The effect of temperature on L-lactic acid fermentation from Fresh Cassava Root (FCR) by Streptococcus bovis was investigated in new mediums: tofu liquid waste (TLW), and TLW with 2wt% concentrated maguro waste (TLW+CMW2) and also with standard medium (trypto soya broth; TSB), comparing with standard media (glucose in TSB) . The experimental results showed that lactic acid fermentations from FCR in three mediums and glucose in TSB were optimum at 39°C. The values of fermentation properties were found to be increasing in order FCR in TSB, glucose in TSB, FCR in TLW+CMW2, and FCR in TLW. The Arrhenius relationships for productivity and specific growth rate were then established. The values of activation energy (Ea) and deactivation energy (Ed) for lactic acid fermentation from all media were found to increase in order from FCR in TLW, FCR in TLW+CMW2, glucose in TSB, and FCR in TSB. The relations for activation energies and deactivation energies were in reverse to those for fermentation properties.
Some biopolymer gelation process shows an inflection point (IP) in a growth curve of a rheological observable. In this note, a kinetic treatment is presented for such a second-order food reaction process dx/dt=K2 (1-x) 2 where a general observable o grows with reaction degree x through the power-law type mixing rule oν= (1-x) oνR+xoνP. For-1<ν<1, the observable-time curve could possess IP at o*= (1-ν) 1/ν (1+ν) -1/νoP and K2t*=2-1 (1+ν) ν-1 (1- (oR/oP) ν) -1 with the maximum growth rate do/dt|t*=22 (1-ν) (1/ν) -1 (1+ν) - (1/ν) -1ν (1- (oR/oP) ν) -1oPK2. These results show that oR dependence disappears in the product (1+K2t*) do/dt|t*. The whole o-t curve is linearized with the transformation (oνP-oνR) (oνP-oν) -1=1+K2t. The case of ν=0 is compensated with a logarithmic type (In o) mixing rule.