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pH control and the “shoulder” effect in parallel fermentation pathways
Author(s) -
Tanner Robert D.,
Overley John R.
Publication year - 1974
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260160405
Subject(s) - fermentation , chemistry , constant (computer programming) , lactobacillus , lactobacillaceae , biochemistry , food science , biological system , computer science , biology , programming language
In an effort, to develop comprehensive mathematical models for use in optimizing fermentation processes, product rate data taken at constant pH's for the lactic acid fermentation ( Lactobacillus delbrueckii ) were analyzed. It was observed that the rate of acid synthesis‐time trajectories exhibited a “shoulder” effect at pH's less than 5. That is, a nearly constant rate of synthesis for up to 10 hr in the late growth phase, out of a maximum total fermentation time of 70 hr. This effect was used as a clue from which to structure the proposed model with parallel pathways. Simulating shunting pathways does, in fact, demonstrate that, the notion of parallelism is consistent with the expression of a shoulder. It is postulated, therefore, that a differential pH effect between two parallel pathways can account for the presence of a shoulder when both routes prevail, and no shoulder when either pathway predominates.