Characterization of walnut flour by-product of oil extraction and its use in a gluten-free sponge cake

BURBANO MOREANO, J.J.; CABEZAS, D.M.; CORREA, M.J.

Congreso; 2021 AOCS Annual Meeting & Expo; 2021

American Oil Chemists' Society

Walnut flour (WF) is a by-product of the edible oil industry, obtained from the press cake milling. The compositional characteristics (high lipid, protein, and fiber contents) made WF attractive for improving the nutritional quality of gluten-free products. This work aimed to characterize WF and evaluate the effect of WF addition on the thermal and textural behavior of batters and sponge cake quality. The proximate composition of WF and fatty acid and amino acid profiles were obtained. The control sponge cake contained rice flour and corn and cassava starches. Two levels of WF were used: 10% (WF10) and 20% (WF20). The thermal transitions and texture of batters were determined by DSC and back-extrusion, respectively. Finally, baking quality was evaluated based on specific volume and crumb hardness. WF has high lipid (55.7%), protein (24.6%), and dietary fiber content (9.4%). The primary fatty acids were linolenic acid (59.8%), oleic acid (15.47%), and α-linolenic acid (14.68). WF contains relatively high Arginine levels and a low Lysine/Arginine ratio (0.345), which has been related to an antiatherogenic effect. During heating, the batters exhibited two endotherms corresponding to the starch gelatinization and the dissociation of the amylose lipid complex. In all formulations, gelatinization showed a split endotherm, typical of processes with water restriction. The gelatinization enthalpy decreased with increasing WF concentration, with values ranging from 6.19 J/g (control) to 3.37 J/g (WF20). The dissociation of the amylose-lipid complex showed a displacement to lower temperatures and an increase in enthalpy with WF addition. The textural parameters such as firmness and consistency index increased with WF level. Sponge cakes with WF showed higher specific volume and slightly lower crumb hardness than the control. Results show that the addition of WF affects the thermal and textural properties of batters, while also improving the baking quality of the sponge cakes.