Sucrose substitution in cake systems is not a piece of cake

The global cake market is substantial and growing, but cakes are high in sucrose. Dietary guidelines promote sucrose reduction, which is relatively easy in drinks but challenging in cakes due to sucrose's multiple functional roles beyond sweetness (rheology, aeration). Cake making involves mixing to incorporate air bubbles and baking, where starch gelatinization and protein denaturation solidify the batter. High batter viscosity is linked to efficient air incorporation. This study hypothesizes that the quantity and quality of the batter liquor (BL), the aqueous phase of the batter, are crucial when using sucrose substitutes. The researchers examined the effects of sucrose reduction and substitution with maltitol, mannitol, oligofructose, or inulin on sponge cake BL properties, air incorporation, and biopolymer transitions during baking. They also investigated whether these findings extended to cream and pound cakes. The substitutes considered have lower caloric content, are bulkier, and offer varying degrees of sweetness and solubility. The potential negative effects of using these substitutes, particularly in higher quantities, were also considered, prompting investigation into mixtures as potential solutions. While viscosity is important, it's not the only factor determining cake quality. Starch gelatinization and protein denaturation, occurring during baking, significantly affect texture. The study aimed to evaluate the effects of sucrose reduction/substitution on these transitions using differential scanning calorimetry (DSC) and rapid viscosity analysis (RVA).

The introduction extensively cites previous research on cake making, ingredient functionality, food reformulation, sucrose's role in foam stability, batter viscosity and its relation to air incorporation, and the impact of biopolymer transitions on cake texture. It highlights the challenges of sucrose replacement and the need for understanding the interplay between different ingredients and processes in cake production. The review underscores that simple sweetness replacement is insufficient and that the functional properties of sucrose must be carefully considered when seeking substitutes.

The study used various methods to examine the effects of sucrose substitutes. Sponge, cream, and pound cakes were prepared with different sugar compositions (detailed in Tables 1 and 4). Batter density (BD) was measured to assess air incorporation. Sponge cake batter liquor (BL) was isolated by ultracentrifugation, and its viscosity was determined using a rheometer. Time-domain 1H NMR was used to analyze proton mobility in the BL, providing insights into water-molecule interactions with sucrose and its substitutes. The effective volumetric hydrogen bond density was calculated. Differential scanning calorimetry (DSC) examined the effects of sucrose and substitutes on starch gelatinization and protein denaturation, both separately and within the batters. Rapid viscosity analysis (RVA) studied batter structure setting. Finally, cake texture was analyzed using texture profile analysis. Statistical analysis (Tukey's test and polynomial correlation) was employed to compare results and identify correlations between different properties. Specific details regarding the materials used, the batter-making processes (sponge, cream, and pound cakes), the isolation of BL, NMR analysis, DSC measurements, RVA, cake baking, and the analyses of cakes are described extensively in the "Methods" section.

Time-domain 1H NMR showed that water mobility in the BL is related to the hydrogen bond density of the sucrose or its replacers. Sucrose content influences BL quantity and viscosity, affecting air incorporation during mixing. Maltitol, like sucrose, yielded adequate BL volume and low water mobility. Mannitol's poor solubility resulted in less air incorporation and higher batter density. Oligofructose, though dissolving completely, caused delayed starch gelatinization and negatively impacted cake texture. Mixtures of mannitol and oligofructose showed improved properties, overcoming the shortcomings of individual substitutes. Strong correlations were observed between BL viscosity and both water mobility (T2 relaxation time) and batter density. DSC analysis revealed that oligofructose significantly delayed starch gelatinization compared to sucrose and maltitol, impacting the overall batter transition temperature and cake texture. Combining mannitol and oligofructose yielded biopolymer transition temperatures more similar to the control (sucrose). The findings from sponge cakes largely extended to cream and pound cakes, though the influence of substitute solubility on batter density was less pronounced in emulsion-type cakes due to the stabilizing effect of the lipid phase. Maltitol showed promising results as a sucrose replacement, while mannitol-oligofructose mixtures proved effective in improving the overall characteristics, particularly in addressing the shortcomings of oligofructose alone.

The results highlight that successful sucrose replacement requires consideration of both batter liquor properties (quantity, water mobility) and the impact on biopolymer transitions during baking. The study demonstrates that simply replacing sucrose's sweetness isn't sufficient; its functional role in influencing water interactions and biopolymer transitions must be considered. The findings explain why certain substitutes, such as mannitol and oligofructose, individually exhibit limitations, yet their mixtures demonstrate improved performance, suggesting synergistic effects. The study's implications extend to the optimization of cake recipes and the development of healthier, lower-sucrose baked goods. The strong correlations found between different batter and cake properties support a mechanistic understanding of the processes involved.

This research reveals the crucial factors for successful sucrose substitution in cakes. The quality of the batter liquor, characterized by sufficient volume and low water mobility, is essential for proper air incorporation. Furthermore, maintaining appropriate timing of starch gelatinization and protein denaturation is vital for optimal cake texture. Maltitol emerged as a suitable substitute, and mixtures of mannitol and oligofructose demonstrated the potential to overcome the limitations of individual substitutes. Future research could explore other sucrose substitutes and further optimize substitute mixtures for various cake types, exploring the underlying molecular mechanisms in more detail.

The study focused on specific sucrose substitutes and cake types. The findings may not be directly generalizable to all types of cakes or to all potential substitutes. The study primarily employed a model cake system, potentially differing from commercial formulations. Further research should investigate a wider range of substitutes and cake formulations and delve into the impact on other aspects of cake quality, like flavor and shelf life.