Evaluation of oxygen partial pressure, temperature and stripping of antioxidants for accelerated shelf-life testing of oil blends using 1H NMR

Loes J.G Hoppenreijs,Claire C Berton-Carabin,Arend Dubbelboer,Marie Hennebelle

doi:10.1016/j.foodres.2021.110555

Abstract

Lipid oxidation compromises the shelf-life of lipid-containing foods, leading to the generation of unpleasant off-flavours. Monitoring lipid oxidation under normal shelf-life conditions can be time-consuming (i.e. weeks or months) and therefore accelerated shelf-life conditions are often applied. However, little is known on their impact on the lipid oxidation mechanisms. In this study, different oxygen partial pressures (PO2; 10 and 21%), temperatures (20, 30 and 40 °C), and the removal of antioxidants through stripping of the oil were tested to accelerate lipid oxidation. Increasing the incubation temperature of stripped oil blends from 30 to 40 °C reduced the onset of lipid oxidation from 4 to 2 weeks, whereas the PO2 had no impact. Surprisingly, at room temperature, an increase in PO2 resulted in a longer onset time (10 weeks under 10% oxygen, 15 weeks under 21% oxygen). We hypothesize that this is due to a shift in (initiation) mechanism. In non-stripped oil, an increase in PO2 from 10 to 21% decreased the onset time from 16 to 10 weeks (40 °C). Temperature elevations and stripping led to a shift towards more trans–trans diene hydroperoxides, as compared to the cis–trans conformation. Additionally, oil stripping led to an increase in oxidized PUFAs with three or more double bonds in which the hydroperoxide group is located between the double bond pattern, instead of on the edge of it. Lastly, it was shown that small additions of LC-PUFAs (0, 0.3, 0.6, 1.2 and 2.3%, w/w) accelerate lipid oxidation, even in relatively stable stripped oils. In conclusion, increased PO2 and slightly elevated temperatures hold fair potential for accelerated shelf-life testing of non-stripped oils with a limited impact on the lipid oxidation mechanisms, whereas stripping significantly changes propagation mechanisms.

Highlights

Dietary intakes of long chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic acid (ARA, C20:4 n-6), eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, C22:6 n-3) are known to have a beneficial effect on cardiovascular diseases, cognitive dysfunc tion and inflammation (Kotani et al, 2006; Mickleborough, 2009; Wijendran & Hayes, 2004)
This raises an important problem as LC-PUFAs are known to be prone to lipid oxidation, which leads to loss of nutritional value and the formation of off-flavours (Arab-Tehrany et al, 2012), and de termines the shelf-life to a large extent (Fenaille, Visani, Fumeaux, Milo, & Guy, 2003)
As the oil blends used are relatively stable against oxidation, we evaluated the impact of food-relevant LC-PUFA concentrations (0–2.4%, w/w) on the oxidation rate and extent in stripped oil blends

Summary

Introduction

Dietary intakes of long chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic acid (ARA, C20:4 n-6), eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, C22:6 n-3) are known to have a beneficial effect on cardiovascular diseases, cognitive dysfunc tion and inflammation (Kotani et al, 2006; Mickleborough, 2009; Wijendran & Hayes, 2004) They are important for the development of the retinal and nervous systems in foeti and infants (Carlson & Colombo, 2016; Kolanowski, Jaworska, & Weißbrodt, 2007). The health benefits of LC-PUFAs encourage in dustries to develop regularly consumed products enriched in such LCPUFAs, e.g. spreads, margarines, salad dressings and infant formula (Henry, 2009) This raises an important problem as LC-PUFAs are known to be prone to lipid oxidation, which leads to loss of nutritional value and the formation of off-flavours (Arab-Tehrany et al, 2012), and de termines the shelf-life to a large extent (Fenaille, Visani, Fumeaux, Milo, & Guy, 2003)

Methods

Results

Conclusion