Research Objective
The overall goal of this research was to develop a plant-based scrambled egg alternative that mimics the texture, taste, and colour of real eggs. The project screened both pulse protein and canola protein isolates from various commercial sources as the base of the formulations based on their functionality, and then examined the role of hydrocolloids, calcium, and processing conditions on their “egg”-forming abilities. Current plant-based scrambled egg alternatives on the market experience water retention issues (causing the cooked product to appear wet) and softer textures compared to real egg. Since gelation and emulsion stability are the key attributes for vegan egg formations, they were the focal point of the project.
Where and how was the research conducted?
The research was conducted at the University of Saskatchewan (Saskatoon, SK). Pulse and canola proteins were sourced from commercial partners across North America. The main reseach was lab-based followed by scale-up and further product development at the Saskatchewan Food Industry Development Centre.
Why?
Research on the development of a replacement for scrambled egg that coagulates and forms a strong gel when cooked on a skillet/frying pan is severely lacking. Despite this, commercial products exist. The leading product is “JUST Egg”, a pourable liquid/emulsion that resembles scrambled egg when cooked in a similar manner with its primary ingredient being mung bean protein. While an innovative product, JUST Egg does not match the textural properties of real egg. Syneresis occurs after cooking giving the product an unappealing “wet” appearance. Based on preliminary data of the texture properties, cooked JUST Egg has a lower hardness, springiness, and gumminess than scrambled egg made with liquid eggs, suggesting that upon chewing it has less resistance to breakdown in the mouth. JUST Egg also has a sticky adhesive quality to it that regular scrambled eggs do not have. Therefore, the market is ripe for a product that more closely mimics the texture of real egg. This project considers a range of pulse and canola protein isolates for their potential as a scrambled egg replacer; examines strategies for modifying protein ingredients for enhanced functionality; examines both formulation and processing approaches to develop egg-like structures.
Objective: Characterization of plant protein isolates
Eleven different protein isolates [faba bean, lentil, pea (x5), chickpea, and canola (x3)] were examined for their solubility, emulsion stability, water/oil holding, and rheology (flow behavior and gelation). Based on these initial findings (primarily based on their emulsifying and gelling potential), 1 pea and 2 canola protein isolates were selected for further evaluation. Gelling capacity of these isolates were closet to that of the ‘JUST Egg’ (commercial plant-based egg replacer) and real egg samples, but still weaker in nature indicating a softer product.
Objective: Production and characterization of modified commercial pulse protein isolates
pH-shifting strategies involving acidic or alkaline treatments were applied to enhance the selected protein’s functionality. Despite some changes in functionality, the process did not enhance the gelling properties, instead having an inverse effect on the 1 pea and 2 canola protein isolates from Obj. 1. Only one canola protein isolate was selected to move forward on based on their gelling abilities.
Objective: Formulation development of plant-based egg replacer
The impact of various hydrocolloid types (gellan gum, high methoxyl (HM) pectin and carrageenan)/concentration (0.25 vs 0.5%), calcium, and mode of shear (polytron vs high pressure homogenization) on canola protein isolate emulsions and their skillet cooked product were examined. Emulsions and “egg-like” textures formed with canola protein isolate combined with HM pectin (0.5%) and calcium showed the most promising structures, when produced using high pressure homogenization. Droplet sizes were significantly smaller, emulsifying stability was improved and similar or improved textures were obtained.
Objective: Enhancement of plant based egg replacer formulation
Formulations were then flavored with “egg” flavouring to mimic the taste of real egg, however improvement to the colour of the canola protein isolate-ingredient is needed. Work was done in collaboration with the Saskatchewan Food Industry Development Centre.
What are the results of this project in more detail?
Characterization of unmodified/modified protein isolates
Eight commercially-sourced and three pilot-scale plant protein isolates/concentrates were screened for their potential as ingredients in a liquid egg replacer. There was a wide range in the structural and functional properties within the pulse proteins or canola proteins indicating the important role of the extraction and processing method to produce the isolates. Overall, the pulse proteins formed weak gel structures compared to the canola proteins however, one pea protein isolate (PPI) formed a strong heat-set gel. A pH shift treatment was used to modify the aforementioned PPI and two different canola protein isolates (CPI). Acidic pH shifting induced more changes to the protein isolates than alkaline pH shifting. However, neither acidic nor alkaline pH shifting induced significant enough changes to the gelling behaviour of the proteins to justify its use in formulating a plant-based egg replacer with commercial potential.
Bench-top formulation
Formulating the plant-based egg replacer emulsions with CPI, high-methoxy pectin (0.5%) calcium (50 mM) and canola oil via a high-pressure homogenizer resulted in good emulsion viscosity, droplet size, and stability. The pectin performed better than the other hydrocolloids tested (carrageenan and gellan gum). High-pressure homogenization produced superior emulsion properties in comparison to mechanical shear with a benchtop homogenizer. The texture of the egg-like patty (i.e., the cooked emulsion) was more similar to real egg than a commercial plant-based egg replacer (i.e. “JUST Egg”).
Scale up (Saskatchewan Food Industry Development Centre)
Enhancement of the colour and flavour of the canola-based egg replacer emulsion was successful as it showed similar flavour and texture as JUST egg and real eggs in the sensory test. However, there is still room for improvement as colour remains an issue. From the trials, it is evident that the canola protein isolate is very important to producing the egg-like structure, but it also imparts a base colour that is difficult to change unless lightened with titanium dioxide.
Recommendations for future work
- Removal of colour pigments within the plant protein ingredients during or post-fractionation is important to enhance thefinal product colour.
- Modifying protein structure to give enhanced aggregation and gelling potential, possibly in the form of micro-particulates.Current proteins on the market are inherently weak. Increased focus on modifying pulse protein’s geling capacity is of interest.
What benefit will these outcomes bring to farmers in SK?
Plant proteins represent an important ingredient used in the creation of the liquid egg replacer product. According to global and Canadian market analysis from the National Research Council Canada (2019) on the plant-based protein market, the total protein demand will increase in 2054 to 943.5 million tonnes and the plant-based protein market is expected to reach $10.8 billion by 2022. The project will support the value-added utilization of pulse and/or canola proteins, as the key ingredient within the egg replacer, to better diversify its market utilization. We worked with local ingredient suppliers (AGT Foods and Ingredients, Merit Foods) as the source of our materials. The project will benefit producers by increasing demand for their product by secondary processors to meet this market gap.