Fermentation is an anaerobic process in which an organism releases energy from glucose even in the absence of oxygen. 

Limitations of fermentation include:

• Introduction of undesired microorganisms increases the risk of contamination, resulting in lower yields or impure products
• The need for specialized equipment and can increase the costs
• Energy-intensive operations and the need for stringent conditions increase energy consumption 
• The multifaceted nature of microorganisms can result in unexpected and undesirable end products  
• The end product is often impure and has to undergo further purification treatment 
• Microbial cultures are likely to exhibit natural variations over time, potentially compromising the quality and consistency of the end product
• Undesirable or contaminant microbes may also grow and multiply in some fermentation setups, outcompeting the desired microbes, resulting in altered product profiles or lower product yields