Preserving Omega-3 Oils with Antioxidants from Chia & Flaxseed

28

Omega-3 fatty acids are essential nutrients that play a vital role in maintaining heart health, supporting brain function, and reducing inflammation. These fats, particularly alpha-linolenic acid (ALA), are termed “essential” because the human body cannot produce them on its own they must be obtained through diet.

However, oils rich in these beneficial fats such as chia, flaxseed, and Sacha inchi oils face a significant challenge: they spoil quickly due to oxidation, a chemical reaction where oxygen interacts with fats, leading to rancidity, nutrient loss, and the formation of harmful compounds.

Natural Antioxidants Key Players in Preventing Oil Oxidation

Natural antioxidants are compounds found in plants, herbs, and spices that prevent or slow oxidation. Unlike synthetic antioxidants like BHA (butylated hydroxyanisole) and BHT (butylated hydroxytoluene), which have raised health concerns, natural options are considered safer and often provide additional health benefits. Antioxidants work through several mechanisms:

• Free radical scavenging: Donating electrons to neutralize unstable molecules.

• Metal chelation: Binding to pro-oxidant metals like iron and copper, which accelerate oxidation.

• Regeneration: Recycling other antioxidants (e.g., vitamin C regenerating vitamin E).

Rosemary extract, for example, contains powerful compounds like carnosic acid and carnosol, which donate hydrogen atoms to neutralize free radicals. In one experiment, adding 5,000 mg/kg of rosemary extract to chia oil doubled its oxidative stability a measure of how long the oil resists spoilage keeping it fresh for months.

Green tea extract, rich in catechins like epigallocatechin gallate (EGCG), works by scavenging free radicals and binding to pro-oxidant metals like iron. When combined with rosemary extract in a 1:1 ratio, it extended chia oil’s shelf life by 90 days at room temperature.

Tocopherols, a form of vitamin E naturally present in oilseeds, are another critical group of antioxidants. Gamma-tocopherol, abundant in chia and flaxseed oils, is especially effective at breaking free radical chains.

For instance, adding 500 mg/kg of gamma-tocopherol to flaxseed oil increased its induction time a lab test measuring how long an oil resists oxidation under heat—from 2.5 to 6.7 hours. Other antioxidants, like thymol from thyme and rosmarinic acid from oregano, not only prevent oxidation but also inhibit microbial growth, offering dual protection.

Chia, Flaxseed, and Sacha Inchi Oils: Stability Challenges

The study focuses on three omega-3-rich oils, each with distinct compositions and vulnerabilities:

Chia oil, extracted from Salvia hispanica seeds, contains 65% ALA, 20% linoleic acid (omega-6), and smaller amounts of oleic acid and saturated fats. While it boasts natural antioxidants like gamma-tocopherol (500 mg/kg) and polyphenols such as chlorogenic acid (plant compounds with antioxidant properties), its low omega-6 to omega-3 ratio (0.24–0.31) makes it prone to rapid oxidation.

Flaxseed oil, derived from Linum usitatissimum seeds, has a similar profile, with 60% ALA and 17% linoleic acid. Its high gamma-tocopherol content (460–610 mg/kg) offers some protection, but the oil still degrades quickly under light or heat.

Sacha inchi oil, sourced from Plukenetia volubilis seeds, stands out with 50% ALA and 35% linoleic acid, giving it a higher omega-6 to omega-3 ratio (0.52–0.83). While this ratio is still better than most vegetable oils, the oil’s elevated omega-6 content increases oxidation risk.

However, Sacha inchi oil compensates with exceptionally high levels of gamma-tocopherol (1,643 mg/kg) and delta-tocopherol, along with beta-carotene (a pigment with antioxidant properties), which collectively enhance its stability.

Effective Methods to Stabilize Omega-3-Rich Oils

The study explores four primary methods for stabilizing omega-3 oils, each with unique advantages and limitations:

1. Bulk Oils
Adding antioxidants directly to oils is the simplest approach. For example, ascorbyl palmitate (AP)—a fat-soluble form of vitamin C—reduced peroxide values (a measure of primary oxidation products) in chia oil by 60% over 12 months when used at 2,500 mg/kg.

Similarly, tomato lycopene (a carotenoid antioxidant) added to linseed oil lowered TBARS (thiobarbituric acid reactive substances)—a marker for rancidity caused by secondary oxidation—by 35%, showcasing the potential of fruit-derived antioxidants.

2. Oil Blends
Mixing omega-3 oils with more stable oils can improve shelf life. A blend of 80% sunflower oil and 20% chia oil achieved an omega-6 to omega-3 ratio of 2.7:1, closer to the ideal range.

When fortified with rosemary extract (5,000 mg/kg), the blend maintained peroxide values below 10 meq/kg (milliequivalents per kilogram) for a full year, demonstrating the synergy between blending and natural antioxidants.

3. Emulsions
Oil-in-water emulsions, where oil droplets are dispersed in an aqueous phase, protect omega-3s but are vulnerable to oxidation at the oil-water interface. Pickering emulsions—a type of emulsion stabilized by solid particles like proteins or polysaccharides—showed promise.

For example, flaxseed oil stabilized with self-assembled particles from flaxseed protein and mucilage reduced TBARS (a rancidity indicator) by 50% compared to conventional emulsions. Nanoemulsions, which use ultrafine droplets (100–600 nanometers), further enhanced stability. Astaxanthin—a red pigment and antioxidant from shrimp shells—boosted flaxseed oil’s oxidative stability by 70% in nanoemulsion form.

4. Microencapsulation
Encasing oils in protective matrices like maltodextrin (a carbohydrate) or alginate (a seaweed-derived gum) shields them from oxygen and light.

 Spray-dried chia oil microcapsules with rosemary extract retained 97% of their omega-3 content after 60 days, while freeze-dried Sacha inchi oil powders enriched with camu camu extract (a berry high in vitamin C) achieved 95% encapsulation efficiency and resisted oxidation better than synthetic BHT.

These methods not only extend shelf life but also enable the use of omega-3 oils in dry products like protein bars and powdered supplements.

Emerging Technologies in Omega-3 Oil Preservation

The study highlights cutting-edge technologies poised to revolutionize omega-3 oil preservation:

Active packaging, such as films coated with oxygen-scavenging compounds like ascorbic acid, reduced chia oil’s oxidation rate by 40% in trials. Enzymatic modification, where lipase enzymes rearrange fatty acids on glycerol molecules, created oxidation-resistant triglycerides in Sacha inchi oil, extending its shelf life by 30%.

Another promising approach involves phenolipids—omega-3 molecules chemically bonded to phenolic acids like caffeic acid.

This hybrid structure improved both stability and bioavailability (the body’s ability to absorb nutrients) in lab tests, offering a dual benefit.

Overcoming Challenges in Natural Antioxidant Applications

Despite these advances, challenges remain. For example, while rosemary and green tea extracts work synergistically, combining tocopherols with citric acid sometimes reduces efficacy due to antagonistic interactions. Cost is another barrier; supercritical CO₂ extraction, though eco-friendly, costs $50 per kilogram of rosemary extract, limiting its industrial adoption.

Additionally, some antioxidants, like oregano extract, can impart bitter flavors at high concentrations, requiring careful formulation.

---

Future of Omega-3 Oil Preservation

Looking ahead, researchers are exploring underutilized sources like algae-derived fucoxanthin (a marine antioxidant) and fruit peels (e.g., pomegranate) for novel antioxidants.

 Nanoencapsulation techniques, such as chitosan-alginate nanoparticles loaded with curcumin (a turmeric compound), have already shown potential by improving flaxseed oil’s thermal stability by 40%.

Machine learning models are also being developed to predict optimal antioxidant blends, reducing trial-and-error in product development.

Conclusion

Natural antioxidants offer a safe, effective way to preserve the health benefits and freshness of omega-3-rich oils. From rosemary-stabilized chia oil to microencapsulated Sacha inchi powders, these solutions align with consumer demand for clean-label (minimally processed, additive-free) and sustainable products.

By integrating advanced technologies like active packaging and enzymatic modification, the food industry can overcome oxidation challenges and deliver nutrient-dense oils to a global audience. As research continues to uncover new antioxidants and refine delivery methods, the future of omega-3 preservation looks brighter than ever, promising longer shelf lives, better taste, and enhanced nutritional value for consumers worldwide.