Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on Them
Freezing has been widely used for long-term food preservation. However, freezing-thawing (FT) treatment usually influences the texture and structure of food gels such as konjac. For their texture control after FT treatment, it is important to clarify the structural change of food gels during the FT...
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| Format: | Article |
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MDPI AG
2022-09-01
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| Series: | Polymers |
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| Online Access: | https://www.mdpi.com/2073-4360/14/18/3703 |
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| author | Hiroyuki Takeno Ryuki Hashimoto Yunqiao Lu Wen-Chuan Hsieh |
| author_facet | Hiroyuki Takeno Ryuki Hashimoto Yunqiao Lu Wen-Chuan Hsieh |
| author_sort | Hiroyuki Takeno |
| collection | DOAJ |
| description | Freezing has been widely used for long-term food preservation. However, freezing-thawing (FT) treatment usually influences the texture and structure of food gels such as konjac. For their texture control after FT treatment, it is important to clarify the structural change of food gels during the FT process. In this study, we investigated the aggregated structures of konjac glucomannan (GM) gels during the FT process using simultaneous synchrotron small-angle X-ray/wide-angle X-ray scattering (SAXS/WAXS) techniques. The FT treatment resulted in more crystallization of GM, and consequently, a large increase in compressive stress. In-situ SAXS/WAXS measurements revealed the following findings: on freezing, water molecules came out of the aggregated phase of GM and after the thawing, they came back into the aggregated phase, but the aggregated structure did not return to the one before the freezing; the gel network enhanced the inhomogeneity due to the growth of ice crystals during freezing. Furthermore, we examined the influence of additives such as polyvinyl (alcohol) (PVA) and antifreeze glycoprotein (AFGP) on the mechanical and structural properties of freeze-thawed GM gels. Although the addition of PVA and AFGP suppressed the crystallization of GM, it could not prevent the growth of ice crystals and the increase in the inhomogeneity of the gel network. As a result, the compressive stresses for freeze-thawed GM gels containing PVA or AFGP were significantly higher compared with those of GM gels without FT treatments, although they were lower than those of freeze-thawed GM gels. The findings of this study may be useful for not only the texture control of freeze-thawed foods but also the improvement of the mechanical performance of the biomaterials. |
| first_indexed | 2024-03-09T22:46:47Z |
| format | Article |
| id | doaj.art-bfb06d2901d841ddba1684a9176c3666 |
| institution | Directory Open Access Journal |
| issn | 2073-4360 |
| language | English |
| last_indexed | 2024-03-09T22:46:47Z |
| publishDate | 2022-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Polymers |
| spelling | doaj.art-bfb06d2901d841ddba1684a9176c36662023-11-23T18:28:23ZengMDPI AGPolymers2073-43602022-09-011418370310.3390/polym14183703Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on ThemHiroyuki Takeno0Ryuki Hashimoto1Yunqiao Lu2Wen-Chuan Hsieh3Division of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu 376-8515, Gunma, JapanDivision of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu 376-8515, Gunma, JapanDivision of Molecular Science, Graduate School of Science and Technology, Gunma University, Kiryu 376-8515, Gunma, JapanDepartment of Biological Science and Technology, College of Medicine, I-SHOU University, No. 8, Yida, Yanchao, Kaohsiung 82445, TaiwanFreezing has been widely used for long-term food preservation. However, freezing-thawing (FT) treatment usually influences the texture and structure of food gels such as konjac. For their texture control after FT treatment, it is important to clarify the structural change of food gels during the FT process. In this study, we investigated the aggregated structures of konjac glucomannan (GM) gels during the FT process using simultaneous synchrotron small-angle X-ray/wide-angle X-ray scattering (SAXS/WAXS) techniques. The FT treatment resulted in more crystallization of GM, and consequently, a large increase in compressive stress. In-situ SAXS/WAXS measurements revealed the following findings: on freezing, water molecules came out of the aggregated phase of GM and after the thawing, they came back into the aggregated phase, but the aggregated structure did not return to the one before the freezing; the gel network enhanced the inhomogeneity due to the growth of ice crystals during freezing. Furthermore, we examined the influence of additives such as polyvinyl (alcohol) (PVA) and antifreeze glycoprotein (AFGP) on the mechanical and structural properties of freeze-thawed GM gels. Although the addition of PVA and AFGP suppressed the crystallization of GM, it could not prevent the growth of ice crystals and the increase in the inhomogeneity of the gel network. As a result, the compressive stresses for freeze-thawed GM gels containing PVA or AFGP were significantly higher compared with those of GM gels without FT treatments, although they were lower than those of freeze-thawed GM gels. The findings of this study may be useful for not only the texture control of freeze-thawed foods but also the improvement of the mechanical performance of the biomaterials.https://www.mdpi.com/2073-4360/14/18/3703konjac glucomannanfreezing-thawingsynchrotron small-angle/wide-angle X-ray scattering |
| spellingShingle | Hiroyuki Takeno Ryuki Hashimoto Yunqiao Lu Wen-Chuan Hsieh Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on Them Polymers konjac glucomannan freezing-thawing synchrotron small-angle/wide-angle X-ray scattering |
| title | Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on Them |
| title_full | Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on Them |
| title_fullStr | Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on Them |
| title_full_unstemmed | Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on Them |
| title_short | Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on Them |
| title_sort | structural and mechanical properties of konjac glucomannan gels and influence of freezing thawing treatments on them |
| topic | konjac glucomannan freezing-thawing synchrotron small-angle/wide-angle X-ray scattering |
| url | https://www.mdpi.com/2073-4360/14/18/3703 |
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