The below passage is an excerpt of an article authored by Stable Micro Systems (SMS). For more information, visit SMS’ website.
The increased interest in plant-based foods have presented a wide range of challenges, not the least of which is the process of replacing one ingredient - the egg.
From emulsifying sauces, adding shine to pies, aerating chocolate mousse, and adding moisture and fat to cakes, eggs have many interesting functions in baking.
Using a whole egg in a recipe combines the individual properties of the yolk and white. Eggs emulsify and bind, solidifying when heated. When combined with sugar, eggs trap air, adding lightness to a recipe. Alternatively, egg components may be used separately, with whipped egg white forming a stable foam for things like meringues, while yolks, when used alone in things like custard or pastry cream, provide high fat and emulsification.
While vegans have been replacing eggs in their baking for a while, now most supermarkets have a ‘plant based’ aisle, featuring products made with replacement ingredients or adjusted recipes. Egg free does not necessarily mean a product is vegan – dairy products may be included. As with any product, thorough testing is crucial before releasing a new food to market, or it will be passed over for a brand that has carried out the necessary research and set higher standard.
Meringue is one food that seems impossible to make without eggs. However, chickpea water, also known as “aquafaba”, forms into soft peaks when whipped, just like egg whites. The next challenge of making a meringue is to ensure crispness. Due to the irregular shape of most meringues, crispness is most easily measured using a penetration test. A 2mm cylinder probe allows multiple test sites on the same sample, and is best applied to areas with a flat surface. A crisp meringue will show a definite force peak with a sharp drop off; a flaccid meringue will show a more gradual peak.
Volscan Profiler C
Eggs give brioche its fluffy texture, rich flavor and yellow color. They can be replaced with buttermilk and yellow food coloring, but this can affect the softness and volume, compromising the loaf’s fluffiness. Brioche volume can be measured using a simple measurement in the VolScan Profiler, a benchtop laser-based scanner that measures the volume, density and dimensional profiles of solid products.
Bread V Squeeze Rig
A common method for testing bread or brioche softness is to squeeze the bread, creating a ‘V’ shape with the hand. The Bread V Squeeze Rig imitates this process. Consisting of ‘V’ shaped rounded ‘fingers’ which are lowered onto the loaf, the rig compresses the bread and measures the force used. Post-test calculations provide an indication of freshness – the lower the force and higher the value of springiness, the fresher the loaf. This non-destructive test, which allows repeatable analysis of the bread, is both simple and quick, because it does not require sample preparation, and the loaf can be analyzed within the packaging.
Compression test
Similarly, sponge cake’s richness and structure relies on eggs, although golden syrup or even vinegar can act as replacements. Springiness is vital in a sponge cake – when squeezed, it should push back and return back to its original size. Relaxation tests can measure springiness. During a relaxation test, the Texture Analyzer compresses a sample by a specific amount over a set time period. Exponent software allows the springiness to be calculated from the force-time graph.
Three Point Bend Rig
Cookies rely on eggs to create chewiness. Replacing the eggs usually calls for a recipe adjustment (by increasing water and fat content), and can be tested with a three-point bend test. Unlike the sudden force drop in a meringue penetration test, a three-point bend of a chewy cookie should show a shallow profile, just as the consumer would feel a gradual increase in force as they break the cookie apart.
TTC Spreadability Rig
Both eggless pastry cream and eggless mayonnaise are now available commercially. Pastry cream replaces eggs with custard powder or potato starch; mayonnaise can use thickened soy milk, but both should have a soft and smooth consistency. With mayonnaise generally eaten as a sauce base or spread thinly on sandwiches, it requires a lower viscosity than pastry cream (which must hold its shape), so their tests will not necessarily be the same. Pastry cream is well-suited to the TTC Spreadability Rig, which holds a small volume of sample in a female cone and displaces it completely with a male cone. This test also measures the sample’s adhesiveness during the unloading period.
Mayonnaise can be tested using the Back Extrusion Rig, which is comprised of a sample container centrally located beneath a disc plunger. The disc plunger performs a compression test, extruding the product up and around the edge of the disc. This measures the consistency of viscous products. Using the back extrusion principle (i.e. using a disc on the probe adapter), the consistency can also be determined while the product is still in a container straight from the production line. This rules out pre-stressing of the material caused by transfilling, which is usually unavoidable when using other methods.
The ‘egg free’ concept is such an important area of research that Campden BRI, who provide the food industry with scientific, technical and advisory services, has a new ‘club’ dedicated to egg replacements. The aim is to find the most suitable replacement for each product category, based on an increased understanding of the mechanisms of plant-based egg replacements.
To learn about Texture Analysis techniques for your egg free range, contact your TTC rep.
