One-Pot Procedure for Recovery of Gallic Acid from Wastewater and Encapsulation within Protein Particles

详细信息    查看全文

• 作者：Himan Nourbakhsh ; Ashkan Madadlou ; Zahra Emam-Djomeh ; Yi-Cheng Wang ; Sundaram Gunasekaran ; Mohammad E. Mousavi
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2016
• 出版时间：February 24, 2016
• 年：2016
• 卷：64
• 期：7
• 页码：1575-1582
• 全文大小：469K
• ISSN：1520-5118

文摘

A whey protein isolate solution was heat-denatured and treated with the enzyme transglutaminase, which cross-linked ≈26% of the amino groups and increased the magnitude of the ζ-potential value. The protein solution was microemulsified, and then the resulting water-in-oil microemulsion was dispersed within a gallic acid-rich model wastewater. Gallic acid extraction by the outlined microemulsion liquid membrane (MLM) from the exterior aqueous phase (wastewater) and accumulation within the internal aqueous nanodroplets induced protein cold-set gelation and resulted in the formation of gallic acid-enveloping nanoparticles. Measurements with a strain-controlled rheometer indicated a progressive increase in the MLM viscosity during gallic acid recovery corresponding to particle formation. The mean hydrodynamic size of the nanoparticles made from the heat-denatured and preheated enzymatically cross-linked proteins was 137 and 122 nm, respectively. The enzymatic cross-linking of whey proteins led to a higher gallic acid recovery yield and increased the glass transition enthalpy and temperature. A similar impact on glass transition indices was observed by the gallic acid-induced nanoparticulation of proteins. Scanning electron microscopy showed the existence of numerous jammed/fused nanoparticles. It was suggested on the basis of the results of Fourier transform infrared spectroscopy that the in situ nanoparticulation of proteins shifted the C–N stretching and C–H bending peaks to higher wavenumbers. X-ray diffraction results proposed a decreased β-sheet content for proteins because of the acid-induced particulation. The nanoparticles made from the enzymatically cross-linked protein were more stable against the in vitro gastrointestinal digestion and retained almost 19% of the entrapped gallic acid after 300 min sequential gastric and intestinal digestions.