Pectinase + Chilling = Acidity Reduction?

[Nick Smyth]

Hi all,

Relatively inexperienced cidermaker here.  I tested some apple juice acquired in the Boston area the other day, and my acidity kit indicated that it was at 1.05% tartaric acid, or around .94% malic. I was disheartened because this is way too high, according to most guides that I have read (Andrew's and Claude's, for example). I added pectic enzyme and placed in a 50 Fahrenheit chamber. Around 30 hours later I took it out, and on a whim, tested it again. The juice, which by now was very clear, registered around .65% tartaric, or .58% malic.  I re-tested to confirm this result.

I have read nothing about pectic enzyme reducing acidity levels, in fact, on this site Andrew has written that it should actually increase acidity levels. I find it hard to believe that I have discovered some effect that has somehow gone unnoticed by the cider making community. Any explanations for this bizarre result? I thought that liquid temperature might be affecting acidity readings, but I can find no source that says that this can happen. I am going to run a more rigorous test on a gallon of unfiltered juice, dividing it into four parts and adding enzymes at different times to gauge possible acidity changes, but I was wondering if anyone had any hypotheses that might explain this strange result. 

[Claude Jolicoeur]

I agree this is strange! Could it be that as the pectins got degraded by enzymatic action and precipitated, they carried some acidic compounds with them?
Looking forward for the results of your more rigorous investigations.
Claude

[Andrew Lea]

It doesn't fit with any fruit juice chemistry that I know. I suspect more likely some measurement error. What about the alkali you use for the titration? Does it come ready prepared?  How do you measure the end point?

Like Claude I await your further data with interest! 

Andrew 

Sent from my iPhone

--
--
Visit our website: http://www.ciderworkshop.com
 
You received this message because you are subscribed to the "Cider Workshop" Google Group.
By joining and posting to the Cider Workshop, you have agreed to abide by our rules, and principles. Please see http://www.ciderworkshop.com/resources_principles.html
 
To post to this group, send email to cider-w...@googlegroups.com
To unsubscribe from this group, send email to cider-worksho...@googlegroups.com
For more options, visit http://groups.google.com/group/cider-workshop?hl=en
 
---
You received this message because you are subscribed to the Google Groups "Cider Workshop" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cider-worksho...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.

[Chris Rylands]

I too am willing to bet that no new science is at play here. Is the actual makeup  of the Pectinase blend known, is it just for apple, or is it loaded up with other variations of the enzyme intended for citrus juice, wine, beer, or berry processing? What is the carrier for the enzyme? Did somehow an acid neutralizing agent find its way into the blend, residual compound on tool, container, or equipment? 

Eagerly waiting for your results!  

Best regards

Chris Rylands

CiderSupply.com

[Nick Smyth]

Hey again everyone,

Your suggestions are definitely plausible, so I'm beginning my tests tonight.  I'm starting with a single batch of juice that registered .65% tartaric, I've divided it into 4, and will be feeding three samples pectinase at different times, leaving the 4th as a control.  I am also rigorously cleaning all instruments.  I'll test all four at the same time and let you know if there is any reduction... I'm skeptical but I just wanted to ask if anyone had heard of this before.  Thanks!


Nick

[Nick Smyth]

So, just for the record, I completed my very cautious attempts to replicate the previous results today. They are as Andrew expected: pectinase has no measurable effect on acidity levels.  Samples of juice that had been clearing for 12, 24 and 36 hours respectively registered the same TA levels as a control sample with no pectinase. 

Onwards and upwards,


Nick

[Claude Jolicoeur]

I guess we conclude from this your first test at .94% malic would have been an error from the tester probably. These are things that happen...
Claude