Here goes some gum arabic info . . . I was first introduced to it at Bonny Doon when Randall Grahm brought it back from one of his jaunts to France, around 1999 or so. We did extensive bench trials with it in many of the Bonny Doon wines, and in some cases chose to add it to reds and whites alike.
Gum arabic was first introduced in France’s wine industry (at least 75 years ago, I believe) as a bid to help improve tartrate stability. Not “another chemical” to add to wine, it’s an entirely natural product that comes from trees! Gum arabic, also known as gum acacia or Arabinol®, is a naturally-occurring large carbohydrate molecule polymer extracted from the sap of two specific species of African Acacia trees: A. senegal and A. seyal. In the case of gum arabic, the polymer is highly branched, consisting of arabinose, rhamnose, and galactose. The long polysaccharides contained in gum arabic products act as colloid protectors, which will prevent and slow down the reactivity of different molecules. It’s been used for centuries in the production of candies, jams, and other foods and beverages. In fact, you can find it in some medieval food and cosmetic recipes!
If you were to go to a winemaking store, you would probably find a product labeled Arabinol®, which is a purified liquid form of gum arabic. When added to wines, it slows down the condensation of the molecules that eventually form tartrate crystals, i.e “wine diamonds,” or those little shards that might look like broken glass in the bottom of your wine bottles. By the way, these crystals are completely harmless, and, even if you imbibe them, they won’t hurt you. Gum arabic and Arabinol® products can also lessen the perception of astringent and bitter tannins. They can be used on whites and reds when there is a need to improve viscosity and mouthfeel. Because Arabinol® contains large polysaccharide molecules, it is quite thick and is perceived as “sweet” on the palate even though it’s technically not a sugar fermentable by wine yeast. This property means that it’s really important to mix your tank or barrels very well after any addition.
With any gum arabic or Arabinol® product, it is very important to run bench trials against other products in order to calibrate dosage and flavor because Arabinol® is not always a positive thing for every wine. In fact, I find that in a lot of wines it simply doesn’t help the wine and can actually detract from certain supporting qualities of the wine.
When added to sparkling wines, Arabinol® improves the finesse of the perlage, or bubbles. In young red wines and rosé wines, it can improve color stability. Specifically on your Cabernet Sauvignon . . . you’d have to do bench trials to see. In some cases gum arabic products might improve mouthfeel, in some cases not. I find it is not a uniform quality-adder, and like residual sugar adjustments, is not linear, i.e. adding more doesn’t always get you “more” positive effect. You have to find the sweet spot with each wine individually. When it works, it can impart a sense of mouthfeel and sweetness and longer finish without adding fermentable sugar. It doesn’t affect the aging of a wine in a positive or negative way.
Results don’t necessarily change from varietal to varietal, i.e. there aren’t some wines where I would say “it never works” or others that it should always be used. It’s just that each type, style, and varietal is different — Arabinol® can add positive things to wines but all-in-all I don’t tend to use it in my winemaking very much. I think it’s a valuable, easy, affordable addition to keep in your winemaker’s toolbox for bench trials, but in reality it’s not one I break out very often.