Stan and Odete, your sauce is probably fermenting because yeasts or bacteria survive on the ingredients or enter during preparation, then grow in the bottled sauce. Yeasts can consume the vegetables’ sugars and produce gas. Cleaning the bottles helps, but the sauce itself needs a reliable preservation process. [Penn State Extension](https://extension.psu.edu/lets-preserve-basics-of-home-canning)

Small jars may be eaten before spoilage becomes noticeable. Adding lemon juice and vinegar does not establish that the whole mixture contains enough acid for safe storage.

**Garlic and oil need particular care:** an inadequately acidified mixture can support bacteria that cause botulism. You cannot judge that risk by smell or taste. For your current recipe, take these precautions:

- **Discard batches that have unexpectedly fermented.** Do not taste them or try to rescue them by boiling.
- **Refrigerate fresh sauce immediately at 4°C or colder.** Until the recipe has been assessed for safety, use the conservative garlic-in-oil limit of **four days**, or freeze portions promptly. [National Center for Home Food Preservation](https://nchfp.uga.edu/how/freeze/vegetable/freezing-garlic-in-oil/)
- **For bottles stored at room temperature, use a tested preservation recipe** and follow its ingredient quantities, container sizes and heat processing instructions exactly. The [NCHFP’s tested hot sauce recipe](https://nchfp.uga.edu/how/can/how-do-i-can-tomatoes/easy-hot-sauce/) is one option. Keeping your own formulation requires a food preservation specialist to assess its acidity and processing requirements.
- **Wash chillies under running water; stop using bleach on them.** Household produce washing guidance specifically advises against bleach. [FoodSafety.gov](https://www.foodsafety.gov/blog/safe-ways-handle-and-clean-produce)

For keeping your wife’s recipe as it stands, freezing small portions is the most practical option.