In 1937 Salvo Chemical Corporation started the industrial production of vanillin from lignin oxidation using spent liquors from pulp and paper industry by the Howard’s [96] patented technology [91, 97]. In Canada, Howard Smith Chemicals, Ltd. also began the industrial conversion of concentrated spent sulfite liquor to vanillin with technology based on the process developed by Hibbert and Tomlinson [98]. In the same country, one other industrial unit started up at about 1945 by Ontario Paper Co., Ltd. that, besides vanillin, recovered also fermentable sugars from liquor [91]. In the beginning of 1950s, Monsanto Chemical Company substituted the process of synthetic vanillin from eugenol by the lignosulfonates oxidation process using fermented spent sulfite liquor [97].

Until 1980s, the major vanillin supply market share was provided by the oxidation of lignin from the sulfite pulping [99]. After that, industrial units of lignin-derived vanillin faced constrains that forced them to close [91]. Addition­ally, since the 1980s, changes introduced in the pulp and paper industry processes led to a decrease of lignin availability: at that time, kraft process emerges as the competing pulping process that includes the recovery boiler for burning the spent liquor allowing the recovery of pulping chemicals and producing energy. Since then, guaiacol-based vanillin has gained relevance [97]. Nowadays the synthesis of vanillin from petrochemical guaiacol accounts for 85% of the world supply, with the remaining 15% being produced from lignin [99].

The high market prices of vanilla beans and their limited supply and the increasing concern for alternatives to the non-renewable raw materials, have encouraged the research for alternative pathways for natural flavor production. A detailed review on biotechnological routes of vanillin production using different substrates and biosynthesis methods can be found elsewhere [100, 101]. Com­mercially, vanillin obtained by fermentation from ferulic acid is considered the only profitable biocatalytic route [101, 102].

As future prospect, the concern for alternatives to the non-renewable raw materials and the emerging lignocellulosic-based biorefineries could lead to a promising future for lignin-derived vanillin; the condition is the profitability of the production process using as raw material spent liquor lignins or lignins from new biomass conversion technologies. Due to constant efforts of several R&D centers around world, many challenges for the profitable large scale application of lignin as source of aromatics, and vanillin in particular, are being progressively overcome.