Conventional plate counting with selective agars is time-consuming and labor intensive for the detection and enumeration of microorganisms associated with food-borne illnesses from food and environmental samples. In addition, it may be unsuitable for the rapid estimations required for food sanitation and hygiene. To overcome these technical challenges, a superior method, termed FISHFC (fluorescence in situ hybridization [FISH] in combination with filter cultivation [FC] on a membrane filter), was developed. The FISHFC method has equal detection accuracy to the conventional plate counting method. It enumerates only viable food-borne pathogens from food samples within 8-17 h, which suggests that the accurate evaluation of pathogen contamination can be completed within two working days. Therefore, the FISHFC method with species-specific detection probes contributes to ensuring food safety. This article introduces the rapid enumeration FISHFC method for the estimation of food-borne pathogens.
Hydration analysis of sugars and amino acids was conducted with a focus on the viscosity of liquid food models. The interaction between pectin molecules in aqueous sugar solutions was also analyzed as a model of food macromolecule interactions. The viscosity-related parameters used for analysis of solute-solvent interactions were Bη, dBη/dT, Bη/V2, BT1, and BT2, as well as the parameters h and α. Specific viscosity-related parameters, ηsp and —dηsp/dAW, were used for the analysis of interactions between food macromolecules in aqueous sugar solutions. Using these parameters, it is anticipated that the mechanisms of liquid food hydration at the molecular level will be clarified in the near future.
Low water activity and the glass state in dried foods restrict the growth of microorganisms and increase food stability. Vitrification of foods is related to the texture. Thus, hydration and vitrification are essential factors determining the physical properties and quality of foods. Inelastic neutron scattering (INS) is a promising research method for the analysis of water mobility and glass transition of food materials. Neutrons easily penetrate materials, and can be used to non-destructively investigate the molecular dynamics of food materials. INS generates information about the vibrational density of states, relaxation and diffusion processes, and mean-square displacement. Molecular dynamics (MD) simulation provides information regarding molecular structure and dynamics on an atomic scale, and is thus complementary to INS. It was found that the hydration level dependence of the onset of protein glass transition is correlated with the percolation transition of hydration water. In addition, the hydration water dynamics changed significantly at the transition temperature. The percolation of hydration water induces protein glass transition.