摘要:

This paper presents a formulation in dimensionless terms of the equations pertaining to first‐order processes that follow Arrhenius kinetics, and applies them to problems in food thermoprocessing. the need for it arose from attempts to understand the relation between destruction of pathogenic microorganisms and formation of chemical markers in the food. During processing food is subjected to a thermal pulse that affects the markers and microorganisms. the dimensionless formulation makes it convenient to obtain equations expressing the relation between the decadic reduction in microbial population and the rise in marker concentration for temperature‐time profiles of forms hitherto not conveniently calculable. Measurements of chemical markers can be used with these formulas to predict destruction of microorganisms. Examples are given of calculations demonstrating the feasibility of this approach when a single marker is monito

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1993.tb00320.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The batch retort model developed uses a heat transfer equation for heat conduction in cylindrical cans, first order kinetics for microbial inactivation, first order kinetics for quality losses and a transient energy balance to estimate steam consumption. For a given retort, lethality process and quality retention, the transient energy balance equation in the model allowed the identification of feasible time‐temperature profiles reducing energy consumption, total process time or both. In the examples analyzed and depending upon product specifications, time‐variable retort temperatures reduced process time by 18–55 min. These examples suggested that a change from constant to time‐variable retort temperatures could increase canning capacity by

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1993.tb00321.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

For low‐viscosity foods, in a piston filler (FMC PN010), power‐law relationships were found between the number of cycles/minute at which splashing occurred on the rim of a container versus viscosities of the test fluids. Splashing was due to either the breakup of a discharge jet in the nozzle or overflow of discharge fluid over the rim of a container. the formation of droplets due to breakup of discharge jets was confirmed by solution of the flow equations on a Cray‐2 super computer. With foods containing particulates in a low‐viscosity liquid, splashing occurred when the food hit the bottom of the container and again when the plunger hit the top of the heaped food. With foods having high magnitudes of yield stresses, the plug formed in the discharge nozzle of the filler contributed to heaping of th

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1993.tb00322.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The bulk volume shrinkage of canola and wheat were measured for the temperature range of 20–80C and relative humidity range of 15–90%. the volume decreased exponentially with time as seed moisture content was reduced. For canola, an oilseed, shrinkage and moisture reduction were linearly correlated with a shrinkage coefficient of about 1.0. For wheat, a starchy grain, the relationship was also linear but the coefficient was greater than 1.3. the shrinkage coefficients for both wheat and canola did not show a correlation with drying temperature but varied linearly with relative humidity of the drying

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1993.tb00323.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Kinetics of thermal inactivation of trypsin (bovine pancreas) were evaluated in the temperature range, 90–130C, common to aseptic processing of high/low acid foods. Aliquots of trypsin in buffer, at three pH values, 3.8, 5.1 and 6.0, were subjected to selected heat treatments at various temperatures. Kinetic parameters were evaluated from the residual enzyme activity. Reference k and D values (at 121.1C) ranged from 0.0719 to 0.349 min−1and 32.0 to 6.6 min, and Eaand z values ranged from 84.9 to 69.9 kJ/mole and 33.1 to 39.9C, respectively, in the pH range 3.8–6.0. the thermal inactivation resistance of trypsin in the acid and low acid pH range makes it a potential bioindicator for high temperature thermal proc

ISSN:0145-8876    

DOI:10.1111/j.1745-4530.1993.tb00324.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY