Nutritionists have long touted olive oil as a healthy alternative to other types of cooking oils and fats used to prepare foods. According to the Mayo Clinic, olive oil's monounsaturated fatty acids help lower cholesterol levels and prevent heart disease. Many health agencies such as the World Health Organization and the National Institutes of Health cite studies that credit olive oil's antioxidants and vitamin E content with helping to prevent different types of cancer. Refining olive oil robs it of its of certain health benefits. Filtering is a process that removes particles of olive fruit from oil, and some consumers consider unfiltered oil a less refined and healthier choice.
Oil Grades and Filtering
For centuries, people crushed olives with stone presses, and collected the oil. Today, that simple mechanical method is used to produce extra virgin olive oil, the industry's highest grade.The term extra virgin reflects the production process and the oil's acidity level, which must be less than .5 percent. Virgin olive oil, a second grade of premium oil, follows the same production process but fails to meet the required acidity level. Lower grades of oil sold as pure or refined olive oil contain small amounts of extra virgin or virgin oil mixed with oil that has been extracted during a second or third press of olives, usually with the help of solvents and heat. Some premium oils are filtered, or drained through cotton, to remove olive particles that can spoil when exposed to light. Filtering extends their shelf life. Oil manufacturers also filter lower grade oils to remove impurities from processing.
Taste
Cooks who prefer unfiltered oil claim that the particles of olive enrich the oil's flavor. Claude Weiller of the California Olive Ranch compares the olive particles in oil to the pulp that comes in oranges juice. Weiller acknowledges a shortened life span for unfiltered oil, and advises consumers who choose unfiltered oil to check the dates on bottles and to store the oil in a cool, dark place. Other oil manufacturers say the particles have little effect on flavor, and filtered or unfiltered is a matter of personal taste.
Appearance
Filtering plays a role in the appearance of olive oil. Unfiltered oil can appear cloudy or can have layer of sediment on the bottom of the bottle. Compared to the translucent gold and green color of filtered oil, unfiltered oil may look like a lesser quality product. While marketing may have played a role in the decision to filter olive oil, the decision not to filter oil has become a selling point with consumers looking for natural whole foods.
Standards
In October 2010, the U.S. Department of Agriculture set new standards for olive oil. In order to market oil as extra virgin, it must meet standards for odor, acidity and chemical or nutritional content. Oil is also inspected for clarity after it has been stored for 24 hours, but there is no specific standard. Individual food inspectors judge whether cloudy or unfiltered oil can be labeled and sold as high-quality extra virgin olive oil.
References
- MayoClinic.com; If Olive Oil Is High in Fat, Why Is It Considered Healthy?; Donald Hensrud, M.D.
- The Vine Times; Olive Oil: Demystifying Liquid Gold; Al Hernandez
- Olive Oil Times; Will That Be Filtered, or Non?; Lisa Lucke; April 2010
- California Olive Ranch; Filtered Vs. Unfiltered Olive Oil; April 2010
- Olive Oil Times; Understanding the New USDA Olive Oil Standards; Alexandra Kicenik Devarenne, et al.; September 2010
- Olive Oil Times; USDA Olive Oil Standards Appendices; September 2010
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