An excellent fermentation process of course include a high product yield and low residual sugar conecntration. However, the concentration you mention is rather low and could be accepted as a good indicator of a successful fermentation process.

Dear Lu,

There are two possibilities that must be verified. The first is the assimilable nitrogen content required for the yeast to reach the required population. The second is the dissolved oxygen content; if there is not enough oxygen the yeast will not use all the assimilable nitrogen, making the fermentation slow or due to lack of ergosterol (synthesized from oxygen) the fermentation can stop before the end of the fermentable sugars.

Based on your data, we can, as indicated by the other two speakers, mentioned that the fermentation is "complete". It is important to monitor the consumption of your substrate C, in addition to the production of your product, with the consumption of oxygen. The role of KLa is often important, hence the importance of determining it. Never forget that microorganisms often undergo fermentation stress and therefore may negatively impact your fermentation. Don't hesitate to contact me for any information

Completion of fermentation process indicates low concentration of glucose i.e. 0.2 g/Lit. The completion process depends on the initial glucose content, pH, nitrogen assimilation, Dissolved oxygen etc. In most fermentation process the organism unable to utilise glucose when the concentration is less than 0.2 g/Lit and this low level is a biological indication to the organism to look for alternative carbon source/s and it is normally protein source. So, one need to find out the glucose consumption kinetics against Biomass built up. All the above factors put together decides the production capacity of a microorganism. In your case, 0.2 g/L would have been reached may be at log 48 hr to 60 hr. You may check the initial pH of the medium and at 72 hr.