Effect of flaxseed processing on engineering properties and fatty acids profiles of pasta

Abstract Flaxseed contains numerous bioactive compounds which induce various biological effects. Among bioactive compounds, flaxseed contains 38–45% oil, of which up to 59% is α-linolenic acid. Focus has recently been put on the technical difficulties of processing flaxseed pasta and studies have shown that flaxseed could tolerate some processing conditions. A close link between pasta processing conditions and the in vitro digestion of the food matrix has also been identified. The aim of this study were (1) to understand the impact of flaxseed processing and content on engineering properties of pasta after the extrusion, the drying and the cooking process; (2) to characterize the fatty acids profile of flaxseed-enriched pasta during the processing and after the in vitro digestion. Two processes were considered prior to the incorporation of flaxseed into pasta at levels of 15% and 30% (dry basis): (Process A) conditioning and milling of flaxseed; (Process B) conditioning of flaxseed, oil pressing, milling of flaxseed cake and reformulation. Results showed that pressing oil from flaxseed and then milling the flaxseed cake (Process B) allowed obtaining an average particle size smaller than milling the whole flaxseed (Process A) which doubled the flaxseed-to-semolina particles ratio. Flaxseed processing, prior to the incorporation into pasta, and content had impacts on engineering properties after the extrusion, the drying and the cooking process and, affected the protection and the release of free fatty acids during in vitro digestion. While free fatty acids profiles remained relatively stable through all steps of pasta processing, they were affected by the in vitro digestion. Decrease in the proportion of omega-3 fatty acid (C18:3) was more important for the Process A compared to the Process B.