Effects of Coating by Chitosan, TiO2 Nanoparticles, and Sodium Tripolyphosphate as Crosslinker on Stored Cucumber Fruits

Abstract

Cucumber fruit contains essential nutrients and fibers and is used widely in salads dressing. Scarce research is available on its storage with nanoparticles and chitosan combined effects. Hence, the objective of this current research was to evaluate some Physico-chemical properties and microbial activity after coating with the combination of chitosan, TiO2 nanoparticles, and sodium tripolyphosphate to enhance the cucumbers storability and prolong the shelf-life. The cucumbers fruits were divided into four groups and dipped into several coating solutions for 10 minutes such as distilled water (Cu-uncoated), chitosan 1% (Cu-Chitosan), chitosan 1%, titanium dioxide nanoparticles 1% (Cu-Chitosan-TDN), and chitosan 1%, titanium dioxide nanoparticles 1%, sodium tripolyphosphate 2% (Cu-Chitosan-TDN-ST), respectively. The cucumber samples were then air-dried at ambient temperature and chilled to 10 °C for storage and evaluation for every seven days until three weeks. Cu-uncoated had the highest weight loss with a value of 5.15%, followed by Cu-Chitosan 4.11% while Cu-Chitosan-TDN and Cu-Chitosan-TDN-ST reported the least weight loss of (3.43% and 3.01%, respectively) after 7 days of the storage period. The results reported that the firmness of the samples was found to be decreased during the whole storage time except in the treatments Cu-Chitosan-TDN-ST and Cu-Chitosan-TDN in which it was noticed to be better in firmness after 21 days of storage (55.12 N/mm and 50.67 N/mm), respectively. Total soluble solids were lower in the coated cucumbers compared with the uncoated samples. Titratable acidity of Cu-Chitosan-TDN-ST 0.26% treated sample increased more as compared with Cu-Chitosan-TDN 0.24% samples at the end of the storage period. The highest increase in pectin content was recorded for Cu-Chitosan-TDN samples 0.042 g/100 g on the 21st day. Nano-coating with the combination of chitosan declared the dietary fiber content changes rate than in samples with the addition of sodium tripolyphosphate. Besides, the antimicrobial activity of the chitosan/nanofilms has been improved with the addition of sodium tripolyphosphate as crosslinker 3.67 CFU/g on the 21st day of storage. Thus, nano-coating with the combination of sodium tripolyphosphate has proven to be efficient method in extending the shelf-life of cucumber samples.