RESUMEN
Recently, packaging industry has turned to biodegradable packaging, and poly(lactic acid) has become the most remarkable polymer. However, the high oxygen permeability of PLA films significantly limits their use. Therefore, this study, it was aimed to improve the oxygen barrier properties of PLA films without adversely affecting the mechanical and water vapor barrier properties. Biodegradable PLA-Zein bi-layer films were produced by changing PLA and zein thickness. Transparent and UV barrier bi-layer films were obtained. Mechanical properties of PLA films were improved by the production of bi-layer films. Water vapor permeability of bi-layer films increased whereas the permeance decreased with zein coating of PLA. Multi-criteria decision hierarchy was used to select the best bi-layer films based on mechanical, permeance, and opacity results. Oxygen barrier properties of PLA film significantly improved by zein coating, and hydrophobicity of PLA film was not affected by zein coating. The crystallization and melting temperatures of films decreased when compared to PLA films, supporting the mechanical results. Homogeneous, non-porous, and smooth film surface was obtained and zein layer was in good compatibility with PLA layer. These results suggest that zein coatings could be used to decrease oxygen permeability of PLA films without negatively affecting other properties.
Asunto(s)
Zeína , Zeína/química , Resistencia a la Tracción , Embalaje de Alimentos/métodos , Vapor , Poliésteres/química , Permeabilidad , Oxígeno/químicaRESUMEN
BACKGROUND: Royal jelly (RJ) is a unique beehive product and has been recommended for human health since ancient times because of its antioxidant, antimicrobial, antiproliferative, neuroprotective, anti-lipidemic and anti-aging features. However, the biggest obstacle in the use of RJ is the need for cold storage and the instability of bioactive components over time. In the present study, 10-hydroxy-2-decenoic acid (10-HDA) content, as well as antioxidant [using 1,1-diphenyl-2-picrylhydrazy and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) methods] and antimicrobial activity (five Gram-positive, five Gram-negative and three yeasts), were comparatively evaluated for three RJ forms, two of which can be stored at 24 ± 1 °C during storage. RESULTS: Microencapsulated royal jelly (MRJ) stored at room temperature succeeded in preserving its 10-HDA content, a major bioactive compound, during the 6 months, with respect to lyophilized royal jelly (LRJ) and fresh RJ stored at 4 °C. The initial 10-HDA contents of RJ, LRJ and MRJ were determined as 1.90%, 5.26% and 2.75%, respectively. Moreover, the total phenolic content, antioxidant capacity and antimicrobial activity mostly remained constant throughout the storage period (P ≥ 0.05). Gram-positive strains were generally more sensitive than Gram-negative strains. In the present study, the in vitro simulated digestion analysis showed that MRJ can tolerate the digestion process. CONCLUSION: Overall, the encapsulation process was considered as one preservative technique for RJ. The microencapsulation of RJ as shown in the results of the present study are encouraging in terms of enabling the local beekeeping sector to achieve ease of production and increased product diversity. MRJ shows promise as a commercial product with a high export value for producers. © 2022 Society of Chemical Industry.