The mango wine started to smell of sulfur. There are 3 possible explanations:
1. Contamination. I did not disinfect the airlock tubing, and the batch was possibly contaminated this way.
2. The heat. It has been hot and the high heat may have thrown off the fermentation.
3. The yeast. The wine yeast I bought, Red Star Montrachet, reputedly releases a sulfur smell.
Thus far I have tried to keep the brew cool with those freezer packs you put on your head. The smell diminished. I have also racked the wine into a new vessel, recharged it with more sugar, and sealed the cap so that it will naturally carbonate. Now I really regret not going with champaigne yeast.
Additionally I recharged the old vessel with more sugar, frozen orange juice and orange juice pineapple concentrate, and more water. It is again fermenting. Because I was able to reuse the yeast, the costs are much lower than I previously thought. I can either calculate that this batch costs a dollar less or that both batches cost fifty cents less. Someone call my accountant.