Nutritional and Bacteriologic Evaluation as Part of a Raw Meat Quality Control Program
Six lots of raw horsemeat diet (Zoo Carnivore Diet, Dallas Crown, Inc., Kaufman, TX, USA) were analyzed in triplicate for selected nutritional and bacteriologic components. Aliquots of frozen meat were submitted to a commercial laboratory (Dairy One, Inc., Ithaca, NY, USA) to determine proximate composition, mineral levels, and gross energy. Additional aliquots were thawed at 10°C for 44 h, and then maintained at 37°C for an additional 24 h. Positive control samples were created by adding lyophilized microorganism preparations (Epower™ Microorganisms, MicroBioLogics, Inc., St. Cloud, MN, USA) to aliquots. During thawing (T=0, 24, 44, 68 h), the samples were screened for Salmonella spp. using an enzyme-linked immunosorbent assay (Reveal®, Neogen® Corporation, Lansing, MI, USA), and numbers of Escherichia coli and coliform bacteria were determined using a ready-made culture medium system (3M™ Petrifilm™ E. coli/Coliform Count Plate, 3M™ Microbiology Products, St. Paul, MN, USA).
Mean percentages of crude fiber and moisture were below guaranteed maximum values for each lot. However, mean levels of crude fat, sodium, calcium, and phosphorus for each lot were below the guaranteed minimum values. Mean crude protein levels were below the guaranteed minimum values in four of six lots.
One aliquot was weakly positive for Salmonella spp. at T=0, but negative at all subsequent time points. Frozen meat samples had low numbers of E. coli and coliform bacteria. Coliform bacteria typically increased with length of thaw, but changes in E. coli numbers over time were less predictable.
This project was supported by funds from the Sacramento Zoo and a grant from the Columbus Zoo and Aquarium Fund for Conservation. The authors thank Neogen® Corporation, 3M™ Microbiology Products, and MicroBioLogics, Inc. for donation of some of the products used in this research.