Multiscale Characterization of Rice Starch Gelation and Retrogradation Modified by Soybean Residue (Okara) and Extracted Dietary Fiber Using Rheology, Synchrotron Wide-Angle X-Ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) Spectroscopy

Okara, the soybean residue from soy milk and tofu production, offers significant potential as a sustainable, fiber-rich ingredient for starch-based and gluten-free food systems. This study investigates the comparative effects of whole okara and its extracted dietary fiber (DF) on the retrogradation,...

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Main Authors: Aunchalee Aussanasuwannakul, Suparat Singkammo
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Foods
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Online Access:https://www.mdpi.com/2304-8158/14/11/1862
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author Aunchalee Aussanasuwannakul
Suparat Singkammo
author_facet Aunchalee Aussanasuwannakul
Suparat Singkammo
author_sort Aunchalee Aussanasuwannakul
collection DOAJ
description Okara, the soybean residue from soy milk and tofu production, offers significant potential as a sustainable, fiber-rich ingredient for starch-based and gluten-free food systems. This study investigates the comparative effects of whole okara and its extracted dietary fiber (DF) on the retrogradation, rheological properties, and nanostructural organization of rice starch (RS) gels. Rice starch suspensions were blended with 5–20% (dry basis) of either whole okara or DF, thermally gelatinized, and analyzed using dynamic rheology, synchrotron-based Wide-Angle X-ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) spectroscopy. DF markedly reduced the gelation temperature and enhanced storage modulus (G′), indicating earlier and stronger gel network formation. WAXS analysis showed that DF more effectively disrupted long-range molecular ordering, as evidenced by suppressed crystallinity development and disrupted molecular ordering within the A-type lattice. FTIR spectra revealed intensified O–H stretching and new ester carbonyl bands, with progressively higher short-range molecular order (R<sub>1047/1022</sub>) in DF-modified gels. While whole okara provided moderate retrogradation resistance and contributed to network cohesiveness via its matrix of fiber, protein, and lipid, DF exhibited superior retrogradation inhibition and gel stiffness due to its purity and stronger fiber–starch interactions. These results highlight the functional divergence of okara-derived ingredients and support their targeted use in formulating stable, fiber-enriched, starch-based foods.
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spelling doaj-art-cabe8131daab445caaad2b3d6b85eaeb2025-08-20T03:46:50ZengMDPI AGFoods2304-81582025-05-011411186210.3390/foods14111862Multiscale Characterization of Rice Starch Gelation and Retrogradation Modified by Soybean Residue (Okara) and Extracted Dietary Fiber Using Rheology, Synchrotron Wide-Angle X-Ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) SpectroscopyAunchalee Aussanasuwannakul0Suparat Singkammo1Department of Food Chemistry and Physics, Institute of Food Research and Product Development, Kasetsart University, Bangkok 10903, ThailandSynchrotron Light Research Institute (Public Organization), 111 University Avenue, Muang District, Nakorn Ratchasima 30000, ThailandOkara, the soybean residue from soy milk and tofu production, offers significant potential as a sustainable, fiber-rich ingredient for starch-based and gluten-free food systems. This study investigates the comparative effects of whole okara and its extracted dietary fiber (DF) on the retrogradation, rheological properties, and nanostructural organization of rice starch (RS) gels. Rice starch suspensions were blended with 5–20% (dry basis) of either whole okara or DF, thermally gelatinized, and analyzed using dynamic rheology, synchrotron-based Wide-Angle X-ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) spectroscopy. DF markedly reduced the gelation temperature and enhanced storage modulus (G′), indicating earlier and stronger gel network formation. WAXS analysis showed that DF more effectively disrupted long-range molecular ordering, as evidenced by suppressed crystallinity development and disrupted molecular ordering within the A-type lattice. FTIR spectra revealed intensified O–H stretching and new ester carbonyl bands, with progressively higher short-range molecular order (R<sub>1047/1022</sub>) in DF-modified gels. While whole okara provided moderate retrogradation resistance and contributed to network cohesiveness via its matrix of fiber, protein, and lipid, DF exhibited superior retrogradation inhibition and gel stiffness due to its purity and stronger fiber–starch interactions. These results highlight the functional divergence of okara-derived ingredients and support their targeted use in formulating stable, fiber-enriched, starch-based foods.https://www.mdpi.com/2304-8158/14/11/1862okaradietary fiberrice starchretrogradationrheologyWAXS
spellingShingle Aunchalee Aussanasuwannakul
Suparat Singkammo
Multiscale Characterization of Rice Starch Gelation and Retrogradation Modified by Soybean Residue (Okara) and Extracted Dietary Fiber Using Rheology, Synchrotron Wide-Angle X-Ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) Spectroscopy
Foods
okara
dietary fiber
rice starch
retrogradation
rheology
WAXS
title Multiscale Characterization of Rice Starch Gelation and Retrogradation Modified by Soybean Residue (Okara) and Extracted Dietary Fiber Using Rheology, Synchrotron Wide-Angle X-Ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) Spectroscopy
title_full Multiscale Characterization of Rice Starch Gelation and Retrogradation Modified by Soybean Residue (Okara) and Extracted Dietary Fiber Using Rheology, Synchrotron Wide-Angle X-Ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) Spectroscopy
title_fullStr Multiscale Characterization of Rice Starch Gelation and Retrogradation Modified by Soybean Residue (Okara) and Extracted Dietary Fiber Using Rheology, Synchrotron Wide-Angle X-Ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) Spectroscopy
title_full_unstemmed Multiscale Characterization of Rice Starch Gelation and Retrogradation Modified by Soybean Residue (Okara) and Extracted Dietary Fiber Using Rheology, Synchrotron Wide-Angle X-Ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) Spectroscopy
title_short Multiscale Characterization of Rice Starch Gelation and Retrogradation Modified by Soybean Residue (Okara) and Extracted Dietary Fiber Using Rheology, Synchrotron Wide-Angle X-Ray Scattering (WAXS), and Fourier Transform Infrared (FTIR) Spectroscopy
title_sort multiscale characterization of rice starch gelation and retrogradation modified by soybean residue okara and extracted dietary fiber using rheology synchrotron wide angle x ray scattering waxs and fourier transform infrared ftir spectroscopy
topic okara
dietary fiber
rice starch
retrogradation
rheology
WAXS
url https://www.mdpi.com/2304-8158/14/11/1862
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AT suparatsingkammo multiscalecharacterizationofricestarchgelationandretrogradationmodifiedbysoybeanresidueokaraandextracteddietaryfiberusingrheologysynchrotronwideanglexrayscatteringwaxsandfouriertransforminfraredftirspectroscopy