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  • 1
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical expression is derived to estimate a correction factor for come-up heating, which may be used to calculate mass average survival concentrations. For this derivation, analytical heat conduction formulae are used to estimate transient state temperature distributions in a cylindrical can of heat conduction food. Through the dimensional analysis of the derived analytical expression, 12 dimensionless groups are formulated in order to examine the Influence of various process conditions as well as of food properties on the correction factors. Theoretical correction factors are then computed for various numerical combinations of these dimensionless groups. Through the nonlinear regression analyses of these computed factors, we obtain algebraic equations for representing these factors as a quadratic function of the dimensionless groups. There is fair agreement between the correction factors estimated by using the algebraic equations and by using heat penetration data collected experimentally.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 45 (1980), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A series of theoretical formulae were derived to simulate heat conduction in a finite cylinder whose surface heat transfer conductances on top, bottom, and side surfaces were neither infinite nor identical to each other. These formulae were utilized to determine thermal diffusivity of heat conduction food tilled in a cylindrical can and surface conductances on its surfaces. Error analysis shows 1 mm deviations in locations, where the temperatures are monitored, as well as similar deviations in the height and radius of a cylinder given significant variations in the thermophysical property values. It is also shown that these variations may be significantly reduced if one uses a cylinder whose height and radius are 100 mm or greater. Commercially processed apple sauce and 8% bentonite suspension were filled info cylindrical cans of two different sizes. These cans were then subjected to heat treatments in a still retort. Temperature data collected during these treatments were then utilized to estimate the thermophysical properties of sample materials. There was fair agreement between those estimated and respective literature values.
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  • 3
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A computerized procedure was developed for estimating the critical point correction factor, Cf, of come-up heating in thermal processes, which are applied to cylindrical cans of heat conductive foods. Sterilizing values at the thermal center of the can were used as a criterion for this estimation. Fifteen parameters are required to uniquely determine Cf values. These parameters include z value, thermophysical properties, and can dimensions, as well as operational conditions. Through a dimensional analysis, ten dimensionless parameters were selected to estimate Cf values. A fractional central composite experimental design was applied to evaluate statistically the influence of each parameter on Cf. Through this evaluation, several regression equations were developed for their practical uses. A series of heat conduction experiments were conducted by using several different sizes of cans filled with food simulant, 8% bentonite suspension. Fairly good agreement was found between predicted and observed correction factors.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 44 (1979), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The geometrical configuration of many food products may be approximated with an infinite slab, in so far as their heat transfer characteristics are concerned. Several researchers have utilized formulae for predicting transient state heat conduction in an infinite slab undergoing symmetric heat exchange with surrounding medium. However, in a number of food manufacturing processes, the heat transfer rate through one surface of the slab is not identical to that through another surface. There is a published analytical formula available for estimating transient state heat conduction in an infinite slab subjected to nonsymmetric heat exchange with surrounding medium. However, it is impractical because of mathematical difficulty, to apply directly this analytical formula for estimating the temperature of food subjected to nonsymmetric heating or cooling processes. Therefore, computer programs were developed to simplify this application. The programs are for the estimation of characteristic roots, transient state temperature, f and j values and the location of the thermal center. From computational results obtained by using these programs, we then developed a set of charts to simplify the estimation of food temperatures. Examples for the use of the method are included in this presentation.
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  • 5
    ISSN: 1573-0832
    Keywords: Nocardia otitidiscaviarum ; cutaneous nocardiosis ; toxic substance ; chemical structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract During our studies on toxic substances from clinically isolated Nocarida, a new isolate identified as Nocardia otitidiscaviarum from cutaneous nocardiosis was found to produce a toxic substance called HS-6 that had strong in vitro as well as in vivo toxicity. The mouse intraperitoneal LD50 value was 1.25 mg/kg and the ED50 value for L1210 cultured cells was 0.3 ng/ml. The structure of HS-6 was determined and found to belong to the 16-membered macrocyclic group with a molecular formula of C43H68O12. HS-6 also showed activity against pathogenic fungi such as Cryptococcus neoformans.
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