STUDY OF THE MAJOR PHYSICAL AND CHEMICAL PROPERTIES OF GUINEA-FOWL (NUMIDA MELEAGRIS) MEAT DEPENDING ON THE DURATION OF THE FATTENING PERIOD pH AND COLOUR OF MEAT

A study was carried out on the pH values and colour characteristics of meat from a local population of guinea-fowls (Numida meleagris), fattened to different ages (16, 20, and 24 weeks). It was established that the instrumentally obtained mean values of the pH indicator, reported for the breast meat in the time interval from 25 min. to 24 hours post mortem, ranged within 6.09 to 6.75, whereas for the thigh meat they were in the range of 6.36 to 7.29. It was found that at the 25th minute, as well as at the 24th hour post mortem, the indicator did not depend on the age and sex of the birds.The mean values of L* (colour luminosity) of the thigh meat for the three fattening periods were 39.59 (male guinea-fowls) and 40.07 (female birds), respectively, recorded at the 4th hour. When the meat was stored and the indicator was measured after 24 hours, the colour luminosity ranged from 40.65 to 42.34 in the males and 41.53 to 43.38 in the females. In the breast meat of the experimental male guinea-fowls the colour luminosity (L*) was 45.69 vs. 45.49 for the females at the 4th hour. At the 24th hour there was a statistically insignificant increase of the value both in the males (47.52) and in the females (47.64). Colour luminosity (L*) of the guinea-fowl breast and thigh meat was not sex-dependent.The instrumentally obtained value of the red colour component α* in all the studied samples of breast muscle at the 4th hour was 15.94 (15.65 in the males and 16.23 in the females). The results obtained did not show significant differences at the 24th hour. Male birds have α* (red colour component) of 15.29 and females – 15.78. In the thigh muscle the measured mean values of the red colour component α* were 16.13 at the 4th hour (16.09 in the males and 16.18 in the females) and 15.72 (15,76 in the males and 15.67 in the females) at the 24th hour.The yellow colour component b* in the breast muscle varied from 8,44 to 11,78 at the 4th hour and from 8,78 to 12,86 at the 24th hour (for both sexes taken together). The mean values in the thigh muscle were 4,74 at the 4th hour and 4,47 at the 24th hour, respectively.The following values were established when calculating the colour saturation (C*) of the meat from male and female guinea-fowls: 17,44 – 20,22 for the breast muscle and 15,31 – 17,40 for the thigh muscle at the 24th hour. The highest pigment saturation in the two studied muscle samples was established at 16-week old guinea-fowls (in the breast muscle at the 24th hour and in the thigh muscle at the 4th hour post mortem).The calculated colour difference (ΔE *) in the time interval from 4th to 24th hour after slaughtering the fowls (from the three groups) varied from 2,09 to 3,56 in the breast muscles and from 2,44 to 3,28 in the thigh muscle for both sexes.