Browsing by Author "Baek, Naerin"

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    Characterization of Hydrophobically Modified Titanium Dioxide Polylactic Acid Nanocomposite Films for Food Packaging Applications
    Baek, Naerin (Virginia Tech, 2016-08-12)
    Titanium dioxide (TiO2) polymer nanocomposites improve barrier properties to gas and moisture and mechanical strength as well as providing active packaging functions. However, low compatibility between hydrophilic TiO2 nanoparticles and hydrophobic polymers such as polylactic acid (PLA) causes problems due to the tendency of TiO2 nanoparticles (TiO2) to agglomerate and form large clusters. A surface modification of TiO2 with long chain fatty acid may improve the compatibility between PLA and TiO2. The goal of this study was to enhance barrier properties of oxygen and water vapor, mechanical strength and add light protecting function to PLA composites by incorporation of oleic acid modified TiO2 nanoparticles (OA_TiO2). The objectives of this study were: 1) synthesize TiO2 and modify surface of TiO2 with oleic acid, 2) investigate dispersion stability of TiO2 and OA_TiO2 in hydrophobic media, 3) incorporate TiO2 and OA_TiO2 into a PLA matrix and to characterize properties of TiO2PLA (T-PLA) and OA_TiO2 PLA nanocomposite films (OT-PLA), and 4) to determine stability of green tea infusion in T-PLA and OT-PLA packaging model systems during refrigerated storage at 4 °C under florescent lightening. TiO2 was synthesized by using a sol-gel method and the surface of TiO2 was modified by oleic acid using a one-step method. T-PLA and OT-PLA were prepared by solvent casting. TiO2 and OA_TiO2 were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis and dynamic light scattering. The barrier properties to oxygen and water vapor, morphology, mechanical properties, thermal stability and light absorption properties of T-PLA and OT-PLA were characterized. Dispersion of TiO2 was improved in PLA matrix by the surface modification method with oleic acid. OT-PLA had more effective improvements in the barrier properties and flexibility than T-PLA and PLA, but toughness of the films based on Young's modules of OT-PLA was lower than the T-PLA and the PLA. The OT-PLA may have a potential to be used as transparent, functional and sustainable packaging films, but limited use for complete visible and UV-light protection for photosensitized foods.
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    Effects of Natural Antioxidants on Lipid Oxidation of Menhaden Oil
    Baek, Naerin (Virginia Tech, 2013-01-25)
    Preventing oxidative deterioration of fish oil is a significant challenge for the food industry. Natural antioxidants are widely incorporated into foods and oils to prevent oxidation and extend shelf life. The goal of the study is to investigate the activity of novel antioxidants in menhaden oil and to develop optimum formulations containing mixed tocopherols to control oxidation of menhaden oil. Alpha tocopherol, gamma tocopherol, and delta tocopherol in menhaden oil were found at 0.18mg/g, 0.37mg/g, and 0.14mg/g, respectively, using HPLC analysis. Teng Cha extract effectively delayed oxidation of menhaden oil (MO) when stored at 40°C for eight days by measuring primary oxidation products and secondary oxidation products. The combinations of Teng Cha extract and rosemary extract and combinations of ascorbyl palmitate, citric acid, Teng Cha extract and rosemary extract more effectively improved stability of MO containing mixed tocopherols than Teng Cha extract alone at 40°C storage for eight days by measuring primary oxidation products and secondary oxidation products. From this study, Teng Cha extract can be used as a potential natural antioxidant in food industry, especially in combinations with rosemary extract and tocopherols, extending shelf life of menhaden oil.
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    (−)-Epigallocatechin Gallate Stability in Ready-To-Drink (RTD) Green Tea Infusions in TiO2 and Oleic-Acid-Modified TiO2 Polylactic Acid Film Packaging Stored under Fluorescent Light during Refrigerated Storage at 4 °C
    Baek, Naerin; Kim, Young; Duncan, Susan E.; Leitch, Kristen; O'Keefe, Sean F. (MDPI, 2021-03-29)
    The light-protective effectiveness of titanium dioxide polylactic acid (TiO2 PLA) nanocomposite films (T-PLA) and oleic-acid-modified (OA_TiO2PLA) nanocomposite films was investigated in ready-to-drink (RTD) green tea infusions in oxygen-impermeable glass packaging. The stability of (−)-epigallocatechin gallate (EGCG) was evaluated in RTD green tea infusions in glass packaging covered with PLA (polylactic acid), T-PLA and OT-PLA under fluorescent light during 20 days of storage at 4 °C. Levels of EGCG and color change of RTD green tea infusions were determined. In addition, sensory tests for difference were conducted on green tea infusions in glass packaging without and with complete light protection during 10 days of storage at 4 °C. Of the panelists, 60% noticed sensory differences in the RTD green tea infusion in two different packaging conditions during 10 days of storage under fluorescent light by a triangle test (p < 0.05). During 20 days of storage, levels of EGCG with complete light protection decreased by 10.8% (0.73 mg/mL), and there was a 42.2% loss of EGCG (0.48 mg/mL) in RTD green tea infusions in the glass packaging covered by PLA film. Finally, 3% T-PLA preserved higher levels of EGCG in RTD green tea infusions compared to 1% T-PLA and OT-PLA.
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    Vine tea (Ampelopsis grossedentata): A review of chemical composition, functional properties, and potential food applications
    Carneiro, Renata C. V.; Ye, Liyun; Baek, Naerin; Teixeira, Gustavo H. A.; O'Keefe, Sean F. (2021-01)
    Herbal teas like vine tea (Ampelopsis grossedentata) have been traditionally consumed worldwide because of their health-promotion and pleasant taste. Vine tea and its main bioactive component, dihydromyricetin, have gained attention because of their potential applications in food, material, and pharmaceutical sciences. Vine tea and dihydromyricetin have been suggested as potential natural antioxidants to extend shelf life of foods. Studies have also suggested potential application in packaging and food safety. Additionally, dietary supplementation with vine tea extract have shown great potential to prevent metabolic diseases, which can justify its application in novel functional foods. This review discusses the chemistry, functional properties, and potential applications of vine tea and dihydromyricetin in the food industry. Although vine tea extracts and dihydromyricetin have shown promising results, further studies on optimal application, thermal stability, synergetic effect with other natural antioxidants, consumer acceptability, and sensory profile of vine tea are needed to support food product innovation.