The study describes the relationship between visual and instrumental measurements for colour and tenderness between five South African beef breeds: Bos indicus (Brahman), Sanga type (Nguni), British Bos taurus (Angus), European Bos taurus (Charolais) and the composite (Bonsmara). Ten animals per genotype were used (total = 50). The carcasses were split and the right sides were electrically stimulated, while the left sides were not stimulated. Steaks were aged until three days post mortem on polystyrene plates and until 9, 14 and 20 days post mortem in vacuum bags. The steaks were evaluated by visual analysis for colour, marbling, fibre separation, surface texture and structure integrity by a 10-member trained panel. Colour was also measured by the CIE L*, a*, b* system using a Minolta meter, and tenderness was measured by means of Warner-Bratzler shear force. High negative correlations were observed between the visual colour and L* (r = −0.809), b* (r = −0.698) and high positive correlations were observed between the visual colour and hue (r = 0.797). There were also negative correlations between shear force and structure integrity (r = −0.410) and fibre separation (r = −0.401). Very low negative correlations were observed between colour and shear force (r = −0.242). Therefore, although it may be possible to judge meat colour by visual analysis, it does not appear possible to predict tenderness by colour judgment. There is potential for an experienced eye to predict tenderness by observing visual structural properties such as fibre separation and structural integrity.Keywords: Meat colour and tenderness, tenderness prediction, trained visual panel, visual analysis

________________________________________________________________________________ AbstractThere are a number of laboratory methods that could be used to estimate the adequacy of full-fat soybean (FFSB) heat treatment. The protein despersibility index (PDI) has been claimed to have the most constant response to the heating of FFSBs. In this study, the PDI method has been subjected to an interlaboratory test, including the participation of eight laboratories. Seven FFSB samples were processed by dry extrusion at temperatures ranging from 110 to 164 °C and analysed on the PDI. Processed FFSB samples were also assessed in a growth trial of broilers. The analysis of the FFSBs by the PDI method generated adequately-processed FFSB values of between 8.49% and 10.3%. Values above 10.3% described underprocessed and below 8.49% over-processed FFSBs. The PDI method generated a good repeatability limit of 2.1%, but the reproducibility limit (7.73%) was too wide when taking into account the narrow range (8.5 -10.3%) for adequately heat-treated FFSBs. Despite its simplicity and initial indications that it might be the best indicator of FFSB heat treatment, the PDI method did not prove that in this inter-laboratory study.________________________________________________________________________________

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