Effects of formulation and processing conditions on easily extractable lipid and nitrogen components of wheat sourdoughs

Abstract

The changes in free lipid (neutral lipids, glycolipids, and phospholipids) and extractable nitrogen (amino acids, peptides, and proteins) components of unyeasted and yeasted wheat sourdoughs started with Lactobacillus plantarum B-39 were investigated in samples under different processing conditions. A central composite surface response design was used with factor analysis to investigate the effect of flour extraction rate (ash content), added water, presence or absence of yeast, and fermentation temperature on readily extractable lipid and nitrogen components. Absolute values for extractable protein and non-protein components were highly correlated with ash content of flour (factor 1); whereas phospholipids and neutral lipids were closely connected with added water (factor 2). Sixty sourdoughs were classified into three groups: 1) high-ash fermented sourdoughs produced high (>350 mg kg-') total nonprotein amino nitrogen and medium (<3 mg g-') lipid levels; mid-ash flour doughs had lower levels of both components; 2) low-ash fermented sourdoughs produced low (<300 mg kg-') levels of amino acids and peptides and medium lipids levels, and 3) unfermented sourdoughs had low (<250 mg kg-I) levels of non-protein nitrogen components and most made with lowash flour had medium lipid levels; most made with medium and high-ash flours had high (>4 mg g-I) neutral lipid levels and were largely separated from the low-ash group. The most promising sourdoughs for bread were those with low added water, fermented from higher ash flour with maximum levels of extractable amino acids, peptides and proteins and medium to high polar and neutral lipid levels.