Myofibrillar Ca-ATPase Activity Research Articles

Concentration Dependent Effect of Enzymatic Fish Protein Hydrolysate on the State of Water and Denaturation of Lizard Fish (Saurida wanieso) Myofibrils during Dehydration

To utilize fishery waste products as functional food material, the fish protein hydrolysate (FPH) was prepared from fish scraps of three marine species by protease treatment. The added-concentration dependent effects of FPH (2.5-12.5%, dry weight/wet weight) on the state of water and denaturation of lizard fish myofibrils were evaluated by desorption isotherm curves, myofibrillar Ca-ATPase activity, and unfrozen water which was determined by differential scanning calorimetry during dehydration. The water activity (Aw) in myofibrils was distinctly decreased with the increasing concentration of FPH from 2.5% up to 10.0%, although the Aw added with 12.5% of FPH was almost equal to that with 10.0% of FPH. The amount of unfrozen water in myofibrils during dehydration was increased by the addition of FPH, and the greatest increase was found at 5.0-10.0%. The FPH suppressed the inactivation of myofibrillar Ca-ATPase activity during dehydration, and a larger effect of suppression was observed at 7.5% addition of FPH. These findings suggest that peptides produced in FPH functioned to stabilize the hydrate water surrounding the myofibrils and suppressed their dehydration-induced denaturation.

スケトウダラ塩漬肉の乾燥中に起こる筋原繊維タンパク質の変性に及ぼすソルビトールの影響

Meat blocks from walleye pollack were soaked in solutions containing 0.5-1.5M NaCl, 0.5-1.0M sorbitol. or their combinations with varied ratios for 24 hours at 4°C. After soaking, the cured meats were subjected to dehydration at 15°C. Changes in weight, NaCl and sorbitol concentrations of the meat, and myofibrillar Ca-ATPase activity together with crosslinking of myosin heavy chain of the same meat were investigated as a function of dehydration time. The results were as follows: (1) The meats containing 0.40-0.70M NaCl, 0.37-1.02M sorbitol, or combinations of 0.38-1.68M NaCl and 0.34-0.85M sorbitol were subjected to the dehydration process. (2) The rates of reduction of the weight of cured meats agreed well with the increase in NaCl and sorbitol concentration of the same meats induced by the dehydration. (3) The rate of dehydration of the cured meats was not related to the rate of denaturation of myofibrillar protein of the same meats. It is thus likely that the water retention ability of the meat is controlled by the concentration of NaCl and sorbitol, and their relative proportion in the meat, which was prepared by curing.

スケトウダラすり身の酸処理による肉糊のゲル形成能とミオシン重鎖の変化

Frozen surimi from walleye pollack, which contained sugars but no polyphosphate, was thawed and acidified to pH 6.0 on addition of a small amount of acid (HCl). During treat-ment with the acid at 2°C, part of the surimi was taken out, neutralized with dilute alkali (NaOH), and subjected to the following investigation. The quality of the surimi thus acid-treated was assessed by measuring its myofibrillar Ca-ATPase activity and cross-linking of myosin heavy chain along with gel formation of the salt-ground meat set at 25°C, which was prepared from the same surimi material. It was found that a decrease in myofibrillar Ca-ATPase activity of surimi together with a deterioration of the gel-forming ability of the salt-ground meat were both proceeded by the passage of time for acid treatment, and that the setting gel-forming ability of the salt-ground meat, which was prepared from neutralized surimi after 48h of acid treatment, was comparable to that of salt-ground meat from acidified surimi without neutralization. These results indicated that an irreversible deterioration in the quality of surimi was induced under an acidic environment even when the surimi material was stored in ice.

マアジ塩漬肉を乾燥するときに起こる筋原線維タンパク質の変化

Minced meat from horse mackerel was soaked in 3M NaCl solution for various periods at 4°C, in order to set the NaCl concentration of the meat in the range of 0.14-1.90M. The cured meat was then dehydrated at 20, 30, and 40°C, and the changes in myofibrillar Ca-ATPase activity, salt concentration, and myosin heavy chain in the meat were investigated as a function of the dehydration time. With the increase in salt concentration of the cured meat together with the rise in tempera-ture applied to dehydration, myofibrillar Ca-ATPase was rapidly inactivated. On the other hand, myosin heavy chain in the cured meat only decreased with concomitant formation of its polymer when the cured meat containing 0.68-1.60M NaCl was subjected to dehydration at 30°C However, almost no change occurred during dehydration of such cured meat at 20 or 40°C. The results propose a favourable process for manufacturiing dried products from salted horse mackerel.

塩漬によって起こる魚肉中の筋原線維タンパク質の変化

Meat blocks of walleye pollack and horse mackerel were soaked in various concentrations of NaCl solution in a range between 1.0 and 3.0M. During the soaking, the changes in NaCl concentration, myofibrillar Ca-ATPase activity, and subunit composition of myofibrillar protein of the meat were measured. The results obtained were as follows: (1) NaCl permeated quickly into the meat at an early stage of soaking and reached its maximum plateau. The maximum value increased as the NaCl concentration of the soaking medium increased. (2) By increasing the NaCl concentration of the soaking medium, the rate of inactivation of myofibrillar Ca-ATPase of the meat was increased. (3) When the NaCl concentration of the soaking medium was low, cross-linking reaction of myosin heavy chains in the meat proceeded rapidly at an early stage of the soaking, but its rate was suppressed in the following period. (4) Regardless of the NaCl concentrations of the soaking medium employed, the progress of the cross-linking reaction was dependent on the integrated value of salt concentration of the meat and the soaking time.

魚類筋原繊維の脱水に伴って起こる水の状態およびＡＴＰａｓｅの失活に対するアミノ酸の添加効果

Changes in the state of water and ATPase activity during dehydration procedures of white croaker myofibrils were investigated in the presence of various amino acids by monitoring the desorption isotherm profile and myofibrillar Ca-ATPase activity. Amino acids were classified into four groups by their effect on myofibrillar Ca-ATPase inactivation; (1) amino acids exerting marked suppressive effect on inactivation such as Na-Glu and Na-Asp, (2) those exerting moderate suppressive effect such as Gly and Ala, (3) those exerting little or no effect on inactivation such as Val, Leu, and Ile, and (4) those accelerating the inactivation including hydrophobic amino acids. The addition of acidic amino acids exhibiting a remarkable suppres-sive effect on ATPase inactivation increased the content of monolayer and multilayer water adsorption of myofibrils.

高栄養魚肉食品素材の開発に関する研究―ＶＩＩＩ 凍結貯蔵マイワシを原料とした高栄養魚肉食品素材の製造

Live sardines were chilled in ice-water for 1h or 8h, and frozen with liquid N2 (S1(L), S8(L)), followed by storing at -80°C or -20°C for 30 days. A new foodstuff known as highly nutritional fish meat (HNFM) was prepared from the frozen sardines. In this study, changes of gel-forming ability and myofibrillar Ca-ATPase activity of HNFM were investigated with respect to the frozen storage condition of the material. The gel-forming ability and Ca-ATPase activity of HNFM prepared from S1(L) were slightly changed during -80°C storage. During -20°C storage, they kept to be fairly. On the other hand, those of HNFM prepared from S8(L) decreased during the frozen storage. A particulary marked decrease in the values of two parameters was observed in HNFM from S8(L)stored at -20°C. These results suggest that, to manufacture HNFM possessing excellent gel-forming ability from frozen sardines, it is important to freeze extremely flesh fish rapidly and to store at lower temperature.

氷蔵および凍蔵中におけるコノシロのかまぼこ原料としての特性の変化

Properties of gizzard shad which were stored at low temperature as raw material for fish jelly products were studied. From the viewpoint of gel-forming ability, this fish was classified into the group of easy-setting and easy-disintegrating fish such as sardines. Hunter whiteness of kamaboko obtained was about 20% less than that of white-meat fish such as Alaska pollack. The fish exhibited a strong gel-forming ability such as that of lizard fish. Gel-forming ability of the fish decreased to about 70% of the original ability during 12 days iced storage. The tolerant period of iced storage of the fish as material for fish jelly products was estimated to be about 10 days. Gel-forming ability of frozen fish meat was about the same as that of unfrozen fish meat. Minced fish meat stored at -25°C which was frozen after being washed with alkaline-salt solution showed fairly strong gel-forming ability even after a frozen storage period as long as 6 months, while the fish meat which was frozen after being washed with water had weak gel-forming ability. The gel-forming ability of the minced meat washed with alkaline-salt solution or water was found to be significantly correlated to total myofibrillar Ca-ATPase activity and the solubility of myofibrils in the minced meat which was stored on ice or frozen stored at -25°C. No such correlation was observed in the case of minced meat frozen stored at -50°C, even though alkaline-leaching was employed.

高栄養魚肉食品素材の開発に関する研究 ＶＩ 水中ミンス工法の採用による高栄養魚肉食品素材の品質の改良

By introducing underwater mincing of fresh raw material, the quality of the food stuff tentatively named highly nutritional fish meat for food stuff (HNFM) was appreciably improved. The quality of HNFM thus obtained was examined by total activity of myofibrillar Ca-ATPase and gel forming ability of it. The quality of HNFM prepared from the minced meat in suspension (pH 7.0) as the intermediate raw material hardly changed, while such raw material was stored 2°C for 28h. However, that of HNFM prepared directly from the meat of sardine lowered rapidly during the sardine as the raw material stored at the same condition. The first order rate constant of denaturation rate of myofibrillar Ca-ATPase indicated that myofibrillar protein in the minced meat in suspension was 10 times more stable than that in the muscle tissue of round fish. Deteriorations of gel forming ability of both HNFM from the minced meat in suspension and round fish muscle were paralleled with the denaturation of myofibrillar Ca-ATPase activity of them.

高栄養魚肉食品素材の開発に関する研究―Ｖ マイワシの鮮度が高栄養魚肉食品素材の品質におよぼす影響

A food stuff tentatively named highly nutritional fish meat for food stuff (HNFM) was prepared from round sardine stored for 5 days at 2°C by the method previously described, and the changes in several properties were investigated. The quantity of volatile com-pounds (VC) arisen from the minced meat increased during the storage of the round sardine, but that from HNFM hardly changed. HNFM prepared from the stored sardine gave off little undesirable odor. The gel-forming ability and myofibrillar Ca-ATPase activity of HNFM rapidly decreased during the storage of the round fish even at a low temperature as raw material. On the contrary, Ca-ATPase activity of dewatered-ground meat was kept at a high level during the storage, and the deterioration of gel forming ability was remarkably suppressed. For the purpose of manufacturing the HNFM of high quality, it is essentially important to prepare it from the fresh fish as rapidly as possible and to freeze it with the addition of cryoprotectants.

筋原繊維タンパク質とソルビトールなど添加物の濃度が冷凍変性に及ぼす影響

The protective effect of some additives, such as sorbitol, Na-glutamate, and Na-acetate against freeze denaturation of carp myofibrillar protein was investigated by measuring change in first order rate constant (kD) for inactivation of its Ca-ATPase as a function of protein con-centration (M) for frozen storage with additive. Myofibrills were mixed with either one of the above mentioned additives in a medium of 0.16M KCl, 40mM Tris-maleate (pH7.5)to give the final concentrations of additives and myofibrillar protein between O-0.24M and 2-20mg/ml, respectively. During frozen storage, decrease in myofibrillar Ca-ATPase activity was measured with a laspe of time and the kD was calculated. It was thus found that the kD of the mixture were almost identical where the molar concentration of each additive was kept the same but that of myofibrillar protein however varied considerably. From the results mentioned above, a possible mechanism for the protection of freeze denaturation of myofibrillar protein by sorbitol, and the like, was discussed.

マサバの鮮度が筋原線維たんぱく質の冷凍変性に及ぼす影響

When the chub mackerel Scomberjaponicus was kept in icewater, a decline in freshness proceeded accompanying the changes in toughness, pH and K value of muscle. In most specimens full rigor occurred between 2-28h after death, and the resolution of rigor mortis around 20h after death or later. The pH of muscle was between 6.5 and 7.0 immediately after instant death, but rapidly decreased down to 5.7-6.0 during and after full rigor. The K value of muscle did not exceed 5% during pre-rigor but later increased remarkably with the lapse of time. Chub mackerel specimens of such different degrees of freshness were stored frozen at -30°C for several months. The effect of freshness on the extent of freeze-denaturation of muscle protein was then studied in terms of myofibrillar Ca-ATPase activity. It was observed that there was much more marked denaturation in hte muscle when frozen during post-rigor (pH<6.0, K>5%) than then frozen during pre-rigor.