July 31, 2018

A recent study by Liang et al. from the University of British Columbia, found that the sugars content of baked cakes may differ from the actual amount of sugar listed as an ingredient.  

Sugars have many functional roles in foods essential for food quality, including taste, aroma, texture, volume, appearance and preservation. When heated, sugars participate in non-enzymatic browning reactions including the Maillard reaction and caramelization, which give baked goods their characteristic golden brown colour and pleasing aroma. These processes results in the degradation of sugars during baking with associated losses in calories available for absorption and metabolism.

Bakery products are major food sources that contribute to added sugars intake. However, there is currently a limited understanding of how the sugars content in recipes changes during the baking process, thus affecting the amount of sugars in the final product. This can pose an issue because “the content of sugars in foods and related calories that appear on nutrition food labels are often derived from the summation of recipe ingredients rather than from actual measurements after processing”.

In this study, the researchers wanted to measure the amount of sugars lost during these processes, and to compare changes in cakes made with table sugar (sucrose) and those made with invert sugar (glucose and fructose in equal proportions). The results found a significant reduction in sugars content with greater losses for invert sugar (average 21.7%) than sucrose (average 6.4%) when baked at 180o C. The researchers also measured the caloric content before and after heat treatment and found that the calorie losses corresponded to the relative amount of sugars lost.

What does this mean for baked goods? The study concluded that heat used to produce bakery products “result[s] in non-enzymatic browning reactions that lead to significant reductions in content of sugars and potentially those related calories available for absorption and metabolism”. In order to learn more about this topic, the authors suggest that “future whole-body digestibility and energy studies are in order to establish the significance of these findings especially on caloric control and glycemic responses attributed to dietary sugar intakes from baked products”.  It is possible that after more research, the amount of sugars added as ingredients may not be the correct amount to list on the Nutrition Facts label; which could mean that the sugars content needs to be analyzed again after baking.

 

To read a Q&A with the UBC authors of the study, please visit:

UBC News, Sugar loss during baking means calorie counts could be off

To read the full-text open-access article, please visit: 

Liang N, Chen XM, Kitts DD. Sugar Loss Attributed to Non-Enzymatic Browning Corresponds to Reduce Calories Recovered in Low-Molecular-Weight Fraction. J Nutr Food Sci. 2018;8(674):2.

 

For more information on the functions sugar plays in foods: