Anaerobic fermentation, also called lacto-fermentation, is a traditional method of preserving food that also enhances its nutritional value. This process involves the conversion of sugars into lactic acid by beneficial bacteria, primarily from the Lactobacillus family, in an oxygen-free environment. The absence of oxygen is crucial, as it prevents the growth of harmful bacteria and allows the good bacteria to thrive, ensuring the fermentation is both safe and effective.