The influence of suspension method, electrical stimulation and ageing on the intrinsic tenderness of Bonsmara beef and the meat trade's perception thereof

Abstract

Very few if any South African abattoirs apply the tenderstretch method to increase meat tenderness. Furthermore, the majority of abattoirs do not electrically stimulate carcasses, nor do they age meat. Consumers, however, regard tenderness as the single most important component of meat quality, which justifies the application of methods at abattoirs to enhance tenderness. In this study the effect of electrical stimulation, hip suspension and ageing on tenderness of the M Longissimus of 32 Bonsmara steer carcasses was investigated, as well as the perception of the meat trade towards the acceptability of alternatively suspended carcasses by the Bloemfontein meat trade. Half of the carcasses (16) were electrically stimulated. After dressing all 32 carcasses were split in halves (64). Thirty-two carcass halves (16 ES and 16 NES) were hip suspended while the remaining 64 carcass halves remained conventionally suspended. After 24 hours chilling the M Longissimus of each half was dissected from the carcass and divided into two samples. One sample from each half was immediately frozen at - 18°C, while the other was allowed to age for 7 days at between I - 3 °C before being frozen. Small pieces of muscle were removed from each sample, before freezing, for histological analysis. The frozen samples were each cut into three steaks, allowed to thaw and then grilled. The tenderness was measured by means of shear force (Instron Universal Testing Machine, fitted with a Warner Bratzler shear device) on steaks grilled to an internal temperature of 70°C. Sarcomere lengths were measured and cooking data (cooking loss, evaporation loss, drip loss and thawing loss) recorded. A questionnaire was used to test the acceptability of hip-suspended carcasses by the meat trade in the Bloemfontein area. When applied individually, all the above-mentioned treatments significantly reduced the shear force (tenderness) of the meat. In combinations, the treatments had a cumulative effect, especially when carcasses were Achilles suspended. Neither extended ageing nor electrical stimulation (ES) had a significant effect on tenderness when carcasses were hip suspended. Sarcomere lengths were significantly increased by hip suspension, but not affected by ES and ageing. Thawing loss was significantly reduced by ES, as well as by ageing in combination with ES or hip suspension. The suspension method, ageing and electrical stimulation had no effect on cooking loss, drip loss and evaporation loss. Electrical stimulation and hip suspension as individual treatments significantly improved the tenderness of meat, but in combination did not significantly complement each other. In combination with ageing, both treatments produced the most tender meat with the least thawing loss. Depending on the market sector, there definitely is a place for all three specified methods in the South African meat trade. In general, the 40 respondents to the questionnaire did not approve of the appearance of hip suspended carcasses. They were also concerned that it would take up too much space in their chillers and that it would cause difficulty during dissecting. The majority of respondents, however did not envisage problems with transport and with effective chilling and were of the opinion that their clients would accept and purchase the dissected cuts. The majority (72.5%) of respondents indicated that they would accept hip-suspended carcasses if the study proved that it would be more tender than conventionally suspended carcasses. Fifty-two point five percent (52.5%) were of the opinion that the meat trade in Bloemfontein would accept hipsuspended carcasses. Through a comprehensive extension and marketing campaign hipsuspended carcasses should be accepted by the South African meat trade.