Characterization of the substrate specificities of baking lipases for use in fine baked goods

The guidelines for fine bakery goods define these as baked goods that contain at least 10 parts fat and/or sugar per 90 parts grain mill products. In baked goods, it is common to use flour treatment agents to compensate for natural variations in flour properties and achieve consistent product characteristics. The use of enzymes enables the production of clean label products, as baked goods are heated to high temperatures at the end of the manufacturing process, inactivating the enzymes they contain so that they no longer have any technological effect. Enzymes are therefore considered processing aids. Lipases cause partial hydrolysis of the flour nonpolar and polar lipids to form surface-active fatty acids, di- and monoacylglycerides, and modified phospho- and galactolipids.

The aim of the research project was to characterize the substrate specificities of baking lipases for use in fine bakery goods. The goal was to identify lipases that, due to their substrate specificity, do not release short-chain fatty acids but have positive properties in terms of dough stability, product volume, texture, and freshness retention.

Seventeen baking lipases were first characterized using the p-nitrophenyl assay with regard to their substrate specificity for fatty acids of different chain lengths. The substrate specificity of the lipases towards the natural substrates butter, margarine, rapeseed oil, and wheat germ oil was similar for all seventeen baking lipases within an emulsion. It was therefore dependent on the accessibility of the fatty acid residues within the emulsion and did not correlate with the specificities previously determined in the p-nitrophenyl assay.

Three recipes were established for baking trials: a simple sponge cake without eggs, a classic pound cake, and yeast-based brioche. Seven selected lipases did not result in any off-flavors in the products. The lipases generally had a greater effect on the dough and product properties of sponge cakes than on those of pound cakes and brioche. In sponge cakes, three of the seven lipases reduced the density and stickiness of the dough and liquefied it. In the product, they resulted in a softer crumb structure, reduced resilience and cohesion of the products, and also prevented staling. They were also suitable for maintaining the original product properties when the proportion of water or butter in the recipe was reduced. 

Overall, it was found that lipases are suitable for replacing traditional emulsifiers in fine baked goods.