Changes in pasta proteins induced by drying cycles and their relationship to cooking behaviour

Spaghetti produced in a pilot plant was dried using three different drying conditions: 60 °C for 7.5 h; 75 °C for 5.5 h; 90 °C for 5 h. Proteins of spaghetti were characterized by size-exclusion chromatography (SEC) and size-exclusion–high-performance liquid chromatography (SE-HPLC). As the temperature of the drying cycles increased, a progressive decrease of the small and large monomeric proteins and an increase in molecular size of the large polymeric proteins (LPPs) were observed. Drying temperature at 60 °C already induces a significant increase in the molecular size of the LPPs and a significant decrease of the other protein fractions. At 70 and 90 °C, large and small monomeric proteins as well as LPPs polymerized as seen by a progressive shift towards higher molecular weights in the SEC profile as temperature increased. The changes in the chromatographic profiles were accompanied by increasing amount of total unextractable polymeric protein (UPP). A decrease in stickiness and an increase in firmness corresponded to the formation of large and insoluble protein aggregates.