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.