Insufficient heating causes decreased digestibility, or increased growth of microorganisms while excessive heating (overcooking) not only impairs the usual texture, or eating-quality, of various food including starchy food and meat/fish meat, but also leads to the generation of hazardous factors such as acrylamide and heterocyclic amine. Consequently, it is important to describe various changes in the physical properties of food materials that occur during thermal processing, based on the heat transfer phenomenon in order to determine optimal values for heating. In this article, (1) study of moisture transfer and reaction in starchy food during cooking, and (2) reaction kinetics of thermal denaturation of protein are described.
A pasta extrusion die is subjected to stresses in several directions when pasta is extruded. Estimating this stress numerically and correctly is useful to design high-performance and high-efficiency pasta dies and machines. Therefore, DEFORM-3D finite element simulation software is used to measure the stress on a die and to visualize the pasta material flow. DEFORM-3D is commonly used in the plastic processing field. Some important results obtained from this study are the following: (1) The deformation resistance function is σ＝0.033 MPa. (2) Stress distribution of the die can be calculated numerically and visualized clearly. The die hole edge shows the maximum equivalent stress, σeq＝18.3 MPa. (3) Flow of the pasta in the container is also visualized clearly. (4) The flow rate for other die holes is obtained quantitatively. This knowledge is useful for pasta die and machine design.
In this study, we investigated the effects of freezing and subsequent storage on γ-aminobutyric acid (GABA) accumulation in soybean (Glycine max) cotyledons. According to direct observations and an indirect analysis with Cole-Cole plots of soybeans, the membrane structure in freeze–thawed soybeans was partially destroyed and the degree of destruction increased with a decrease in the freezing temperature. GABA generation in freeze–thawed soybeans was accelerated during storage after thawing. The optimum pH for GABA generation reaction was investigated; the decrease in pH in stored soybeans was found to result in an increase in GABA generation. The higher GABA accumulation after freeze–thawing of soybeans may have been caused by the freeze–thaw-induced structural destruction, which improved substrate transfer and enzymatic reactions.
Recently, a new beverage was developed that forms a bubble-containing gel and expands in the stomach, so that it suppresses hunger despite being low in calories. In order to improve the hunger suppression effect of the beverage, it is important to clarify the optimum preparation conditions of the beverage so that it stretches the stomach wall to a larger extent, and for a longer time. Factors affecting the volume of a bubble-containing gel and its volume-retention capacity were investigated by in vitro digestibility evaluation using the human Gastric Digestion Simulator (GDS). It was determined that the degree of esterification of the pectin used and concentration of citric acid in the formulation affected the expansion volume of the gel immediately upon reaction with artificial gastric juice. Furthermore, the degree of amidation of the pectin used and physical properties of the gel also affected the retention capacity of the gel volume. For maximizing the expansion volume of the bubble-containing gel and its retention capacity after consumption of this beverage, it is necessary to consider the degree of esterification and amidation and the citric acid concentration in the formulation.
Pulsed Electric Field (PEF) treatment is considered as nonthermal due to application of ultra short high voltage pulses in liquid foods to extend their shelf life. In today’s world, water decontamination becomes extremely necessary to safeguard people from health ailments. The objective of this work focusses on inactivation of naturally prevailing Escherichia coli and Fecal coliform bacteria in environmental water using titanium electrodes. In this study, the PEF treatment chamber was designed to be used for both static and continuous modes of treatment. Bipolar square wave pulses having 1μs pulse width at a rise time of 160 ns and pulse repetition frequency between 48 to 50 Hz were used in this research. From the results, it was observed that titanium effectively inactivated both the microorganisms at a minimum treatment time of 60 seconds at 33.9°C while conventional stainless steel required 120 seconds at a temperature of 40.1°C under the same experimental conditions. Also, the relationship between treatment time and temperature remained linear despite the change in electric field. Results confirmed that (i) Titanium is more suitable in PEF for water decontamination due to its high reactivity than stainless steel (ii) Using titanium, complete ABSENCE of the two microorganisms could be possible in water at a nominal field strength of 24 kV/cm with much less temperature requirement.
The correlations between physical properties and sensory evaluated scores of Japanese soup stock (Dashi) added jelly were analyzed using statistical analysis methods. Five kinds of sample jellies were tested for their viscoelastic properties by texture test to obtain 3 parameters of hardness[Pa], cohesiveness [-] and adhesiveness[J/m3]. Sensory evaluation by 29 female student panelists were conducted to obtain sensory evaluated scores of preference, hardness of jelly, aroma and taste intensity of Dashi, cohesiveness, ease of swallowing and persistence in mouth. High correlations were found between sensory preference, hardness of jelly, aroma and taste intensity of Dashi by partial correlation analysis. Partial Least Square (PLS) regression analysis were conducted to preference and sensory evaluated scores which assumed to having a linear relationship, and then successfully obtained a regression equation showing R2＝0.99. From the ranking of Variable Importance in Projection (VIP) values obtained from PLS, it was found that preference of the jelly has a higher contribution to taste and aroma terms than terms related to its mouthfeel. However, in the case of a data set in a nonlinear relationship, it was considered necessary to examine the statistical analysis which having flexibility to model the nonlinear relationship and the substitution parameters.