Yesso scallop (Mizuhopecten yessoensis) is one kind of economic fishery product in Japan. Adductor muscle is the main edible part of scallops, which has a high nutritive value. It has great popularity in making sushi and sashimi using both fresh and frozen-thawed scallop adductor muscle as raw materials in Japan. Nevertheless, people prefer to eat fresh adductor muscle because the quality of frozen-thawed adductor muscle could decline rapidly. However, the hardening of fresh scallop adductor muscle during storage is a major problem. The structure of the sarcoplasmic reticulum (SR) may be damaged with prolonged storage, thereby releasing internal Ca2+ into the cytoplasm, ultimately leading to muscle contraction. Dantrolene sodium (DS) has been reported to inhibit muscle contraction. However, DS is mostly used in the medical field, and there is no report that DS inhibits the hardening of aquatic products. The present study was conducted to examine the inhibiting effect of DS on the hardening of fresh scallop adductor muscle.
The fresh-shucked scallop adductor muscle (n = 60) was divided into three groups: control (non-immersion), seawater (immersed for 1 h), and DS group (immersed for 1 h). All the groups were stored at 4 ? for 7 days. The photos were taken each day to calculate the hardening rate. The determination of pH value and ATP-related compounds was taken to indicate the changes in freshness. Scanning electron microscope (SEM) was used to compare the changes in microstructure of scallop adductor muscle before and after hardening. The SR was also extracted and observed by transmission electron microscope (TEM).
When the adductor muscle in control group showed signs of hardening on day 2, there was almost no change in the DS group compared with the initial. When the hardening rate in control group reached 33.3% on day 4, only one adductor muscle in the DS group was completely hardened, which may be due to individual differences. The results indicated that dantrolene sodium has an inhibiting effect on the hardening of scallop adductor muscle. This study provides ideas for exploring the delay of scallop adductor muscle hardening.