Development of novel ultrathin structures based in amaranth (Amaranthus hypochondriacus) protein isolate through electrospinning

Abstract

Amaranth protein isolate (API) ultrathin structures have been developed using the electrospinning technique. The effects of pH, type of solvent and surfactant addition on the spinnability, morphology and molecular organization of the obtained structures have been studied. Regarding the effect of pH on API electrospinning, capsule morphologies were only obtained at extreme pH values (i.e. pH 2 and pH 12), which allowed the solubilisation of the proteins, and the process was favoured when the solutions were previously heated to induce protein denaturation. Fibre-like morphologies were only obtained when the solvent used for electrospinning was hexafluoro-2-propanol, as this organic solvent promotes the formation of random coil structures and, thus, an increase in the biopolymer entanglements. Capsule morphologies were obtained from the API-containing formic acid solutions and this solvent was better for electrospraying than the acetic acid, probably due to the higher viscosity and lower surface tension of the solutions thereof. Addition of 20 wt.-% of Tween 80 considerably improved the formation of capsule-like structures from the formic acid solution, as this surfactant contributed to the formation of alpha helical structures. Similar results were obtained when combining the surfactant with the reducing agent 2-mercaptoethanol. However, denaturation of the protein structure was not sufficient for fibre formation through electrospinning, as the solution properties play a fundamental role in determining the morphology of the electrospun structures.

Stable nisin food-grade electrospun fibers

“…The first stage, observed up to 120°C, is related to the loss of adsorbed and bound water (Neo et al 2013a) and the second stage is attributed to the decomposition of the sample and the formation of a carbonaceous residue (Zhu et al 2014). Similar results have been reported by Aceituno-Medina et al (2013a). In the case of nisin loaded nanofibers, the first stage of loss weight decreased as the concentration of nisin increased; thus suggesting that nisin contributes to the hydrophobicity of the fibers, rendering less entrapment of water molecules and the need of less energy to release the solvent molecules from the fiber.…”

“…To protect nisin antimicrobial activity, some nanostructure materials have been developed, for example nanoparticles, nanoliposomes and nanofibers (Sadiq et al 2016). Natural polymers such as zein (Neo et al 2013a), whey protein (Sullivan et al 2014), soy-protein (Har-el et al 2014, and amaranth protein (Aceituno-Medina et al 2013a) have been used to develop electrospun mats. The mats are composed by fibers with micro or nanoscale diameters and display packaging desirable characteristics such high surface area and porosity, absorbability of liquids, semi permeability for vapors and gases and capability for incorporating heat sensitive bioactive compounds (de Faria et al 2015).…”

Characterization, release and antioxidant activity of curcumin-loaded amaranth-pullulan electrospun fibers

“…The Amaranth Protein Isolate (API) was prepared based on the methodology previously reported by Aceituno-Medina et al (2013a). Formic acid of 95% purity, Tween 80, Pul (M w~1 00000), curcumin, 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), potassium persulfate, pancreatin, bile and methanol were supplied by SigmaeAldrich Co. (St. Louis MO, USA).…”

“…In our group, the ability of an amaranth protein isolate (API) combined with pullulan (Pul), a spinnable carbohydrate polymer (Fig. 1), to generate electrospun microstructures was demonstrated (Aceituno-Medina, Lopez-Rubio, Mendoza, & Lagaron, 2013a, 2013b. These structures can be used to encapsulate a wide variety of bioactive compounds which biological activities can be diminished due to processing, gastrointestinal conditions or to the inherent characteristics of the food matrix such as pH, redox potential, water activity, enzyme content, etc.…”

Food Nanoscience and Nanotechnology

“…However, edible proteic systems, such as the above mentioned, or gelatin and collagen, cannot be electrospun from aqueous solutions due to extensive hydrogen bonding resulting in gel formation, and therefore toxic or aggressive solvents are required to produce these nano-fibers. Casein or wheat proteins have poor electrospinnability and need to be mixed with other polymers such as PEO, PVA, or other synthetic biopolymers like polylactic acid or ɛ-caprolactone with the use of toxic solvents (Xie and Hsieh 2003;Castro-Enriquez et al 2012;Montano-Leyva et al 2011;Selling et al 2012;Aceituno-Medina et al 2013). This limits the edibility of the resulting systems.…”