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Karamucki T., Gardzielewska J., Rybarczyk A., Jakubowska M., Natalczyk-Szymkowska W. (2011): Usefulness of selected methods of colour change measurement for pork quality assessment. Czech J. Food Sci., 29: 212-218.A few selected methods of the meat colour change determination were compared with regard to their usefulness in the assessment of the quality of minced pork. The study was carried out on 128 samples of the muscle longissimus lumborum, taken from 128 carcasses weighing 70-105 kg (equal number of both sexes -64), obtained from pigs slaughtered in an industrial process line. The relationships were determined between the meat quality traits (concentrations of basic chemical components in the meat, colour, sensory analysis of wateriness and firmness, WHC and pH u ), and the changes in colour parameters measured in CIELAB and CIELCh scales, total colour change (Δe*), and the changes determined by Karamucki using the modified Kortz method. It was found that the most useful method for the quality assessment was the Kortz method modified by Karamucki, used to determine the stability of the meat colour (expressed as % colour change) and based on the measurements of absorbance at wavelengths 580 nm and 630 nm, before and after the change of colour. Out of the meat colour parameters, the most useful for assessing the meat quality were the changes in redness (a*) -CIELAB scale, and hue angle hº -CIELCh scale. The changes in colour determined by the aforementioned methods were a better indicator of the pork quality than the total colour change (Δe*).

Experimental material consisted of one-day Pharaoh quail chicks, which were separated into three experimental groups. The birds of group I received a fodder, the nutritive value of which was consistent with recommended feeding standards for growing quails, whereas for those of group II and III the protein level was lowered in all feed mixes appropriated for the whole rearing period. During the experiment, individual body weight, feed consumption, and bird deaths and their health culling were controlled. At the age of 42 days, 11 males of each group, with a body weight similar to the group mean, were slaughtered. In blood samples collected, the level of amylase was assayed, as well as quail slaughter value was calculated and depot fat and extramuscular fat contents were determined. Meat chemical determinations were made (dry matter, protein and fat contents), as well as physicochemical (pH, colour, water binding capacity) and sensory ones (cooked meat and bouillon). Basing on the performed examination, it was found that a lowered level of protein in fodder did not affect quail body weight, slaughter yield, or breast part and leg participation in body weight. Carcass fatness decreased and meat water binding capacity improved. The values of majority of other examined meat qualitative traits were similar to those obtained in control group.

The relaTionship beTween colour and ph in cold-sTored quail breasT muscle* * T a d e u s z K a r a m u c k i ♦ , J ó z e f a G a r d z i e l e w s k a , M a ł g o r z a t a J a k u b o w s k a , K i n g a R y b a k , J u s t y n a G a r c z e w s k a Faculty of Biotechnology and Animal Breeding, West Pomeranian University of Technology, Judyma 24, 71-466 Szczecin, Poland ♦ Corresponding author: tadeusz.karamucki@zut.edu.pl abstract The purpose of this study was to analyse the colour of the breast muscles of Japanese pharaoh quail on the first day after slaughter and again after further six days of cold storage, in relation to their muscle ph. The material for the study consisted of 40 breast muscles taken from the carcasses of six-week-old Japanese Pharaoh quail. Based on pH results, the muscles were divided into three groups: I (pH = 5.51-5.70), II (pH = 5.71-5.90) and III (pH = 5.91-6.10). After this the muscles were stored for a further 6 days at 4°C. It was found that the pH of freshly dissected quail breast muscle is a good indicator of the colour stability of muscles cold-stored at 4°C for six days. The lowest degree of colour stability was observed in the pH range 5.51-5.70. In the sensory evaluation muscles displaying this degree of colour instability were considered unacceptable or barely acceptable. In contrast, muscles in the pH ranges 5.71-5.90 and 5.91-6.10 displayed a high degree of colour stability and were considered acceptable in the sensory evaluation. The colour changes that occurred during storage of the muscles were due to changes in the values of all of the colour parameters (L*, a*, b*, C* and hº); however, the greatest changes were found in the case of redness (a*) and the hue angle (hº). The changes were caused both by alterations in the amount of pigment reached by light, and by changes in the relative amounts of the chemical forms of myoglobin.