The motivation for developing mathematical models for food production is to quantitatively derive various product qualities from the product components and processing conditions. This paper introduces the author’s studies on the modeling of the freeze-drying processes. The ice crystal formation is an important factor in determining the freeze-drying kinetics. Here, an approach to simulate the freezing process for estimating the ice crystal sizes was introduced, and the results was further applied to simulate the progress of freeze-drying. In freeze-drying of food, drying progresses three-dimensionally as the outer surface receives radiative heat, and the sublimation surface area changes as the progress of drying. The author proposed a model that simplifies these phenomena and verified the simulation results. An attempt to quantification of the occurrence of collapse, which could be related to the quality of freeze-dried products, was also introduced. The deformation under the changes in moisture content and viscosity due to drying was simulated, and the resulting deformation level was used as quantitative data. It is expected that these approaches will contribute to the development of methodologies that can easily and quantitatively handle the complex food qualities.

This study focuses on the development of a novel extraction method using subcritical fluids, the application of innovative techniques for analyzing the bacterial community of fermented foods, and the establishment of a novel method for isolating an unknown microorganism. To achieve efficient extraction of food-derived components, a subcritical fluid extraction method employing aqueous organic solvents was devised. The results demonstrated improved extraction efficiency compared to conventional subcritical water extraction methods. Additionally, a small-scale subcritical water treatment system was developed and applied to elucidate the thermal degradation characteristics of major components in Japanese peppermint essential oil. Furthermore, a bacterial community analysis of a traditional naturally fermented vegetable beverage (kôso liquid) revealed the dominance of an unknown lactic acid bacterium (LAB). This LAB exhibited characteristics of being difficult to culture, and pure culture was initially unachievable. However, a novel isolation method devised by the author enabled successful pure cultivation. The newly isolated LAB was named Apilactobacillus kosoi. Collaborative research further demonstrated that this bacterium exhibits remarkably high intestinal immunomodulatory activity. It was clarified that a novel lipoteichoic acid component in its cell wall contributes significantly to its immunostimulatory effects.

Obesity prevention is crucial for controlling lifestyle disease and extending healthy life expectancy. Focusing on the appetite suppression by gastric wall stretching, the company affiliated with the first author developed and evaluated a carbonated beverage that forms a bubble-containing gel under the acidic conditions of gastric juice. A carbonated beverage containing pectin was developed from the viewpoints of easy to intake, stability, and convenience. The findings were obtained regarding the state of the bubble-containing gel in the human stomach and the improvement of satisfaction. Next, we conducted an in vitro evaluation of the bubble-containing gels using the Gastric Digestion Simulator that simulates gastric peristalsis. The results of the analysis indicated that low esterification/high amidation pectin and low citric acid concentration in the beverage improved the swelling and stability of the bubble-containing gel. In 2014, the company affiliated with the first author launched a beverage that forms a bubble-containing gel in the stomach. The results of this study were used for product renewal after 2018.

This research has developed a multi-functional food printer that significantly enhances conventional food production technology. The new 3D food printer employs a quad-screw nozzle system and offers three advanced printing methods: duplicator, multi-color and dual-mixing print. In particular, the mixing print technology has shown that it is possible to customize food products according to individual swallowing ability by combining two different hardnesses of material based on the microbially derived polysaccharide, curdlan. Food ink was prepared with 4.3 wt% and 3.6 wt% curdlan concentrations and tested using five different mixing ratios: (i) 0.00:1.00, (ii) 0.25:0.75, (iii) 0.50:0.50, (iv) 0.75:0.25, and (v) 1.00:0.00. The rupture strength tests demonstrated that the maximum stress increased with the 4.3 wt% curdlan concentration, yielding results of (i) 2.0 × 10⁵, (ii) 2.2 × 10⁵, (iii) 2.5 × 10⁵, (iv) 4.1 × 10⁵, and (v) 4.8 × 10⁵ [N/m²]. These findings confirm that the system allows precise control over texture through mixing ratios, supporting the creation of meals that meet individual swallowing needs. Furthermore, this technology enables gradation printing, which not only naturally changes the color of the food but also provides different textures depending on the part being consumed.

The rehydration process of dried wheat flour noodles (flat noodles) prepared by adding 0, 5, 10, and 15% wheat gluten by weight to wheat flour was measured at temperatures ranging from 40 to 80°C. Regardless of the gluten content, the rehydration process at any temperature was well described by an empirical hyperbolic equation regarding the rehydration time. The equilibrium moisture content and initial rehydration rate were smaller for the noodles with higher gluten content. The temperature dependence of equilibrium moisture content varied significantly between 50 and 60°C at any gluten content, reflecting the gelatinization temperature of the starch in the flour, and could be expressed by the van’t Hoff equation for the high-temperature region. The change in rehydration enthalpy at high temperatures was almost independent of the gluten content of noodles. The temperature dependence of the initial rehydration rate could also be expressed by the Arrhenius equation over all temperature ranges tested, and the activation energy for rehydration was almost independent of the gluten content.