Okara flour: its physicochemical, microscopical and functional properties
Abstract
Purpose
Okara, which is the residue of hydrosoluble extract from soybean obtained after soymilk and tofu production, has high nutritional value and can be used for ingredient in specific food products. This study aims to evaluate the production and properties (physicochemical, microscopical and functional ones) of okara flour (OF) obtained from okara as a by-product of soymilk and tofu production.
Design/methodology/approach
Wet okara resulted from the soymilk process underwent convective drying up to reach mass stability (60°C for 12 h). OF properties were analyzed by official methods by AOAC, i.e. mineral composition was evaluated by atomic absorption equipment; color; water absorption index (WAI); milk absorption index (MAI); oil absorption capacity (OAC); and foam capacity (FC) required mixtures with water, milk and oil, separation and gravimetry, respectively; and microstructure was determined by a scanning electron microscope.
Findings
Results showed the potential OF has as a source of protein (24.74 g/100 g) and dietary fiber (58.27 g/100 g). Regarding its color after the drying process, OF was markedly yellow (b* parameter 20.16). Its WAI was 3.62 g/g, MAI was 4.33 g/g, OAC was 3.68 g/g and FC was 1.32 per cent. The microscopic analysis of OF showed that both loose and agglomerated particles had irregular structures and indefinite forms.
Originality/value
Production of flour from wet okara can be an alternative use of this by-product. This study showed important characteristics of OF and its possible application to the food industry. Thus, OF was shown as a potential ingredient with high nutritional value.
Keywords
Acknowledgements
The authors are thankful to CNPq/SETEC for its financial support (Process 469104/2014). This study was partly funded by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (Capes) – Code 001.
Conflict of interest. The authors declare no conflict of interests.
Authors’ contributions. Marco A. P. da Silva, Ailton C. Lemes, Marcio da S. Vilela and Mariana Buranelo Egea have supervised this study. Daiane Costa dos Santos, Josemar Gonçalves Oliveira Filho, Jhessika de Santana Silva and Milena Figueiredo de Sousa have conducted all experimental work. All authors have read and approved the final manuscript.
Citation
Santos, D.C.d., Oliveira Filho, J.G.d., Silva, J.d.S., Sousa, M.F.d., Vilela, M.d.S., Silva, M.A.P.d., Lemes, A.C. and Egea, M.B. (2019), "Okara flour: its physicochemical, microscopical and functional properties", Nutrition & Food Science, Vol. 49 No. 6, pp. 1252-1264. https://doi.org/10.1108/NFS-11-2018-0317
Publisher
:Emerald Publishing Limited
Copyright © 2019, Emerald Publishing Limited