408 Novel food packaging techniques 0.8 Storage time Oxygen level Fig. 19.3 Parameter levels for the interaction term(Day.Temp. O2)in equation 19.7 From Fig. 19.3 the effect of the factors can be interpreted individually, and the stable interval between approximately 40-80%O2 is evident as an elbow in the It is rather surprising that 40%O2 is sufficient to ensure the stability of the bright red meat colour, as an O2 level of 70-80% is commonly used in the industry. The applied product to headspace volume ratio for the experiments in Tables 19.1 and 19.2 was approximately 1: 9. The large headspace volume might be the cause for only minor changes in headspace gas xyge partial pressure)taking place during storage. However, when packaging fresh meat products for retail sale, a large headspace volume is common. Furthermore, large amounts of oxygen have to permeate over the film or be used for meat/ microbial metabolism before a noteworthy change in oxygen partial pressure takes place and the meat colour will be affected The GEMANOVa model is an excellent tool for choosing the optimal setting for the individual factors The knowledge of the stable interval can be used when optimising headspace gas composition or the permeability of the packaging material as a reduction in the applied oxygen level leaves the possibility of using more carbon dioxide or nitrogen in the package headspaceFrom Fig. 19.3 the effect of the factors can be interpreted individually, and the stable interval between approximately 40–80% O2 is evident as an elbow in the plot. It is rather surprising that 40% O2 is sufficient to ensure the stability of the bright red meat colour, as an O2 level of 70–80% is commonly used in the industry. The applied product to headspace volume ratio for the experiments in Tables 19.1 and 19.2 was approximately 1:9. The large headspace volume might be the cause for only minor changes in headspace gas composition (oxygen partial pressure) taking place during storage. However, when packaging fresh meat products for retail sale, a large headspace volume is common. Furthermore, large amounts of oxygen have to permeate over the film or be used for meat/ microbial metabolism before a noteworthy change in oxygen partial pressure takes place and the meat colour will be affected. The GEMANOVA model is an excellent tool for choosing the optimal setting for the individual factors. The knowledge of the stable interval can be used when optimising headspace gas composition or the permeability of the packaging material as a reduction in the applied oxygen level leaves the possibility of using more carbon dioxide or nitrogen in the package headspace. Fig. 19.3 Parameter levels for the interaction term (Day
Temp
O2) in equation 19.7 (unpublished data). 408 Novel food packaging techniques