Quantitative Spatiotemporal Mapping of Lipid and Protein Oxidation in Mayonnaise.

Suyeon Yang,Johannes Hohlbein,John P M Van Duynhoven,Aletta A Verhoeff,Donny W H Merkx

doi:10.3390/antiox9121278

Suyeon Yang, Johannes Hohlbein + Show 3 more

Open Access

https://doi.org/10.3390/antiox9121278

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Abstract

Lipid oxidation in food emulsions is mediated by emulsifiers in the water phase and at the oil–water interface. To unravel the physico-chemical mechanisms and to obtain local lipid and protein oxidation rates, we used confocal laser scanning microscopy (CLSM), thereby monitoring changes in both the fluorescence emission of a lipophilic dye BODIPY 665/676 and protein auto-fluorescence. Our data show that the removal of lipid-soluble antioxidants from mayonnaises promotes lipid oxidation within oil droplets as well as protein oxidation at the oil–water interface. Furthermore, we demonstrate that ascorbic acid acts as either a lipid antioxidant or pro-oxidant depending on the presence of lipid-soluble antioxidants. The effects of antioxidant formulation on local lipid and protein oxidation rates were all statistically significant (p < 0.0001). The observed protein oxidation at the oil–water interface was spatially heterogeneous, which is in line with the heterogeneous distribution of lipoprotein granules from the egg yolk used for emulsification. The impact of the droplet size on local lipid and protein oxidation rates was significant (p < 0.0001) but minor compared to the effects of ascorbic acid addition and lipid-soluble antioxidant depletion. The presented results demonstrate that CLSM can be applied for unraveling the roles of colloidal structure and transport in mediating lipid oxidation in complex food emulsions.

Highlights

Unsaturated fatty acids are nutritionally important [1] and often consumed in the emulsified form, such as infant formula, milk, mayonnaise, and dressings
Local oxidation rates of lipids within dispersed oil droplets and proteins at the interface or in the continuous water phase can be quantitively assessed via segmentation and tracking of individual droplets and fitting with a semi-empirical model
In the presence of tocopherol, ascorbic acid acts as a lipid antioxidant and as a protein pro-oxidant in the water phase

Summary

Introduction

Unsaturated fatty acids are nutritionally important [1] and often consumed in the emulsified form, such as infant formula, milk, mayonnaise, and dressings. The physical stability of these food emulsions is enhanced by surface-active lipids and proteins at the oil–water interface [2,3]. The presence of these emulsifiers, compromises chemical stability by promoting lipid oxidation, which leads to off-flavors and compromised nutritional value [4]. It is known that these reactions are catalyzed at the droplet interface and that antioxidants can be active in the lipid droplet phase, the water phase, and at the oil–water interface [8,9]. There is growing evidence that colloidal surface heterogeneity and the transport of oxidation reaction intermediates play a critical role in the onset and the rate of oxidation [10,11]

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