Thymol Nanoencapsulated by Sodium Caseinate: Physical and Antilisterial Properties

Abstract

In this work, thymol was encapsulated in sodium caseinate using high shear homogenization. The transparent dispersion at neutral pH was stable for 30 days at room temperature as determined by dynamic light scattering and atomic force microscopy, which agreed with high ζ potential of nanoparticles. The slightly decreased particle dimension during storage indicates the absence of Ostwald ripening. When molecular binding was studied by fluorescence spectroscopy, thymol was observed to bind with tyrosine and possibly other amino acid residues away from tryptophan of caseins. At pH 4.6 (isoelectric point of caseins), the stabilization of thymol nanoparticles against aggregation was enabled by soluble soybean polysaccharide, resulting from the combined electrostatic and steric repulsions. The encapsulated thymol showed the significantly improved antilisterial activity in milk with different fat levels when compared to thymol crystals, resulting from the quicker mixing and increased solubility in the milk serum. The transparent thymol nanodispersions have promising applications to improve microbiological safety and quality of foods.

Penetration of blood–brain barrier and antitumor activity and nerve repair in glioma by doxorubicin-loaded monosialoganglioside micelles system

“…The high magnitude of zeta potential can prevent particle aggregation during storage. 31 Compared to cationic NPs, anionic NPs cause less disruption of plasma-membrane integrity, weaker damage of lysosomal and mitochondrial membrane, 32 and less neuron toxic response. 33 As shown in transmission electron microscopy (TEM) images, the DOX-loaded GM1 micelles were spherical with an average diameter of 5-21 nm, but the particles size was mainly between 8 and 14 nm for the mixed micelles ( Figure 1C).…”

Eugenol Nanoencapsulated by Sodium Caseinate: Physical, Antimicrobial, and Biophysical Properties

“…Additionally, NaCas is hydrophilic and is expected to have a hydrophile-lipophile balance closer to eugenol than thymol. These factors can contribute to the better capacity of NaCas emulsifying eugenol in the present study than that of thymol [14].…”

“…3) were prepared with 20.0 mg/mL NaCas and up to 38.5 mg/mL eugenol (Table 1), and the EE% was higher than 86% (Table 1). These characteristics were better than 50 mg/mL NaCas emulsifying up to 10 mg/mL thymol as stable dispersions [14]. NaCas consists of mixtures of α s1 -, α s2 -, β-, and κ-caseins at proportions of approximately 4:1:4:1 that are all known to be surface active, with β-casein being recognized for the greatest contributor of emulsifying properties [18].…”

“…The self-assembly properties of caseins have been used to nanoencapsulate hydrophobic molecules such as bixin and curcumin [10,11]. NaCas has been used to encapsulate EO components with and without other ingredients such as zein and lecithin [12][13][14]. Thymol nanoemulsified by NaCas showed a significant improvement of anti-listerial activity in milk with different fat contents when compared to free thymol [14].…”

“…NaCas has been used to encapsulate EO components with and without other ingredients such as zein and lecithin [12][13][14]. Thymol nanoemulsified by NaCas showed a significant improvement of anti-listerial activity in milk with different fat contents when compared to free thymol [14]. However, much is unknown about the biophysical properties of EO components after nanoencapsulation.…”