Speakers – June 1, 2022 – Concurrent 5C
Amal Mohamed, Ph.D. Candidate – McGill University
This research focused on developing active packaging materials by using sodium caseinate-carboxymethyl chitosan (NaCa: CMCH) and calcium caseinate-carboxymethyl chitosan (CaCa: CMCH) edible films. Caseinates protein films were prepared from sodium and calcium caseinate solutions (8% w/v) for each one and carboxymethyl chitosan solution was 2% all solutions mixed in appropriate ratio to obtain the following proportions: 100:0, 0:100, 75:25, and 50:50 (NaCa: CMCH) and (CaCa: CMCH) containing artemisia extract (AE) (1 and 3% w/w) added as natural antioxidants, and glycerol (5% w/w) as a plasticizer. All films were Thicker and more translucent films (p < 0.05) were produced when a higher concentration of AE was used. Adding the AE resulted in an improvement in the water vapor barrier and mechanical properties of film at ratios 75:25 and 50:50. The mechanical test revealed an increase in the tensile strength, a decrease in elongation at break, and a decrease in water vapor permeability. The antioxidant activity increased with a greater concentration of AE incorporated in both films (p < 0.05) with more impact in sodium caseinate films compared to calcium caseinate film in DPPH and ABTS analysis. DPPH analysis on NaCa at 75% film revealed the highest antioxidant activity (90%) at 3 % of AE. Moreover, the water solubility of the films at 50:50 containing 3% of the AE for both films showed higher value with 66% and 64% respectively for NaCa-50 and CaCa -50. FTIR analysis showed good compatibility for all films while the SEM showed homogeneous and smooth surfaces containing no obvious crack or holes.
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.