Sucrose and leavening agent functionality in cake systems

Promovendus/a: Thibault Godefroidt

Promotor(en): Prof. dr. ir. Jan Delcour

Cakes are widely consumed bakery products which unfortunately contain ingredients which are associated with health-related issues, i.e. sucrose and, in many instances, phosphate-containing leavening agents. Based on the cake type, the ingredient bill further contains additional components. Sponge cake is made from flour, egg, sucrose, and leavening agent only, while cream and pound cake recipes contain either oil or margarine on top.

In a first experimental part, the focus was on sucrose functionality. The effects of sucrose, polyols (i.e. maltitol and mannitol), and dietary fibers (i.e. oligofructose and inulin)] on batter and cake quality were tested. The soluble substitutes maltitol and oligofructose act similarly to sucrose regarding most batter and cake properties. However, there are slight differences regarding the moment of structure setting during baking when oligofructose is used. Insoluble mannitol and inulin have severe negative effects batter and cake quality. Interestingly, the combination of oligofructose and mannitol is an optimal sucrose substitute in sponge, cream, and pound cake recipes, even if these components on their own are suboptimal sucrose substitutes.

A different approach to alleviate the negative consequences of reducing the sucrose content in cake systems was to alter the mixing atmosphere from air to pure nitrogen gas (N2) or CO2. The effect of different mixing atmospheres was found to depend on the solubility of the used gas in the aqueous (and lipid) phase(s). N2 is slightly less soluble in BL than air. As a result, its use causes the batter to be slightly more stable. CO2 is significantly more soluble in BL than air, resulting in unstable, denser batter. However, during baking CO2 becomes less soluble, resulting in an improved leavening phase. In sponge cake making, the negative effect of CO2 on foam density overshadows the positive effect on leavening, resulting in significantly worse sponge cake quality. For cream cakes, the opposite occurs where the effect on leavening is more pronounced than the effect on batter density, resulting in improved cream cake quality. Additionally, the use of CO2 atmosphere lowers batter pH, which facilitates protein network formation during baking and leads to slightly improved cake texture.

In the second experimental part, the focus was on leavening agent functionality. In order to replace the inorganic phosphate-containing leavening acid sodium acid pyrophosphate (SAPP), organic replacers (i.e. adipic, fumaric, citric, and α-ketoglutaric acid) were tested. Citric and α-ketoglutaric acid are very soluble at room temperature. They dissolve mostly during the batter mixing phase which qualifies them as early-acting HXs. As a result, only low amounts of CO2 can be formed and released during baking, resulting in low volume cakes. Adipic and fumaric acid, just like SAPP, have low solubility at room temperature which qualifies them as late-acting HXs. As they release most of the CO2 from NaHCO3 during baking, their use leads to cakes of high volume and quality. It is also shown that the CO2 release should occur before structure setting to optimally affect cake volume.

A different approach to remove inorganic phosphate-containing SAPP is to use enzymatic leavening. The potential of using glutamic acid decarboxylase (GAD ST) enzyme alongside its substrate monosodium glutamate (MSG) and its cofactor pyridoxal 5’‑phosphate was explored in both pancakes and cream cakes. While the quantity of MSG affects the total amount of CO2 produced, the concentration of the enzyme GAD ST and its cofactor determine the rate of CO2 release. Additionally, the efficiency of the enzymatic system heavily depends on the batter pH and temperature. A pH (about 5.5) lower than the usual (pan)cake pH, a temperature around 55 °C, and a heating rate lower than typical heating rates during baking are needed for the enzyme to work optimally. Under such conditions, enzymatic leavening is at least equally effective as chemical leavening.