I wouldn’t worry too much about anyone getting sick from your wines as long as the water you use is clean and the alcohol is above 10%. As a professor of enology at UC-Davis used to always say in class, “No human pathogen can survive in wine.” Essentially this means that since wine (and she was talking about a typical grape wine here, by the way) has such a high level of alcohol and acid (typically 11%+ and 5.0 g/L+ respectively), no microbe disease agent that can harm people would be able to survive in that kind of hostile environment. So I wouldn’t worry about giving your friends food poisoning as long as your beverages have those kinds of statistics too.
You might be concerned, however, with the palatability and the practicality of turning some of your more exotic fruits
into wines. Fruit wines (or “country wines” as they’re sometimes called) can be a challenge to make because of the raw material itself and often need to be blended with other juices (or diluted with water and/or grape juice) to ferment to the alcohol level and acidity we’re typically looking for. Citrus fruits, for example, just have far too much acid and far too little sugar to ferment nicely to a wine on their own. No wine yeast would enjoy that environment nor would you enjoy the final result.
Then there are the biological/physiological challenges many fruits present. Quinces have a lot of pectin which makes them tend to be hazy (see the last question and answer about pectin hazes). Fruits like peaches or other soft stone fruits ferment down into a big sludgy gloppy mess, which, if you’re not careful to stir often enough, can produce hydrogen sulfide due to lack of oxygen to the yeast. In the case of something like a coconut, I’d be wary of the high fat content and would not even attempt that one.
Fruits other than grapes also can lack the necessary amino acids and micronutrients that wine yeast need to conduct a healthy fermentation and must therefore be carefully supplemented with a yeast nutrient mix. There are many, many reasons why winemakers think “grapes” when we think “wine.” These little grapey nuggets of sugar, acid, water, tannin and aromatic compounds simply are nature’s most practical and balanced raw material for winemaking.
So what’s a fruit-loopy winemaker to do? I suggest strategically blending your exotic esoterica with some variety of grape juice concentrate, using a pectolytic enzyme in the juice or must stage, and carefully adjusting sugar and acidity as needed before fermentation to achieve the winemaking style (alcohol level and acid level) you are looking for. That way you’ll get the flavor and fun of your jack fruit, pineapples or bananas (or whatever fruit you’ve got!) plus the biological “backup” of grapes.
When you choose a concentrate, however, try to pick a concentrate that makes sense for the fruit wine you want to blend it with. For example, some folks making blueberry or blackberry wine tend to buy Zinfandel or Cabernet Sauvignon concentrate. And on the other hand, you will probably want to use a neutral white Vitis vinifera concentrate such as Chardonnay, Sauvignon Blanc or even Thompson Seedless to give yourself a nice backdrop against which to show off your tropical treasures.
