Have you ever thought about what pH really means and why it might be important to cider making? Well you should. It is one of the key measurements that can help you make better hard cider. It’s also one if the easiest to measure since inexpensive and reasonably accurate pH meters are readily available or even pH strips. The pH of your juice and hard cider is related to acidity but it’s not the same as titratable or total acidity. The letters pH were coined by Danish chemist Soren Sorensen but it’s uncertain whether the ”p” stood for power or potential as the languages he published in indicated both possible meanings. The ”H” definitely stands for hydrogen. Whether is it power or potential, pH is defining the ability of hydrogen ions to react with other compounds. Acids, which are solutions with a pH below 7.0 have positively charged hydrogen ions while bases have negatively charged hydroxide ions. Bases are solutions measuring over 7.0 in pH. Bases are also sometimes referenced as alkaline. Pure water is the neutral solution that has neither positively or negatively charged ions and a pH of 7.0.
pH is measured on a logarithmic scale, which means that for every 1 point change, the impact is 10 times. If the pH of one cider is 4.0 and other is 3.0, the cider that is 3.0 is 10 times more acidic than the one at 4.0. The cider at 4.0 is 1,000 more acidic than pure water at 7.0. That means the cider at 4.0 is 10,000 times more acidic than pure water. That is because the 4.0 cider is 3 points away from water at 7.0 (10*10*10=1,000). The 3.0 cider is 4 points away from water (10*10*10*10=10,000). This highlights the impact of a ciders at pH 3.7 versus 3.2. That 0.5 point difference means your 3.2 cider will be 5 times as acidic. How do you think that will taste? How does that impact the ability for yeast and bacteria to work? How might that impact the formation of flavor and aroma compounds?
You can use your own internally built pH meter, your mouth, and assess acidity. Human saliva is generally around a pH of 7.0. However, you really need to train your taste and that means at least initially understanding what a cider, juice, or apple with a pH of 3.0 tastes like versus one with a pH of 4.0. Some initial work recording pH values for different apples will help you blend and assess how that apple might ferment and ultimately how that cider might taste. If you have a dry cider with a pH of 3.2, it might not be desirable. Yes, there are other factors at work like residual sweetness, aroma compounds, and fusel alcohols but, pH is fundamental to understanding your cider. That is because it impacts how many compounds are formed. Higher acidity weakens the cell walls of organisms. It can also impact the formation of various compounds. A great example is the impact of adding sulfites (Campden) to a juice. The lower the pH, the more effective the sulfites you add will be. This can easily lead to over treatment and non-fermentation if you add too much. It’s why understanding pH and acidity are important elements to making good cider.
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