Three Thawing Methods to give You different quality of Antarctic krillApr. 25,2016
Antarctic krill is widely distributed throughout the ocean around Antarctic continental shelf. With large fishable amount and rich nutrition, Antarctic krill becomes the key point for marine resource development. Due to various limits, Antarctic krill has to be frozen on workboat, and then transported to land for secondary processing. As the first step before processing, thawing method has a deep effect on Antarctic krill’s quality. Nowadays, Antarctic krill in China is mainly used for general food, the fish meal production and shrimp sauce which have different specific requirements on the raw material quality. So, what kind of thawing method can you choose to ensure the quality of Antarctic krill suitable for processing different products?
CAO Rong from Yellow Sea Fisheries Research Institute of Chinese Academy of Fishery Sciences used the smart chip temperature recording system to show the temperature change during the thawing process of Antarctic krill, and compared the effects of different thawing methods on the quality of Antarctic krill, so as to make efficient use of Antarctic krill resources.
The study has compared three kinds of thawing methods, that is, static water thawing (unfreeze vacuum-packing samples in 25 ℃ warm water), natural air thawing (unfreeze samples under natural conditions at 25 ℃), and low-temperature air thawing (unfreeze samples at low temperature of 4℃), the effects of which on the quality of Antarctic krill are listed as follows.
For static water thawing, the complete thawing is done in 51 min, the speed of which is really fast. In this way, Antarctic krill keeps a complete shape without shedding tissue, excellent gloss, and characteristic krill odor, becoming good raw materials for food processing.
For natural air thawing, it takes 220min to complete the thawing, the speed of which is comparatively slow. Nevertheless, whether in 51min or in 220min, there is small effect on the degradation degree of Antarctic krill protein and Antarctic krill can keep its freshness. Hence, both static water thawing and natural air thawing are suitable for the fish meal production to ensure its quality.
For low-temperature air thawing, it takes as long as 826min to complete the thawing, which leads to weak gloss, bad smell and serious degradation of the protein. Antarctic krill is no longer fresh and its quality is not in conformity with the standards of food and fish meal processing. However, every coin has two sides. At such a low temperature, Antarctic krill’s rich unsaturated fatty acid can not be destroyed easily, which is suitable to extract Antarctic krill oil.
As a whole, the selection of different thawing methods should be determined by the requirements of the goal products. If you want fresh raw materials for food processing, static water thawing is the best method; want high-quality fish meal, both static water thawing and natural air thawing are proper choices; want good Antarctic krill oil, low-temperature air thawing may be the most appropriate one.
The research findings are published in the 17th issue of Transactions of the Chinese Society of Agricultural Engineering, 2015. The bilingual version has been launched already.