No abstract

No abstract

No abstract

No abstract

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 O /CO 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.

The objective of the present study was to determine the inhibitory effect of dietary rosemary diterpenes on the formation of the volatile organic compounds (VOCs) responsible for rancid flavour in raw lamb meat. The lamb diet was supplemented during the fattening stage with two levels (200 and 400 mg/kg feed) of a dietary rosemary extract (DRE) containing carnosic acid and carnosol (1 : 1, w/w). The formation of VOCs (determined by headspace solid-phase microextraction at 40°C and MS) and odour deterioration (assessed by quantitative descriptive analysis) were monitored in meat fillets (longissimus dorsi-lumborum muscle) packed in a 70/30 O 2 /CO 2 protective atmosphere and kept at 2°C for up to 14 days. The raw meat odour deteriorated under pro-oxidizing conditions due to the development of an incipient rancidity caused by the formation of volatiles from lipid oxidation. A total of 46 volatile compounds were determined in lamb headspace: 18 aldehydes, seven alcohols, seven organic acids, six ketones, four furan compounds, two benzene compounds, one ester and one terpenoid. The use of DRE contributed to inhibit VOC formation and rancidity. Heptanal, octanal, nonanal and 2-pentyl-furan were the only VOCs affected ( P < 0.05) by the diet at any storage time. In general, VOC formation rate during storage was lower ( P < 0.05) in the meat from lambs that received a diet supplemented with 400 mg DRE/kg feed than in the meat from lambs receiving no dietary supplementation. VOC inhibition was less effective when the dose of DRE was reduced to 200 mg/DRE kg, although it depended on the VOC analysed. The intensity of rancid odour correlated ( P < 0.05) with the values of 43 of the 46 VOCs. The highest coefficients were obtained for octanol and octanal ( R > 0.75; P < 0.001), although similar values were obtained for the coefficients of a large number of carbonyl, alcohols and furan compounds, among other volatiles, which can be considered molecular markers of rancidity in raw lamb meat. Principal component analysis confirmed that the differences in the VOC profile make it possible to identify whether or not samples have been reinforced with dietary rosemary diterpenes. Thus, VOC profiling can be regarded as a useful tool for assessing the dietary treatments used in sheep to improve the oxidative stability of lamb meat.

Two dietary rosemary extracts (DREs) containing diterpenes (carnosic acid and carnosol at 1:1 and 2:1 w:w) were tested in fattening lambs to stabilize the sensory quality of cooked and chill-stored patties. A total of 63 lambs were fed freely for 80 ± 5 d with a basal diet supplemented or not with DRE. Minced leg meat from each lamb was used to make patty batches. The patties were cooked at 72 ºC for 2 min, aerobically packed, kept at 2 ºC for up to 4 d and then reheated. Sensory traits (color, odor, flavor, and texture), CIELab color, and lipid oxidation (assessed as TBARS) were determined. In a first experiment, the lamb diet was supplemented with 600 mg of 1:1-DRE or 2:1-DRE kg(-1) feed. The 1:1-DRE diet delayed discoloration, flavor deterioration, and rancidity, while the 2:1-DRE diet was ineffective in this respect. In a second experiment, 4 supplementation levels of 1:1-DRE (0, 200, 400, and 600 mg kg(-1) feed) were compared. Flavor deterioration was delayed when the lamb diet was supplemented with at least 400 mg 1:1-DRE kg(-1) feed. The effects of the diet on the odor, flavor, and color were corroborated by differences in TBARS and CIELab. The results obtained suggest that rosemary diterpenes and/or their active secondary compounds deposited in muscle can act as endogenous antioxidants in cooked lamb. The carnosol intake seems crucial in the antioxidant actions achieved through DRE. The use of rosemary antioxidants in animal feeding would allow meat-based dishes to be preserved longer without adding preservatives.

No abstract