STORAGE RESULTS IN LOSS OF THE ANTIGENOTOXIC PROPERTIES OF LENTINULA EDODES (SHIITAKE MUSHROOM) AND DEVELOPMENT OF IN VIVO GENOTOXICITY

In this study, we have investigated the stability of the antigenotoxic properties of dried of Lentinula edodes (Berk.) Singer mushroom powder stored at room and at − 20C. Mice were pretreated by gavage for 15 consecutive days with 0.6 mL/day of an aqueous extract of dried L. edodes powder prepared at 60C. On day 15, the mice were intraperitoneally injected with 50 mg/kg N-ethyl-N-nitrosourea (ENU); 3 h later, peripheral blood was withdrawn from the animals and used to evaluate DNA damage using the comet assay. The mice were sacrificed 24 h after the ENU treatment and the bone marrow used to measure the frequency of micronucleated polychromatic erythrocytes. The results indicated that storage at both room temperature and at − 20C significantly reduced the antigenotoxic effects of the mushroom powder. In addition, whereas freshly dried mushroom powder was nongenotoxic, storage of the powder at − 20C resulted in genotoxic activity ( P <  0.05). Taken together, our data indicate that constituents of L. edodes powder are altered during storage, resulting in both genotoxicity and a reduction in antigenotoxicity.     

PREDICTING INTERNAL TEMPERATURE RESPONSE TO CONDUCTION-HEATING OF ODD-SHAPED SOLIDS

Heat penetration experiments were carried out in a hot water bath with small blocks of a solid polycarbonate material cut into various shapes (cylinder, cube and oval) to obtain heat penetration factors for each shape. These factors, along with characteristic dimensions from the odd shapes were then used in the finite cylinder heat transfer model to predict accurately the temperature at the center of each block in response to measured dynamic bath temperatures. Results showed sufficiently good agreement between predicted and measured center temperature profiles to justify use of the finite cylinder model for rapid evaluation of process deviations in thermal processing of foods in odd-shaped containers.     

Evaluation of the Properties of Polystyrene Divinylbenzene Adsorbents for Debittering Grapefruit Juice

Various physical properties of polystyrene divinylbenzene adsorbents involved in the removal of the bitter compounds naringin and limonin from grapefruit juice were investigated in a series of batch reaction processes. The removal of naringin from model systems and, naringin and limonin from grapefruit juice increased with the degree of cross-linkage and surface area of the adsorbents which had a solid density higher than 1.2 g/mL (dry) to ensure complete submersion. The specific surface area appeared to be the major factor in the debittering process. Regeneration with 95% ethanol was found to be more efficient than warm water. Sensory evaluation tests showed that more than 65% of the panelists preferred the less bitter treated juice over the control.     

Fire and explosion hazards associated with milk spray drying operations*

Recent reports in the literature indicate that incidents involving fires and explosions in the spray drying of milk products are increasing in number. While milk powder is not highly explosible, the conditions for a dust explosion, apart from the ignition source, are almost always present in certain areas of a spray drying system during its normal operation. Self-ignition of deposits is known to be possible at the high temperatures in a spray drier. At best, this can cause product degradation and discoloration and at worst it can provide the source of ignition for an explosion. This paper is an attempt to draw together recent work on fire and explosion prevention and protection for milk powders.     

Effect of Marination upon Mineral Content and Tenderness of Beef

This study compared marinated and nonmarinated beef to determine differences in semimembranosus muscle tenderness and selected mineral content. The minerals analyzed were iron, zinc, magnesium and sodium. Marination resulted in a significantly more tender muscle, as determined by shear values and trained panel evaluations. Mineral content was significantly affected by marination with substantial losses of iron, zinc, and magnesium and increased sodium. Marination would be a feasible method of enhancing tenderness of more economical cuts of beef; however, the subsequent loss and/or gain of minerals should be considered.     

Spontaneous ignition of milk powders in a spray-drying plant

A company operating a spray-drying plant for skimmed milk and fat-filled powders asked the Fire Research Station for help in determining the cause of a series of fires. The subsequent investigation showed that the powders could undergo spontaneous ignition in certain circumstances. The thicknesses of powder deposit on the spray-drier walls necessary for there to be a risk of self-ignition were calculated. These were sufficiently close to those encountered in practice to suggest that self-ignition represents a real problem. Mechanisms for the occurrence of fires in the fluid-bed instantizers are also put forward. Preventive measures are suggested.     

Predicting Thermophilic Spore Population Dynamics for UHT Sterilization Processes

A mathematical model of Bacillus stearothermophilus spore populations during lethal heating treats activation of dormant spores and inactivation mechanisms affecting dormant/activated spores. Rate constants of activation/inactivation processes were determined from isothermal survivor curves of experiments in 105, 110, 115, and 120°C and corresponding simulations with the model. Variations of rate constants with temperature were incorporated by Arrhenius equations responding to general temperature regimes. Tests demonstrated high correspondence between experimental survivor curves and those generated by simulations with the model for isothermal and dynamic, lethal heating. Tests also indicated Arrhenius rate constants at low lethal temperatures (105-120°C) and the model may apply to ultra high temperature. The new model was more effective than the traditional model in representing and predicting spore population dynamics during lethal heating.