The tests at Audubon following the incidents in 2002 of difficult boiling have now been summarized and published. The copies of the publications are available on request from Audubon. Among the main conclusions was that this phenomenon was unrelated to either starch or dextran and the use of the appropriate hydrolytic enzymes (amylase and dextranase) had no positive effect. It was also found that the viscosity of the hard to boil massecuites was not elevated, and surfactants, lubricants, soda ash and several other additives that were tested were found of no value.
Only lowering the pH of the molasses or the massecuite was found effective and was found to immediately restore normal boiling. This was accomplished by addition of about 1:1 diluted hydrochloric acid directly into the pan. The effect was found to be progressive, that is the boiling rate kept increasing with the increasing amount of the acid that was added, up to about 1 % hydrochloric acid added on the massecuite weight. At this addition level the required amount of (concentrated) hydrochloric acid in a 40-ton pan would be about 100 gal, probably too much to be feasible, but a significant improvement, that is doubling or tripling of the boiling rate was seen in our tests at addition levels as low as 0.2% on massecuite, or some 40 gal of a 1:1 diluted hydrochloric acid in a 40-ton pan.
An equivalent measure, although not yet tested at Audubon or elsewhere, might be to lower the pH set-point in clarification during the hard to boil period. Progressively lowering the pH set point to 6.0 or below might be attempted.
Please inform us of any hard-to-boil massecuite incidents, so that we can take some samples to investigate further.