 months separately at -9°C, -13°C (glass transition temperature (T(g)) of beef determined by Differential Scanning Calorimetry (DSC)) and -18°C. Total volatile basic nitrogen (TVB-N) and Thiobarbituric acid-reactive substances (TBARS) were determined at 1, 3 and 6th months of storage. Cryoprotectants and storage period had a significant effect (P<0.05) on the TVB-N and TBARS values. Although there were no statistically significant differences between storage at -13°C (T(g)) and -18°C, storage at -9°C had different effects on TVB-N and TBARS.