Speakers – June 1, 2022 – Concurrent 5C
Malek El-Aooiti, Ph.D. Candidate – Ryerson University
Controlling particlestabilized food interfaces
Food-grade particle-stabilized (or Pickering) water-in-oil (W/O) emulsions have gained considerable interest in recent years for controlled release applications. The present work presents a method for the deliberate, controllable release of a solute from the dispersed aqueous phase of W/O emulsions stabilized by micron-scale crystals of glycerol monostearate (GMS), a surfactant commonly used in processed foods. Demulsification of GMS-stabilized emulsions and subsequent solute release of NaCl, used as a marker, could be triggered by addition of a small amount of demulsifying surfactant to the oil phase of the starting emulsion. Changes in emulsion morphology were characterized with light microscopy and scanning electron microscopy. The release of NaCl following surfactant addition was characterized, showing evidence of concentrateddependent release. It was found that demulsification and release was driven by changes in the wettability of the GMS crystals at the oil-water interface following addition of the demulsifying surfactant. Overall, this work presents a simple, reproducible approach for the controlled destabilization of, and solute release from, Pickering emulsions.
Satwik Majumder, Ph.D. Candidate – McGill University
Satwik Majumder is a Ph. D student in the Department of Food Science and Agricultural Chemistry, McGill University, Canada. Mr Majumder addresses the implications and applications of sustainable nanotechnology in the field of food and agricultural safety and security. He is investigating the prevalence of antimicrobial resistance in livestock of Canadian farms. His ultimate aim is to develop nano-enabled therapeutics to combat multi-drug resistant bacteria and curtail bacterial infections in livestock. Over the years, Mr Majumder has authored/co-authored several peer-reviewed journal articles, holds a patent, and received scholarships from industrial agencies and institutional groups. He also serves McGill as a teaching assistant, student safety representative and AGSEM delegate.
Nanocomposite of halloysite nanotube with silver and tannic acid as a sustainable antibacterial material for food safety and security
The spoilage and wastage of food due to undesired changes in physicochemical properties and microbial contaminations are major concerns to food safety and security. In addition, the emergence of antimicrobial resistance (AMR) among pathogenic bacteria in livestock and their potential transmission to public health have raised challenges worldwide. Sustainable nanotechnology applications addressing field-deployable antimicrobials, and functional food packaging, have the potential for reducing food wastage and controling infections. In this study, a nanocomposite (GH-TA-Ag-NT) containing nanosilver (AgNPs) grafted onto tannic acid (TA)-modified halloysite nanotubes (HNT) was generated and tested for physicochemical and antibacterial properties. The Transmission Electron Microscopy, Fourier Transformed Infra-Red, Dynamic Light Scattering, and X-ray Diffraction Spectroscopies confirmed the synthesis of the nanocomposite. GH-TA-Ag-NT demonstrated enhanced stability, drug-bioavailability with a slow-release of Ag+ and TA. The nanocomposite showed excellent antibacterial performance in comparison to commercial TA-stabilized AgNPs when tested against E. coli ATCC 25922, S. aureus ATCC 25923, and a multi-drug resistant (MDR) Salmonella enterica serovar Typhimurium (isolated from infected swine) owing to the combinatorial effect mediated through anti-efflux/anti-biofilm properties, oxidative stress, loss of bacterial membrane potential, and integrity. The toxicity and antibacterial efficiency of GH-TA-Ag-NT to remediate gastrointestinal infection were demonstrated in the S. Typhimurium infected Caenorhabditis elegans model. The nanocomposite was less toxic, reduced Salmonella colonization significantly in 24 h of exposure, and improved worm survivability. Moreover, GH-TA-Ag-NT showed antioxidant properties owing to the release of TA from the HNT lumen and showed antibacterial effect when incorporated in polymeric matrix. In summary, we demonstrated a unique and novel strategy to counter AMR bacteria applying Nanoenabled Antibacterial Combination Therapy (NACT) with GH-TA-Ag-NT with multi-functional characteristics that could resolve the common challenges of poor bioavailability, cytotoxicity, stability, drug release, and overdosing. The nanocomposite not only warrants its potential use as a therapeutic against zoonotic pathogens but could also be used in packaging films to reduce food spoilage. Keywords: Food safety and security, Animal agriculture, Packaging films, Sustainable nanotechnology, Halloysite nanoclay, Tannic acid, Nanosilver, Nano-enabled Antibacterial Combination Therapy (NACT), Antimicrobial resistance (AMR), Zoonotic infections, Salmonella enterica serovar Typhimurium, Caenorhabditis elegans.
Shweta Mistry, Ph.D. Candidate, Ryerson University
“Hello, my name is Shweta Mistry and I am a Ph.D. candidate in the Biomedical physics program at Ryerson University and did my undergraduate studies in Materials and Nanoscience from the University of Waterloo. My research focuses on characterizing glycerol monooleate and water based liquid crystals and associating its structural properties to its rheological properties. Such knowledge can be used to tailor the properties of these structures for use in food and pharmaceutical products.”
Glycerol monooleate (GMO)
Glycerol monooleate (GMO) is a commonly used surfactant in the food and pharmaceutical industries. The admixture of GMO and water can form liquid crystals (LCs) with a controllable microstructure upon changes in temperature or GMO:water ratio. Our research hypotheses are that (a) the LC phase directionality dominates the yielding and large deformation behaviour of LCs and that (b) strain-rate frequency superposition (SRFS) may be used to directly measure both the long and short relaxation time of GMO-water LC structures. The microstructure and rheology of GMO-based LCs were characterized as a function of temperature and composition. The structure was assessed using X-ray scattering and polarized light microscopy. Small and large deformation rheology was determined using frequency and amplitude sweeps as well as large amplitude oscillatory shear and SRFS. A binary GMO-water phase diagram was used to identify the presence of lamellar and two cubic phases at temperatures below 65 °C, irrespective of the water:GMO ratio, with a hexagonal phase dominating at higher temperatures. Rheology revealed unique yielding and relaxation times for each of these phases. Via amplitude sweeps, the cubic phases demonstrated a distinct G′′ overshoot that was absent in the lamellar and hexagonal phases. Parameters extracted from the Lissajous plots, namely the stiffening and thickening ratios, provided further insights into their structural deformation. Finally, SRFS showed that these LCs measurably differed in structural relaxation times. We confirmed our hypothesis that each LC phase has unique rheological behaviour upon large deformation and, by linking rheology with X-ray scattering data, showed that their symmetry defined their rheology.
Dr. Saji George, Associate Professor, McGill University
Dr Saji George is an Associate Professor in the Department of Food Science and Agricultural Chemistry at McGill University and holder of Canada Research Chair in Sustainable Nanotechnology for Food and Agriculture. He received a Bachelor’s degree in Food Science & Quality Control and a Master’s in Biotechnology from Mahatma Gandhi University, India. After obtaining a PhD from the National University of Singapore, Dr. George completed a postdoctoral training in nanotoxicology from University of California, Los Angeles, USA. Prior to his joining at McGill in January 2017, Dr George was spearheading Centre for Sustainable Nanotechnology at Nanyang Polytechnic. His current research is
aimed at understanding the relationship between nanomaterial properties and their hazardous and beneficial biological outcomes with the goal of developing sustainable nanotechnology applications for addressing challenges in food safety and security. On going research projects include developing quantifiable biomarkers involved in adverse outcome pathways (AOP) for major gastro-intestinal pathologies including inflammation and food allergy and developing nanotechnology enabled antibacterial combination therapy. The knowledge developed from his group have been disseminated through 65 peer reviewed articles (cited >7000 h-index of 36), 7 patents (3 awarded, 4 under review), and over 40 invited talks. He had served as a technical committee member in ISO/TC 229 (dealing with Environmental Safety and Health of Nanomaterials). His excellence in teaching and research have been recognized by Ministry of Education, Singapore through the best mentor award and PS21 ExCEL Gold/Silver Awards in 2015 and 2016.
Enhancement of food allergy by food additive nanomaterials
The global prevalence of food allergy characterized by abnormal immune response to food protein antigens is increasing. While the reasons for this increase in food allergies are not entirely understood, potential role of food additive nanoparticles cannot be overlooked as nanoparticles have been implicated in allergic inflammation of respiratory system. We have studied interactions of food additives nanoparticles with food matrices and proteins that revealed the potential of nanoparticles to enhance antigenicity and allergenicity of food proteins. Our studies have shown that addition of food additives nanoparticles such as SiO2 and TiO2, to milk for example, will lead to preferential surface adsorption of allergenic proteins such as