Preventing and Treating Volatile Acidity (VA) in Cider
Last updated: 11/2023
Applies to: Cidermakers looking for strategies to prevent and treat volatile acidity in cider.
VOLATILE ACIDITY
Acetic acid, a major contributor to volatile acidity (VA), is a naturally occurring compound that can impart a sharp, acidic taste to cider. This is why elevated VA is often referred to as “vinegar taint.” Beyond sensory impacts, acetic acid can be inhibitory to yeast at concentrations greater than 0.6 g/L and cause sluggish fermentations at concentrations greater than 0.8 g/L. Additionally, there are legal limitations in the United States for VA concentrations in cider, please see ttb.gov.
Acetic acid is produced by various microorganisms including bacteria (acetic acid and lactic acid) and yeast at all production stages (fruit, fermentation, and aging). Therefore, diligent antimicrobial and sanitation practices throughout the cidermaking process are key to preventing volatile acidity.
PREVENTING VOLATILE ACIDITY
BEST PRACTICE | EXPLANATION | RECOMMENDATION (product, dosage, notes) |
|---|---|---|
Minimize time between processing and fermentation Consider adding an antimicrobial agent | Juice is a nutrient-rich source that may be contaminated with spoilage organisms. These organisms can consume sugar, organic acids, and YAN and produce volatile acidity | Use one of the following antimicrobial agents: • SO2: Potassium Metabisulfite • Non-Saccharomyces yeast: INITIA™ |
| Employ good cleaning and sanitation practices in the cellar | Appropriate procedures prevent the growth of microorganisms in tanks, hoses, equipment, barrels etc., to ensure spoilage is minimized | Use DESTAINEX LF to clean tanks and equipment |
| Run juice analysis, including VA (acetic acid) and malic acid | Analyzing juice gives a baseline. Proactive monitoring of VA levels throughout fermentation and storage helps to track trends and make data-based decisions | Send a sample to a service laboratory for analysis if you do not have in-house abilities |
| Initiate fermentation using an appropriate strain of yeast | By quickly starting fermentation the indigenous microflora will be quickly suppressed minimizing their ability to produce VA | Use one of the following to initiate alcoholic fermentation: • Non-Saccharomyces yeast: BIODIVA™ (25 g/hL) • Saccharomyces yeast: select strain based on cider style (25 g/hL) |
| Employ a complete fermentation nutrition plan • Measure YAN • Use a rehydration nutrient • Use fermentation nutrients | Avoid yeast stress and potentially sluggish fermentations by providing essential nutrients | Click here for assistance crafting a nutrition plan (choosing nutrients, dosages, and timing of additions) |
| Minimize oxygen pickup in the cellar | Elevated oxygen can accelerate growth of acetic acid bacteria and production of acetic acid | Keep headspace to a minimum (except during active fermentation) and blanket headspace with protective gases (CO2, argon, or nitrogen) to minimize oxygen contact with liquid |
| Control bacteria growth by maintaining adequate cider chemistry and by employing appropriate antimicrobial agents | Acetic and lactic acid bacteria can metabolize many compounds in cider to produce VA. | Use one of the following methods to prevent microbial activity:
Acetic acid bacteria growth can be suppressed at low temps and pHs, with moderate SO2 levels, or BACTILESS. Lactic acid bacteria growth can be suppressed at low temps and pHs, with moderate SO2 levels, BACTILESS, or LYSOZYME |
TREATING VOLATILE ACIDITY
BEST PRACTICE | EXPLANATION | RECOMMENDATION (product, dosage, notes) |
|---|---|---|
| Reverse osmosis | This is a membrane separation technique that allows undesirable molecules to be excluded based on molecular weight | For reverse osmosis providers see links here: https://wineindustrynetwork.com/suppliersearch.php? |
| Blending with lower VA lots | Blending dilutes VA | Please note: this dilution technique can lower VA but may have impacts on aroma, texture, and stability. Before blending out a high VA lot, conduct trials. Once blending is complete, run a full chemical panel and assess microbial stability (via in-house methods or testing at an outside laboratory) to avoid potentially further spreading acetic acid bacteria. |
| Perform bench trials to determine the most suitable treatment for your cider | These products may help to mask volatile acidity and refresh aromas | Perform bench trials with some of the following tannins
or yeast derivative nutrients (add anytime before the end of |