Thermostable Proteinase in Salted Anchovy Muscle

Salted anchovy fillets produced in Japan were severely degraded above 35°C and were solubilized completely in a few hours at 55°C. In contrast, raw anchovy fillets were not solubilized, but the solubility of fillets gradually increased during the salting process. In contrast, salted and raw anchovy fillets from southern Europe were relatively stable. Proteolytic activity that digested myosin heavy chain in vitro was found in muscle extracts from both types of salted fillets. Enzymes with activity were high-temperature-active serine proteinases with substrate specificities similar to trypsin. Optimal pH was 7.4 (Japan) and >8.5 (Europe). Neither enzyme showed collagen-degrading activity.     

Effects of Heat Transfer by Radiation and Convection on Browning of Cookies at Baking

The effects of modes of heat transfer (radiation or convection) on the baking color development of food were studied. An experimental baking oven that could be altered to two heat transfer modes was designed; the ratio of heat by radiative transfer to total heat transferred was about 30% or 70%. The glucose-glutamate solutions were heated at different air temperatures to measure the browning rates to calculate the activation energies. Cookies were baked at 200°C to measure the lightness of color on the surface and the surface temperature. It was clarified that the development of color depended on the temperature only.     

Apparent Heat Transfer in a Forced Convection Oven and Properties of Baked Food

Parameters for expressing the heating performance and baking results of sponge cakes dependent on heating performance in a forced convection oven were studied. The heating performance of a forced convection oven may be expressed by the apparent heat transfer coefficient which was measured at various air temperatures and velocities. Both the air velocity and temperature of the circulating air affected the apparent heat transfer coefficient in a forced convection oven and determined the final properties of the baked food. The effects of these parameters on sponge cakes baked in the forced convection oven were observed.     

Investigation and Improvement of the Staggered Labyrinth Seal

Recent studies on staggered labyrinth seals have focused on the effects of different parameters,such as the pressure ratio and rotational speed on the leakage flow rate.However,few investigations pay sufficient attention to flow details and the sealing mechanism,which would be of practical importance in designing seals having higher performance.This paper establishes a theoretical model to study the seal mechanism,thus revealing that leakage is determined by the pressure ratio and geometric structure.Numerical simulation is implemented to illustrate details of the flow field within the seal structure.Viscous dissipation is used to quantitatively investigate the contribution that each location makes to the seal performance,revealing that orifices and stagnation points are the most important positions in the seal structure,generating the most dissipation.The orifice is carefully studied by using the theoretical model.Experiments for different pressure ratios are conducted and the results match well with those of the theoretical model and numerical simulation,verifying the theoretical model and analysis of the seal mechanism.Three new designs,based on a good understanding of the seal mechanism,are presented,with one reducing leakage by 24.5%.