What is the correct way to do Acid Starch Hydrolysis?

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Discussion Overview

The discussion centers on the methods and challenges of acid starch hydrolysis, particularly using corn as a substrate. Participants explore various acids, temperatures, and durations for the hydrolysis process, as well as the testing for sugar production and fermentation potential. The conversation includes both practical experimentation and theoretical considerations related to the chemistry involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant describes their attempts using different acids (vinegar and hydrochloric acid) and questions the appropriate amounts and conditions for effective starch conversion.
  • Another participant inquires about methods to test for sugar presence and clarifies what type of sugar is being referred to.
  • One participant reports using a hydrometer to measure sugar concentration and identifies the sugar as maltose, questioning the taste and presence of iodine.
  • There are suggestions regarding the amount of vinegar needed for the hydrolysis process and the cooking time required for the corn mixture.
  • Some participants propose that boiling off water and vinegar can concentrate sugar for fermentation, while others express concerns about the boiling off of alcohol first.
  • One participant questions the use of acid for malting and suggests allowing yeast to hydrolyze starch instead, referencing traditional bourbon-making methods.
  • Another participant shares historical methods of starch hydrolysis using vinegar and expresses a desire for precise measurements and conditions rather than trial and error.
  • There is a mention that baking soda and sodium bicarbonate are similar, and a participant argues that acetic acid may be too weak for efficient starch hydrolysis.
  • One participant provides information on industrial methods, suggesting the use of enzymes as an alternative to acid hydrolysis.

Areas of Agreement / Disagreement

Participants express a range of views on the effectiveness of different acids, methods of testing for sugar, and the best practices for starch hydrolysis. There is no consensus on the optimal approach or conditions for achieving successful hydrolysis.

Contextual Notes

Participants mention various assumptions about the effectiveness of acids, the role of enzymes, and the conditions necessary for starch conversion, but these assumptions remain unresolved. The discussion reflects a mix of practical experimentation and theoretical knowledge without definitive conclusions.

gary350
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Homework Statement
Need help
Relevant Equations
don't know
I have tried corn mill, now I am trying corn from a grocery store can.

I tried 5% vinegar, now I am trying 40% hydrochloric acid.

Heat to 150° F for 2 hours. Starch should turn to sugar but it is not working?

I don't know how much acid to use to make this work?

1 lb corn + 2 lbs water + acid + 150° F for 2 hrs

What am I doing wrong?
 
Last edited:
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How do you test for the presence of sugar? (And what do you mean by sugar? glucose?)
 
Borek said:
How do you test for the presence of sugar? (And what do you mean by sugar? glucose?)

I have been tasting it. I have not done Iodine test yet because it taste like water. If there is sugar should I not be able to taste it? I wonder if too much acid will destroy starch? What is the correct about of vinegar for 1 lb of corn + 2 lbs of water. The thick sticky mixture has been turning to water mix like it should but no sugar taste? Grocery store corn in a can is cooked is that a problem?
 
Today I tested sugar with a wine makers hydrometer i get a reading of 1.040 that is enough sugar to make 5.1% alcohol in fermented wine. After doing more research I learned the sugar I am getting is MALTOSE that is why I can't taste it. No iodine to be found the pharmacy does not sell it anymore. I did more test with grocery store corn in a can needs 1/4 cup of vinegar is all the acid that is required for 1 lb of corn to convert starch to sugar. Bring to a boil for 30 minutes it is finished, sticky glue corn mixture turns to water & corn. Pour through a strainer, save liquid, throw away the corn. The starch white milk color is no longer there. I added yeast soon I will learn if Maltose sugar will ferment. Sugar could be concentrated to a high hydrometer reading 1.086 by boiling off some of the water to get 12% alcohol.
 
gary350 said:
Sugar could be concentrated to a high hydrometer reading 1.086 by boiling off some of the water to get 12% alcohol.
Won't the alcohol boil off first?
 
epenguin said:
Won't the alcohol boil off first?

Boil the water & vinegar off before fermenting it. Boiling is a wine makers trick since the law does not allow the addition of sugar to commercial wine you squeeze out juice then boil off water until sugar becomes concentrated enough to give you the high alcohol you want in your wine. Boil water away until syrup is thicker than honey then add water again to get a hydrometer reading of 1.086 for 12% alcohol or 1.090 for 12.6% wine. Law does not apply to home wine makers they can use sugar if they want.
 
Why don’t you let the yeast hydrolyze the starch from the corn grit? That’s how bourbon is made. Why are you trying to malt with acid? I don’t think you are getting maltose from corn. Barley - maltose and glucose. Corn - Glucose
 
Last edited:
chemisttree said:
Why don’t you let the yeast hydrolyze the starch from the corn grit? That’s how bourbon is made. Why are you trying to malt with acid? I don’t think you are getting maltose from corn. Barley - maltose and glucose. Corn - Glucose

Whiskey is made with 70% corn, 20% barley, 10% rye. The process soaked in 100°F water until barley germinates. There is enough enzyme in malted barley to convert some of the corn starch to sugar. One of the experiments in high school chemistry 50 years ago was to heat corn with acid at a certain temperature for certain length of time so acid will convert all the starch to sugar. That was 50 years ago my brain does not work well anymore. I have forgotten more than I ever knew. I don't remember how this is done? I tried vinegar. My industrial chemistry book says to use Hydrochloric acid. I tried Hydrochloric acid too. I don't know how much acid to use, I don't know what temperature to cook it, I don't know low long to cook it? 50 years ago I had a man show me now he did it using vinegar. He mixed 1 pint of corn meal with 1 gallon of water when it began to boil he started adding vinegar and stir well. He stirred the mix and kept adding vinegar for 30 minutes. Cooked corn meal is like glue very thick then it changes to water & white color. Keep stirring and adding vinegar, keep adding vinegar until all the white color is gone. That is the trial & error method. LOL I was hoping to learn the exact amounts of each, corn, water, acid, temperature, time, without doing trial are error method? I also think the mixture needs something extra like yeast nutrient to feed the champagne yeast to get 20% alcohol. Chemistry book says, add enough sodium bicarbonate to neutralize acid. Sodium bicarbonate is not easy to find at a reasonable price I wonder if baking soda will work but it has a horrible flavor.
 
Last edited:
Baking soda and sodium bicarbonate are mostly the same thing.

Acetic acid is IMHO too weak for an efficient starch hydrolysis.
 
  • #10
The industrial acid hydrolysis is done with 1molar HCL at ~180F for hours, like 24 hours! Hate to do that kind of thing at home when I can just add some malted barley or a few oz of amylase enzyme at 120-150F for an hour or so. These things are widely available at brewing supply stores. There are several in my city or I can order them online.

Bulk bicarbonate is cheap in the laundry isle.
 

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