Investigation of the structural, thermal and antimicrobial properties of composite protein nanofibers to be obtained by electrospining method

Enzymatic and microbiological degradation of foods in the process from production to the consumption is an important problem that needs to be monitored in all stages including transportation, packaging and storage. Today, solutions to these problems are sought with the opportunities offered by developing technologies. Safe coating or packaging of foods with nanotechnology based, natural biopolymer nanofiber film materials is among the subjects that have been intensively researched recently. Nanofiber materials are produced by electrospinning technique. The use of nanofibers obtained from animal and vegetable proteins through enrichment with natural antimicrobial substances has promoted nanopackaging materials in terms of food protection and preservation. In particular, with the addition of carrier polymers such as polyethylene oxide (PEO), polyvinyl alcohol (PVA), polycaprolactone (PCL), spinnability of proteins and mechanical properties of the resultant nanofibers can be improved. The aim of this study is to obtain composite nanofiber film materials from whey and soy proteins by electrospinning in the presence of PEO, to characterize these films by microscopic, spectroscopic, thermal and antimicrobial methods, and to investigate their food application. While fiber formation was clearly observed in the samples whose morphology was examined through electron microscopy, bead formations were also observed rarely. According to the Fouirer Transform Infrared Spectrometer (FTIR) findings, the fingerprinting regions of PAS, PEO and turmeric extract in the structure of composite nanofiber were determined. Thermogravimetric analysis (TGA) findings, revealed that the fibers indicated thermal resistance up to 250-300 ºC. As a food application, when nanofibers were coated to tangerine, they became more durable in terms of texture than the control samples. The L, a and b values of fresh tangerine before coating were 57.42±0.99, 33.50±1.64 and 47.97±1.26, respectively. They were 58.32±1.46, 35.39±1.24 and 45.85±2.32, obtained from tangerines washed after coating and incubation. According to these results, there were no significant change detected in tangerine peel color before and after coating. The whiteness (WI) and yellowness (YI) indexes of tangerines coated with nanofibers were 1.04 and 144.22, respectively. Accordingly, the nanofibers were almost white in color and the yellowness was higher in the samples containing turmeric extract. It was determined that the viscosity of the solution without turmeric extract was 521.99±3.39 cP, while the solution with turmeric extract was 456.83±5.39 cP. According to the findings, whey protein and PEO based nanofiber film materials doped with turmeric extract were regarded as functional products that can be successfully applied in the coating and protection of target fruits.