How to judge freshness by looking at the eyes of a hairtail

Whether hairtail is fresh can be determined by observing the clarity, protrusion, and color changes of the eyes. Fresh hairtail eyes are clear and transparent, slightly raised, and black or dark blue in color. After spoilage, they become cloudy, sunken, gray, or whitish.

The cornea of fresh hairtail fish is transparent like water droplets, and the eyeball is full, protruding, and clearly black and white. This is due to muscle contraction during the rigidity period after death, which causes the body fluid to flow towards the eyes. Corneal transparency gradually decreases with protein denaturation, and the eyeball sinks due to water loss. Freshly preserved hairtail within 24 hours after fishing can usually maintain this state, which is common in hairtail caught and sold in coastal areas.

The surface of the eyeball of stale hairtail may appear misty and cloudy, and in severe cases, it may appear as a milky white membrane covering, which is a protein denaturation phenomenon caused by bacterial decomposition. The degree of eyeball retraction is directly proportional to the time of death, and hairtail that has been refrigerated for more than 3 days often shows significant collapse. Partial frozen hairtail may experience eye congestion and redness after thawing, which is often related to cell rupture caused by repeated freezing and thawing.

It is recommended to prioritize choosing hairtail fish with clear and full eyes when purchasing, and to make a comprehensive judgment based on factors such as gill redness and muscle elasticity. If abnormal turbidity or obvious indentation of the eyeball is found during processing, the fish meat should be checked for any odor or abnormal mucus secretion. Daily storage should be kept refrigerated at zero degrees Celsius and consumed as soon as possible. Prolonged freezing can cause damage to the crystalline structure of the eyeball, affecting the accuracy of judgment.