New Zealand Journal of Agricultural Research abstracts
Factors affecting tenderness of electrically stimulated poultry
CARRICK E. DEVINE
Technology Development Group
HortResearch
Private Bag 3123
Hamilton, New Zealand
DAVID J. C. WILD
TRACEY L. CUMMINGS
MIRINZ Centre, AgResearch Ltd
Private Bag 3115
Hamilton, New Zealand
HARVEY REED
Harvey Reed Consultants
Private Bag
Hamilton, New Zealand
Abstract Effective electrical stimulation parameters for
breast muscle of poultry deboned at the end of the processing line were
determined. For experimental studies, 14.3 half sine-wave pulses per s, 80 V
peak, 10 ms duration were applied for 60 s between head and cloaca of birds
removed after stunning and bleeding and then returned to the processing line.
Some birds were held at a constant temperature to determine rates of pH fall.
Electrical stimulation caused a fall in pH of 0.26 pH units. The rate of pH
fall was accelerated, so that at 20deg.C, ultimate pH after stimulation was
reached in 120 min versus 300 min for no stimulation and at 40deg.C, ultimate
pH after stimulation was reached in 220 min versus 80 min for no stimulation.
Unrestrained muscle entering rigor mortis at 40deg.C shortened by 25.4%
and when entering rigor mortis at 20deg.C shortened by 7.6% with the
mean shear force being 13.42 and 8.13 kg F, respectively. The effectiveness of
electrical stimulation was determined by comparing the shortening and
tenderness of breast muscles that were either left on the carcass or after
cutting them from the breast bone and humerus 60 min post stimulation and aged
at 0-3deg.C for 72 h. For cut muscles, electrical stimulation reduced muscle
shortening (P < 0.05). The greatest difference in tenderness occurred
between stimulated intact breasts (mean 3.34 kg F) versus cut non-stimulated
breasts (mean 13.5 kg F) (P < 0.001), but there was still a
significant difference in shear force between cut non-stimulated versus cut
stimulated breasts (P < 0.05). A commercial processing line using
electrical stimulation (230 V, 14.3 half sine-wave pulses per s, 10 ms
duration), via rubbing electrodes to head/neck area and legs applied for 120 s,
in the post stunning and bleeding area was examined. When the breast was cut
from non-stimulated muscles at 65 min post slaughter (6.5-7deg.C), the meat was
tough with mean shear force of 8.7 kg F (maximum 15.5 kg F), and for stimulated
cut muscles, the mean shear force value was significantly lower at 3.2 kg
(P < 0.001). There was no significant difference between any of the
stimulated muscles cut at 65-80 min and non-stimulated intact muscles. With low
rigor temperatures at 7deg.C, electrical stimulation has no
disadvantages and allows early deboning without toughening.
Keywords poultry; tenderness; rigor; electrical
stimulation; temperature; ageing
New Zealand Journal of Agricultural Research, 2001, Vol. 44: 171-175
0028-8233/01/4402&3-0171 $7.00/0 (c) The Royal Society of New Zealand
2001
PDF file of entire paper: medium quality (424K); (scanned from paper original: notes about this process)
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