Winemaker Weekly: Wine Acids

Since we are making fruit wine, as opposed to grape wine, the consideration of acids will be different for each fruit. Generally speaking, grape juice or must (must is the juice and fruit parts before it is fermented completely) contain both tartaric and malic acids, with lesser amounts of citric and other minor acids. Usually, this is fairly predictable, depending on the grape variety, and winemakers make adjustments to get a certain pH, and a certain level of acid in their finished wines. This is done by strategic actual additions of either extra acid (usually tartaric, or maybe malic and/or citric) or, if the acidity is too high, the extra acid is neutralized by additions of an alkaline product (such as calcium carbonate).

So, you may ask, what do acids do?

Acids affect the taste profile of your wine. Think of a lemon, or even an orange. Both are high in citric acid, with the lemon being very high, and it gives your mouth a brisk, clean feeling. The orange is also high in natural sugar, and has slightly less acid anyway, but the sugar makes the acid taste less acidic, and your mouth reacts in the expected way. If you’ve ever had sweet and sour sauce, which is a combination of acid (vinegar is high in acetic acid) and sugar, it’s a pleasant taste if combined properly in the right proportions.

Each acid promotes a different mouthfeel and taste to the wine. Malic acid is rather harsh (green apples are very high in malic acid), so many winemakers choose to convert malic acid to lactic acid (the acid of milk), giving the wine a smoother, almost buttery feel and taste. Tartaric acid, in the correct proportion, is very beneficial in accentuating the other flavours, aromas and tastes of the wine.

This week I am studying the composition of the fruits I will be using to make wine.

First is Haskap.

 
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Studies have been done to determine exactly what acids Haskap contains. Depending on the cultivar, the main acids of Haskap are Citric, Malic and some Quinic acid. Because most fruits (other than grapes) are so high in natural acids, higher than what would taste good in wine, Winemakers dilute the juice with water, usually in a ratio of 1 part juice to 2 or 3 parts water. In other words, if I have 250 mL of Haskap juice, chances are (depending on my acid measurements that I will be doing), I will be diluting with 500 to 750 mL of water. Then I would add natural table sugar to achieve enough sugar to ferment to around 11 - 14 % alcohol. Natural Haskap has a sugar that would ferment to about 8 or 9 % alcohol but, remember, we have to dilute that, so without the extra addition of sugar, our wine would not have the desired alcohol.

Next session I will discuss the plan for Rhubarb. Rhubarb is technically a vegetable, did you know that?