Cider Quiz Answers: Question #5

1. Add sulfite (Campden) to the juice before fermentation: Incorrect Answer – Sulfites are most effective at inhibiting lactic acid bacteria. Yet, the largest population of lactic acid bacteria in apple juice that has been produced with good sanitation should mostly be homofermentative strains that do not produce acetic acid, so inhibiting these won’t reduce undesirable aromas. In fact, adding sulfites could actually increase your risk of undesirable flavors because if it’s not adjusted for pH, an overdose of sulfites is likely to occur. This delays fermentation and creates the potential for oxidative reactions that can produce undesirable aromas and flavors. While adding sulfites can reduce the loss of phenolics, it won’t have a large impact on aroma. If you are trying to minimize undesirable aromas, adding sulfites isn’t the best option. 

2. Ensure fermentation starts quickly: Correct Answer – Yeast that are actively fermenting prevent bacteria and other reactions that can produce undesirable reactions. Yeast use the nutrients needed by bacteria and can also secrete compounds that suppress bacteria. Active fermentation also uses and pushes oxygen out of the fermenter. Oxygen is required for mold and acetic acid bacteria to grow. Ultimately, if you want to prevent undesirable aromas, your top priority should be to ensure the yeast you want to dominate starts fermenting quickly. The best way to achieve this fast start to fermentation and ensure the desired yeast dominates is to inoculate with it. 

3. Avoid large amounts of headspace: Incorrect Answer – Headspace can cause the creation of undesirable aromas but this risk is greatest after fermentation completes. A larger amount of headspace is only a risk for undesirable aromas during fermentation if the yeast growth and fermentation process are delayed. If fermentation starts quickly, the oxygen in the large headspace is quickly utilized by yeast or pushed out by the large amounts of CO2 produced during fermentation. Ciders produced from juice with a normal starting specific gravity near 1.050 will produce CO2 at over 30-times the volume of juice, keeping oxygen rich air from the surface and providing a protective layer of CO2. CO2 is denser and will sit on top of an actively fermenting juice. 

4. Ensure all sugars are fermented: Incorrect Answer – Residual sugar, sugar not fermented by yeast, is a potential risk for creating undesirable aromas. If yeast become stuck and unable to process more sugar, lactic acid and acetic acid bacteria can still process this residual sugar during aging. The risk is that acetic acid is produced. However, acetic acid bacteria would require oxygen so oxygen exposure is the greater risk at this stage. Lactic acid bacteria will process this sugar in an anaerobic environment, the production of acetic acid in cider is lower risk because homofermentative strains of lactic acid bacteria should be more prevalent. These don’t tend to produce acetic acid like heterofermentative strains do. Traditional French keeved ciders are an example of this condition as they are usually naturally sweet with some residual sugar and still age well.  

There are many potential ways to create undesirable aromas and flavors. Most involve oxygen exposure or sanitation issues, but the most effective way to avoid these conditions is to ensure fermentation starts quickly. A fast start to the fermentation inhibits bacteria and mold and it creates CO2, which is an effective protector against oxygen. Getting fermentation to start quickly is a best practice and something you should actively seek. The best way to achieve this is through inoculation of yeast. This doesn’t mean you can’t utilize wild or unique yeasts. Just consider creating a starter from the wild yeasts before inoculating with this harvested culture. Ensuring fermentation starts quickly will help you produce less undesirable aromas and off-flavors.  

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