Recently, remarkable progress in the fields of IT, biotechnology, space-technology has been achieved. However, it seems that only low development has been achieved in the retort sterilization technology, especially in the methods to estimate temperature of central part of foods exactly. An improved estimation method named ATS method (Ambient Temperature Slide method) was developed to solve some theoretical and practical problems in the sterilization technology in 2006. Both accuracy and convenience of the ATS method have been inspected enough so far by many experimental data, however, the ATS method have been doubted regarding propriety of assumption that the deviation rate (β) of temperature of central part of packed foods from space-mean temperature is equal to one (1). This theoretical problem could be solved by using a similarity relation between the temperature history curves of the space-mean and the central part of the packed food. In addition, it was found that a heat-transfer coefficient (h) was a very small value compared to conventional expectation by using one-dimensional finite-difference method in retort sterilization. This new finding should be investigated by further experiments.
A theoretical method to calculate the evolution of the size distribution of oil-droplets in O/W emulsions over time was proposed based on the model where the coalescence rate of two oil-droplets was expressed by second-order kinetics using the rate constant evaluated from the activation energy for coalescence. The force between two oil-droplets of different diameters was appropriated by the force between two oil-droplets of equivalent diameter, and the increase in the rate of the number density of oil-droplets was estimated by solving the mass balance equation. The evolution of the size distribution of oil-droplets in several conditions agreed well with well-known features of coalescence of oil-droplets in O/W emulsion such as instability with larger oil-droplet size.
Katsuobushi is one of the most famous Japanese traditional foods and it has been empirically known that giving moisture was effective to realize good shaving with yielding less powder. In this article, in the aim of finding scientific elucidation for this presumption, shaving experiments were carried out with varying moisture content of the Katsuobushi under the almost constant temperature as 25°C. For the experimental consistency, the moisture content of the sample was controlled by using saturated salt solutions and the commercial shaving equipment was introduced. As a result, it was found that most of the shaved product was obtained as powder if the moisture content was less than 0.5% d.b. With gradual increasing of moisture content of Katsuobushi, the powder content gradually decreased, and at the condition moisture content reached about 14% d.b., the powder content drastically decreased. By referring existing data, the glass transition temperature of Katsuobushi of 14.4% d.b. in moisture content was appeared to be about 25°C, that coincided with the sample temperature at the shaving. From the result, it would be elucidated that moistured Katsuobushi could be shaved with less powder content because the glass transition temperature of the Katsuobushi went down below the actual temperature at the shaving and the Katsuobushi turned into rubbery state.