Forces Involved in Soy Protein Gelation: Effects of Various Reagents on the Formation, Hardness and Solubility of Heat-Induced Gels Made from 7S, 11S, and Soy Isolate

The effects of various reagents on the formation, hardness and solubility of heat-induced gels of soybean 7S, 11S globulins and isolate were studied. Gels were formed in 30 mM Tris HCl buffer (pH 8.0) with or without reagents by heating at 80°C for 30 min. The results indicated that electrostatic interactions and disulfide bonds are involved in the formation of 11S globulin gels; mostly hydrogen bonding in 7S globulin gels and hydrogen bonding and hydrophobic interactions in soy isolate gels. Analyses of the proteins solubilized from the gels indicated that the basic subunits of 11S globulin interact with 7S globulin in soy isolate gels. The contribution of certain acidic subunits to network formation in US soy isolate gels is limited     

High-Pressure Synthesis of Perovskites Pb(Li1/4Nb3/4)O3 and Pb(Li1/4Ta3/4)O3

Complex perovskite-type compounds with the general formula Pb(B⁺_1/4B⁵⁺_3/4)O₃, where B⁺= Li⁺ and B⁵⁺= Nb⁵⁺ or Ta⁵⁺, were synthesized using a high-pressure technique and studied by X-ray powder diffraction. The X-ray patterns were indexed on the basis of a cubic cell with a ₀= 4.071 Å for Pb(Li_1/4 Nb_3/4)O₃ and a ₀= 4.052 Å for Pb(Li_1/4Ta_3/4)O₃. Electrical properties of the new perovskites were also studied.     

Ion Exchange in Alkali Layers of Potassium β -Ferrite ((1 + x)K2O · 11Fe2O3) Single Crystals

The potassium ions in potassium β-ferrite ((1 + x)K₂O ·11Fe₂O₃) crystals were exchanged with Na⁺, Rb⁺, Cs⁺, Ag⁺, NH₄⁺, and H₃O⁺ in molten nitrates or in concentrated H₂SO₄. On the other hand, spinel and hexagonal ferrites were formed by soaking the crystals in the melt of divalent salts. The crystals of K⁺, Rb⁺, and Cs⁺β-ferrites decomposed to form α-Fe₂O₃ at high temperatures of 800° to 1100°C. In addition, H₃O⁺, NH₄⁺, and Ag⁺β-ferrites decomposed to form α-Fe₂O₃ at relatively low temperatures of 350° to 650°C, in accordance with the stabilities of the inserted ions. The electrical properties of some β-ferrites were measured.     

Changes in ω-3 Polyunsaturated Fatty Acids in the Chum Salmon Muscle During Spawning Migration and Extrusion Cooking

The effects of spawning migration and extrusion cooking on o-3 polyunsaturated fatty acids (PUFAs) in chum salmon muscle were studied. Total lipid content in the muscle of the fish during spawning migration was lower than that during feeding migration. However, the content increased to double those in the raw materials by pretreatment of extrusion cooking. Lipids of muscle and outer layer during spawning migration contained higher percentages of docosahexaenoic acid (22:6) than those during feeding migration. Moreover, PUFAs were not lost by extrusion cooking and its pretreatment. These results suggest that production of foods containing a rich amount of W-3 PUFAs is possible by extrusion cooking of the muscle of chum salmon during spawning migration.     

PREDICTING AN EQUILIBRIUM STATE VALUE FROM TRANSIENT STATE DATA

Values of many biological, chemical and physical factors approach their respective equilibrium state values when constant reactive potentials are applied to these factors. These equilibrium state values are frequently required for analyzing their transient processes. Mathematical analyses of available data on transient state values of various factors revealed that most of these values could be estimated by using an exponential formula, A procedure was developed for the reliable prediction of equilibrium values through the proper application of the formula to transient state values. For this development, it was assumed that transient state values were given at equal time intervals. According to a number of experimental computations, errors of equilibrium state values predicted by the developed procedure were less than 5%. The procedure estimated equilibrium values with less than 50% the time effort required by conventional procedures and will be of great use for reliably predicting equilibrium state values, especially when a factor converges very slowly to its equilibrium condition.     

A NEW METHOD FOR DETERMINING THE APPARENT THERMAL DIFFUSIVITY OF THERMALLY CONDUCTIVE FOOD

Two empirical parameters, j and f, have been used to determine the thermal diffusivity values of food by several researchers. Since there are considerable variations in j values, a new procedure was developed for the experimental determination of thermal diffusivity of foods without using this parametric value. A sample was filled into a cylindrical cell whose diameter and length were approximately 10 and 130 mm, respectively. The temperatures of the sample were monitored at the mid-point of the central axis and on the inside surface of the cell. These temperatures were used to estimate thermal diffusivity values together with an analytical formula for heat conduction in an infinite cylinder. The method was utilized to determine the thermal diffusivity, Biot number, and surface heat conductance values of water, 60% sucrose solution, glycerine, cherry tomato pulp, and apple pulp. There was close agreement between thermal diffusivity values determined experimentally and such values available in published literature. Mathematical procedures are presented for estimating errors in the thermophysical property values determined experimentally, where there are errors in locating temperature sensors in a sample, errors in the shape of the diffusivity cell, and errors in the temperature sensing device.     

Partial Characterization of Muscle Collagens from Prawns and Lobster

The abdominal muscle tissues of giant river prawn, fleshy prawn and spiny lobster contained 2.4–2.6% collagen of the total tissue protein. Alkali-insoluble proteins were prepared from the muscle tissues by treatment with 0. 1N NaOH at 4°C and found to exhibit the amino acid composition typical of collagen. The muscle collagens, consisting of α chain-sized components, were then isolated by limited pepsin digestion and characterized by a high content of hydroxylysine and its glycoside and a low content of alanine. In addition, subcuticular membranes covering the muscle tissues were found to be comprised mainly of such an alkali-insoluble collagen.