Innovative antibacterial and antifungal coating films of chitosan/nano zinc oxide/essential oil on grape preservation

Abstract

The effects of some innovative antibacterial and antifungal coating films of chitosan/nano zinc oxide/essential oil (C-ZNO-EO) on grape preservation for human health were studied during the storage periods on (0, 4, 7, 14, and 16) days. Several evaluation approaches were evaluated such as the bacterial evaluations against the presence of the mesophilic aerobic bacteria. The polyamines evaluation was studied by thin-layer chromatography (TLC) for putrescine and spermidine. Soluble sugars were detected by high-performance liquid chromatography (HPLC) for fructose, glucose, and sucrose. Iron, zinc, and manganese were absorbed by the spectrum spectrophotometer. The antifungal properties have been examined against Botryis cineraa, Aspergillus niger, and Tubingensis. The results reported that the highest mesophilic aerobic bacteria (4.73 Log CFU g−1) was recorded in the control grapes on the 16th day, whereas the lowest level (2.05 Log CFU g−1) was recorded for C-ZNO-EO. The polyamines ranged from 12.18 nmol g−1 FW to 10.1 nmol g−1 FW, and from 21.35 nmol g−1 FW to 16 nmol g−1 FW for putrescine and spermidine during the storage periods, respectively. The grapes treated with C-ZNO-EO achieved the maximum increase in glucose and fructose contents (40.61 and 30.05 μmol/g FW), while grapes treated with chitosan/nano zinc oxide (C-ZNO) achieved the maximum increase in sucrose (0.982 μmol/g FW) compared with chitosan (C) and control treatments at the end of the storage periods, respectively. Using C-NZO-EO treatment had a positive effect on the mineral compositions and the antifungal against Botryis cineraa, Aspergillus niger, and Tubingensis. The innovative antibacterial and antifungal coating film by C-NZO-EO was the best treatment for grape preservation.