An investigation of changes in physical and chemical properties of kavurma during processing

In this study, changes in pH, moisture content, 2-thiobarbituric acid reactive substance (TBARS) value, Hunter colour values (L*, a*, b*), browning index (BI), textural attributes and headspace flavour of cooked meat product (Kavurma) were followed during the processing. Three different salt (1.5%, 2.0% and 2.5%) concentrations and fat percentages (20%, 25% and 30%) were studied during 160 minutes of cooking. Salt, fat and time had significant effects (P<0.05) on the pH, moisture content, TBARS, Hunter L* and a* values. Increase in salt and fat content caused to decrease (P<0.05) in pH, moisture content, Hunter L* and a* values. However, increase in time caused to increase in pH and TBARS. TBARS values were in the range of 0.14 - 2.05 mg/kg during the cooking process. Among all the samples at the end of cooking, the lowest TBARS value (0.67 mg/kg) was obtained at the salt content of 2.0 % and at the fat content of 25% (S5).The a* value decreased sharply during the first 40 minute, after that remained constant. However, L* value firstly increased (P<0.05) up to 80-100 minutes, then decreased. Hunter b* values affected significantly (P<0.05) by salt content and time but fat didn?t cause a significant change in b* value. Among 25 flavoring compounds identified by headspace GC- MS technique, the major compounds were n-butane, n-heptane, n-hexane, n-octane, n-butanal, 3-methylbutanal, n-pentanal, 2,3-pentadione, n-hexanal, heptanal, 3-methly-1-butanol, and n-octanal. Time didn?t cause a significant change in hardness and chewiness in most of the samples. Adhesiveness values sharply increased (P<0.05) in the samples of S1 (1.5% Salt- 20% Fat), S3 ( 1.5% Salt- 30% Fat), S4 (2.0% Salt- 20% Fat) and S6 (2.0% Salt- 30% Fat) within the first 20 min of processing and then became constant (P>0.05) until end of the process.Key Words: Cooked meat product (Kavurma), GC-MS, flavour, texture, TBARS, colour