The Science Behind Personal Care Oils: How Refining Impacts Quality

What Defines a High-Quality Skin Care Oil?

Oils play a critical role in skincare, hair care, and body care, forming the foundation of countless formulations and wellness products. However, not all oils are created equal. Their quality depends on several factors, including the origin of the raw material, production methods, and the conditions under which the oils are stored and handled. Elements such as exposure to light, heat, and oxygen can significantly degrade an oil’s nutrient stability and effectiveness.

When selecting oils like Red Raspberry Seed Oil, or any oil for personal care, understanding these variables is crucial. Each oil has a distinct profile of fatty acids and essential nutrients. A truly high-quality oil contains beneficial compounds such as tocopherols (Vitamin E), polyphenols, carotenoids (Provitamin A), and nourishing fatty acids. Careful production, minimal processing, and proper storage are key to preserving these valuable properties.

Unfortunately, even oils labeled as “Organic,” “Cold-Pressed,” “Unrefined,” or “100% Pure” are not immune to issues such as adulteration, mislabeling, or nutrient loss during processing. Without robust transparency and traceability, these claims often become little more than marketing buzzwords, leaving consumers with products that fail to deliver on their promises.

This article explores how refining processes can alter the quality of carrier oils, uncovers common shortcomings of mass-market options, and highlights the critical importance of sourcing oils from trusted producers. By understanding these essential factors, consumers and businesses unfamiliar with the intricacies of this industry can make more informed choices about the oils they use in their wellness routines, skincare products, and formulations.

Refining Oils: The Process, Trade-Offs, and Nutritional Impact

Refining oils involves processes such as bleaching, deodorizing, and de-gumming, which aim to enhance clarity, odor, and shelf stability while removing impurities. These techniques address practical concerns by targeting free fatty acids, phospholipids, waxes, peroxides, aldehydes, and ketones; compounds that can cause undesirable flavors, odors, and inconsistencies in appearance. For industries requiring uniformity across batches, such as mass-market cosmetics, pharmaceuticals, and large-scale food manufacturing, refining is a common process to meet batch-to-batch quality specifications. However, achieving this consistency often comes at the expense of the oil's nutrient profile and bioactivity.

Heat is integral to nearly all refining methods. Even in lighter processes, such as using bentonite clay for purification, heat is required to activate refining agents. Temperatures as low as 150°F can degrade essential bioactive compounds, including tocopherols (Vitamin E), polyphenols, which are valued for their antioxidant and therapeutic properties. Other highly sought-after bioactive compounds, such as phospholipids, squalene, and phytosterols, are also degraded.

Beyond the inevitable loss of these beneficial properties, refining often results in the formation of potentially harmful compounds, such as trans-fatty acids, glycidyl esters, 3-MCPD esters, and polymeric triacylglycerols. These byproducts raise concerns about the long-term effects of regular consumption and use, depending on the oil and the methods used during refining.

Certain oils, including hemp, soybean, rapeseed, palm, corn, and sunflower oils, require refining to make them suitable for consumption or specific applications. These oils may contain undesirable or harmful compounds in their raw state, or they might be highly reactive, making them prone to oxidation and spoilage. While refining may be necessary for the functionality and safety of certain oils, the decision to refine is usually driven by commercial considerations of uniformity and mass appeal. Refining reduces odors, improves clarity, and extends shelf life, all good things, one would think. But there are downsides to refined oils.

Key Negative Effects of Refining:

• Loss of Tocopherols (Vitamin E): Up to 50% of tocopherols can be lost during refining, reducing the oil’s antioxidant capabilities (European Journal of Lipid Science and Technology Study).
• Reduction in Beta Carotenes (provitamin A): These compounds, essential for skin health and radiance, are highly sensitive to heat and significantly reduced during refining (Beta Carotene Study).
• Polyphenol Depletion: Refining strips away antioxidants and anti-inflammatory polyphenols, diminishing the oil’s therapeutic potential (Vegetable Oils: Effects of Processing, Storage, and Use on Nutritional Value).
• Fatty Acid Changes: High-heat deodorization can destabilize unsaturated fatty acids, creating harmful trans fatty acids and altering the oil’s natural balance (High-Oleic Safflower Oil Study).
• Formation of Harmful Compounds: Refining can result in the creation of trans-fatty acids, glycidyl esters, 3-MCPD esters, and polymeric triacylglycerols. (Scientific Word Journal).

It’s worth noting that the USDA’s National Organic Program allows certain refining processes, such as the use of natural substances like bentonite clay and heat treatments, while maintaining an oil’s organic certification. Bentonite clay, is listed on the National List of Allowed and Prohibited Substances (§205.605(a)) and has been approved for use in organic processing since April 21, 2001 (65 FR 80548, 66 FR 15619).

Variability in Refining: Light vs. Heavy

Not all oils are refined to the same extent. Depending on how the oil is extracted - mechanically (pressed) or chemically (solvent extraction) - and the desired results, the refining process can differ significantly in intensity and impact on the oil’s properties. While terms like "light refining" and "heavy refining" are generalizations rather than technical classifications, they help convey the spectrum of refining methods, process aids, and technologies commonly employed.

• Light Refining: This process focuses on removing sediments, minor impurities, and lowering peroxide values, which measure oxidative stability. Despite being labeled "light," it often requires heat application, with bentonite clay being one of the most common agents used for purification. Typical temperatures range between 70–80°C (158°F–176°F). Light refining is commonly applied to mechanically extracted oils to enhance clarity (limpidity), reduce odor, and improve shelf-life stability.
  
• Heavy Refining: This process involves more intensive and multi-stage treatments, often incorporating chemical solvents, alkali neutralization, bleaching agents, and deodorization techniques. These steps are designed to thoroughly remove impurities, stabilize the oil, and ensure a consistent color, odor, and extended shelf life. Heavy refining frequently uses high temperatures exceeding 200°C (392°F), which can degrade sensitive nutrients and lead to the formation of potentially harmful compounds, such as trans-fatty acids. Solvent-extracted oils are particularly likely to undergo heavy refining due to the need for additional processing to remove residual solvents and achieve desired quality standards.
  

For consumers seeking nutrient-rich oils, raw, unrefined, cold-pressed options remain the gold standard. These oils are extracted without the use of solvents and bypass all refining processes, allowing them to retain their natural scent, color, and full spectrum of bioactive compounds. As a result, they offer the most value in both nutritional and cosmetic applications.

Below is a diagram illustrating how oils are typically refined:

Diagram outlining the chemical and physical refining process for carrier oils extracted through mechanical pressing or solvent extraction.

Source: Adapted from Gharby, S. (2022). Refining Vegetable Oils: Chemical and Physical Refining. The Scientific World Journal, 6627013. https://doi.org/10.1155/2022/6627013.

The Pitfalls of Mass-Produced Oils: Mislabeling and Nutrient Loss

Purchasing oils for skincare, hair care, and other personal care products from large online platforms, resellers, white-label brands, or even grocery stores often comes with significant compromises. Issues such as adulteration, dilution, and mislabeling are alarmingly common. A UC Davis study on avocado oils revealed that nearly 70% of private-label products (those produced by third-party processors and sold under grocery store or retailer brands) were either rancid or mixed with lower-quality substitutes. This lack of oversight leaves consumers uncertain about the purity, quality, and origin of their purchases.

However, the issue isn’t limited to avocado oil. Popular personal care oils, including raspberry seed oil, olive oil, rosehip oil, argan oil, grapeseed oil, jojoba oil, coconut oil, sunflower oil, and almond oil are also frequently misrepresented. Labels boasting claims such as "Cold-Pressed," "Unrefined," or "100% Pure" suggest high-quality, minimally processed products, yet these terms remain largely unregulated in the personal care industry.

The term "Organic" further complicates matters. Unlike food products, "Organic" is not regulated by the USDA National Organic Program (NOP) for personal care items. Only terms such as "Certified Organic" or "100% Organic" are subject to strict USDA standards, ensuring traceability and compliance at every stage, from raw material sourcing to final packaging.

This distinction is critical: not all Certified Organic oils are created equal, just as not all oils are created equal. Just because an oil is "Certified Organic" doesn't mean that it wasn't exposed to high heat or other refining steps in its production. 

Understanding these nuances equips consumers to make more informed choices. Transparent labeling, combined with provenance and traceability, serves as a reliable indicator of a producer's commitment to quality over marketing jargon.

Artisanal Producers: Intimate Knowledge Builds Trust

Large ingredient distributors and mass-market suppliers almost exclusively rely on paperwork, certifications, and lab results to vouch for an oil’s quality, frequently without ever opening, inspecting, or testing the oil before re-packaging and re-selling it. While these documents are valuable and necessary for commerce, they cannot replace the direct, firsthand knowledge that comes from being deeply involved in every stage of production. Without understanding how a truly raw, virgin oil should look, smell, taste, and feel (and analyzing its micronutrient and free fatty acid profile before use in formulations or bottling) there’s no way to confidently guarantee that an oil meets the standards implied by labels and claims such as "Cold-Pressed," "Unrefined," or "100% Pure."

Even in an era dominated by large-scale industrial oil production, organoleptic evaluation (the sensory assessment of an oil's taste, appearance, aroma, and texture) remains one of the most reliable indicators of authenticity and quality. This traditional method, when paired with modern analytical tools such as lab analysis, can reveal inconsistencies that paperwork alone might miss.

Over more than a decade of producing Red Raspberry Seed Oil, we’ve encountered oils marketed as "Raw, Cold-Pressed, Unrefined Raspberry Seed Oil" with colors ranging from clear to pale yellow or even pink - clear indicators of heavy processing, adulteration, or added coloring. Third-party micronutrient analyses of such oils consistently reveal fatty acid profiles and nutrient contents that deviate significantly from what we observe in our own production. Yet, these oils remain prevalent in the market, making it challenging for consumers to accurately assess quality.

Take olive oil, for instance. If you’ve ever tasted authentic virgin, cold-pressed olive oil from regions like Spain, Greece, or California, you’ve likely noticed its bold, spicy flavor and nuanced notes - qualities that are stripped away in the refined, mass-market versions commonly found on grocery store shelves. Even among raw, unrefined oils, subtle variations exist due to factors like growing regions, olive varieties, and production methods, all contributing to distinct flavor profiles and characteristics.

The same principle applies to personal care oils like Red Raspberry Seed Oil and Cranberry Seed Oil. Without firsthand experience of the authentic, unrefined product, it’s nearly impossible to fully appreciate the unique qualities that set it apart from heavily processed or adulterated alternatives.

As a small, artisanal producer with full oversight of our supply chain, we have an undeniable advantage: we can speak truthfully and confidently about the quality of our oil because we are involved at every stage of production. From the subtle variations in color, aroma, texture, and feel to the nutrient profile (not just in every batch but even during the pressing process itself) we know our oils intimately. Years of hands-on experience have sharpened our ability to recognize nuances that others might overlook: the warm scent of freshly pressed oil, the ideal temperature of the collection pan, or the clarity of the oil after filtering. This direct involvement ensures that every bottle reflects the true integrity of the oil, free from the inconsistencies and uncertainties that arise in complex, outsourced supply chains.

Traceability Is a Responsibility, Not a Luxury

Brands and distributors have an ethical duty to ensure that their claims about sourcing, production, and processing are truthful and verifiable. This goes beyond liability and compliance; it’s about respecting the trust of customers who rely on these products for health and wellness.

Managing and distributing many different oils, sourced from many different producers, presents an enormous challenge for companies. Ensuring consistent quality across a diverse product range requires staff to possess detailed knowledge of each oil’s unique characteristics. Unfortunately, in practice, many such operations lack this expertise.

At its core, traceability isn’t just about paperwork or locality, it’s about firsthand knowledge of all the steps of production - which allows one to personally vouch for the product’s integrity. Producers who are intimately involved in their craft can look a customer in the eye and assure them, with confidence, that every bottle represents genuine quality, transparency, and care.

By choosing to support producers who prioritize integrity and craftsmanship over standardization and mass appeal, buyers are not only investing in superior oils but also helping to create a marketplace where authenticity and accountability set the standard, not the exception.

Sources and References

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• Micronutrients in Vegetable Oils: Impact of Crushing and Refining Processes on Vitamins and Antioxidants – ResearchGate
  • Examines nutrient losses in sunflower, rapeseed, and soybean oils during crushing and refining, highlighting reductions in tocopherols, sterols, and polyphenols.
• Effects of Refining Processes on the Physicochemical Properties of Some Selected Vegetable Oils – Journal of Chemical Sciences
  • Explores the chemical and physical changes in palm, palm kernel, and soybean oils post-refining, including reductions in peroxide and acid values.
• Supercritical CO2 Degumming and Physical Refining of Soybean Oil – Academia.edu
  • Analyzes SC-CO₂ degumming for reducing phosphorus and iron content, improving oil clarity, and enhancing oxidative stability.
• Refining of High Oleic Safflower Oil: Effect on Sterols and Tocopherols – ResearchGate
  • Examines nutrient losses, including sterols and tocopherols, during the degumming, bleaching, and deodorization of safflower oil.
• Physical Refining of Sunflower Oil – Academia.edu
  • Explores the advantages of physical refining over chemical refining, focusing on economic benefits, environmental impact, and improved processing technologies.
• Effects of Seed Roasting on Tocopherols, Carotenoids, and Oxidation in Mustard Seed Oil During Heating – ResearchGate
  • Examines the effects of roasting mustard seeds on oil quality, showing improved oxidative stability, preserved tocopherols, and enhanced carotenoid content.
• Vegetable Oils: Effects of Processing, Storage, and Use on Nutritional Value – SpringerLink
  • Discusses how refining, storage, and cooking processes impact the nutritional composition and oxidative stability of vegetable oils.
• Refining Vegetable Oils: Chemical and Physical Refining – PMC
  • Compares chemical and physical refining, detailing nutrient loss and formation of unwanted by-products like 3-MCPD esters.
• Edible Oil Refining: Current and Future Technologies – Wiley Online Library
  • Explores innovative technologies in oil refining, including enzymatic degumming, nanoneutralization, and sustainability-focused processes.
• Ecological-Safe and Low-Cost Activated Bleaching Earth – ScienceDirect
  • Evaluates thermal activation methods for environmentally friendly bleaching earth and their impact on oil quality.
• Minor Constituents in Canola Oil Processed by Traditional and Minimal Refining Methods – ResearchGate
  • Compares traditional and minimal refining techniques, highlighting nutrient retention benefits and quality improvements in canola oil.
• Phytosterols in edible oil: Distribution, analysis and variation during processing – ScienceDirect
  • This study highlights the impact of oil refining on phytosterol content, emphasizing the need for improved methods to minimize nutrient loss and preserve quality in edible oils. Enhanced analytical techniques and further research into degradation mechanisms are critical to maximizing the health benefits of phytosterols.
• National Organic Program (65 FR 80548) – Federal Register
  • Outlines USDA regulations for organic certification, including standards for oil refining processes.
• National Organic Program Correction (66 FR 15619) – Federal Register
  • Provides corrections and clarifications to the National Organic Program regulations.
• USDA Organic Regulations on Cosmetics and Personal Care – USDA
  • Clarifies labeling standards for organic cosmetics, personal care, and body care products under USDA guidelines.
• UC Davis Article on Avocado Oil Adulteration – UC Davis
  • Highlights findings on avocado oil adulteration, rancidity, and mislabeling in retail products.
• 2023 Study: Quality and Purity of Private Label Avocado Oil – Food Control
  • Revealed that 70% of private-label avocado oil samples were rancid or adulterated, emphasizing ongoing quality control issues.