Speakers – June 2, 2022 – Concurrent 2B

Role of Interfaces in Food Systems – The path to enhancing safety, stability and functionality

Dr. Cansu Ekin Bonacina, Ankara University

Cansu Ekin Gumus-Bonacina is an Assistant Prof. at Ankara University – Department of Food Engineering. She received her bachelor’s and master’s degree from Ankara University’s department of food engineering, where her studies involved studying the sterol and wax contents of hazelnut oils. Dr. Bonacina obtained her Ph.D. in Food Science (2017) from the University of Massachusetts Amherst under the guidance of Professor David Julian McClements on the subject of “Utilization of Natural Emulsifiers and Their Derivatives To Formulate Emulsion-Based Delivery Systems For Hydrophobic Nutraceuticals” at the Food Biopolymers & Colloids Research Laboratory. Dr. Bonacina is involved in research on emulsion-based delivery systems, with special emphasis on natural emulsifiers.


Emulsifiers From Natural Sources as Alternatives to Synthetic Ones

Food industry is trying to find natural alternatives to synthetic emulsifiers. Plant-based proteins are common options. For example, legume proteins, such as pea, lentil and bean proteins are traditionally consumed worldwide and they were shown to have promising functional properties and stability characteristics. In addition, emulsifying properties of novel protein sources such as insect-based proteins are also being investigated. Moreover, natural polysaccharides such as plant-derived mucilages, are gaining popularity regarding their functional properties. Each emulsifier option has advantages and disadvantages. For instance, protein-stabilized emulsions tend to be unstable under various environmental conditions, while a high amount of polysaccharides are needed to produce small droplet sizes. Therefore, it is important to test their stability in model food systems.

Dr. Erica Pensini, Associate Professor – University of Guelph

Dr. Erica Pensini received her bachelor and MASC at the Politecnico di Milano (Italy). She worked in the environmental consulting industry (AECOM and MWH Stantec, Milan), before completing her PhD in Environmental Engineering from the University of Toronto in 2012. Here, she investigated the remediation of chlorinated compounds and heavy metals using nano-scale zero valent iron. Between 2012 and 2014, she held a position as a Postdoctoral Researcher at the University of Alberta, where she mainly investigated the mechanisms of emulsion stabilization and destabilization in the context of bitumen recovery. She then worked as research associate for SANJEL in Calgary (developing fracking fluids) and as scientist for SABIC in the Netherlands (investigating methods to mitigate fouling in a steam cracker). Pensini joined the School of Engineering at the University of Guelph in 2017 where she is currently an associate professor. The Pensini lab focuses on water treatment, soil remediation and the development of bio-based materials as plastic substitutes.


Zein Reactors on an Air Bubble: Using a Food Grade Protein and Laccase for Environmental Remediation

Authors: Tatianna Marshall1, Alejandro G. Marangoni2, Thamara Laredo3, Klaudine M. Estepa1, Maria G. Corradini2,4, Loong-Tak Lim2, Erica Pensini1*

1University of Guelph, School of Engineering, 50 Stone Road East, Guelph (ON), N1G 2W1, Canada

2University of Guelph, Food Science Department, 50 Stone Road East, Guelph (ON), N1G 2W1, Canada

3Lakehead University, Centre of Excellence for Sustainable Mining & Exploration, Chemistry Department, 500 University Ave, Orillia (ON), L3V 0B9, Canada

4Arrell Food Institute, University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1, Canada

*Corresponding author: email: epensini@uoguelph.ca; phone: +1 519-824-4120 ext. 56746


Zein is a commercial corn protein and laccase is an enzyme found in edible mushrooms (such as Tremella fuciformis, a gelatinous mushroom used in the Asian cuisine and also known as ‘snow fungus’). Here, we use zein and laccase to treat water polluted by naphthalene using two approaches.

The first approach uses laccase-containing solid zein sorbents coagulated with either CaCl2 at pH=13 or with Fe2Cl3 at pH=10. Fluorescence spectroscopy demonstrates that laccase degrades naphthalene in water at neutral pH. Laccase activity is pH-dependent: laccase retains its activity after exposure to pH values as high as 10, and has maximum activity at pH=5.5. Laccase immobilized in zein sorbents coagulated with Fe2Cl3 at pH=10 has a relative activity of approximately 8%. In contrast, laccase activity significantly decreases in zein sorbents coagulated with CaCl2 at pH=13. Attenuated total reflection Fourier-Transform Infra-Red (ATR-FTIR) spectroscopy shows that naphtalene sorption onto zein sorbents occurs because of hydrophobic interactions and CH/p bonding between naphthalene (the p base) and the aliphatic groups (hydrogen donors) of non-polar residues of zein. Gas Chromatography Mass Spectroscopy (GC-MS) demonstrates that our sorbents remove naphthalene from water. The sorption capacity of zein sorbents is  14 mg/g at 21⁰C, and followed first-order kinetics with a rate constant of 0.0066 min-1.

The second approach uses zein and laccase to stabilize air bubbles in water, producing “reactors on an air bubble” for air sparging applications. Air sparging injects air in contaminated aquifers to strip volatile contaminants from groundwater. Small, stable air bubbles with large surface area promote contaminant removal. Laccase at the bubble surface enables naphthalene degradation. Surface tension measurements show that laccase and zein adsorb at the air-water interface at either acidic or alkaline pH. At acidic pH, the compression isotherms of zein-laccase films at the air-water interface differ from those of the individual components, suggesting zein-laccase co-adsorption. At alkaline pH, iron promotes co-adsorption of zein-laccase at the air-water interface, likely by modulating their electrostatic interactions. Foams are stable at alkaline pH, with either zein alone or zein-laccase complexes, and iron enhances foam stability. These results indicate that zein and laccase can facilitate the remediation of naphthalene by promoting air bubble stability and naphthalene sorption at the air-water interface, as well as its enzymatic degradation.

Katherine Petker, Ph.D. Candidate – University of Guelph

Katherine Petker completed her B.A.Sc. degree in Chemical Engineering at the University of Ottawa in 2017. She began her PhD in Food Science in Fall 2018 in the Cereal Lab at the University of Guelph. Her research focuses on the use of cereal proteins for the production of colloidal nanoparticles. She is particularly interested in the aggregation behaviour of prolamin proteins/nanoparticles and the utilization of these particles to build and stabilize novel food products.


Stabilization of fluid interfaces with cereal prolamin nanoparticles

The stability of emulsions and foams is strongly influenced by the interfacial characteristics (i.e. interfacial tension and rheology, electrostatic repulsion) imparted by the emulsifiers used to coat the droplets or bubbles. Surface-active colloidal protein nanoparticles show promise for use as stabilizers in food emulsions and foams, although their behaviour at fluid interfaces is not well understood. Past studies of nanoparticles made from gliadin, the prolamin protein found in wheat, have indicated that that the deformation and interaction of particles at air-water interfaces are partly responsible for their foamstabilizing abilities. The objective of this study is to further investigate the structure-function relationship of gliadin nanoparticles (GNPs) by examining the behaviour of untreated and chemically hardened GNPs at air-water and oil-water interfaces, whereby hardening stabilizes the nanoparticle matrix. GNPs were prepared using a liquid anti-solvent precipitation method and chemically hardened by adding glutaraldehyde to the GNP dispersions and stirring for 1 h. The stability of GNPs to redissolution in aqueous ethanol was determined by measuring the particle size distribution and polydispersity index of GNPs before and after dispersing in 70 v/v% ethanol. The interfacial tension and dilational viscoelastic moduli of the GNP dispersions at air-water and oil-water interfaces were determined using drop shape tensiometry. GNP-stabilized oil-in-water emulsions were prepared by shear homogenization and the microstructure of emulsions was characterized using cryogenic scanning electron microscopy (cryo-SEM). Particle size and polydispersity measurements showed that particles treated with glutaraldehyde demonstrated stability to disintegration in aqueous ethanol (70 v/v%), while untreated GNPs appeared to break apart under these conditions, with smaller particle sizes and higher polydispersity. Air-water and oil-water tensiometry revealed that interfaces populated with untreated GNPs had lower interfacial tension and higher dilational viscoelastic moduli than what was observed for hardened GNP dispersions. Cryo-SEM micrographs revealed that emulsions stabilized with untreated GNPs formed more continuous oil droplet networks with more connections between droplet interfaces, implying interaction between protein particles on neighboring oil droplets and in the continuous phase. Emulsions stabilized by hardened GNPs had a more discontinuous microstructure, with flocs of aggregated oil droplets throughout the continuous phase. These results suggest that the deformability of untreated GNPs plays an important role in their ability to rapidly adsorb, rearrange, and interact at fluid interfaces to form coherent viscoelastic protein films. Furthermore, the flexibility of protein particles is essential to the formation of a continuous emulsion microstructure due to the interaction between adsorbed particles on neighbouring oil droplets and in the continuous phase. These findings provide important insight into the mechanisms by which protein nanoparticles stabilize fluid interfaces which can aid in the design of particle stabilizers for edible emulsions and foams.

Dr. Ebenezer Falade

Dr. Falade Ebenezer graduated from the Federal University of Technology in Akure, Nigeria, with a bachelor’s degree in microbiology and a master’s degree in food microbiology. In January 2022, he received his PhD in Agricultural Food Processing and Utilization from the Graduate School of the Chinese Academy of Agricultural Sciences, Beijing China. His PhD research focused on Interfacial stability mechanism of sweet potato protein peptides emulsion influenced by ultrasound microwave-assisted enzymatic hydrolysis and environmental factors under high hydrostatic pressure, with the goal of improving the emulsifying capability and antioxidant activity of sweet potato protein peptides using emerging processing technologies. As part of his research findings,he identified peptide sequences and predicted structural conformation of dominant antioxidant and emulsifying sweet potato protein peptides at emulsion interfaces.  Ebenezer is a member of Nigerian Institute of Food Science and Technology and has served as teaching assistant in microbiology department of Federal University of Technology Akure. Dr. Ebenezer has authored and co-authored five published journal articles, three invited lectures, and two significant food science initiatives/conferences. He is currently open for partnership or postdoctoral research funding for studies involving food hydrocolloids, protein functionality, encapsulation and delivery systems, nanotechnology, lipid oxidation, or any other food-related study.


Peptides as natural functional ingredients in food emulsion

Protein hydrolysates used as functional food ingredients have recently gathered attention majorly due to their functional activities displayed in model systems. However, protein hydrolysate emulsions are unstable under long time storage due to their poor adsorption at emulsion interface. In this study, ultrasound microwave (UM)-assisted enzymatic hydrolysis was used to prepare sweet potato protein hydrolysates (SPPH) with improved emulsifying properties. And high hydrostatic pressure (HHP) was used to further improve the physically stability. In addition, to better understand the potential use of SPPH as natural functional ingredients in food emulsion, the identification and characterization of peptides adsorbed at oil/water interface were investigated. It was found that UM-assisted enzymatic hydrolysis significantly improved emulsifying properties of SPPH. HHP enhanced physically stability of SPPH emulsions, and increased the adsorption and antioxidant activity of SPPH in interfacial layer. Additionally, changes in peptide conformation and position of some specific amino acids were revealed by structure-activity relationship analysis. It can be inferred that the absorbed peptides in interfacial layer was responsible for the physical stability of the emulsions Thus, UM and HHP have great potential in peptides production with enhanced functionality.


Dr. Xiaonan Lu, Professor – McGill University

Dr. Lu is professor and Ian & Jayne Munro chair in food safety in the Department of Food Science and Agricultural Chemistry at McGill University. Before that, he was assistant and associate professor at Faculty of Land and Food Systems, The University of British Columbia (2013-2020). His research focuses on food safety and food microbiology. Lu’s lab develops innovative and rapid sensing, instrumentation systems, and detection methods for ensuring food safety as well as preventing food bioterrorism and fraud. His lab also applies molecular biology and genomic approaches to investigate stress response and pathogenesis of microorganisms that pose threats to agri-food systems and public health. He has published more than 130 peer-reviewed papers. He is the recipient of Young Scientist Award from Agricultural & Food Chemistry Division, American Chemical Society (2021), Samuel Cate Prescott Outstanding Young Scientist Award from Institute of Food Technologists (2021), Larry Beuchat Young Researcher Award from International Association for Food Protection (2017), and Young Scientist Excellence Award from International Union of Food Science and Technology (2015). 


Development of a novel interface of active packing integrating immobilized zinc oxide nanoparticles to control Campylobacter jejuni in raw chicken meat:

Zinc oxide nanoparticles (ZnO NPs) are regarded as a safe and stable antimicrobial that can inactivate bacteria by several potential working mechanisms. We aimed to incorporate ZnO NPs into packaging material to control Campylobacter in raw chicken meat. ZnO NPs were first incorporated into three dimensional (3D) paper tubes to identify the lethal concentration against Campylobacter jejuni, which was selected as the working concentration to develop 2D functionalized absorbing pads by an ultrasound-assisted dipping technique. The functionalized pad was placed underneath raw chicken meat to inactivate C. jejuni and the predominant chicken microbiota at 4°C within 8 days of storage. Immobilized ZnO NPs at 0.856 mg/cm2 reduced C. jejuni from ~4 log CFU/25 g raw chicken meat to an undetectable level after 3 days of storage. Analysis by inductively coupled plasma-optical emission spectroscopy showed that the Zn level increased from 0.02 to 0.17 mg/cm2 in treated raw chicken meat. Scanning electron microscopy validated the absence of nanoparticle migration onto raw chicken meat after treatment. Inactivation of C. jejuni was associated with the increase of lactic acid produced by Lactobacillus in raw chicken meat in a pH dependent manner. Less than 5% of Zn2+ was released from ZnO NPs at neutral pH, while up to 88% was released when the pH was <3.5 within 2 days. Whole transcriptome sequencing (RNA-Seq) analysis demonstrated a broad effect of ZnO NPs on genes involved in various cellular developmental processes as annotated by gene ontology. Taken together, the results indicate that functionalized absorbing pads inactivated C. jejuni in raw chicken meat by immobilized ZnO NPs along with the controllable released Zn2+.