Neutral Lipids in Free, Bound, and Starch Lipid Extracts of Flours, Sourdough, and Portuguese Sourdough Bread Determined by NP-HPLC-ELSD

• Published in: Cereal chemistry 2011-07, Vol.88 (4), p.400-408
• Main Authors: Rocha, J.M, Kalo, P.J, Malcata, F.X
• Format: Article
• Language: English
• Subjects: baking; Biological and medical sciences; Cereal and baking product industries; cleaning; corn; diacylglycerols; fermentation; Food industries; free fatty acids; Fundamental and applied biological sciences. Psychology; hexane; high performance liquid chromatography; light scattering; phospholipids; rye flour; solid phase extraction; sourdough; sourdough bread; starch; Starch and starchy product industries; sterol esters; triacylglycerols
• ISSN: 0009-0352; 1943-3638
• DOI: 10.1094/CCHEM-11-10-0157

A detailed analysis was developed, focused on the neutral lipids (NL) in free (FL), bound (BL), and starch lipid (SL) extracts of maize and rye flours, sourdough, and broa (a traditional bread manufactured in Portugal). Selective sequential extraction of said lipids with hexane at 20°C, water-saturated n-butanol at 20°C, and n-propanol-water (3:1, v/v) at 100°C was performed to clean the lipid extracts from extraneous impurities, and isolation thereof from glyco- and phospholipids was by solid phase extraction of NL; these classes were then quantitatively assayed by HPLC, using evaporative light scattering detection, with calibration curves prepared with standard mixtures of NL. The BL and SL contents in the original flours increased and that of FL decreased throughout the fermentation and baking processes. The dominant NL class was not the same in all lipid extracts; the highest concentrations of triacylglycerols and the lowest concentrations of free fatty acids were detected in FL-with the former accounting for 82, 76, and 71% of the total FL in flours, sourdough, and bread, respectively. Triacylglycerols and free fatty acids also accounted for the highest concentrations found in BL: these, together with diacylglycerols, contributed up to 84% of the total neutral BL. High levels of free fatty acids and low levels of the remaining NL classes were typically found in SL: free fatty acids, triacylglycerols, sterol esters, and diacylglycerols accounted for approximately equal to 90% of the total SL.