Postharvest Physicochemical Properties and Fungal Populations of Treated Cucumber with Sodium Tripolyphosphate/Titanium Dioxide Nanoparticles during Storage

Ebtihal Khojah,Mahmoud Helal,Rokayya Sami,Mohammed Saeed Alkaltham,Abeer Elhakem,Ahmad Mohammad Salamatullah,Nada Benajiba

doi:10.3390/coatings11060613

Abstract

Cucumbers have a limited shelf-life, from 10 to 14 days at commercial temperatures with relative humidity (80%). The aim of the work was to evaluate the postharvest physicochemical properties and fungal populations of cucumber treated with sodium tripolyphosphate/titanium dioxide nanoparticles during storage at 10 °C to prolong the shelf-life to 21 days. Cucumber samples treated with chitosan/sodium tripolyphosphate/titanium dioxide nanoparticles (Cu-CHS-TDN-ST) and (Cu-CHS-TDN-ST) were found to be in a well-hydrated state and with a green-colored appearance upon day 21, with excellent quality for consumption. Chitosan coating (Cu-CHS) alone prolonged the cucumber shelf-life for 14 days of storage. The Cu-CHS coating was less evident in reducing the respiration rate of cucumbers on day 14 than both nanocoatings, which were reported at the end of the storage period to be 5.09 and 5.38 mg·kg−1 h−1 for Cu-CHS-TDN-ST and Cu-CHS-TDN, respectively. The Cu-CHS-TDN-ST treatment reduced the loss of ascorbic acid content to 13.17 mg/100 g, delayed chilling injury, and had the highest chlorophyll contents during the whole storage period. The presence of sodium tripolyphosphate with the nanocoating delayed tissue damage. Peroxidase enzyme activity reached the maximum of 54.65 Ug−1 for Cu-CHS-TDN-ST on day 21, followed by Cu-CHS-TDN 50.1 Ug−1. On day 21, the fungal populations of Cu-CHS-TDN samples (3.77 log CFU/g) were more than that of Cu-CHS-TDN-ST (3.15 log CFU/g) against Cu-Control (100 % spoiled). It was noted that the Cu-CHS-TDN-ST and CHS-TDN-ST coating treatments were capable of preserving the cucumber samples’ quality during storage. The addition of sodium tripolyphosphate as a crosslinker for stabilizing the nanoparticle polymers in the coating treatments prolonged the shelf-life and achieved excellent quality for the cucumbers.

Highlights

Cucumber (Cucumissativus L.) is a low-calorie fruit, rich in iron, magnesium, and potassium with a high moisture content
The materials used for the coating solutions were sodium tripolyphosphate, titanium dioxide nanoparticles, chitosan, and acetic acid (98%) as a preservative
Symptoms of chilling injury appear as severe shriveling, surface pitting, sunken spots, water-soaked areas, and decay which could be due to ethylene, amino cyclopropane carboxylic acid, and putrescine increase [18,29]

Summary

Introduction

Cucumber (Cucumissativus L.) is a low-calorie fruit, rich in iron, magnesium, and potassium with a high moisture content. Cucumber quality is based on several factors such as shape, color, texture, size, absence of any signs of physical or microbial changes [1]. The cucumber tends to have some physicochemical changes, microbial populations, and desiccation, which influence the appearance and lower the nutrients. A chilled condition of 10 ◦ Cwas applied to solve those problems which became more disposed to the quality loss after 2 weeks [4]. The American Food and Drug Administration (AFDA) reported that TiO2 nanoparticles are non-toxic and safe to be used in human food. They are used for their white coloring, photo-protective, coloring of TiO2 photoprotective, and photocatalytic properties. Sodium tripolyphosphate is an economical chemical component that can act as a crosslinker for stabilizing the nanoparticle polymers in nanoparticle formations [17]

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