Effect of adding of different forms of oregano (Origanum vulgare) on lamb meat burgers quality during the storage time

The effect of adding different oregano formats (GO: ground; OEX: extract; OEO: essential oil; OLO: oleoresin) on quality of vacuum packaged lamb burgers, during 14 days, was evaluated by pH, colour (L*, a* and b*), lipid oxidation and microbial growth [Total Viable Count (TVC), Enterobacteriaceae, Pseudomonas spp. and Lactic acid bacteria (LAB)]. A control batch (without spice) was used. After 10 days of storage, there was a marked decrease of pH in all samples, OEX reached the lowest value. There was variation in L*, in OEX burgers (P< 0.001), on a* in OEX (P< 0.05) and in OEO ones (P< 0.001). At the end of essay, samples showed similar TVC and Pseudomonas spp. count, the lowest LAB count values were observed in OLO burgers (P< 0.001). GO OEO and OLO samples showed low rancidity, with values ranging from 0.12 to 0.25 mg MDA/kg meat raw.