Hello! That is a very common question, especially when adapting traditional recipes to a multicooker.
To answer directly: vinegar serves two essential purposes in borscht, both for color and for flavor.
First, regarding the color: red beets contain natural pigments called betalains (specifically betacyanin). These pigments are chemically sensitive to both prolonged heat and pH levels. When beets are simmered in neutral or alkaline water, especially in a sealed multicooker, the pigment breaks down, turning the broth a faded orange or muddy brown. Adding an acid like vinegar lowers the pH, stabilizing the pigment so your soup retains its vibrant, deep ruby-red color throughout cooking.
Second, regarding the taste: beets, carrots, and onions are naturally high in sugars, which can make the broth taste overly sweet or earthy on its own. The acidity of the vinegar cuts through that sweetness and balances the richness of the broth, giving borscht its signature sweet-and-sour profile.
As a practical tip, add a tablespoon or two of standard white vinegar, apple cider vinegar, or lemon juice directly to your grated beets while sautéing them before adding the rest of the liquid. This locks in the color right from the start.
I hope this helps your budget multicooker batch turn out great!
