No.65 (October,2003)
No.65 (October,2003)
A－370 Minoru KIMURA
Studies on the quality control of the Japanese scallop adductor muscle
In recent years, the price of the Japanese scallop Mizuhopecten yessoensis is declining with increasing production.On the other hand, although the requirement of the consumers is severe to the freshness and the quality, there is little research on the relation between the quality of products and the components in the scallop adductor muscle,compared with fish. The rigor of the adductor muscle comes into question, as the surface of the adductor muscle becomes blackish and tough. Therefore, the purposes of this study are to grasp the property for high quality of scallop adductor muscle products, to develop the distribution system for the high quality, to improve the added value,and to expand the consumption.
In the chapter I, seasonal variation of growth and components were examined in the scallop adductor muscle. The weight of adductor muscle was highest in August. Glycogen content increased from spring to summer（highest in August, 3．6％）, and protein content increased from spring to autumn（highest in October, 19.8％）. The content of glycogen and protein per piece of adductor muscle was highest in August. The relation between glycogen and protein contents on the dry matter basis showed a converse correlation. The content of ash varied between 1．5％ and 1．6％ and decreased from spring to autumn. The level of potassium was highest and ranged from 420 to 480 mg／100 g. The total amounts of ATP and its related compounds increased from spring to summer（highest in July, 9.3μmol/g）.Scallop adductor muscle has two peaks in April and October（highest, 410 mg／100 g）in arginine level, and also two peaks in March and November（highest, 102 mg／100 g）in octopine level, respectively. The total amounts of free amino acids ranged between 2000 and 2600 mg／100 g and increased from spring to summer. Taurine and glycine were main free amino acids and over 60％ of the total amounts of free amino acids. As for taste active free amino acids, glycine, alanine and glutamic acid were contained in large amounts. The level of glutamic acid was highest in the spawning season（132 mg／100 g in May）．Glycine and alanine levels were highest in August（857 mg／100 g and 264 mg／100 g, respectively）．
In the chapter II, the influences of storage temperatures, washing methods and fishing seasons on the rigor of scallop adductor muscle were examined from the rheological and biochemical viewpoints. During storage at －3，0 and 5℃ the rigor of adductor muscle progressed fastest at －3℃，followed by 0℃. The ratio of adductor muscle in rigor reached 100％ after 4days at －3℃ and after 6days at 0 and 5℃, respectively. Therefore, the storage at －3℃ was unsuitable for quality control. In the adductor muscle in rigor, breaking strength and pH value were low, and K value was high, compared with normal adductor muscle. It was observed that the rigor occurred when K value exceeded 20％ and pH value decreased below 6.5. In the adductor muscle of scallop washed in distilled water breaking strength, ATP concentration and pH value decreased, and K value increased remarkably during storage at 0℃, while not remarkably in the adductor muscle washed in artificial seawater or without washing. The ratio of scallop adductor muscle in rigor was 100％ after 2days by washing in distilled water and after 5days by washing in artificial seawater or without washing. The washing treatment of scallop adductor muscle with fresh water was unsuitable even for a short time, and that with seawater was desirable. Decrease in ATP concentration and pH value, development of rigor and accumulation of octopine progressed much faster during storage at 0℃ in the adductor muscle of scallop caught in September than that in April. Fishing seasons influenced the quality of scallop.
In the chapter III, quality control with gas packagings and antibacterial sheet was examined in the scallop adductor muscle. Packaging with N2 gas accelerated rigor and initial decomposition. In the adductor muscle packed with mixture of O2 and CO2，initial decomposition was delayed but rigor was developed, as CO2 concentration increased. On the other hand, in the adductor muscle packed with O2 gas it was observed that the decrease in ATP and pH value, development of rigor, accumulation of octopine and increase in total viable counts were delayed for about two days, compared with that packed with air. During storage at 5℃ the rigor occurred after 4days without wrapping, after 5days by paper towel and after 6days by antibacterial sheet, respectively. In the adductor muscle wrapped in antibacterial sheet, it was observed that the decrease in ATP and pH value, and the increase in total viable counts were delayed, compared with control.
From these results, the following procedures should be done in order to distribute the scallop adductor muscle of high quality.
In recent years, the price of the Japanese scallop Mizuhopecten yessoensis is declining with increasing production.On the other hand, although the requirement of the consumers is severe to the freshness and the quality, there is little research on the relation between the quality of products and the components in the scallop adductor muscle,compared with fish. The rigor of the adductor muscle comes into question, as the surface of the adductor muscle becomes blackish and tough. Therefore, the purposes of this study are to grasp the property for high quality of scallop adductor muscle products, to develop the distribution system for the high quality, to improve the added value,and to expand the consumption.
In the chapter I, seasonal variation of growth and components were examined in the scallop adductor muscle. The weight of adductor muscle was highest in August. Glycogen content increased from spring to summer（highest in August, 3．6％）, and protein content increased from spring to autumn（highest in October, 19.8％）. The content of glycogen and protein per piece of adductor muscle was highest in August. The relation between glycogen and protein contents on the dry matter basis showed a converse correlation. The content of ash varied between 1．5％ and 1．6％ and decreased from spring to autumn. The level of potassium was highest and ranged from 420 to 480 mg／100 g. The total amounts of ATP and its related compounds increased from spring to summer（highest in July, 9.3μmol/g）.Scallop adductor muscle has two peaks in April and October（highest, 410 mg／100 g）in arginine level, and also two peaks in March and November（highest, 102 mg／100 g）in octopine level, respectively. The total amounts of free amino acids ranged between 2000 and 2600 mg／100 g and increased from spring to summer. Taurine and glycine were main free amino acids and over 60％ of the total amounts of free amino acids. As for taste active free amino acids, glycine, alanine and glutamic acid were contained in large amounts. The level of glutamic acid was highest in the spawning season（132 mg／100 g in May）．Glycine and alanine levels were highest in August（857 mg／100 g and 264 mg／100 g, respectively）．
In the chapter II, the influences of storage temperatures, washing methods and fishing seasons on the rigor of scallop adductor muscle were examined from the rheological and biochemical viewpoints. During storage at －3，0 and 5℃ the rigor of adductor muscle progressed fastest at －3℃，followed by 0℃. The ratio of adductor muscle in rigor reached 100％ after 4days at －3℃ and after 6days at 0 and 5℃, respectively. Therefore, the storage at －3℃ was unsuitable for quality control. In the adductor muscle in rigor, breaking strength and pH value were low, and K value was high, compared with normal adductor muscle. It was observed that the rigor occurred when K value exceeded 20％ and pH value decreased below 6.5. In the adductor muscle of scallop washed in distilled water breaking strength, ATP concentration and pH value decreased, and K value increased remarkably during storage at 0℃, while not remarkably in the adductor muscle washed in artificial seawater or without washing. The ratio of scallop adductor muscle in rigor was 100％ after 2days by washing in distilled water and after 5days by washing in artificial seawater or without washing. The washing treatment of scallop adductor muscle with fresh water was unsuitable even for a short time, and that with seawater was desirable. Decrease in ATP concentration and pH value, development of rigor and accumulation of octopine progressed much faster during storage at 0℃ in the adductor muscle of scallop caught in September than that in April. Fishing seasons influenced the quality of scallop.
In the chapter III, quality control with gas packagings and antibacterial sheet was examined in the scallop adductor muscle. Packaging with N2 gas accelerated rigor and initial decomposition. In the adductor muscle packed with mixture of O2 and CO2，initial decomposition was delayed but rigor was developed, as CO2 concentration increased. On the other hand, in the adductor muscle packed with O2 gas it was observed that the decrease in ATP and pH value, development of rigor, accumulation of octopine and increase in total viable counts were delayed for about two days, compared with that packed with air. During storage at 5℃ the rigor occurred after 4days without wrapping, after 5days by paper towel and after 6days by antibacterial sheet, respectively. In the adductor muscle wrapped in antibacterial sheet, it was observed that the decrease in ATP and pH value, and the increase in total viable counts were delayed, compared with control.
From these results, the following procedures should be done in order to distribute the scallop adductor muscle of high quality.
- In order to wash scallop adductor muscle after harvest, sterilized seawater or artificial seawater should be used. The washing treatment with fresh water is not suitable as the rigor was accelerated.
- Storage temperature at 5℃ should be carried out. The rigor is developed at the temperature lower than 5℃．
- As the rigor occurs quickly during storage in the adductor muscle of scallop caught in summer, it is undesirable to cool scallop excessively.
- It is possible to retain the high quality by packaging with O2 gas or by covering with antibacterial sheet.
A－371 Izumi SAKURAI，Tomonori KANETA and Yutaka HATA
Environmental characteristics in Japanese surf clam Pseudocardium
sachalinense bed off Yoichi coast, west Hokkaido, Japan
Sedimentary condition, bottom disturbance and macrobenthic structure of the shallow sandy bottom off Yoichi westHokkaido, Japan, were studied in relation to a surf clam Pseudocardium sachalinense bed. Surveys were conducted inApril, July and November 2001,depth ranged from 0.sediment tended to increase with water depth in addition to be high from April to July（0．42-5.g, respectively）and low from November to February（0.29-1．35 and 0.disturbance of calculating Shields number（Φ）as an index tended to be low with water depth and fluctuated markedly with seasonal change of wave action and effect of topographical features. According to principal component analysis using sedimentary condition and bottom disturbance, five sedimentary types（I, II, III, IV and V）were divided. Type I, very high TC and low Φ, and type II, low TC and high Φ occurred in 6-12 m depth in parts from April to July and from November to February, respectively, although type III, high TC and low Φ distributed in6-15 m depth through the year. Type IV, low TC and very high Φ, and type V, low TC and Φ were found in 3 m depth from April to July and from November to February, respectively. Five macrobenthic communities（A, B, C, D and E）were identified according to cluster analysis using the similarity index（Cπ），and characterized as dominant presence of Umbonium costatum and Goniada maculata in A, Scaphechinus griseus and juvenile of P. sachalinense in B, juvenile of Felaniella usta in C, Eohaustrius eous and S. griseus in D, and Nephtys caeca and Urothoe grimaldii in E. A - community was constantly found in6-9 m depth with sediment of type I, II and III, and B - and D - communities occurred in 3 m depth with sediment of type IV and V through the year. In 12-15 m depth, distribution patterns of the dominant species in each community changed seasonally by their recruitment. It was suggested that the sedimentary condition were suitable for burying and feeding of the clam but mortality due to the bottom disturbance and competition with S. griseus would occur in the habitat.
sachalinense bed off Yoichi coast, west Hokkaido, Japan
Sedimentary condition, bottom disturbance and macrobenthic structure of the shallow sandy bottom off Yoichi westHokkaido, Japan, were studied in relation to a surf clam Pseudocardium sachalinense bed. Surveys were conducted inApril, July and November 2001,depth ranged from 0.sediment tended to increase with water depth in addition to be high from April to July（0．42-5.g, respectively）and low from November to February（0.29-1．35 and 0.disturbance of calculating Shields number（Φ）as an index tended to be low with water depth and fluctuated markedly with seasonal change of wave action and effect of topographical features. According to principal component analysis using sedimentary condition and bottom disturbance, five sedimentary types（I, II, III, IV and V）were divided. Type I, very high TC and low Φ, and type II, low TC and high Φ occurred in 6-12 m depth in parts from April to July and from November to February, respectively, although type III, high TC and low Φ distributed in6-15 m depth through the year. Type IV, low TC and very high Φ, and type V, low TC and Φ were found in 3 m depth from April to July and from November to February, respectively. Five macrobenthic communities（A, B, C, D and E）were identified according to cluster analysis using the similarity index（Cπ），and characterized as dominant presence of Umbonium costatum and Goniada maculata in A, Scaphechinus griseus and juvenile of P. sachalinense in B, juvenile of Felaniella usta in C, Eohaustrius eous and S. griseus in D, and Nephtys caeca and Urothoe grimaldii in E. A - community was constantly found in6-9 m depth with sediment of type I, II and III, and B - and D - communities occurred in 3 m depth with sediment of type IV and V through the year. In 12-15 m depth, distribution patterns of the dominant species in each community changed seasonally by their recruitment. It was suggested that the sedimentary condition were suitable for burying and feeding of the clam but mortality due to the bottom disturbance and competition with S. griseus would occur in the habitat.