Defoaming Control for Sustainable Foam Cleaning Agents Using Methyl Branched Fatty Acid Salt

 We have discovered a new sustainable defoamer that can reduce the required rinse water by one-third.

 Foams are widely used in commercial cleaning agents because they create a sense of cleaning power, improving the visibility of cleaning areas, and cleaning vertical surfaces. However, foam cleaning agents used in restaurant kitchens and food processing plants require large amounts of water for rinsing; therefore, a defoaming technology that can reduce rinse water is desired from a sustainability perspective. Generally, silicone- and organic-based defoamers are used, but many have poor foaming properties and display poor stability in aqueous cleaning agents. Surfactant-based defoamers are sought to solve this problem; however, a trade-off usually exists between foaming/foam stability and defoaming performance, which is difficult to solve.

 Therefore, we focused on branched fatty acid salts, which are easily soluble in detergents but are hydrophobized and defoamed by the hardness components during rinsing. Detailed analysis of BAM images and π-A isotherms suggests that fatty acids form aggregated oily domains (liquid condensation films) at the gas-liquid interface during rinsing, which destabilize the foam film. Furthermore, we discovered that fatty acids with excellent defoaming properties can be categorized based on the calculated cohesive energy density and that the methyl branched fatty acid salt (Me-C18FA salt) was the most efficient defoamer.

 Notably, a kitchen foam cleaning agent containing the Me-C18FA salt enabled the reduction of the amount of rinse water by approximately 1/3 that used for a typical cleaning agent. In addition, because the Me-C18FA salt is effective at low concentrations, it is sustainable from a low-chemical perspective and is expected to be applied to a wide range of foam cleaning agents.