Incorporating rosemary diterpenes in lamb diet to improve microbial quality of meat packed in different environments.

The dietary use of phytochemicals may contribute to improving lamb meat preservation under different packing atmospheres. The objective was to test the preservative potential of a dietary rosemary extract (RE) containing carnosic acid and carnosol (at 1:1 w:w) in chilled lamb patties packed in air, vacuum and 70/30 O2 /CO2 modified atmosphere. Three experimental diets, (C) control, (RE) C plus 600 mg RE/kg feed and (E) C plus 600 mg vitamin E/kg, were given to fattening lambs. Unlike the C- and E-diets, the RE-diet had a double antimicrobial and antioxidant effect on the lamb patties packed in all the environments studied. The RE-diet inhibited total viable and lactic acid bacteria and Enterobacteriaceae, but not Brochothrix thermosphacta and Pseudomonas spp. and also improved oxidative stability (measured as CIE Lab color and thiobarbituric reagent substances), appearance and odor. The E-diet had a better antioxidant effect than the RE-diet but had no antimicrobial effects. Escherichia coli and Salmonella spp. were not detected. The dietary use of RE was most suitable for preserving vacuum-packed meat, which is more exposed to spoilage by anaerobic bacteria, while the use of dietary vitamin E allowed better control of oxidation in the meat packed in a bacteriostatic and oxidizing environment.