Lipid Oxidation in Walnut Flour: The Role of Oleosomes in their intact matrix

Lipid Oxidation in Walnut Flour: The Role of Oleosomes in their intact matrix

Acevedo-Estupinan, M.V., Decker, E.A.

Department of Food Science, University of Massachusetts, Amherst, MA 01003, USA

Abstract: Lipid oxidation in food systems remains a complex and challenging area of research. While the mechanisms of lipid oxidation are well-established, the interactions in real-world food matrices often lead to unexpected behaviors. Oleosomes, plant organelles known for their ability to store polyunsaturated lipids, have emerged as a focal point recently. However, their role in the entire food matrix, such as walnut flour, remains poorly understood due to the diverse molecular species involved in lipid oxidation.

This study investigated the impact of walnut flour oleosomes on lipid oxidation. We analyzed intact walnut flour, walnut flour with reduced surface lipids, and extracted walnut oil for tocopherol degradation, antioxidant capacity, and  formation of primary and secondary lipid oxidation products.

Our results revealed differences in oxidation behavior in intact walnut flour compared to extracted oil. While all tocopherols were consumed in extracted oil during the lag phase, intact walnut flour exhibited a more complex antioxidant defense, with only 20% of total tocopherols oxidized. Total antioxidant capacity decreased more than tocopherols during storage indicating a more complex antioxidant activity.

Understanding the oxidation mechanisms in foods containing oleosomes is crucial for developing novel antioxidant technologies to increase food safety and decrease waste.