Effect of freezing method and frozen storage duration on odor-active compounds and sensory perception of lamb

The effects of different freezing methods (nitrogen freezing tunnel, air blast freezer and home freezer) and frozen storage duration (1 month and 10 months) have been studied by sensory analyses and chemical analyses of odor-active compounds. The sensory analyses showed that fresh meat was significantly (p < 0.05) juicier than frozen meat. Meat frozen in the air blast freezer (ABF) and stored during 10 months had the highest lamb flavor intensity, significantly different from meat frozen in a home freezer (stored for 1 and 10 months) or in a nitrogen tunnel and stored for 1 month. The fresh sample was characterized by lower levels of Strecker aldehydes, 2-phenoxyethanol, cresols and to a lesser extent 2-methylbenzaldehyde, and higher levels of furaneol, which was not even detected in frozen samples. These compounds, together with the relative levels of octanoic acid and ethyl hexanoate, could be used as markers to detect whether lamb meat has been frozen. In chemical terms, the ABF samples were the most similar to fresh meat. Remarkably, in most cases the relative chemical aroma composition had no significant differences as a result of freezing. This helps explain the high sensory similarity observed. Only pyrazine levels changed significantly with frozen storage duration. No oxidation aromas or rancidity have been detected in fresh or frozen lamb. (C) 2013 Published by Elsevier Ltd.