Yes, a kombucha that smells like rotten eggs or sulfur is likely spoiled due to unwanted bacteria or yeast producing hydrogen sulfide. Discard it to avoid potential health risks.
Kombucha's characteristic tangy and slightly vinegary aroma comes from the fermentation process involving a symbiotic culture of bacteria and yeast (SCOBY). However, if your kombucha develops a foul odor resembling rotten eggs, sulfur, or something generally 'off,' it indicates a problem. This smell is often caused by the presence of undesirable bacteria or yeast strains that produce hydrogen sulfide (H2S) as a byproduct of their metabolism. These unwanted microorganisms can outcompete the beneficial ones, leading to spoilage and potentially harmful compounds. Several factors can contribute to this, including contamination during the brewing process, improper sanitation of equipment, or an imbalance in the SCOBY's microbial composition. If you detect this smell, it's best to err on the side of caution and discard the batch. Consuming spoiled kombucha could lead to gastrointestinal distress or other health issues.
To prevent spoilage, always sanitize your brewing equipment thoroughly with a food-grade sanitizer before each batch. Also, maintain a healthy SCOBY by providing it with the correct ratio of tea and sugar, and ensure proper ventilation during fermentation to discourage the growth of anaerobic bacteria.