title: Spoilage of light (PSE-like) and dark turkey meat under aerobic or modified atmosphere package: microbial indicators and their relationship with total volatile basic nitrogen.
abstract: 1. The aim of this work was to evaluate the shelf life of turkey meat from different colour categories (Pale, Soft and Exudative (PSE)-like), intermediate and dark), packaged under aerobic or modified atmosphere (MAP) conditions; also to establish a relationship between microbial quality and total volatile basic nitrogen (TVB-N), evaluating its capacity for shelf life determination. 2. Breasts were selected according to luminance (L*) and pH(24): L >/= 51 and pH < 5.8 for light colour, 43 < L < 51 for intermediate colour, L </= 43 and pH > 5.8 for dark colour. Sliced meat was packaged under aerobic or MAP conditions with 50% N(2) and 50% CO(2), then stored in the dark at 0 +/- 1 degrees C for periods of 12 or 25 d. Meat under aerobic conditions was evaluated for microbiological characteristics and TVB-N on d 0, 5 and 12. This evaluation was extended to include d 19 and 25 when samples were under MAP conditions. 3. The dark meat group after 12 d of storage in aerobiosis presented significantly higher plate counts of aerobic mesophilic, psychrotrophic micro-organisms and higher TVB-N than other meat colour categories. The shelf life of turkey meat under MAP was one week longer for intermediate and light colour meat (20 d) than for dark meat. TVB-N values of 20 to 30 mg NH(3)/100 g turkey meat correspond to advanced spoilage stages. We proposed 14 mg NH(3)/100 g as the limit of freshness acceptability for turkey meat. 4. TVB-N was an indicator of turkey meat microbial spoilage but was not a suitable early predictor for microbial spoilage and in particular for turkey meat stored under MAP conditions because counts of micro-organisms were moderately correlated (Pseudomonas spp. and Enterobacteriaceae) with this index, as they were inhibited by MAP gas mixture and storage temperature used in the present study.
authors.affiliation: Faculdade de Medicina Veterinária, CIISA, U.T. Lisbon, Av. da Universidade Técnica, Polo Universitário, Alto da Ajuda, Lisboa, Portugal.
authors.forename: M J
authors.initials: MJ
authors.lastname: Fraqueza
authors.forename: M C
authors.initials: MC
authors.lastname: Ferreira
authors.forename: A S
authors.initials: AS
authors.lastname: Barreto
mesh_terms: D000332:Aerobiosis; D000818:Animals; D001272:Atmosphere / Q000737:chemistry; D003116:Color; D005516:Food Microbiology / Q000592:standards*; D018857:Food Packaging / Q000379:methods*; D005519:Food Preservation / Q000379:methods*; D008460:Meat / Q000382:microbiology* / Q000592:standards*; D009584:Nitrogen / Q000494:pharmacology*; D013997:Time Factors; D014422:Turkeys
chemical_list: D009584:Nitrogen