Moisture Distribution and Texture of Various Types of Cooked Spaghetti

Cooked spaghetti of various types (fresh, dried, frozen, luncheon, and long‐life spaghetti) was examined for moisture distribution by magnetic resonance imaging (MRI). Moisture content was calculated from spinspin relaxation time (T₂) of water proton, based on the correlation between T₂ and moisture content of pulverized durum semolina standard gel samples. Boiled samples of dried and frozen spaghetti had a distinct low moisture region at the center, which was not clearly observed in the other types of boiled spaghetti samples. In particular, the moisture content of boiled long‐life spaghetti was almost homogeneous. Texture of cooked spaghetti samples was evaluated using the force‐distance curve of a mechanical property test. For dried and frozen spaghetti, higher force was observed at the region corresponding to the low moisture core compared with the other types. The luncheon spaghetti and long‐life spaghetti showed a lower breaking force and a larger dip after the peak force representing soft and brittle texture caused by moisture homogeneity. These results indicated that MRI could be used for the quality evaluation of cooked spaghetti through imaging of the moisture distribution, which reflects the mechanical property.     

Role of taurine deficiency in inducing green liver symptom and effect of dietary taurine supplementation in improving growth in juvenile red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis> fed non-fishmeal diets based on soy protein concentrate

This study was conducted to investigate the mechanism of green liver symptom induction and the effect of dietary taurine supplementation on growth performance in juvenile red sea bream fed non-fishmeal diets based on soy protein concentrate (SPC). Juvenile fish (initial BW 72 g) were fed for 20 weeks on SPC diets supplemented with taurine at levels of 0, 1.0, and 2.0%. In the taurine-unsupplemented SPC diet group, specific growth rate (SGR) and feed conversion ratio (FCR) were significantly inferior (P < 0.001), and incidence of green liver was observed in 70% of fish. In this group, hepatopancreatic and plasma taurine concentrations were lowest (P < 0.05), hepatopancreatic content of bile pigments was highest (P < 0.05), and osmotic tolerance of erythrocytes was inferior (P < 0.05) among the dietary treatment groups. Serum osmolality of all treatment groups was at similar levels. These physiological abnormalities as well as SGR and FCR were improved by dietary taurine supplementation. These results indicate that the mechanism for induction of green liver symptom is bile pigment overproduction due to increased hemolysis because erythrocytes become osmotically fragile due to dietary taurine deficiency. Taurine supplementation of SPC diets is essential for maintaining normal physiological condition and growth performance in juvenile red sea bream.     

In vitro reduction of manganese dioxide by a ferrireductase system from the white-rot fungus <Emphasis Type="Italic">Phanerochaete sordida</Emphasis> YK-624

Reduction of manganese dioxide is demonstrated for an in vitro ferrireductase system that includes NADPH-dependent ferrireductase and the iron-binding compound (IBC) isolated from the white-rot fungus Phanerochaete sordida YK-624. The Fe(II)–IBC complex was more effective in reducing manganese dioxide to Mn(II) than were complexes of Fe(II) and organic acids of low molecular weight such as nitrilotriacetate, although IBC also reduced manganese dioxide to Mn(II) in the absence of Fe(II). The generated Fe(III)–IBC complex was a better substrate for NADPH-dependent ferrireductase than were other ferric chelates, suggesting that the Fe(III)–IBC complex is reduced to an Fe(II) complex by NADPH-dependent ferrireductase. Moreover, production of the Fe(III)–IBC complex by the reduction of manganese dioxide in a reaction system containing Fe(II) and IBC was observed to be coupled to reduction of the Fe(III)–IBC complex by NADPH-dependent ferrireductase. These results indicate that the ferrireductase system of P. sordida YK-624 plays an important role in the reduction of manganese dioxide, which is necessary for the production and function of manganese peroxidase.     

Effects of feeding time,water temperature,feeding frequency and dietary composition on apparent nutrient digestibility in rainbow trout Oncorhynchus mykiss and common carp Cyprinus carpio

A series of experiments was conducted to evaluate the effects of feeding time (daytime vs nighttime feeding), dietary fat content (8 and 20%), feeding frequency (trout 1–3 times/day, carp 2–7 times/day), water temperature (trout 18 and 11°C, carp 25 and 17°C), on the apparent nutrient digestibility in rainbow trout and common carp. The feeding time had little effect on the macronutrient digestibility in both species. In trout, starch digestibility decreased with the decrease of water temperature and with increase of feeding frequency, but in carp, increase of the feeding frequency markedly decreased the macronutrient digestibility and phosphrrus absorption of the high fat diet. Fat digestibility of the beef tallow diet decreased relative to the pollock oil diet in carp, without affecting the phosphorus absorption. Inclusion of raw starch, the digestibility of which was lower than that of gelatinized starch, increased the phosphorus absorption in carp. These results suggest that reduction of water temperature and increase of feeding frequency notably decreased starch digestibility in trout while in carp, the effects of feeding frequency and water temperature on macronutrient digestibility and phosphorus absorption are notable for a high fat diet.     

Supplemental effect of vitamin A in diet on the reproductive performance and egg quality of the Japanese flounder Paralichthys olivaceus (T & S)

This study investigated supplemental effects of vitamin A in diet on reproduction of Japanese flounder Paralichthys olivaceus (T & S). Broodstock were fed either a non‐supplemented diet (control diet; CD) or a vitamin A‐supplemented diet (supplemental diet; SD) 1 month before and during the spawning season. Both dietary groups began to spawn in mid‐January. At the beginning of spawning, no notable differences were found in spawning or egg quality between treatments. Egg production of the CD broodstock began to decrease from mid‐April and spawning stopped in late May, whereas the SD group continued to spawn until the end of June. Buoyant egg rate of the CD group was lower than that of the SD group throughout the spawning period. Hatching rate was not different between the CD and SD groups. The percentage of normal larvae in the CD group was significantly lower than in the SD group. It is concluded that a low vitamin A content in the diet has some negative effects on reproduction of flounder. The importance of supplementation of vitamin A in broodstock diet of the Japanese flounder is suggested.     

Effect of water temperature and short-term fasting on macronutrient self-selection by common carp (Cyprinus carpio)

The influence of water temperature (17 and 25 °C) and a period of fasting on the self-selection of macronutrients were examined in common carp held on a 12:12-h light/dark cycle. Eight replicate groups of juvenile carp (ca. 15 g body weight at 17 °C and 25 g at 25 °C) were fed with three test diets [high-protein (HP), high-fat (HF) and high-carbohydrate (HC) diets] by individual self-feeders for 3 weeks, followed by a 2-week period of fasting and then 3 weeks of refeeding. At 17 °C, the carp initially selected the HP and HF diets [HP/HF/HC (%)=38:40:22], whereas at 25 °C, the carp selected the HP diet over the others (55:21:24). After fasting, the carp tended to increase their demand for the HF diet at 17 °C and for the HC diet at 25 °C, but the overall self-selection of the test diets did not differ markedly from that prior to fasting. Carp held at 17 °C had higher relative whole body fat content and plasma triglyceride concentration; the latter decreased markedly during fasting. These results suggest that water temperature influences the macronutrient selection by carp: a relatively high demand for both protein and fat at 17 °C and for protein at 25 °C. Two weeks of fasting, however, did not markedly alter their macronutrient selection.     

Biochemical composition of eggsin relation to egg quality in the Japanese eel, Anguilla japonica

This paper presents the relationship between egg quality and egg biochemical composition of cultured and wild Japanese eel, Anguilla japonica. Eggs were obtained by artificialinduction of maturation. Fertilization and hatching rates were used as characteristics of egg quality. Egg quality characteristics showed large variation; fertilization rate, 0–96; hatching rate, 0–84%. The biochemical composition also showed a large variation. There was no marked relationship between egg quality and fatty acid contents of eggs, except for n-6 highly unsaturated fatty acids (HUFA). Both the fertilization and hatching ratesincreased proportionally withincreases of the -tocopherol g(-Toc) contentin eggs. A more significant correlation was found between the amount of -Toc relative to the amount of HUFA and egg quality. The results of this study show that the egg quality of Japanese eel is affected by the –Toc level, andin particular, the ratio of -Toc to HUFAin the eggs. Abbreviations: BHT – butylhydroxytoluene; EFA – essential fatty acids; FAME – fatty acid methyl esters; HPLC – high performance liquid chromatography; HUFA – highly unsaturated fatty acids; NADH – nicotinamide adenine dinucleotide; NADPH - nicotinamide adenine dinucleotide phosphate; ROS – reactive oxygen species; -Toc –-tocopherol.     

Effect of root exudates on growth of newly isolated nitrifying bacteria from barley rhizoplane

An ammonia-oxidizing bacterium, strain PJA1, and nitrite-oxidizing bacterium, strain PJN1, were newly isolated from the rhizoplane of barley. The cells of strain PJA1 were lobate, compartmentalized, and showed characteristics of the genus Nitrosolobus. The similarity of the 16S rRNA gene to Nitrosolobus multiformis ATCC25196 was 99.04%. The cells of strain PJN1 were rod-shaped. The similarity of the 16S rRNA gene to Nitrobacter agilis ATCC14123 was 98.57%. These newly isolated bacteria were identified as Nitrosolobus sp. PJA1 and Nitrobacter sp. PJN1, respectively. The exudates prepared from barley roots of both the pre-heading and post-heading stages promoted the growth of strain PJA1 (15–20% increase). The growth of the non-rhizoplane strains like Nitrosomonas europaea ATCC25978 was remarkably inhibited by the exudates. The growth of strain PJN1 was also remarkably promoted by the root exudates at the pre-heading stage (6 time increase), and by the root exudates at the post-heading stage (2.5 time increase). The root exudates did not effect the growth of Nitrobacter winogradskyi IFO14297, isolated from the non-rhizoplane.     

Levels of available micro-nutrient metals in some Japanese soils as measured by aspergillus niger with special reference to their threshold values

This paper presents the levels of available amounts of zinc, copper, and molybdenum as measured by Asp. niger (Mulder strain) in soils of Japan with special regard to their threshold values. Results obtained are as follow: 1) Levels of available zinc in soils examined ranged from 0.4 to 27 ppm. The threshold value for available zinc is adequelty represented as a function of the soil pH value, and was estimated to be around “0.5 × (soil pH value)-0.5” ppm (soil pH value >1). 2) Levels of available copper in soils examined ranged from 0.3 to 5 ppm, and the threshold value for available copper lies near 0.5 ppm. However, the value is more suitably represented as a function of the soil carbon content. This value was shown to be around “0.1 × (carbon % in the soil)” ppm. 3) Levels of available molybdenum in soils examined ranged from 0.01 to 0.13 ppm with the average about 0.10 ppm. The threshold value for available molybdenum is well expressed as a function of the soil pH. The value was estimated to be around “-0.04 × (soil pH value)+0.30” ppm (soil pH value <7.5).