Enzyme-assisted liquefaction of ginger rhizomes (Zingiber officinale Rosc.) for the production of spray-dried and paste-like ginger condiments

A novel process for the production of spray-dried ginger powder and paste-like ginger condiments was developed on pilot plant scale. The process includes the operations of fine grinding, enzymatic hydrolysis, finishing, pasteurization and spray-drying, respectively. Before scaling-up the enzymatic hydrolysis was optimized on laboratory scale using D-optimal design and analyzed by response surface methodology considering the individual and interactive effects of temperature (40–55 °C), pH (4.0–6.0), and enzyme concentration (500–5000 ppm) on the reduction of viscosity of the ginger homogenate. In-process determination of gingerols and shogaols demonstrated that pungency is hardly influenced by cell wall degrading enzymes, but significantly affected by temperature and pH. An enzyme mixture composed of cellulolytic and pectinolytic activities at a 2:1 ratio yielded maximal tissue digestion and highest retention of pungent principles within 2 h, applying a dosage of 5000 ppm at 40 °C and pH 4.0. During processing the amounts of 4-, 6-, 8- and 10-gingerol slightly diminished, while 6- and 8-shogaol faintly increased. The ginger digest obtained after finishing turned out to be a valuable raw material to be processed into various ginger products. Pasteurization and spray-drying resulted in homogenous paste-like ginger preparations and spray-dried ginger powder, respectively. Additionally, the solid residue contained large amounts of pungent principles, which enables its application as a flavoring agent. Consequently, the process described in this study allows an exhaustive utilization of ginger rhizomes for the production of various ginger applications.