Malt in storage: Changes in amylase, protease, and cellulase activities and their effects on the Maillard reaction

How dynamically changing amylase, protease, and cellulase affect the progression of the Maillard reaction (MR) during malt storage necessitates further investigation. The malt was stored for 6 months to explore this question. During storage, cellulase activity, total Maillard intermediate (MI), and total Maillard product (MP) contents significantly increased (p < 0.05) by 731%, 7.58%, and 145% compared with the first month, respectively. Amylase and protease activities and total Maillard substrate (MS) content significantly increased (p < 0.05) by 4.50%, 151%, and 48.1%, respectively, but subsequently decreased. Additionally, cellulase and protease activities significantly correlated (p < 0.05) with MS. MS correlated significantly with MI fructose–isoleucine, fructose–phenylalanine, fructose–asparagine and fructose–alanine. Except for the significant correlation between fructose-alanine and furfuryl alcohol, the other MI correlated significantly with five representative MP with a roasted and sweet aroma. In conclusion, enhanced cellulase and protease activities facilitated MS, MI, and final flavor substance production.