Unrefined vs Refined Oils

Unrefined Oils

Unrefined Oil are oil that are as close to their natural form as possible.  They are produced without heat, solvents or chemicals. The Cold Pressed oil that comes from our processing equipment usually has a pronounced colour, flavour and aroma. Other large-scale oil producers will often remove these characteristics by refining, to produce a standardised, bland, odourless oil. Our company however, offers unrefined oils for their natural health giving properties.

For example, many oils (such as Hemp Seed Oil) are naturally rich in antioxidants that are significantly reduced by refining. The unrefined oil can therefore be more stable, giving a longer shelf life, and the antioxidants also confer additional health benefits. The natural flavour and aroma of unrefined oils can also be a selling point, for use in health food and culinary applications.

Refined Oils

If a stable, clear, and odourless oil is required there are various refining techniques available. These methods fall into two categories: physical refining and chemical refining. Both techniques are, of course, suitable for use with food-grade products. Some customers, however, may wish to obtain as 'natural' an oil as possible, so physical refining methods are more appropriate.

Physical methods

• Filtering.  The unrefined ‘crude’ oil taken directly from pressing is often cloudy because it contains fragments of seed material or sediment. This sediment can be removed by filtration (to a specific micron rating) to leave a clear, sediment free, and bright oil.
• Deodorising. The strong flavour and pungent aroma of certain oils can be removed by heating the oil under high vacuum. All volatile components are driven off, including most oxidation products, leaving the oil virtually odourless.
• Winterisation. Seed oils naturally contain varying amounts of waxes and gums that are suspended in the oil following extraction. These compounds can cause the appearance of haze or cloudiness in oils during their shelf life. For certain specifications and applications, this cloudiness is deemed unacceptable, particularly in clear-encapsulated products. Winterisation involves holding the oil at a low temperature to encourage these components to crystallise, allowing them to be removed by a final filtration.

Chemical methods

• Degumming. Gums (phosphatides), plus any chlorophyll and destabilising metal ions, are removed by washing the oil with high purity water and food-grade phosphoric acid.
• Neutralisation. The oil is treated with an alkali solution that neutralises any free fatty acids, which can then be removed, along with any lecithin and phospholipids.
• Bleaching. The oil is mixed with a carefully measured quantity of diatomaceous earth which absorbs the colour components from the oil. The process is a gentle one, and does not involve the use of chemical bleach, as is sometimes assumed. This process also removes metal ions, any residual chlorophyll and other components that may adversely affect the stability of the oil.

Storage & Handling

The way you store and handle oils is very important for maintaining oil quality. Whether refined or not, all oils are sensitive to heat, light and exposure to oxygen.

Midlands Nutrition offers two main types of oils; Monounsaturated and Polyunsaturated.

Oils that are Monounsaturated i.e. Olive Oil, Avocado Oil and Sunflower Oil tend to have a longer shelf life than polyunsaturated oils. These oils can be kept in a cool dry place away from direct sunlight and can also be refrigerated.

On the other hand polyunsaturated oils i.e. Flaxseed Oil, Hemp Seed Oil and Rosehip Oil, are sensitive to heat and should not be cooked with. Exposing these oils to heat, light and oxygen will lessen their shelf life and nutritional profile. These oils need to be kept refrigerated or even frozen.

Freezing oils will prolong the quality and freshness of the oil without damaging any of the oils properties (flavour and quality). Some oils will stay in liquid form but others will become solid.

Oils for distribution or retail should be packaged into dark glass containers, which will protect the oil from light. The headspace of the bottle should be flushed with nitrogen to remove any oxygen on top of the bottle. Oils that are subjected to heat, light and oxygen will become rancid. Rancid oil has an unpleasant aroma and taste, and is in fact bad for you if consumed.

Shelf Life

For Bulk Oils, our specification for shelf life is: If stored in unopened containers at less than 20c Deg Celsius, the oil can expect to have a shelf life of 12 months.

For Private Label or Retail Ready Oils, our recommendation is: Keep refrigerated and once opened consume within 3 months.

This is a guideline only, and it is the buyer's responsibility to ensure the integrity and quality of the product by validating shelf life of each product in their own packaging format.