Composition and Properties of Aquafaba: Water Recovered from Commercially Canned Chickpeas

Summary

Aquafaba is a viscous juice from canned chickpea that, when stirred vigorously, produces a relatively stable white froth or foam. The primary research goal is to identify the components of aquafaba that contribute viscosifying/thickening properties using nuclear magnetic resonance (NMR), ultrafiltration, electrophoresis, and peptide mass fingerprinting.

Abstract

Chickpea and other pulses are commonly sold as canned products packed in a thick solution or a brine. This solution has recently been shown to produce stable foams and emulsions, and can act as a thickener. Recently interest in this product has been enhanced through the internet where it is proposed that this solution, now called aquafaba by a growing community, can be used a replacement for egg and milk protein. As aquafaba is both new and being developed by an internet based community little is known of its composition or properties. Aquafaba was recovered from 10 commercial canned chickpea products and correlations among aquafaba composition, density, viscosity and foaming properties were investigated. Proton NMR was used to characterize aquafaba composition before and after ultrafiltration through membranes with different molecular weight cut offs (MWCOs of 3, 10, or 50 kDa). A protocol for electrophoresis, and peptide mass fingerprinting is also presented. Those methods provided valuable information regarding components responsible for aquafaba functional properties. This information will allow the development of practices to produce standard commercial aquafaba products and may help consumers select products of superior or consistent utility.

Introduction

Increasingly vegetarian products are being developed that mimic the properties of meat, milk, and eggs. The functional properties of pulses are important in their current uses in food applications and their properties are being explored in the development of replacements for animal protein. For example, dairy alternatives sales were $8.80 Billion USD in 2015 and this market is growing rapidly. This market is projected to grow to $35.06 billion by 2024. Moreover, the upward trend in demand for plant-based milk substitutes is, in part, a result of consumer health concerns regarding cholesterol, antibiotics, and growth hormones often used in milk production¹. Similarly, vegetable protein and hydrocolloid egg replacer markets are rapidly expanding and a compound annual growth rate of 5.8% is expected for these materials over the next 8 years with sales of $1.5 billion USD expected in 2026². A growing number of consumers prefer vegan protein sources, allergen reduced diets and reduced carbon footprint for food products. Demand for pulse-based products, especially from lentil, chickpea, and faba bean are steadily growing due to the high protein content, dietary fiber and low saturated fat content of pulses³. Pulses also contain phytochemicals with potentially beneficial biological activity⁴.

Commercial entities, scientists and private individuals have taken different approaches to communicate the quality properties of chickpea based egg and milk replacements. Gugger et al.⁵ produced a milk-like product from high starch grains including adzuki bean and chickpea. In their described methods the proponents attempted to show that their product is unique and different from "aquafaba"⁶. In another commercial approach elucidated by Tetrick et al.⁷ a plant-based egg substitute was developed. Their patent application describes methods of combining pulse flour with known thickeners that emulate the function of egg white in baked materials. Typical formulae include 80-90% pulse flour and 10-20% thickening additives.

Peer reviewed literature also indicates the functionality possible with chickpea and has demonstrated that albumin protein fractions obtained from kabuli and desi chickpea flour have good emulsification properties. They have also found a significant effect of chickpea source on the albumin yield and performance⁸.

After the initial internet report describing "aquafaba" by French chef Joël Roessel, an open source movement is showing the utility of aquafaba as a replacement of egg white and dairy protein in many food applications. There are many highly viewed webpages and YouTube videos showing the incorporation of aquafaba in foods that emulate the qualities of ice cream, meringue, cheese, mayonnaise, scrambled eggs, and whipped cream. Most pioneers providing open source aquafaba applications (recipes) obtain their material by straining canned chickpeas and using the liquid in their recipes. These individuals are mostly not trained scientists. Video comments sections indicate that the respondents have copied the recipes and some have failed to replicate the successes of the aquafaba advocates.

All three approaches (corporate, scientific and open source) to developing egg and milk replacements have merit but are missing an important dimension. Applied scientists, basic scientists and individuals promulgating pulse-based products have incompletely characterized and standardized their input material. Standardization of a product for a specific use is a normal industrial practice. Chickpea cultivars have not been standardized for aquafaba quality and industrial canning practices are standardized to produce consistent chickpeas not aquafaba.

Based on studies of other commodities, it is predictable that both genotype and environment will contribute to pulse aquafaba quality. It is known that both genotype and environment affect kabuli chickpea canning properties⁹. Typically, genotypic effects are large between related species and smaller within members of a species. Variation in physical and chemical properties can be minimized through identity preservation that allows the selection of cultivars with desired properties. Environmental effects can also be large and are managed by quality evaluation and blending to standard performance in specific tests¹⁰.

There are many genetically distinct cultivars of chickpea in commercial production. For examples, the University of Saskatchewan Crop Development Centre, a major source of commercial chickpea germplasm, has released 23 chickpea cultivars since 1980 of which 6 are currently recommended for cultivation in Canada. While scientific manuscripts often describe the cultivar used in a study, the patents and internet pages that were surveyed did not indicate the cultivar used or the provenance of the chickpeas. The standardization of cultivars and handling could help users increase their success in using chickpea but this information is not available on canned chickpea products.

The objective of this research is to determine the aquafaba components that contribute foaming properties. Here,the rheological properties of aquafaba from commercial chickpea brands were compared and the chemical properties were studied by NMR, electrophoresis, and peptide mass fingerprinting. To our knowledge, this is the first research which describes the chemical composition and the functional properties of the aquafaba viscosifier components.

Protocol

Separation of Aquafaba from Chickpeas Obtain cans of chick peas from local grocers and open with a manual can opener. Label cans from A to J. Separate chickpeas from aquafaba using a stainless steel meshed kitchen strainer and weigh the separated chickpeas and aquafaba. Obtain a Representative Sample of Chickpeas and Aquafaba for Chemical Analysis. Randomly select ten chickpeas after draining the aquafaba to determine moisture conten…

Representative Results

Each can of chick peas is labeled to indicate the ingredients added during canning. Ingredients included water, chick peas, salt, and disodium ethylenediamine tetraacetic acid (EDTA). In addition, two cans were labeled as "may contain calcium chloride". Three distinct lining colours were observed; white, clear yellow and metallic (Table 1). Brand c…

Discussion

In this research, we have found that chickpea aquafaba from different commercial sources produces foams that vary in both properties (volume and stability of foam) and chemical composition. There was a positive correlation between aquafaba viscosity and moisture content. Foam volume increase (V_f100) was not related to these parameters. Additives such as salt and disodium EDTA might suppress viscosity and foam stability as aquafaba from chickpea canned with these additives had lower viscosity and produced foams…

Materials

Freeze Dryer
Stoppering Tray Dryer	Labconco Inc.	7948040
Mixer
Stainless steel hand mixer	Loblaws	PC2200MR
Viscosity Measurement
Shell cup No. 2	Norcross Corp.
Color Measurement
Colorflex HunterLab spectrophotometer	Hunter Associates Laboratory Inc.
Protein and Carbon Contents
Elemental analyzer	LECO Corp.	CN628
NMR Spectrometry
Spectrafuge 24D	Labnet International Inc.
Syringe filters	VWR International	CA28145-497	25 mm, with 0.45 µm PTFE membrane
Deuterium oxide	Cambridge Isotope Laboratories Inc.	7789-20-0
3-(trimethylsilyl)propionic-2,2,3,3-d4 acid sodium salt	Sigma-Aldrich	169913-1G
Bruker Avance 500 MHz NMR spectrometer	Bruker BioSpin
TopSpin 3.2 software	Bruker BioSpin GmbH
Electrophoresis
Regenerated cellulose membrane	Millipore Corp.		3, 10, 50 kDa (MWCO)
Centrifugal filter unit	Millipore Corp.
Benchtop centrifuge	Allegra X-22R, Beckman Coulter Canada Inc.
Mixer Mill MM 300  bead mill	F. Kurt Retsch GmbH & Co. KG
Eppendorf centrifuge 5417C	Eppendorf
Phosphate buffered saline, pH 7.4	Sigma-Aldrich	P3813-10PAK
Tris-HCl buffer pH 7.4	Sigma-Aldrich	T6789-10PAK
PageRuler Prestained Protein Ladder	Fisher Scientific
Mini-Protein Tetra Cell system	BioRad
Peptide Mass Fingerprinting
Thermo-Savant SpeedVac	BioSurplus		Centrifugal vacuum evaporator
Trypsin buffer			20 µL trypsin in 1 mM hydrochloric acid and 200 mM NH4HCO3
Iodoacetamide	Sigma-Aldrich	I1149-5 g
Trifluoroacetic acid	Fluka	BB360P050
Acetonitrile	Fisher Scientific	L14734
Formic acid	Sigma-Aldrich	33015-500mL
Mass spectrometry vial	Agilent Technologies Canada Ltd.
Agilent 6550 iFunnel quadrupole time-of-flight mass spectrometer	Agilent Technologies Canada Ltd.		Agilent 1260 series LC instrument and Agilent Chip Cube LC-MS interface
HPLC-Chip II: G4240-62030 Polaris-HR-Chip_3C18			360 nL enrichment column and 75 µm × 150 mm analytical column, both packed with Polaris C18-A, 180Å, 3 µm stationary phase.
Agilent MassHunter Qualitative Analysis Software	Agilent Technologies Canada Ltd.
SpectrumMill data extractors	Agilent Technologies Canada Ltd.