Effects of packaging and storage conditions on volatile compounds in gas-packed poultry meat

Volatile compounds released by raw chicken legs packed in modified atmosphere packages were determined in order to develop a spoilage indicator for monitoring the shelf-life of raw chicken. Internal spoilage indicators would react with compounds released during chemical, enzymatic and/or microbial spoilage reactions. The effects of four packaging factors (headspace volume, oxygen transmission rate of the package, residual oxygen and carbon dioxide concentration) and three storage factors (temperature, illumination and storage time) on the amounts of volatile compounds in the headspace of gas packages containing two chicken legs were studied. Statistical experimental design was applied and a linear screening design comprising 18 experiments (fractional factorial) was utilized. Volatile compounds in package headspace were determined by gas chromatography--mass spectrometry using the dynamic headspace technique. The results were compared with the results of sensory evaluation and microbial determinations. The head-space of stored packages was dominated by the following compounds: butene, ethanol, acetone, pentane, dimethylsulphide, carbon disulphide and dimethyl disulphide. In modelling, some interaction terms and squared terms were needed in addition to linear terms. The main factors affecting the amounts of ethanol, dimethyl sulphide, carbon disulphide and dimethyl disulphide were storage time and temperature. Other factors had only minor importance, carbon dioxide concentration and headspace volume being the most significant package parameters. The same four factors also had the greatest effects on the odour of chicken legs.