Effects of enzyme associations on bread dough performance. A response surface analysis

Effects of starch (bacterial cx-amylase and NMYL) and non-starch (xylanase PTP, lipase NVZ and glucose-oxidase GLZ) degrading enzymes on dough quality parameters (rheological, fermentative, textural and thermal characteristic s) were determined by means of the response surface methodology to a centra l composite design of white wheat dough samples. PTP showed linear, interac tive and/or quadratic significant effects on most functional properties. Hi gher dosages of PTP yielded softer and less adhesive doughs with higher gas retention capability but with weakened gluten and poorer machinability (st ickier). Negative linear and positive quadratic effects of PTP were observe d on dough hardness and derived mechanical properties gumminess and chewine ss. Optimized dosage of 30 mg/100 g flour led to improved handling and ferm entative dough characteristics and avoided excessive dough hardness and sti ckiness. The simultaneous presence of PTP and NVZ decreased fermentation ti me and increased dough extensibility. The combination of both PTP and NMYL and/or incorporation of NVZ decreased dough resilience, which corresponded to a greater extensibility and a lower dough consistency. Although GLZ addi tion induced some desirable effects on the final dough volume and the amylo se-lipid complexation, the incorporation of the pair PTP/GLZ into dough for mulas is not recommended because of the reduction of the induced softening effect of PTP. A significant negative and quadratic effect of NMYL addition was observed for the enthalpy of dissociation of the amylose-lipid complex . Incorporation of this enzyme up to 30 mg/100 g flour did not significantl y decrease values for this thermal property. No criteria for optimum dosage of NVZ were established, and it is recommended that doses higher than thos e recommended by the manufacturer (5 mg/100 g of flour) be used.