Verification of the South African pork classification system

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Myburgh, Rita
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University of the Free State
The main objective of this study was to investigate whether the current formulas used in the pork classification system (PORCUS) is still suitable for predicting meat yield over different carcasses yield and weight classes. Ninety seven pork carcasses from different weight categories classed as P, O, and R classification groups were sampled at 4 major South African abattoirs and these pigs were then dissected into different wholesale cuts. These cuts were then dissected into skin, bone, meat and fat. The dissected portions were then weighed and these weights were used to determine true lean yield, which in turn was used to reclassify the carcasses. Pearson correlations coefficients indicated that the % true meat yield by dissection gives better correlations with most of the meat quality parameters in comparison with the % meat yield predicted by the HGP. Only 26.8% of the carcasses were classed correctly with the HGP. For most classes the yield was over predicted by the HGP. There is a general perception that pig carcasses are becoming heavier and leaner, 36 of the selected 97 carcasses that were supposed to yield P, O, and R, recorded actual yields of C, U, and S. From the multiple regression analysis it was clear that the 1992 Bruwer equation over predicts the LMY of the carcasses and in turn this causes the HGP to incorrectly classify the pork carcasses. The old HGP formula used by the HGP is as follows: % Meat = 72.5114 – (0.4618 x fat thickness) + (0.0547 x muscle thickness) The new proposed formula is as follows: % Meat = 77.2281 – (0.9478 x fat thickness) + (0.0263 x muscle thickness) The fat quality parameters, including fatty acid composition and fatty acid ratios, of pigs from different classification groups indicated that as the LM% decreased and the BFT increases, the % IMF, %EFC, AI and C18:0/C18:2 ratio increase and the % FFDM, % moisture, drip loss, IV, RI, DBI, PI, the amount of n-6, MUFA/SFA ratio, PUFA/MUFA ratio and n-6/ n-3 ratio all decreased. There is a constant contrast between classification group P and classification group U and S. Classification group P pigs are associated with healthier fat from a consumer’s point of view, but is seen as an inferior fat from a processors point of view, whereas pigs from classification group S are associated with the quality fat that the processor desires but consumers wish to avoid for health reasons.
Pigs, Meat quality, Fat quality, South Africa, Classification, PORCUS, Hennessey Grading Probe, Dissertation (M.Sc. (Food Science))--University of the Free State, 2019