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Food Technology and Biotechnology, Vol. 41 No. 3, 2003.

Original scientific paper

A Model for Converting Solid State Fermentation Growth Profiles Between Absolute and Relative Measurement Bases

Graciele Viccini ; Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Cx. P. 19046, Centro Politécnico, Curitiba 81531-990, Paraná, Brazil
David A. Mitchell orcid id orcid.org/0000-0001-9355-5520 ; Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Cx. P. 19046, Centro Politécnico, Curitiba 81531-990, Paraná, Brazil
Nadia Krieger ; Departamento de Química, Universidade Federal do Paraná, Cx.P. 19081, Curitiba 81531-990, Paraná, Brazil

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Abstract

A mathematical model is developed for converting between the two measurement bases commonly used in the construction of growth profiles in solid-state fermentation, namely absolute mass ratio m(dry biomass)/m(initial dry matter) and relative mass ratio
m(dry biomass)/m(dry matter). These are not equivalent, due to the loss of dry matter as CO2 during the fermentation. The model is equally applicable to any biomass component used in indirect measurements of growth, such as protein. Use of the model to convert absolute mass ratio of the biomass profiles for the growth of Rhizopus oligosporus to a relative basis gave profiles that agreed well with the experimentally determined relative biomass
profiles. This agreement was obtained for three different fermentations using the same set of parameter values in the model, namely a yield coefficient of m(protein)/m(dry substrate) = 0.2 g/g and a maintenance coefficient of zero, giving confidence in the reliability of the model. The model was then used to show that the measurement basis used can affect the form of the curve and therefore can also affect the conclusion drawn about the type of
kinetics shown by the organism, with the extent of this effect depending on the length of time that growth occurs and the values of the yield and maintenance coefficients. This work shows that great care must be taken in drawing conclusions about growth kinetics in
solid-state fermentation.

Keywords

solid-state fermentation; microbial growth kinetics; logistic equation; exponential growth kinetics; linear growth kinetics

Hrčak ID:

118593

URI

https://hrcak.srce.hr/118593

Publication date:

15.9.2003.

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