Growth-related changes in muscle fibres, characteristics and rheological properties of wild boars meat

摘要

The study compared the muscle fibre, size, its characteristics as well as rhelogical properties of selected muscles: m. quadriceps femoris (QF), m. biceps femoris (BF), m. semimembranosus (SM), m. semitendinosus (ST), and m. longissimus (L) of wild boars of different carcass weight (30±2 and 70±3 kg SD). Muscle fibre cross-section areas and percentages of different fibre types: I (slow oxidative), IIA (fast oxidative-glyeoiytic) and IIB (fast glycolytic) per muscle fibre bundle, were measured usinga computer image analysis program, The relaxation test was used to determine rheological properties and the results were interpreted with a 5-element Maxwell body model. The ST of wild boars was found to contain the highest percentage of type I fibres rather than fibres of IIA, compared to the other muscles tested. A higher percentage of type I fibres was also typical of BF and L, both in young and old wild boars. The lowest percentage of type I and the highest percentage of type IIB fibres were foundin QF and SM. Growth rate influences muscle fibre properties in all muscles; those of old wild boars were found to contain a higher percentage of type I fibres and a lower percentage of type IIB fibres compared to the same muscles of juvenile wild boars,whereas the percentage of type IIA fibres was about the same in the muscles of both wild boar groups tested. Of the all wild boar muscles, the highest mean fibre cross-section area was found in BF and ST, the lowest - in QF and L, whereas the cross-sectional area of I and IIB fibres were markedly larger than the cross-sectional area of type IIA. The mean cross-sectional area of all fibre types increased together with increased growth rate and the largest muscle fibre cross-section areas were in the oldwild boars' muscles. Of the all wild boar muscles tested, the highest sum of elastic moduli was found in L muscles, while the lowest was typical of QF and BF. Meat obtained from wild boar juveniles, compared to old wild boars, indicated lower values ofEO and higher El and E2 elasticity moduli, whereas ml and ml viscous moduli values were not dependent on carcass weight.