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Yuan Chi Master thesis 7.19.pdf (4.65 MB)

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The Influence of Citric Acid, Glycerol and pH on Crosslinking and Their Effects on the Morphology, Mechanical and Thermal Properties of Tapioca Starch Films

Chi, Yuan
http://rave.ohiolink.edu/etdc/view?acc_num=osu1563494987482215

Abstract Details

2019, Master of Science, Ohio State University, Food Science and Technology.
This study investigated the impact of selected treatments on crosslinking in starch edible films. The treatment investigated were citric acid as the crosslinking agent, glycerol as a plasticizer, and the pH of the film-forming solution. To determine the influence of these treatments on the films, the thermal, mechanical, and morphological properties were measured and compared with native starch as a control. The first section (Chapter 2) of this study focused on the effect of citric acid concentrations on the properties of the films. For this analysis, aqueous film-forming solutions containing 5% tapioca starch, 2.2% glycerol and 0, 1, 3, 5, 7 and 9 % (w/w of tapioca) citric acid were prepared. These were gelatinized and cast into Teflon plates and dried at 45oC for 12 hours. To understand the nature of the crosslinking that formed between the starch polymeric chains, an Attenuated Total Reflection Fourier Transformation Infrared Spectroscopy (ATR-FTIR) analysis was performed on all samples. To understand the impact of the treatments on the morphology of the films, the crystallinity of the samples was analyzed by X-Ray Diffraction (XRD). A thermal gravimetric analysis (TGA) was used to investigate the behavior of the films to temperatures ranging from 25 to 600oC. To correlate the influence of the treatments on the mechanical properties of the film samples, the tensile profile analysis (TPA) provided an opportunity to measure the tensile strength, percent elongation and modulus of elasticity of the films exposed to the various treatments. In the second section (Chapter 3) the influence of the plasticizer concentration on the film properties is reported. The edible films were formed by dissolving 5% tapioca starch, 3% citric acid (w/w of tapioca), and 2.1, 2.3, 2.5, 2.7 and 2.9% glycerol into a film-forming solution. The films were formed as described above. The film properties were analyzed by the same methods described in the paragraph above. In the third section (Chapter 4) the influence of different levels of pH’s the properties of the films was investigated. The edibles films were formed by dissolving 5% tapioca, 2.2% glycerol and 3% citric acid (w/w of tapioca) at pH levels of 3, 5, 7, 9 and 11. The films were formed as described above. The film properties were analyzed by the same methods described in the paragraph above. The FTIR results indicated that the crosslinking was facilitated by ester linkages at peak location of 1520 cm-1. It also showed that the degree of crosslinking was be optimized by 9% citric acid, 2.5 % glycerol, and at a pH level of 7. The XRD results showed that 3% critic acid, 2.3% glycerol, and pH 3 provided the starch with the lowest crystallinity. The 9% citric acid, 2.9% glycerol, and pH 11provided the cornstarch with the highest level of crystallinity. The TGA results showed that in general, the physical decomposition temperatures of the crosslinked starch films were lower than that of the native starch film, while the thermal stability of crosslinked starches was higher than the native starch above. The thermal stability was optimized best by the 7% citric acid (w/w of starch), 2.5% glycerol and pH 9. The tensile profile analysis showed that TS, elongation, and elastic moduli of the crosslinked starch films were optimized by the 5% citric acid, 2.1% glycerol and pH 9. This study concluded that crosslinking could be used to improve the mechanical and thermal properties of starch edible films. The study also confirmed that crosslinking caused by critic acid was facilitated by ester linkages between the starch polymeric chains and the carbonyl groups on the citric acid molecule.
Melvin Pascall (Advisor)
John Litchfield (Committee Member)
Matthias Klein (Committee Member)
159 p.
Food Science
Crosslink, starch, citric acid, glycerol

Recommended Citations

Citations

  • Chi, Y. (2019). The Influence of Citric Acid, Glycerol and pH on Crosslinking and Their Effects on the Morphology, Mechanical and Thermal Properties of Tapioca Starch Films [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563494987482215

    APA Style (7th edition)

  • Chi, Yuan. The Influence of Citric Acid, Glycerol and pH on Crosslinking and Their Effects on the Morphology, Mechanical and Thermal Properties of Tapioca Starch Films. 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1563494987482215.

    MLA Style (8th edition)

  • Chi, Yuan. "The Influence of Citric Acid, Glycerol and pH on Crosslinking and Their Effects on the Morphology, Mechanical and Thermal Properties of Tapioca Starch Films." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563494987482215

    Chicago Manual of Style (17th edition)

osu1563494987482215
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© 2019, some rights reserved.Creative Commons License The Influence of Citric Acid, Glycerol and pH on Crosslinking and Their Effects on the Morphology, Mechanical and Thermal Properties of Tapioca Starch Films by Yuan Chi is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.