Effects of Electrical Stimulation and Kidney-Pelvic Fat Removal Before Chilling on Microbial Quality of Beef Tenderloins .

Twenty-four steers (435-567 kg) were used to study the effects of electrical stimulation (50 V for 120 s) and of kidney-pelvic fat removal before chilling (3-4°C) on microbial populations of beef tenderloins on days 1, 4 and 7 post-mortem. Kidney-pelvic fat was stripped from one side of each carcass; the other side remained intact for later fat removal. On each respective chill-day, kidney-pelvic fat was aseptically removed from intact sides, tenderloins were swabbed at two anatomically referenced locations (3rd and 5th lumbar vertebra) and microbial load was determined. The statistical model for data analysis included the effects of electrical stimulation, chill-day, animal within chill-day X stimulation, fat removal, location, and all main effect interactions. Removal of kidney-pelvic fat before chilling resulted in a significantly higher bacterial load on the surface of exposed tenderloins after 24 h of chill. Electrical stimulation produced significantly lower bacterial counts for fat-intact surfaces on chill-day 7 and for fat-removed surfaces on chill-day 4. Kidney-pelvic fat removal allowed for significantly higher bacterial counts on the tail portion of tenderloins (3rd lumbar vertebra) for surfaces from non-stimulated carcasses than the butt portion (5th lumbar vertebra). Mean bacterial counts from electrically stimulated carcasses at the fifth and third lumbar vertebra locations did not differ (P>.10) between fat treatments.