Is oxygen reduction a viable antioxidant strategy for oil‐in‐water emulsions?

Abstract

The impact of 0, 40, 58, 79, 93, and 98% total oxygen reduction on lipid oxidation kinetics in a 1.0% fish oil‐in‐water emulsion (pH 3.0; 32°C) was determined. Atmospheres were modified using nitrogen/oxygen gas blends or high purity nitrogen. Headspace and dissolved oxygen were monitored throughout the study using a non‐destructive technique in which fluorescent sensors were fixed in sealed vials. Lipid oxidation, as measured by lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS), was inhibited at oxygen reductions ≥58%. However, meaningful protection against lipid oxidation was only achieved at oxygen reductions ≥93%. Potential commercial strategies, nitrogen flushing/sparging, and ascorbic acid, were inefficient at reducing oxygen to levels that could significantly inhibit lipid oxidation. Results suggest that near complete oxygen removal is necessary to protect oxygen‐sensitive ingredients, but a need still exists to identify new strategies that sufficiently reduce the oxygen content of emulsions. Practical applications: The practical application of this work is that there is a global demand to remove synthetic additives from food and beverage formulations, and as described in this work, defining the level oxygen reduction that provides meaningful increases in oxidative stability is necessary. Results suggest that the oxidative stability of 1% fish oil‐in‐water emulsions can be extended by reducing system oxygen by ∼58%, but to have a meaningful antioxidant impact greater than ∼93% oxygen removal is required. Further investigation into simulated commercial oxygen removal strategies (e.g., nitrogen displacement of oxygen and ascorbic acid) demonstrated that current industrial strategies are lacking and need to be optimized in order to enhance stability against lipid oxidation. In this work, we design and modify a fish oil‐in‐water emulsion system to have different oxygen concentrations that range from almost complete oxygen removal to atmospheric conditions. The resulting emulsions are characterized over time by non‐destructively measuring oxygen concentrations, both in the headspace and dissolved phase, as shown in the figure of two sensor patches inside a sealed glass vial. The impact of oxygen concentrations on lipid oxidation kinetics is measured and represented in the graphed data. Results suggest that near complete oxygen removal is necessary to provide meaningful protection against lipid oxidation in emulsified systems.

Delivery by Design (DbD): A Standardized Approach to the Development of Efficacious Nanoparticle‐ and Microparticle‐Based Delivery Systems

“…An example of the increase in degradation rate of lutein encapsulated in oil‐in‐water nanoemulsions with increasing temperature is shown in Figure . For temperature‐sensitive active agents, it is important to ensure that they are not exposed to elevated temperatures that may promote their rapid degradation. Oxygen levels : The degradation rate of active agents that are susceptible to oxidation (such as polyunsaturated lipids) typically increases as the concentration of dissolved oxygen in their surroundings increases (Johnson and others ). For these systems, it is often important to reduce the level of oxygen in the system by pulling a vacuum, flushing with nitrogen, or using chemical reagents, although it is often difficult to maintain the low levels required to inhibit oxidation. Pro‐oxidant levels : The degradation rate of active agents prone to oxidation may also be accelerated by the presence of pro‐oxidants in a system, such as transition metals, hydroperoxides, and oxidizing enzymes (McClements and Decker ; Waraho and others ).…”

“…Oxygen levels : The degradation rate of active agents that are susceptible to oxidation (such as polyunsaturated lipids) typically increases as the concentration of dissolved oxygen in their surroundings increases (Johnson and others ). For these systems, it is often important to reduce the level of oxygen in the system by pulling a vacuum, flushing with nitrogen, or using chemical reagents, although it is often difficult to maintain the low levels required to inhibit oxidation.…”

How To Stabilize ω-3 Polyunsaturated Fatty Acids (PUFAs) in an Animal Feeding Study?—Effects of the Temperature, Oxygen Level, and Antioxidant on Oxidative Stability of ω-3 PUFAs in a Mouse Diet

“…Johnson et al showed that substantial inhibition of lipid oxidation in an oilin-water emulsion was not observed until 93% of oxygen was removed from the emulsion. 19 In this work, maximum oxygen reduction was 80%. While this did decrease the rate of lipid oxidation after the lag phase, it did not increase the lag phase compared to the control.…”

“…Crimp cap vials were used in these experiments because they were more oxygen-impermeable than screw-capped vials. Oxygen-sensing fluorescent patches were placed in the headspace of the vial and used to measure the oxygen concentration, following a similar method as described by Johnson et al 19 Oxygen was removed by flushing the vials with nitrogen or nitrogen/oxygen blends for 3 min before crimping the vials closed. The oxygen concentration, expressed as the percentage of oxygen removal compared to atmospheric oxygen, was measured every day.…”

Smart and Active Food Packaging: Insights in Novel Food Packaging

“…Ascorbic acid and α-tocopherol with OS rates of 11.9 and 0.21 cm 3 of O 2 day −1 g −1 , respectively, are highly compatible for AFP (Byun et al, 2011;Rodríguez et al, 2020), but both need to be stimulated by UV, light, heat, or transition metals, which entails higher expenses as compared to nanoiron-based scavengers. Besides, they show low efficacy in oxygen scavenging in high moisture content and avoid lipid oxidation because to inhibit lipid oxidation, 98% oxygen scavenging must be obtained (Johnson et al, 2016). The enzyme function of OS is based on reactions with a specific substance.…”