Effects of blanching and refrigerated storage on quality attributes of hybrid abalone (Haliotidae discushannai × H. diversicolor diversicolor)

Abstract

Live hybrid abalones were compared to blanched abalones stored at 5 °C for 12 days. Blanching lowered the volatile basic nitrogen (VBN) value and total plate count (TPC), extending the shelf‐life of abalone from 6 to 9 days and 9 to 12 days, respectively. TPC of blanched abalone did not exceed 6 log cfu/g even after 12 days storage. The K value of raw abalone was close to 60% when stored at 5 °C for 9 days. Trimethylamine‐nitrogen (TMA‐N) levels (6.82 and 17.61 mg/100g) were detected in live abalone on days 9 and 12, respectively, while TMA‐N was undetectable in blanched abalone after 12 days storage. The K value in blanched abalone remained below 40% throughout the 12 days compared to raw abalone (82%). Taurine was most dominant among the total free amino acids (FAA) in both live and blanched abalone. Practical applications Abalones and small abalones are becoming highly valued aqua‐cultured seafood, especially for seafood lovers. However, it is difficult to keep aqua‐cultured abalone alive in cold conditions. In this case, blanching is a practical process applied to abalones to inactivate enzymes before they are frozen or refrigered, in order to extend their shelf‐life. The results revealed that TPC, TMA‐N, VBN, ammonia and K value could be used as indicators of freshness in hybrid abalone. The results suggest that blanching can significantly extend the refrigerated shelf‐life of abalone. Furthermore, blanching kills the bacteria and germs that may be found in live organisms. Taste and odor are also improved by the blanching process. Based on the VBN value and TPC, blanching extends the shelf‐life of abalone by 3 more days when stored at 5 °C.

Novel application of an optical inspection system to determine the freshness of Scomber japonicus (mackerel) stored at a low temperature

“…2A). Generally, VBN content is 5-10 mg/100 g when the fresh fish, in the moderately fresh 15-25 mg/100 g; when the fish started to spoil, it increased to 30-40 mg/100 g, exceeding 50 mg/ 100 g when it was spoiled (Tsai et al, 2018).…”