การเตรียมฟิล์มโปรตีนถั่วเหลืองสกัดโดยใช้กรดฟีนอลิกและการบ่ม

• المؤلف الرئيسي: อัญชนา อินสวาสดิ์
• مؤلفون آخرون: ธนจันทร์ มหาวนิช
• التنسيق: Theses and Dissertations
• اللغة: Thai
• منشور في: จุฬาลงกรณ์มหาวิทยาลัย 2014
• الوصول للمادة أونلاين: https://digiverse.chula.ac.th/Info/item/dc:34388
• المؤسسة: Chulalongkorn University

This study aimed to explore the effect of phenolic acid addition and heat curing on properties of soy protein isolate film. In the first part of the study, the effect of type, oxidation state and concentration of phenolic acid on properties of soy protein film was investigated. Ferulic, caffeic, and galllic acid, either oxidized or unoxidized, were added to the film at 0.5, 1.0 and 1.5% by weight of soy protein isolate. Phenolic acid addition was found to pose a significant effect (p≤0.05) on tensile strength and elongation at break of the film. Gallic-containing films exhibited the highest tensile strength and elongation at break, followed by those added with caffeic and ferulic acid, respectively. Oxidized phenolic acids were shown to produce a film with higher tensile strength and elongation at break than their unoxidized counterparts. In addition, tensile strength and elongation at break were found to increase with increasing phenolic acid concentration. Protein pattern as monitored using SDS-PAGE, as well as available lysine and total sulfhydryl contents, and also a decrease in FTIR transmittance in the C-N stretching region reflected protein cross-linking in the phenolic-containing samples. Phenolic acid addition resulted in the film with decreasing transparency and L* with a concomitant increase in a*, b* and chroma. Phenolic-containing films demonstrated increasing surface hydrophobicity and decreasing water solubility. Water vapor permeability either decreased or unchanged upon adding phenolic acid. Regarding to moisture sorption behavior at a constant temperature of 25 °C, the film containing 1.5% oxidized gallic acid demonstrated type II isotherm. Water activity was found to significantly affect tensile strength (p≤0.05) but posed no effect on elongation at break (p>0.05). The second part of this research dealt with the investigation of the effect of heat curing on properties of the film added with either oxidized or unoxidized gallic acid at 1.5% level. Curing temperature was varied as 25, 50, 70 and 90 °C with 5, 10 and 15 hr curing time. Heat curing significantly affected tensile strength (p≤0.05) which was found to increase with increasing curing temperature and time. The film containing 1.5% oxidized gallic acid and cured at 90 °C for 15 hr demonstrated the highest tensile strength of 6.54 MPa which was 861% greater than that of the non-phenolic added, non-heat treated soy protein film. Curing temperature and time posed no effect on elongation at break in the 25-70 °C range (p>0.05). However, 90 °C curing caused a reduction in elongation at break of the film. Protein pattern as monitored using SDS-PAGE affirmed protein cross-linking in the heat cured samples. The heat treated films exhibited a decrease in transparency and L* with an increase in a* and b*. Decreasing hue angle and increasing chroma were observed in the heat cured films. In general, heat curing posed a minimal effect on water vapor permeability. However, it was demonstrated that the heat cured film exhibited an increase in surface hydrophilicity. All heat cured samples exhibited lower water solubility as compared to the control (p≤0.05). However, soluble solids content seemed to be unaffected by curing temperature and time. Pertaining to the moisture sorption behavior, the film with 1.5% oxidized gallic and cured at 70 °C for 10 hr exhibited decreasing tensile strength with increasing water activity. However, elongation at break was found to be unaffected by changing water activity.