iSixSigma

Manufacturing

For a hobby last year I started making cider (hard cider in the US). Below are some of the demijohns of apple juice I fermented.

I cracked open a finished bottle and it looked & smelt great, but the taste…. it was insipid, slightly acidic and low in alcohol. Not good. Being in the business of continuous improvement and this being my second year I am ready to develop my manufacturing process.

I have researched the issues and my proposed solutions are.

  • Insipidness: I believe was due to using just eating apples, it should have been a blend of eating, cooking and crab apples. Here is a sample of my raw materials

  • Acidity: I have my pH tester and acid reduction solution.
  • Alcohol: I have my hydrometer and bag of sugar to up the alcohol content.
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So the question is what makes the perfect product? What better than to design an experiment. Being by no means an expert in the practical design of DoE, here is my endeavour. The factors & levels seem to be:

FactorLevels
pH readingTwo levels. Initial pH of blend or set to pH of 3.8 (which is highest recommended level)
Sugar contentTwo levels. Initial natural sugar content or adjusted to give final product of 7% alcohol
Apple BlendTricky, I want to try different combinations but not at the extremes of 100% of any one. I would like to get my blends by having variations of eating apples from 40 to 80%, cooking apples from 40 to 80% and crab apple from 0 to 20%. Not sure on this bit yet, could do with some help

The output will be taste tests scored from 0 to 10. I have a limited number of trails as I only have 8 demijohns. this should create the product to scale-up next year.Any tips on the best design to ensure I get good results?

Comments 8

  1. Ian Walker

    Hi Robin, i would suggest going to Tesco and buying some. It’s not exactly the most rewarding, but your cycle time and yield will surely increase?(!)
    Regards
    Ian

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  2. Robin Barnwell

    Ian, thanks for the Bright Idea, RB

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  3. Bob

    Maybe others will chime in, but here’s what I would recommend:

    Your taste test is somewhat subjective. Measuring taste with a rating scale of 0-10 only works when there are a lot of respondents. I would measure the continuous variables of sugar content and pH, then do the taste test, noting what sugar level and pH range produce a desired, pleasing taste. You then can do further work to determine which process and formulation variables affect the sugar and pH.

    Here is a little mixture design you can try that would fit your number of demijohns:

    Crab Apples Eating Apples Cooking Apples
    20% 40% 40%
    6.67% 46.67% 46.67%
    0% 60% 40%
    10% 50% 40%
    0% 50% 50%
    10% 40% 50%
    0% 40% 60%

    Keep all your other process variables constant – time, temperature, etc.

    Hope this helps.

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  4. Robin Barnwell

    Thanks Bob, what approach did you use to get the trial design?

    Will update once I have a result, around Xmas/New Year

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  5. Mike86

    With fermentations, you start with the yeast age, yeast type, yeast blend (high/low alcohol)and fermentation temperature control. All are critical for flavor and alcohol conversion.

    Exposure to sunlight will really affect off flavors. I can’t tell from the picture if this would be a sunlit room or not.

    Racking the cider to a secondary fermentor after primary fermentation is complete might help. If you’re using a champaign yeast along with your base yeast, a little sugar might send the alcohol level pretty high.

    You’ve really got too many factors to really nail down in a small DOE. This may be why Guiness still blends lots for the right flavor.

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  6. Robin Barnwell

    Thanks Mike

    For the yeast rather than sulphiting and adding yeast am using the natural yeasts found on the apples. May change next year if does not produce enough alcohol.

    The picture shows the juice just after pressing and before it starts to clear. I keep it in a dark place for fermentation.

    Racking is part of the big thing for this year. I invested in a book and have a proper process to follow this year and racking is key. Hopefully this will improve matters.

    Did my first batch over the weekend and feeling confident its going to be a good year. Am busy scrumping for apples.

    RB

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  7. Robin Barnwell

    Love the idea Steve, I was also thinking about using blackberries & raspberries to add some flavor.

    Might well give it a try!

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  8. Steve

    Raisins! This mix could use them to both up the alchohol and improve the flavor considerably. My dad used to make this stuff with plain old apple juice, sugar , yeast and RAISINS. He just placed balloons over the bottle necks until they no longer maintained inflation, decanted the liqud to an oak keg and left it there for 6 month to a year, I couldn’t wait to tap into the keg. It was GREAT! It wasn’t very good coming out of bottles, though. It needs a little taming down time in the oak keg.

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