Yes, you need to burp sealed jars during fermentation to release built-up carbon dioxide. Burp the jars once or twice daily, depending on the fermentation activity.
During fermentation, microorganisms like bacteria and yeast consume sugars and produce carbon dioxide as a byproduct. In a sealed jar, this gas builds up pressure. If the pressure becomes too high, it can cause the jar to explode, which is both messy and dangerous. Burping the jars involves briefly opening them to release the accumulated gas. The frequency of burping depends on how active the fermentation is. Initially, when the fermentation is most vigorous, you might need to burp the jars twice a day. As the fermentation slows down, once a day might be sufficient. You'll notice the pressure decreasing as the fermentation progresses. To burp a jar, simply unscrew the lid slightly until you hear a hissing sound, indicating the release of gas. Then, quickly tighten the lid again. Avoid fully opening the jar for extended periods, as this can introduce unwanted microorganisms and compromise the fermentation process.
Use airlock lids instead of standard canning lids. Airlocks allow carbon dioxide to escape automatically while preventing air and contaminants from entering, eliminating the need for manual burping and reducing the risk of mold growth.