Eunmi Joo a, 1, Yoonjee Chang b, 1, Inyoung Choi a, Seul Bi Lee c, Dong Hoo Kim d, Young Ju Choi c, Chan Suk Yoon d, Jaejoon Han a, b, *
a Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, Republic of Korea
b Department of Food Bioscience and Technology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, Republic of Korea
c EverChemTech Co., Ltd., #313, 314, Human Sky Valley, 959, Gosaek-dong, Gwonseon-gu, Suwon-si, Gyeonggi-do, Republic of Korea
d Agency for Korea National Food Cluster (AnFC), Iksan, 570-749, Republic of Korea
* Corresponding author.
1E.J. and Y.C contributed equally to this work.
Abstract
Whey protein isolate (WPI)-coated multilayer films were developed using polyethylene terephthalate (PET) film as a substrate. To improve the interfacial compatibility between PET film and water-based WPI coating solution, various surface pretreatments (corona discharge, plasma, and primer coating) were applied to PET. Water contact angles of the plasma-treated PET were significantly decreased by 12.8% related to the untreated PET, suggesting an increment of hydrophilic functional groups. Oxygen transmission rates of surface-pretreated multilayer films with WPI coating layer [PET/WPI/nylon/linear low-density polyethylene (LLDPE)] were significantly lower, about 43?234 times, than the multilayer films without WPI film layer. In addition, tensile strength of the plasma-pretreated PET/WPI/nylon/LLDPE films was 13.4 and 21.8% higher, elongation at break was 29.7 and 2.6% higher than the corona discharge- and primer-pretreated films, respectively. Taken together, WPI films are promising candidates for replacing synthetic oxygen-barrier materials. Specifically, plasma-pretreated PET/WPI/nylon/LLDPE films have a high potential as high oxygen-barrier packaging materials.
Keywords : Whey protein, Multilayer film, Surface coating, Corona discharge, Plasma