Assessment of quality of cod roes and relationship between quality and maturity stage

Cod roe landings are subject to great variability regarding their quality and subsequent price for the food industry. A scheme was developed for the classification of cod roe into four quality grades (A, B, C and D) based on appearance and texture attributes as described by cod roe traders. Evaluation of the maturity stage of 80 commercial cod ovaries through the frequency distribution of oocyte diameter and the percentage presence of empty follicular sacks revealed that cod ovaries with commercial value are at stage 4 (ripe or vitellogenic), stage 5 (spawning) and stage 6 (spent) of development. The designated maturity stages were found to be closely related to the described quality grades. This relationship implied that vitellogenic ovaries (stages 4a, 4b and 4c) were of A quality, early spawning ovaries (stage 5a) were most often classed as B quality, advanced and late spawning ovaries (stage 5b and 5c) were of C quality, whilst spent ovaries (stage 6) were of the lowest quality grade (D). Several physicochemical characteristics recorded (eg pH, membrane features) were also found to be related to the quality and the maturity stage of the ovaries. There is a significant relationship between roe quality and moisture content, with roes of higher quality having a lower moisture content.