摘要:

Predictive equations to compute the chilling time, mass loss at the end of chilling, temperature history at the geometric center of round and mass loss history during beef carcass chilling were developed using validated computer models and response surface analysis. Central composite rotatable design was used to obtain quadratic response surfaces for various chilling parameters. Temperatures at the geometric center of round muscle were predicted within 95% confidence interval. Mass loss histories were also predicted within 95% confidence interval after 5 h postmortem. Temperature predictions were within ± 2C and mass loss predictions were within ± 1.0

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1995.tb00351.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

This paper describes how the distributed parameter conduction‐heating numerical model was modified and tested to accurately predict the can center temperature for canned foods which exhibit combined heat transfer of pure conduction with added forced convection caused by mechanical agitation. This innovation will open the door to more widespread use of such mathematical models as part of the control system logic for making accurate adjustments to process conditions in response to unexpected retort temperature deviations on line during thermal processing of canned foods in agitating retort

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1995.tb00352.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Heat transfer coefficients during drying of foods were evaluated from drying data and heat and mass balances. Experimental drying curves for slices and cylinders of potato, apple and carrot were obtained in a laboratory dryer under different drying conditions. the specific heat of the foodstuffs was measured as a function of water content and modelled through a linear relationship. Experimental heat transfer coefficients were correlated by the dimensionless expression NuD= 0.249 ReD0.64and compared with predictions of different equations.

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1995.tb00353.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The analysis of fluid flow in a single screw extruder channel is presented by treating the screw as stationary and rotating the barrel in the opposite direction. It is shown that the calculated shear rates at the barrel and at the screw, during extrusion of a Newtonian fluid under isothermal conditions, do not depend on the choice of formulation, i.e., barrel moving or screw moving. It is also shown that they are independent of choice of coordinate system.

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1995.tb00354.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

A mathematical model was developed for continuous extraction of multicomponent mixture anhydrous milk fat (AMF) with supercritical carbon dioxide (SC‐CO2) as its solvent. At a constant temperature and pressure, the triglyceride mixture was separated into vapor and liquid fractions. the composition distribution (indicated by acyl carbon number), mass distribution and yield of AMF were calculated by the model based on thermodynamic equilibrium and material balance. the feed composition and distribution coefficient were required information in this model. the experimental values for the extract were in good agreement with the model used. the results for the raffinate were not as precisely modeled. the main factors which affected the model were temperature, pressure, solvent/feed ratio and extract fractio

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1995.tb00355.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The modelling of the electrical heating of solid‐liquid food mixtures is an active area of research, reflecting its new importance as a commercial process. Two published models for electrical heating have been compared, and the accuracy of the use of circuit analogies for the prediction of heating rate was examined. It is shown that circuit analogies may not predict the heating rate correctly, especially at low solids fraction. the applicability of circuit analogies for the calculation of the heating effects of isolated particles of significantly different conductivity to the medium is discusse

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1995.tb00356.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Twelve continuous thermal processes were evaluated with the equivalent point method based on time‐temperature histories and the destruction of Blue #2 at four different pH's to provide different kinetic parameters as calibrating reactions. the Arrhenius kinetic parameters for the four reactions were estimated under continuous flow conditions. Three were used as calibrating reactions to determine the equivalent times and temperatures for each process. the loss of blue #2 for the fourth was estimated for each process, using its kinetic parameters and equivalent points based on thermocouple and calibrating reactions. Log concentration reductions, using equivalent points based on calibrating reactions, more closely matched (slope = 0.962, r2= 0.999) actual results than did equivalent points based on thermocouple data (slope = 1.030, r2= 0.976). Thermal process estimates based on calibrating reactions were more useful to estimate kinetic parameters or product quality because they more closely represented the process actually experienced by the produc

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1995.tb00357.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

This paper describes how the distributed parameter conduction‐heating numerical model was modified and tested to accurately predict the can center temperature for canned foods which exhibit combined heat transfer of pure conduction with added forced convection caused by mechanical agitation. This innovation will open the door to more widespread use of such mathematical models as part of the control system logic for making accurate adjustments to process conditions in response to unexpected retort temperature deviations on line during thermal processing of canned foods in agitating retort

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1995.tb00358.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY