Transformation of agro-biomass into vanillin through novel membrane integrated value-addition process: a state-of-art review

Bio-based feedstock utilization for the green manufacturing of valuable organic compounds is reckoned as a crucial goal to be achieved by the global scientific communities in this century to encourage sustainable business while saving the fixed stock of fossil fuels. Vanillin is a key aromatic flavoring compound extensively used in the food and cosmetic industries. Around 12,000 tons of vanillin are widely consumed in a year, and less than 1% of it is obtained from vanilla beans through the costly extraction process. Extensive scrutiny of the existing literature shows that vanillin can be produced bio-technologically from several sources. Currently, the production of vanillin from lignin is enticing because it caters to the supply of renewable aromatics in nature. However, the scaled-up applications of the biological routes are limited owing to the slow process, the requirement for precise process control, the risk of product inhibition and degradation, bacterial strain selection, and a complex downstream purification. These challenges highlight the need for vanillin synthesis through an alternate eco-friendly combined biological–chemical route. This review gives an insight into the development of a novel membrane-integrated photo-microreactor system for converting lignocellulosic biomass to vanillin and downstream purification, which appears to be the most promising bio-chemical, environmentally friendly, and cost-effective choice. The status quo of lignin extraction, purification, recovery, and techno-economic assessment for scale-up are also discussed thoroughly, enabling researchers to comprehend the possible lignocellulosic agro-biomass material conversion methodologies for the production of valuable aromatic compounds.