To make it, chopped apples are covered with water and left to ferment to form ethanol. Natural bacteria convert the ethanol into acetic acid, which is the main component of vinegar.
It's not often that an entire bottle of apple cider vinegar is used in one sitting, which may leave you wondering whether it ever expires.
This article reviews whether apple cider vinegar goes bad, plus storage tips to improve its quality and shelf life.
Shelf Life and Proper Storage Tips
The acidic nature of vinegar makes it a self-preserving pantry staple, which means it generally never sours or expires.
The pH scale, which ranges from 0–14 indicates how acidic a substance is. A pH lower than 7 is acidic, and a pH greater than 7 is basic. Acetic acid, the main constituent of apple cider vinegar, has a highly acidic pH between 2 and 3.
Vinegar has natural antimicrobial properties, which likely contribute to its long shelf life. In fact, vinegar can prevent the growth of illness-causing germs like E. coli, Staphylococcus aureus, and Candida albicans.
In one study, vinegar had the most antibacterial characteristics when compared with coffee, soda, tea, juice, and olive oil.
The best way to store apple cider vinegar is in an airtight container in a cool, dark place away from sunlight, such as in a kitchen pantry or basement. Refrigerating apple cider vinegar is unnecessary and does not improve its shelf life.
Apple cider vinegar is highly acidic and has antimicrobial properties that make it a self-preserving pantry staple. While it technically never expires, storing it in a cool, dark place helps preserve its quality.
How Apple Cider Vinegar Changes Over Time
As vinegar ages, it may undergo aesthetic changes, such as becoming hazy or separating. You may also notice cloudy sediments or fibers at the bottom of the bottle.
This is largely due to exposure to oxygen, which happens every time you open the lid.
Over time, oxygenation also causes the release of citric acid and sulfur dioxide, two preservatives in vinegar.
This could affect how it tastes or contributes to a recipe, but these changes don't significantly affect the nutritional value or shelf life of apple cider vinegar.
Before using apple cider vinegar that you've had for a while, you can smell and even taste it to make sure it'll still work well in your recipe.
Keep in mind that even though apple cider vinegar products may have an expiration date on them, many manufacturers note that its safe to use well beyond this date.
Apple cider vinegar may undergo subtle aesthetic changes over time when exposed to oxygen, but this doesn't significantly change its nutritional quality or shelf life.
The Bottom Line
Apple cider vinegar is acidic and has antimicrobial properties that make it self-preserving. This means that it's safe to consume and use in recipes even if it's old.
However, apple cider vinegar can undergo aesthetic changes over time that may slightly change its taste, texture, or appearance. This is primarily due to chemical changes that happen when it's exposed to oxygen.
Still, these types of changes do not affect the shelf life of apple cider vinegar, and it's not dangerous to consume it when it gets old.
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By Katherine Kornei
Clear-cutting a forest is relatively easy—just pick a tree and start chopping. But there are benefits to more sophisticated forest management. One technique—which involves repeatedly harvesting smaller trees every 30 or so years but leaving an upper story of larger trees for longer periods (60, 90, or 120 years)—ensures a steady supply of both firewood and construction timber.
A Pattern in the Rings<p>The <a href="https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/coppice-standards-0" target="_blank">coppice-with-standards</a> management practice produces a two-story forest, said <a href="https://www.researchgate.net/profile/Bernhard_Muigg" target="_blank">Bernhard Muigg</a>, a dendrochronologist at the University of Freiburg in Germany. "You have an upper story of single trees that are allowed to grow for several understory generations."</p><p>That arrangement imprints a characteristic tree ring pattern in a forest's upper story trees (the "standards"): thick rings indicative of heavy growth, which show up at regular intervals as the surrounding smaller trees are cut down. "The trees are growing faster," said Muigg. "You can really see it with your naked eye."</p><p>Muigg and his collaborators characterized that <a href="https://ltrr.arizona.edu/about/treerings" target="_blank">dendrochronological pattern</a> in 161 oak trees growing in central Germany, one of the few remaining sites in Europe with actively managed coppice-with-standards forests. They found up to nine cycles of heavy growth in the trees, the oldest of which was planted in 1761. The researchers then turned to a historical data set — more than 2,000 oak <a href="https://eos.org/articles/podcast-discovering-europes-history-through-its-timbers" target="_blank" rel="noopener noreferrer">timbers from buildings and archaeological sites</a> in Germany and France dating from between 300 and 2015 — to look for a similar pattern.</p>
A Gap of 500 Years<p>The team found wood with the characteristic coppice-with-standards tree ring pattern dating to as early as the 6th century. That was a surprise, Muigg and his colleagues concluded, because the first mention of this forest management practice in historical documents occurred only roughly 500 years later, in the 13th century.</p><p>It's probable that forest management practices were not well documented prior to the High Middle Ages (1000–1250), the researchers suggested. "Forests are mainly mentioned in the context of royal hunting interests or donations," said Muigg. Dendrochronological studies are particularly important because they can reveal information not captured by a sparse historical record, he added.</p><p>These results were <a href="https://www.nature.com/articles/s41598-020-78933-8" target="_blank">published in December in <em>Scientific Reports</em></a>.</p><p>"It's nice to see the longevity and the history of coppice-with-standards," said <a href="https://www.teagasc.ie/contact/staff-directory/s/ian-short/" target="_blank">Ian Short</a>, a forestry researcher at Teagasc, the Agriculture and Food Development Authority in Ireland, not involved in the research. This technique is valuable because it promotes conservation and habitat biodiversity, Short said. "In the next 10 or 20 years, I think we'll see more coppice-with-standards coming back into production."</p><p>In the future, Muigg and his collaborators hope to analyze a larger sample of historic timbers to trace how the coppice-with-standards practice spread throughout Europe. It will be interesting to understand where this technique originated and how it propagated, said Muigg, and there are plenty of old pieces of wood waiting to be analyzed. "There [are] tons of dendrochronological data."</p><p><em><a href="mailto:email@example.com" target="_blank" rel="noopener noreferrer">Katherine Kornei</a> is a freelance science journalist covering Earth and space science. Her bylines frequently appear in Eos, Science, and The New York Times. Katherine holds a Ph.D. in astronomy from the University of California, Los Angeles.</em></p><p><em>This story originally appeared in <a href="https://eos.org/articles/tree-rings-reveal-how-ancient-forests-were-managed" target="_blank">Eos</a></em> <em>and is republished here as part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.</em></p>
Earth's ice is melting 57 percent faster than in the 1990s and the world has lost more than 28 trillion tons of ice since 1994, research published Monday in The Cryosphere shows.
By Jewel Fraser
Noreen Nunez lives in a middle-class neighborhood that rises up a hillside in Trinidad's Tunapuna-Piarco region.