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

CABEZAS, DARÍO M.; BURBANO JUAN JOSÉ; CORREA, M. JIMENA

Exposici�n; Virtual 2021 AOCS Annual Meeting & Expo; 2021

AMERICAN OIL CHEMISTS SOCIETY

Walnut flour (WF) is a by-product of the edible oil industry, obtainedfrom the press cake milling. The compositional characteristics (high lipid,protein, and fiber contents) made WF attractive for improving the nutritionalquality of gluten-free products. This work aimed to characterize WF andevaluate the effect of WF addition on the thermal and textural behavior ofbatters and sponge cake quality. The proximate composition of WF and fatty acidand amino acid profiles were obtained. The control sponge cake contained riceflour and corn and cassava starches. Two levels of WF were used: 10% (WF10) and20% (WF20). The thermal transitions and texture of batters were determined byDSC and back-extrusion, respectively. Finally, baking quality was evaluated basedon 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 Argininelevels and a low Lysine/Arginine ratio (0.345), which has been related to anantiatherogenic effect.During heating, the batters exhibited two endotherms corresponding tothe starch gelatinization and the dissociation of the amylose lipid complex. Inall formulations, gelatinization showed a split endotherm, typical of processeswith water restriction. The gelatinization enthalpy decreased with increasingWF 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 tolower temperatures and an increase in enthalpy with WF addition. The texturalparameters such as firmness and consistency index increased with WF level. Spongecakes with WF showed higher specific volume and slightly lower crumb hardnessthan the control. Results show that the addition of WF affects the thermal andtextural properties of batters, while also improving the baking quality of thesponge cakes.