Effect of Different Thawing Methods on the Freshness and Volatile Flavor Compounds of Anchovy (Engraulis encrasicholus)

In order to investigate the effects of different thawing methods (microwave thawing, ultrasonic-assisted thawing, saline thawing and low temperature thawing) on the freshness and volatile flavor compounds of anchovy, the thawing time, water-holding capacity, total viable counts and volatile base nitrogen (TVB-N) of the samples with different thawing methods were analyzed, and electronic nose analysis and detection of volatile flavor compounds was also performed. The results showed that the microwave thawing time was the shortest (22.4 min). Samples thawed in microwave oven maintained the largest water holding capacity, total viable counts and TVB-N value. The ultrasonic-assisted thawing group had the lowest total viable counts and TVB-N value and highest sensory score. The electronic nose could distinguish the odor of anchovy under different thawing methods. The odor of the refrigerator thawing was the biggest difference with the other three groups and the freshness was poor. 36, 41, 45 and 43 volatile compounds were identified in anchovy under four thawing methods, mainly aldehydes and alcohols. Among them, hexanal, heptanal, octanal, nonanal, decanal, phenylacetaldehyde, 1-penten-3-ol, 1-octen-3-ol, benzene and trimethylamine played an important role in the overall flavor formation of anchovy after thawing. Combined with thawing efficiency, freshness index and volatile flavor compounds, ultrasonic assisted thawing was determined to be a better thawing method for frozen anchovy. This study can provide a theoretical basis for processing, transportation and comprehensive utilization of anchovy.