The enhanced fatty acids flavor release for low-fat cheeses by carrier immobilized lipases on O/W Pickering emulsions

Abstract

Low-fat cheeses have flavor defects due to low fat content resulting in an insufficient free fatty acids (FFA) flavor release. Lipase immobilization is an attractive approach to increase the efficiency of lipid hydrolysis and FFA release. Here, α-lactalbumin (α-lac) nanotubes (NTs) formed by self-assembly of partially hydrolyzed α-lac peptides were applied as an immobilization carrier for lipases. The aim is to increase the lipase activity and compromise its flavor defects in low-fat cheeses by lipase immobilization on NTs (Lipase-NTs). Firstly, the lipase activity was improved 68% for Lipase-NTs compared with free lipase. Enzyme kinetics analysis suggested that NTs immobilization increased the affinity of lipase to substrate and reduced the potential energy barrier for enzyme reaction. Then Lipase-NTs were applied to stabilize the oil-in-water Pickering emulsion which enlarged reaction areas and improved the accessibility of lipase to substrate. The NTs-lipase emulsion system enhanced the lipase catalytic efficiency, the Lipase-NTs could hydrolyze and release 1.5 times higher amount of FFA compared to free lipases with the identical triglycerides contents by titration measurement. Lipase-NTs milk fat O/W Pickering emulsions were added in low-fat cheese to replace all the original milk fat during the cheese processing. Lipase-NTs O/W emulsion added low-fat cheese showed a twice amount of FFA release compared with normal low-fat cheese containing identical milk fat contents measured by GC-MS. This work provides the inspiration on creating flavor enhanced low-fat foods by lipase immobilization strategy which can improve the enzyme activity and promote the FFA flavor release.