Abstract
The volume of carbon dioxide evolved in a shaking fermentation apparatus was measured at fixed intervals in the same way as stated in the previous paper. Then, the curve showing the rise and fall of fermenting activity was analysed with orthogonal polynomial. This method for the determination of fermenting activity was compared with usual methods of expressing fermenting power, from which the author's method was proved to be more rea-sonable than the others, particularly, in point of deciding initial fermenting activity.
1) It was confirmed that the fermenting power of dry yeast can be expressed in a polynomial lower than cubic, and then that this can be further represented by three factors: an initial fermenting activity (measured as Qco2(20'-40')), a power which increases or recovers fermenting activity (ΔQco2), a miximum fermenting activity (Qeo2(max)).
2) The correlation between the above values, I. P., and t' was examined respectively. Thereupon, the following connections were confirmed: there exists a negative correlation between Qco2(max) and I. P., an almost perfect positive correlation between I. P. and t' and a positive correlation between Qco2(20'-40') and ΔQco2 as well as between Qco2(20'-40') and Qco2(max).
3) In the case of a small Qco2(20'-40') value, the influence of ΔQco2 and the other factors seems to be larger, because the expected Qco2(max) has a large variance, but generally Qco2(20'-40') may be used as a criterion to indicate fermenting power of dry yeast.
4) Also, a positive correlation exists between Qco2(20'-40') and the value of the dough fermentation test, but this is smaller than the value observed between Qco2(20'-40') and Qco2(max). Therefore it is concluded that the influence of factors other than the above three may be stronger in dough fermentation than in sucrose fermentation.
Acknowledgement The author wishes to express his sincere thanks to Prof. I. Yamasaki of Kyushu University for his kind guidance in the course of this work. He is also indebted to Prof. K. Kawamoto of Ehime University for many helpful suggestions concerning mathematical problems.
