Water contamination by mercury and chromium has a direct effect in human health. A promising technology to remove heavy metals by membrane filtration is the use of hybrid membranes produced with whey protein fibrils (WPF) and activated carbon (AC). In this study, the best conditions to produce WPF by heat treatment were determined to maximize the removal of mercury and chromium from water using a central composed design. The results indicated that the best conditions to prepare WPF were 74 °C, 7 h and 3.8% of whey protein with adsorption capacities of 25 and 18 mg/g and removal efficiencies of 81 and 57% for mercury and chromium, respectively. WPF and AC were used to prepare a hybrid membrane that was characterized using transmission electron microscopy, atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller surface area measurements. Batch filtration experiments were performed with the hybrid membrane for chromium and mercury removal at 25, 50 and 100 mg/L to determine its adsorption capacities. A high performance of the hybrid membrane was demonstrated removing efficiently mercury and chromium from water, thus supporting more than ten filtration cycles.

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Chromium pollution represents a worldwide concern due to its high toxicity and bioaccumulation in organisms and ecosystems. An interesting material to remove metal ions from water is a whey-protein-based material elaborated by electrospinning, which is an emerging method to produce adsorbent membranes with diverse applications. The aim of this study was to prepare an adsorbent membrane of whey protein isolate (WPI) and polycaprolactone (PCL) by electrospinning to remove chromium ions from water. The adsorbent membrane was synthesized by a central composed design denaturing WPI using 2-Mercaptoethanol and mixing it with PCL to produce electrospun nanofibers. The adsorbent membrane was characterized by denaturation, Scanning Electron Microscope, Fourier-Transform Infrared Spectroscopy, Contact Angle, Thermogravimetric Analysis, and X-Ray Photoelectron Spectrometry. The adsorption properties of this membrane were assessed in the removal of chromium. The removal performance of the membrane was enhanced by an increase in temperature showing an endothermic adsorption process. The adsorption process of chromium ions onto the nanofiber membrane followed the Sips adsorption isotherm, while the adsorption kinetics followed a pseudo-second kinetics where the maximum adsorption capacity was 31.0 mg/g at 30 °C and pH 2. This work provides a novel method to fabricate a hybrid membrane with amyloid-type fibrils of WPI and PCL, which is a promising adsorbent to remove heavy metal ions from water.

The aim of this study was to assess the inhibitory effect of three commercial bioprotectant agents on the growth of yogurt-spoiling fungi. Mucor circinelloides, Mucor racemosus, Penicillium spp., Saccharomyces exiguus, and Candida intermedia, commonly involved in the spoilage of dairy products, were isolated from spoiled yogurt and were fully characterized using molecular and phenotypic methods. HOLDBAC-YMC™, Lyofast-FPR2™ and MicroGARD 200™ were used as antifungal products. An optimized experimental mixture design was applied to determine the proportion of each bioprotectant in terms of growth-inhibition response against the fungal strains in standard laboratory media. The results of the challenge tests showed that the application of bioprotectants inhibited the growth of the moulds in the range of 85–100% and the growth of yeast between 1.23 and 5.40 log cycles. The optimal combination of the bioprotectants was determined, tested in standard laboratory media and found to inhibit fungal growth. The antifungal effect of the optimal combination of the bioprotectants was validated in yogurt against the most resistant fungal species of the study, M. circinelloides and C. intermedia. The bioprotectants elicited antifungal effect in yogurt by completely inhibiting all of the tested fungi compared to controls. To the best of our knowledge, this is the first time a mixture of commercial bioprotectants has been tested on yogurt as a potential alternative for the biopreservation of yogurt in order to reduce spoilage of fermented dairy products and economic losses.