Lipase performance evaluation using interfacial measurements
Evaluating the effectiveness of different enzyme preparations for baked goods normally requires time-consuming baking trials, but this research has highlighted a physical method that is much quicker and which can utilise model systems. Lipases act on lipids naturally present in key ingredients such as wheat flour and egg. They are claimed to generate surface active materials that have the potential to replace emulsifiers such as DATEM esters in bread, and improve cake quality.
Our work has demonstrated that surface tension measurements can be used to determine exogenous lipase activity in both whole egg and flourwater systems. This offers enzyme manufacturers, ingredient suppliers and end users a rapid route to evaluate the likely performance of lipases in specific systems. The technique could be used most effectively at the enzyme development stage to rapidly screen enzymes with the most promising activity and hence speed up the selection process. Sarab Sahi explains the new approach:
"We studied three commercially available lipases, one with broad substrate specificity and the other two specifically acting on polar wheat flour lipids. The enzymes were added to liquid whole egg and flour-water mixtures separately, and measurements of the surface tension of the two systems were made at intervals. The interfacial tension was measured on a Krüss DSA 100, which analyses the shape of the pendant drop and calculates the interfacial tension on newly formed drops.
Adding lipases to whole egg showed that only one of the three lipases reduced the surface tension of the eggair interface with time and continued to do so during the measurement. The change in the surface tension was indicative of the fact that surface active material was generated as a result of lipase action. When added to the flourwater system all three enzymes were active, with the surface tension decreasing with time, but one lipase was clearly more active than the other two."