A SIMPLE DECISION RULE ON FUZZY EVENTS

Decision making in real problems is done in a fuzzy environment. Thus, Fuzzy-Bayes decision rules have been proposed to cope with a fuzzy state of nature. These decision rules are based on the probability of fuzzy events, or the possibility measure of fuzzy events. Furthermore, a decision rule based on fuzzy utility functions and the possibility distribution of fuzzy events are constructed. However, in these decision rules the fuzziness of the fuzzy expected utility is very big, because these decision rules are based on the extension principle for calculation of the fuzzy expected utility. In this article, avoiding the large fuzziness of the expected utility, we proposed a simple decision rule based on the representation interval of the possibility distributions of fuzzy events and the representation value of the fuzzy utility function. Further, we discuss the application of this simple decision rule to the decision problems, in which the decision maker obtains the one-peak symmetric possibility distribution of a state of nature and the one-peak symmetric membership functions of fuzzy events on a state of nature, by his or her knowledge and his or her belief.     

Emulsion Stabilization by Maillard-type Covalent Complex of Plasma Protein with Galactomannan

Plasma protein was conjugated with galactomannan (GM) in a controlled dry state at 60°C and 79% relative humidity. The covalent attachment of GM to plasma protein was confirmed by SDS-PAGE and gel chromatography. Emulsifying activity of plasma protein-GM complex was 1.4 times and the emulsion stability of the complex was more than 10 times higher than those of plasma protein. In acidic (pH 3) and salt (0.2M NaCl) systems, the complex showed much more effective emulsifying properties than did commercial emulsifiers. Emulsifying properties of the complex were retained after preheating at 80°C for 30 min. Plasma protein-GM complex prepared by Maillard reaction during heating in a dry state could be used for heat-processed foods as a protein emulsifier.     

Further Studies on the Roles of the Head and Tall Regions of the Myosin Molecule in Heat-induced Gelation

Heat induced gelation properties of the two proteolytic fragments of myosin, heavy (HMM) and light meromyosin (LMM), were studied by rigidity measurement in a band type viscometer and by a direct examination using a scanning electron microscope. A heat induced network forming ability for both LMM and HMM was found in 0.6M KCl at a pH 6.0. LMM produced gels corresponding to a reversible helix-coil transition at temperatures ranging from 40–70°C, with little evidence of aggregation as assessed from a turbidity change of the system. Contrary, HMM associated irreversibly producing a gel with increased rigidity at pH 5.0 and a salt concentration of 0.1 M. Oxidation of SH-groups appeared to be involved only in HMM and not in LMM gelation process.     

Suppression of Thermal Denaturation of Myosin Subfragment-1 of Alaska Pollack (Theragra chalcogramma) by Sorbitol and Accelerated Inactivation by Pyrophosphate

Thermal denaturation of myosin subfragment-1 (S-1), prepared from myofibrils (Mf) of Alaska pollack dorsal muscle by chymotryptic digestion, was well suppressed by sorbitol addition in a concentration dependent relationship. ATP and ADP also suppressed the ATPase inactivation significantly at different degrees. On the contrary, pyrophosphate (PPi) accelerated the inactivation by several-fold; half the maximal acceleration occurred at about 30 μn, M PPi concentration. The accelerated inactivation by PPi addition was remarkable at high-salt medium such as 0.5M KC1.     

Relative Roles of the Head and Tail Portions of the Molecule in Heat-Induced Gelation of Myosin

Myosin molecules are cleaved by chymotrypsin digestion into two fragments: subfragment 1, which originates from the globular heads of myosin, and the myosin rod, which originates from the helical tail of the myosin molecule. The heat-induced gelation of these subfragments was compared to that of intact myosin by measuring rigidity, turbidity, and other physico-chemical characteristics of each system. Two features of the heat-induced gelation of myosin, aggregation and three-dimensional network formation were found to be imparted by the subfragment 1 and the rod, respectively. The former involves disulfide exchange and the latter relates to conformational changes arising from a partially irreversible helix-coil transition during heating. Possible relationships are suggested between these physicochemical changes of the myosin head and tail regions upon heating and the heat-induced gelation of myosin.     

Determination of Foaming Properties of Proteins by Conductivity Measurements

A new method was established to estimate the foaming properties of proteins from the conductivity of foams using a simple apparatus that consisted of a glass column with the conductivity cell. A close correlation was observed between the initial conductivity of foams and the foam volumes of heat-denatured ovalbumins or 11 native proteins, suggesting that the initial conductivity of foams can be used as a measure of foaming power. In addition, a close correlation was obtained between the foam stability determined from changes in the conductivity and foam volume with time of heat-denatured ovalbumins or 11 native proteins, suggesting that foam stability also can be estimated from changes in the conductivity of foams. The advantages of the conductivity measurements are to determine the foaming properties more simply and accurately than the currently used methods.     

Enthalpy of Denaturation and Surface Functional Properties of Heated Egg White Proteins in the Dry State

The enthalpy of denaturation (ΔH) and surface properties of proteins were related to elucidate the mechanisms of foaming and emulsifying properties by using various heated egg white proteins in the dry state. Foaming and emulsifying properties of all sample proteins were greatly increased with a decrease in the enthalpy of denaturation as determined by differential scanning calorimetry analysis. In plots, foaming and emulsifying properties correlated linearly with ΔH values for various dry-heated egg white proteins. Thus, the enthalpy of denaturation of proteins seemed to be a significant structural factor governing surface functional properties.     

Milk Curdling by Rennet under High Pressure

The effect of pressure on milk curd formation initiated by rennet was studied under high pressures. The milk used was a 20% solution of skim milk powder in 0.02M CaCl₂. After holding the milk with rennet at 35°C for given periods under high pressure, up to 1300 kglcm², the extent of proteolytic digestion and the curd tension were measured under atmospheric pressure. Rennet and milk protein were not denatured by pressure under the experimental conditions used. The primary phase reaction of milk curdling by rennet (hydrolysis of casein) was not affected by compression. The secondary phase reaction (core formation of casein micelle aggregates) was delayed under high pressure and the tertiary phase reaction (milk curd formation) was accelerated.