All conventional heat processing calculations are based on as few as two equations: a “primary” equation which corresponds to the first order kinetic of microbial inactivation represented by a log-linear survival curve, and a “secondary” equation which describes the effect of the heating temperature on the thermal resistance of target spores. Improvements of heat inactivation modelling consist in the extension of these equations into more general primary models which are able to fit typical non log-linear survival curves and multifactorial secondary models which take non only heating temperature, but also some new other environmental factors into account. A first models generation inputs only factors such as pH or water activity which are related to the heating phase regardless of recovery conditions. A second models generation further includes environmental factors linked to the recovery conditions of incubation for the calculation of heat resistance. These new trends lead to the main following consequences: i. the efficiency of a heat treatment is more suitably characterised by the bacterial inactivation ratio than by the traditional F-value which is no longer additive, ii. The lethality factor concept can be usefully extended to a more general function which would include not only heating temperature, but also main other environmental factors.
Today, Korean style dishes are being globalized, and with such a trend, it should be ensured that they can be safe from foodborne contamination. In this study, QRA, which is a quantitative technique to predict contamination levels and to perform sensitivity and scenario analyses, was performed in order to achieve better safety management for Korean style menu preparations. First, the hygienic conditions of Korean style dishes were surveyed, showing that these foods would not be safe if managed improperly. Saengchae, which was one of the dishes, proved vulnerable to pathogen contamination, and was selected for the case study. As a result, the hazard factor was determined as Staphylococcus aureus, and the hygienic conditions in the restaurant used for the case study were considered safe from food contamination. Through sensitivity analysis, the CCP in the preparation procedure was determined as the storage step. Through scenario analysis, the CL of the resultant CCP was estimated as a storage temperature lower than 15°C, when stored for 3-5 hours. In conclusion, we demonstrated that QRA, known as a versatile solution in quantitative analysis, can be applied successfully to aid conventional HACCP for the safety management of Korean style menu items. Therefore, this study provides an example of a quantitative approach for more extensive cases in the safety management of Korean style dishes.
This paper reviews recent developments on various aspects of food freezing. The various effects of freezing and frozen storage on food quality are described, including the role of glass transition. Methods for calculating freezing time and the evolution of temperature and phase change are reviewed and their underlying assumptions and limitations are critically examined. Finally, recent developments in freezing, thawing and freeze concentration techniques are reviewed: high pressure freezing and thawing, ultrasound assisted freezing, progressive freeze concentration, osmodehydrofreezing, immersion freezing in ice slurry, and the use of antifreeze proteins.
Thermal processing is a very common technique in the food industry. Commonly foods are overprocessed to ensure safety, but this may give excessive loss of quality attributes. Thermocouples are commonly used to obtain temperature-time profiles, but for many products it is not feasible to use them. Time-temperature indicators (TTIs) are small particles containing a reactive species that can be passed through a process and then assayed to measure the process effects. A series of tests have been carried out to determine the feasibility of using TTIs to validate thermal processes, using a pilot scale process vessel. TTI results could show the effects of local wall heating and distinguish between different heating regimes. Particle paths can be quantified using Positron-Emission Particle Tracking (PEPT) ; for viscous fluids of the kind found in food applications there is very close match between the flow of the fluid and of the TTI. Suggestions for the use of TTIs are made.
The mutagenicity of the extracts from defatted rice bran by water or subcritical water treatment at 50°C to 250°C was examined using the Umulac AT test, which is a kit reagent for assaying the genotoxin-induced umu gene expression. The examination revealed that the extract at any temperature was negative for the mutagenicity for both the -S9 and +S9 tests, which assess the mutagenicity of the sample itself and its metabolites, respectively.