Optimisation of hard pretzel production

Summary Absence of a thorough understanding of the baking conditions on hard pretzel quality has resulted in considerable loss of production and on productivity. Baking time, oven zone 1 temperature, drying time and kiln drying temperature were identified as important factors affecting pretzel quality in modern pretzel production, from a total of eleven factors following a screening experiment design. A central composite circumscribe design was then employed to optimise these four variables. The test for lack of fit was not significant ( P  < 0.05) for the responses, except for colour a * values. The analysis of variance of the responses indicated that models explained 99%, 91% and 87% variability for moisture content, Δ E ab and pasting time, respectively. The four variables were optimised when pretzel moisture content, Δ E ab and pasting time were considered simultaneously using desirability function approach. Validation experiment results revealed that the two most important qualities of pretzel, moisture content and Δ E ab could be reliably predicted.