Synthesis of a new thiourea-polygalacturonic acid nanocomplex adsorbent for removing patulin from apple juice simulator and apple juice
2022
Safajoo, Saeede | Sadeghi, Ehsan | Noroozi, Razieh | Muḥammadī, Riz̤ā | Moradi, Leila | Razmjoo, Fatemeh | Paimard, Giti
Patulin is a fungal by-product that contaminates fruits and vegetables, especially apples, and is mainly produced by Penicillium expansum. In the present study, thiourea-polygalacturonic acid (TPGA) complexes were synthesized in three ratios, i.e. 1:1 (T₁P₁), 1:2 (T₁P₂), and 2:1 (T₂P₁). They were evaluated for patulin removal from apple-juice simulated solution. The characterization of TPGA complexes was specified by Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, and scanning electron microscopy. Adsorption tests were carried out to study variable effects of the TPGA ratio, TPGA concentration, contact time, and patulin initial concentration. The results showed that the amide bond was the main binding agent of the TPGA complexes, and the complexes formed aptly in having nano particle sizes. The T₁P₂ nanocomplex gave the best results, which means that polygalacturonic acid was more effective than thiourea in the adsorption process. The results also indicated that increasing the contact time, adsorbent, and patulin concentration ultimately increased the adsorption capacity. This nanocomplex could adsorb the whole toxin at all patulin concentrations (i.e. 25, 50, and 100 μg/L) in short durations (i.e. 1, 2.5 and 5 h, respectively). The results of adsorption tests were well adapted to the pseudo-first order model (with R² of 0.991, 0.993, and 0.996) and Freundlich isotherm model (R² = 0.997). Moreover, these nanocomplexes were able to remove 91.35% of patulin from contaminated apple juice. This work demonstrated that TPGA nanocomplexes can serve as potential materials for removing patulin.
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