Effect of Alternative Sweeteners on Sponge Cakes
Granulated sugar is the unquestioned king of the baking world which has been centuries. It has a much more extensive purpose than being sweet; it is a base block of structure, texture, and colour. But as more and more people demand reduced-sugar and low-carbohydrate diets, bakers are moving toward using other sweeteners. However, replacing sugar with stevia or erythritol is not a one-to-one ratio. This transformation essentially changes the baking chemistry, and the most noticeable results of this change are, perhaps, the dependencies on its fine structure, namely, on the crumb texture of a sponge cake, and on its marvelous, golden-brown color.
To comprehend the effects brought by the alternative sweeteners, we need to value the multidimensional role that sugar plays in a classic sponge cake. Sugar is a hygroscopic substance, and that is why it attracts and holds water molecules. This property is used in baking to slow the setting of the starches as well as the coagulation of the proteins within the flour and eggs. This will enable the cake to rise throughout the baking period, ending with a soft, spongy, and delicate crumb. Secondly, sugar is a major player in the Maillard reaction and caramelization. These sophisticated chemical reactions contribute to the formation of the golden-brown crust and warm, sweet flavours of the cake.
We unbalance this balance when we introduce the other sweeteners. These sweeteners may be broadly divided into two classes: high-intensity sweeteners (such as stevia and sucralose) and sugar alcohols (such as erythritol and xylitol). All the categories influence the sponge cake in different ways.
The Crumb Texture Conundrum
Many sugar-free sponge cakes find their demise in their search for a tender crumb. The loss of the bulk and hygroscopic properties of sugar produces a sequence of textural effects.
- Loss of Volume and Tenderness: Sugar physically disrupts the formation of gluten and coagulation of egg protein, and tenderizes the crumb. In the absence of this interference, the proteins polymerise more slowly and rigidly. A cake baked with a high-intensity sweetener, such as pure stevia extract, which offers sweetness without volume, will tend to be thick, sticky, and pale. It does not contain the structural support that sugar gives, and as a result, the proteins form an excessively tight network, resulting in a collapsed or tough texture.
- The Bulking Agent Problem: To counter this, most of the other sweeteners include bulking agents such as maltodextrin or soluble corn fibre to replicate the volume of sugar. The sugar alcohol erythritol is commonly packaged in a granular (granular) form, which appears like sugar. This aids the introduction of physical structure, but these bulking agents are not an ideal replica of sugar in terms of hygroscopicity. The outcome may include a drier, crumbly cake since these agents may not similarly retain water when baking and after baking. Certain sugar alcohols, such as xylitol, are more hygroscopic and may actually serve to preserve moisture, although they are also capable of creating an unpleasant cooling effect on the palate.
- The Aeration Effect: In traditional sponge cakes, the whipping of granulated sugar by using whole eggs or egg whites is a significant way of raising. The crystals of sugar are very sharp and slice through the protein, assisting in the formation of a stable foam with millions of small air bubbles that are growing in the oven. Other sweeteners used are mainly in different crystal structures or they are dissolved in liquid. This reduces their ability to form and stabilize this important airy foam, resulting in a denser end product with a less open crumb structure.
The Browning Dilemma
A sponge cake is a pale and anemic-looking cake that is not visually attractive and, in many cases, does not have the flavour depth of its browned counterpart. This is where the chemistry of alternative sweeteners has gone so far off-course from sugar.
- The Missing Maillard Reaction: It is a type of chemical reaction that involves the combination of amino acids (the proteins present in the eggs and the flour) with reducing sugars. Sucrose (table sugar) is a disaccharide that dissociates into glucose and fructose, which are reducing sugars, during heating, and is therefore a prolific actor in browning. The majority of all other sweeteners are not reducing sugars. Erythritol, starch and sucralose Erythritol, and sucralose do not react by the Maillard reaction. A sponge cake prepared using these sweeteners alone will be extremely pale even after baking. It will not have the nutty caramel-like flavours that characterize a well-baked sponge.
- None Caramelization: Caramelization is the thermolytic decomposition of sugar as such. It requires temperatures frequently above 170°C (338°F), which are easily obtained on the surface of a baking cake. Other sweeteners do not caramelise. This eliminates another primary colour and flavour development route.
- Finding Solutions: To surmount this, bakers need to be innovative. A blend may include a small portion of a hydroscopic sweetener capable of browning, e.g., allulose. Allulose is a fructose-like long-chain sugar that is highly infrequent and acts like fructose in browning and is commonly touted as the ideal choice of sugar to use to give colour to sugar-free baking. Alternative workarounds also include molasses or honey (adding a small amount of sugar), spices such as cinnamon to add colour, and reducing the temperature to bake it, allowing it more time to dry and develop a little colour without burning.
Navigating the Alternatives: A Baker’s Guide
The secret behind success is that the alternative sweeteners do not constitute a homogenous group. Each has its own properties:
- Erythritol (commonly used in combination with Monk Fruit): is an excellent source of bulk and sweetness with a cooling aftertaste and does not brown. Sometimes crystallizes, which makes it slightly gritty. Best used in blends.
- Allulose: The all-star in moisture retention and browning. It caramelizes and takes part in the Maillard reaction. Nevertheless, it leads to over-browning when not closely attended to, and it is more costly.
- Stevia (Liquid or Powdered Extract): This is very strong but adds no volume or color. It should be combined with a bulking agent and commonly other sweeteners to cover its possible bitter aftertaste.
- Xylitol: Xylitol browns slightly, is highly hygroscopic (good in moisture), and is highly toxic to dogs; in large amounts, it may be laxative.
Conclusion
Learning to bake the sponge cake using other sweeteners is a food science and trade-off lesson. The impact on crumb texture and browning is immense and immediate, and it is hard to deny the irreplaceable place of sugar in conventional baking. To balance the bulk, moisture, sweetness, and browning potential, a subtle technique is needed to achieve a result that is both visually attractive and provides a pleasant texture.
In most cases, a combination of sweeteners is used to produce the desired effect. It might need to accept a bit more compact crumb or a whiter crust. Nevertheless, those who want to minimize the amount of sugar they consume will not have an impossible mission. With an appreciation of chemistry at work, bakers are capable of producing delicious, substitute sponge cakes that, though otherwise dissimilar, may still be a nice snack. Travel is also a reminder that in baking, all ingredients are helpful, and altering a single component will transform the whole symphony.
