Antimicrobial carvacrol in solution blow-spun fish-skin gelatin nanofibers

Authors: LIU, FEI - Jiangnan University; SARICAOGLU, FURKAN TURKER - Ondokuz Mayis University; Avena-Bustillos, Roberto; Bridges, David; Takeoka, Gary; Wu, Vivian; Chiou, Bor-Sen; Wood, Delilah - De; McHugh, Tara; ZHONG, FANG - Jiangnan University

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2018
Publication Date: 3/25/2018
Citation: Liu, F., Saricaoglu, F., Avena Bustillos, R.D., Bridges, D.F., Takeoka, G.R., Wu, V.C., Chiou, B., Wood, D.F., Mchugh, T.H., Zhong, F. 2018. Antimicrobial carvacrol in solution blow-spun fish-skin gelatin nanofibers. Journal of Food Science. 83(4):984-991. https://doi.org/10.1111/1750-3841.14076.
DOI: https://doi.org/10.1111/1750-3841.14076

Interpretive Summary: The objective of this study was to encapsulate carvacrol into FSG-based nanofibers using SBS, and to evaluate the influence of carvacrol ratios on physicochemical properties of fiber-forming solutions and their resultant nanofibers, as well as on antimicrobial activity and storage stability of nanofibers. Our results showed that the physical characteristics of emulsions are crucial for forming nanofibers. Only carvacrol-loaded emulsions with appropriate chain entanglement and surface tension could favor the formation of regular and smooth nanofibers. The AFD of nanofibers shifted to higher values with the addition of carvacrol as compared to the blank nanofibers, and the much higher AFD was observed for the nanofibers incorporating higher ratios of carvacrol. Moreover, the carvacrol droplet in emulsion might be ejected within the FSG continuous phase and distributed beneath the surface of formed nanofibers. The antimicrobial activity of carvacrol was maintained after encapsulating in nanofibers and this was superior for nanofibers with lower carvacrol ratios due to their higher cavacrol retention. The lower RH promoted the retention of carvacrol in nanofibers during the previous four-week storage, while the lower temperature promoted the retention of carvacrol in the end of eight-week storage. The blow spun nanofibers encapsulating active compounds such as carvacrol may be quite useful in the food industry due to the extremely large surface area of nanofibers along with specific functionality

Technical Abstract: Carvacrol is a volatile monoterpenic phenol and main component of oregano essential oil that shows nonspecific antimicrobial activity against foodborne pathogenic bacteria. Fish-skin gelatin (FSG) nanofibers encapsulating carvacrol (15, 20, 25 and 30%, w/w FSG) were successfully prepared via solution blow-spinning (SBS) technique using lecithin (2.475% wb) as the surfactant. FSG emulsions with lower carvacrol ratios (5 and 10%) showed higher values in particle size and surface tension as well as lower values in viscosity and modulus, which led to failure of maintaining nanofibers shape. The formed carvacrol-FSG nanofibers showed round and smooth morphologies with average fiber diameters ranging from 103.2 to 138.1 nm as the carvacrol ratio increased from 15 to 30%. Carvacrol was evenly dispersed within the interior of nanofiber matrix. All carvacrol-FSG nanofibers showed inhibitive effects against the growth of Escherichia coli, Salmonella enterica, and Listeria monocytogenes. Moreover, nanofibers with lower carvacrol ratios showed bigger inhibition zones for E. coli and L. monocytogenes (20 vs. 12.5 mm for lowest to highest carvacrol ratios, respectively). Nanofibers stored at 20 °C (51% RH) showed better retention (40-60%) for carvacrol during the first 4 weeks of storage, while nanofibers stored at 2 °C (70% RH) showed better retention (10-30%) at the end of storage.