To increase hydration properties and soluble fiber content, okara with different moisture contents (30, 35, and 40%) was extruded in single-screw equipment, keeping the temperature (120 °C) and screw speed (115 rpm) fixed. The physical, chemical, and techno-functional properties of extruded and non-extruded okara (control) were evaluated. The microstructure, color, chemical composition, and techno-functional properties of okara were altered after extrusion. The extruded samples showed general microstructure aspects similar between them, with an irregular and rough surface, striated parts, orifices, and some agglomerated particles with distorted, compact, and amorphous appearance, different from control. Among the modified samples, okara extruded with 30% moisture showed more intense changes in relation to the samples extruded with 35 and 40% moisture. Based on the results, it can be inferred that okara extruded with 35% moisture is the most suitable. Under this condition, there was an increase of 80% in soluble fiber content, 45% in water absorption and holding capacity and 11% in solid stability in water, the maintenance of swelling and oil absorption and holding capacities and the reduction of protein solubility in water. X-ray diffraction analysis showed that crystalline phase was affected by extrusion.
CharunuchCBoonyasirikoolPTiengpookC (2003) Using extrusion process for preparation of instant cereal beverage based on corn and soybean. Kasetsart Journal (Natural Science37: 72–83.
2.
ChenLChenJYuL, et al. (2018). Emulsification performance and interfacial properties of enzymically hydrolyzed peanut protein isolate pretreated by extrusion cooking. Food Hydrocolloids77: 607–616. DOI: 10.1016/j.foodhyd.2017.11.002.
3.
ChenYYeRYinL, et al. (2014). Novel blasting extrusion processing improved the physicochemical properties of soluble dietary fiber from soybean residue and in vivo evaluation. Journal of Food Engineering120: 1–8. DOI: 10.1016/j.jfoodeng.2013.07.011
DuboisMGillesKAHamiltonJK, et al. (1956). Colorimetric method for determination of sugars and related substances. Analytical Chemistry28(3): 350–356. DOI: 10.1021/ac60111a017.
6.
DustJMGajdaAMFlickingerEA, et al. (2004). Extrusion conditions affect chemical composition and in vitro digestion of select food ingredients. Journal of Agricultural and Food Chemistry52(10): 2989–2996. DOI: 10.1021/jf049883u (Last accessed March 2020).
7.
FangYZhangBWeiY (2014) Effects of the specific mechanical energy on the physicochemical properties of texturized soy protein during high-moisture extrusion cooking. Journal of Food Engineering121: 32–38. DOI: 10.1016/j.jfoodeng.2013.08.002.
8.
GajulaHAlaviSAdhikariK, et al. (2008). Precooked bran-enriched wheat flour using extrusion: Dietary fiber profile and sensory characteristics. Journal of Food Science73(4): 173–179. DOI: 10.1111/j.1750-3841.2008.00715.x.
9.
GaldeanoMCGrossmannMVE (2005). Effect of treatment with alkaline hydrogen peroxide associated with extrusion on color and hydration properties of oat hulls. Brazilian Archives of Biology and Technology48(1) Curitiba, Brazil: Instituto de Tecnologia do Paraná (Brazil)1): 63–672. DOI: 10.10.1590/S1516-89132005000100010.
10.
GhummanAKaurASinghN, et al. (2016). Effect of feed moisture and extrusion temperature on protein digestibility and extrusion behavior of lentil and horsegram. LWT - Food Science and Technology70: 349–357. DOI: 10.1016/j.lwt.2016.02.032.
11.
GongJLiJXuJ, et al. (2017). Research on cellulose nanocrystals produced from cellulose sources with various polymorphs. Royal Society of Chemistry Advances7(53): 33486–33493.
12.
HoncuISlukováMVaculováK, et al. (2016). The effects of extrusion on the content and properties of dietary fibre components in various barley cultivars. Journal of Cereal Science68: 132–139. DOI: 10.1016/j.jcs.2016.01.012.
13.
HuangYMaY (2016) The effect of extrusion processing on the physiochemical properties of extruded orange pomace. Food Chemistry192: 363–369. DOI: 10.1016/j.foodchem.2015.07.039.
14.
InternationalAOAC (2012) Official Methods of Analysis of AOAC International. AOAC International: Gaithersburg, MD.
15.
KamizakeNKKVaréaGSPrudencioSH (2014). Physicochemical properties of aged soybean components. Journal of Food, Agriculture & Environment12(2): 263–268.
16.
LiHLongDPengJ, et al. (2012). A novel in-situ enhanced blasting extrusion technique - extrudate analysis and optimization of processing conditions with okara. Innovative Food Science and Emerging Technologies16: 80–88. DOI: 10.1016/j.ifset.2012.04.009.
17.
LiSZhuDLiK, et al. (2013). Soybean curd residue: Composition, utilization and related limiting factors. ISRN Industrial Engineering2013: 1–8. DOI: 10.1155/2013/423590.
18.
Mateos-AparicioIMateos-PeinadoCRupérezP (2010). High hydrostatic pressure improves the functionality of dietary fiber in okara by-product from soybean. Innovative Food Science and Emerging Technologies11(3): 445–450. DOI: 10.1016/j.ifset.2010.02.003.
19.
MurateEHPrudencio-FerreiraSH (1999). Propriedades funcionais de concentrado protéico extrusado de sementes de girassol. Brazilian Archives of Biology and Technology42(2): 213-221. DOI: 10.1590/S1516-89131999000200012
20.
OgunwoluSOHenshawFOMockH, et al. (2009). Functional properties of protein concentrates and isolates produced from cashew (Anacardium occidentale L.) nut. Food Chemistry115(3): 852–858. DOI: 10.1016/j.foodchem.2009.01.011.
21.
PietschVLBühlerJMKarbsteinHP, et al. (2019). High moisture extrusion of soy protein concentrate: influence of thermomechanical treatment on protein-protein interactions and rheological properties. Journal of Food Engineering251: 11–18. DOI: 10.1016/j.jfoodeng.2019.01.001.
22.
Prudêncio-FerreiraSHArêasJAG (1993). Protein-protein interactions in the extrusion of soya at various temperatures and moisture contents. Journal of Food Science58: 378–381. DOI: 10.1111/j.1365-2621.1993.tb04279.x.
23.
SegalLCreelyJJMartinAEJr, et al. (1959). An empirical method for estimating the degree of crystallinity of native cellulose using the X-ray diffractometer. Textile Research Journal29: 786–794. DOI: 10.1177/004051755902901003.
24.
SeibelNFBeléiaADP (2009a). The chemical characteristics and technological functionality of soybean based ingredients [Glycine Max (L.) merrill]: Carbohydrates and proteins. Brazilian Journal of Food Technology12(2): 113–122. DOI: 10.4260/BJFT20093607.
25.
SethDBadwaikLSGanapathyV (2015) Effect of feed composition, moisture content and extrusion temperature on extrudate characteristics of yam-corn-rice based snack food. Journal of Food Science and Technology52(3): 1830–1838. DOI: 10.1007/s13197-013-1181-x.
26.
SinghSGamlathSWakelingL (2007) Nutritional aspects of food extrusion: A review. International Journal of Food Science and Technology42(8): 916–929. DOI: 10.1111/j.1365-2621.2006.01309.x.
27.
SpottiMJCampanellaOH (2017) Functional modifications by physical treatments of dietary fibers used in food formulations. Current Opinion in Food Science15: 70–78. DOI: 10.1016/j.cofs.2017.10.003.
28.
StanleyDW (1989) Extrusion cooking. In: MercierCLinkoPHarperJM. Protein Reactions During Extrusion Cooking. Saint Paul: American Association of Cereal Chemists: 321–342.
SteelCJLeoroMGVSchmieleM, et al. (2012) Thermoplastic elastomers. In: El-SonbatiAZ. Thermoplastic Extrusion in Food Processing. Croatia: Intech Open: 265–290.
31.
UllahIYinTXiongS, et al. (2017) Structural characteristics and physicochemical properties of okara (soybean residue) insoluble dietary fiber modified by high-energy wet media milling. LWT – Food Science and Technology82: 15–22. DOI: 10.1016/j.lwt.2017.04.014.
32.
VongWCLiuS (2016) Biovalorisation of okara (soybean residue) for food and nutrition. Trends in Food Science& Technology52: 139–147. DOI: 10.1016/j.tifs.2016.04.011.
33.
WangCLiLSunX, et al. (2019) High-speed shearing of soybean flour suspension disintegrates the component cell layers and modifies the hydration properties of okara fibers. LWT – Food Science and Technology116: 1–5
34.
YangTLiuTLiX, et al. (2019) Novel nanoparticles from insoluble soybean polysaccharides of okara as unique pickering stabilizers for oil-in-water emulsions. Food Hydrocolloids94: 255–267. DOI: 10.1016/j.foodhyd.2019.03.035.
35.
YoshidaBYPrudencioSH (2020a) Alkaline hydrogen peroxide improves physical, chemical, and technofunctional properties of okara. Food Chemistry323: 126776. DOI: 10.1016/j.foodchem.2020.126776.
36.
YoshidaBYPrudencioSH (2020b) Physical, chemical, and technofunctional properties of okara modified by a carbohydrase mixture. LWT - Food Science and Technology134: 11014. DOI: 10.1016/j.lwt.2020.110141.
