This article describes the effects of enzyme activity during mixing on particle lengths of flax. In all of the experiments, the washed flax fragments were placed into 20 ml reaction vessels that were either rotated continuously. In addition, these vessels were placed into larger, 15 cm and 30 cm containers that were modified with an inserted paddle so that the vessels could be picked up by the paddle during rotation and dropped. This created a tumbling effect. The fibre lengths were unaffected when continuously rotated but when incubated in the larger vessels, fibre lengths were significantly reduced. Fibre lengths were reduced when the rotational speeds were increased but intermittent rotation had little effect. Acid hydrolysis also had little effect on the particle size of fibres. Finally, substrate concentrations and enzymes concentrations were examined. This showed that enzyme concentration at 8 mg per g flax was sufficient and that higher quantities did not result in much more activity. There was a difference between substrate concentration but only by about 10%. The study is thoughtful and well presented.
In the abstract, liquefication is mentioned a few times and while it is the ultimate aim of this work, the solid content was not measured that would be a true indicator of whether liquefication had occurred. Personally, I would focus on mentioning decreases in fibre length and mention that you working towards developing a liquefication process.
In the experiments to examine the type of reactor that would be most effective, it is my belief that there are potentially two variables that could influence the results. The reaction vessels in the 30 cm containers would cover a larger radial distance than the smaller 15 cm containers. Consequently, it would be expected that the reaction vessels, like small gears, would rotate more quickly than the anticipated 30 rpm and it is perhaps the increased radial distance covered rather than the presence of the paddle that resulted in more fibre breakdown. Therefore, the ideal control experiment would involve placing the reaction vessels into a similar sized container that does not contain the paddle. I think a critical evaluation should also be discussed.
Disappointingly, saccharification was only measured in the last experiment with enzyme activity that appeared to show a relationship between saccharification and particle size breakdown. It would have been interesting to know the results for the different reactor types. One would expect that enzyme hydrolysis would occur under continuous rotation yet the results on particle lengths show otherwise.
Line 38, P3 water is a poor lubricating agent but a good dispersing agent
Line 17, P6 It is not immediately clear that the reaction vessels were inside the large containers – this needs to be made clearer. Also, what proportion of the reaction vessel was filled? And was this made constant when different quantities of substrate were examined?
The use of free fall has been used regularly which implies a state of motionlessness whereas on line 9 P8 tumbling has been used. Consider that this a better description.
Line 24, P 13 misspelling of lignocellulose
Fig 1 Not clear that reaction vessels are inside 15 and 30 cm containers – need to describe this in the legend. The containers appear to be too packed within the vessels such that they would hardly move in the 15 cm container and few would stay on the paddle in the 30 cm container. Have calculated the dimensions and realize this is not the case – could make the vessels much smaller.
Many of the journals titles in the reference section have not been capitalized.