Take tuna meat as example. The moisture inside of tuna cell starts freezing at -1.5℃. When the temperature reaches -60℃, moisture inside of tuna cell is totally frozen. The biological activities stop and tuna meat sustains no deterioration at this temperature. If temperature is above -60℃, tuna meat deteriorates all the while before it is ultimately consumed. As a result, it will lose its unique super red color and fantastic taste.