Valorization of dairy by-products: Optimized synthesis of 5-hydroxymethylfurfural and levulinic acid from lactose and whey

Abstract

Whey is a by-product of the dairy industry that has a high proportion of organic material. To valorize whey, the optimization of the synthesis of 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) from lactose and whey by utilizing a Brönsted acid as a catalyst was performed. The Box-Behnken statistical model was used to analyze and optimize reciprocal interactions between the reaction variables. As a result, 45.6% yield of LA from 0.3 M lactose and 0.6 M HCl catalyst/M substrate was achieved at a reaction temperature of 195 °C for 60 min. In addition, 25.4% yield of 5-HMF was obtained from 0.2 M whey (as lactose) and 0.3 M HCl/M substrate by heating it to 195 °C for 45 min. More 5-HMF was obtained from whey than lactose under identical reaction conditions. While lactose was converted more rapidly than whey to LA. A nonlinear sigmoid model producing high coefficient of determination values adequately explained the effects of combined severity factor levels on 5-HMF and LA yields from lactose. On the other hand, the case of whey was not well-matched with low R2 values. These findings imply that the use of lactose and whey as feedstocks for platform chemical synthesis will continue.