In Praise of Palm Oil

Palm oil is obtained from the fruit of the oil palm tree, Elaeis guineensis. The majority of palm oil is produced in Malaysia and Indonesia where growing conditions are ideal. Typically, a palm plantation produces about 6,000 lbs. of palm oil per acre per year. The life cycle of a palm plantation is about 30 years, after which the old trees are removed and replaced with new tree varieties. The latest varieties are expected to yield up to 50% more palm oil per acre, greatly increasing palm oil output on the same acreage of planted land.

Fruitful details

A palm fruit has about a 2-in. diameter and consists of a hard nut called a kernel, surrounded by a fleshy fruit layer. Palm oil is obtained from the fleshy layer without solvents or chemicals by treatment with steam followed by pressing. The pressed oil, called crude palm oil, is bright-red in color, due to a high content of natural beta-carotene, a vitamin A precursor. For food use, crude palm oil is further refined to remove color and odor using steam, vacuum and natural clay. Also present is a group of natural antioxidants called tocotrienols, which contribute to the stability and shelf life of the oil. Tocotrienols also help protect the body against the effects of oxidation and free-radical formation.

Palm oil’s natural balance of saturated and unsaturated fatty acids is composed mainly of an equal amount of palmitic acid (C16:0) and oleic acid (C18:1), and contains no trans fat. For every gram of saturates consumed, a gram of unsaturated fat will also be consumed. Recent nutrition research has shown that the saturated fat in palm oil raises human levels of high-density lipoprotein (HDL, or “good”) cholesterol, partially counteracting saturated fat’s well-known effect of raising low-density lipoprotein (LDL, or “bad”) cholesterol.

A functional palm reading

Palm oil is naturally semisolid at room temperature (melting point, or MP, of approximately 39°C), making it an excellent shortening for many food applications without the need for further processing. Palmitic acid, the main saturated fat in palm oil, naturally forms small, stable crystals (called beta-prime) that are excellent at stabilizing small air cells and imparting a smooth, creamy texture to shortening with enhanced functionality for baked goods.

Over the past 30 years, many different shortenings have been tailored for specific applications using partial hydrogenation, a process that gives rise to trans fats. Palm oil can help supply similar functionalities without hydrogenation. Although palm oil is a single natural product, it is highly versatile due to a physical process called fractionation. During fractionation, the fat is melted and cooled slowly to produce a slurry of high-melting-point crystals suspended in liquid oil. The crystals are separated from the liquid component by filtration, and the resultant “fractions” have completely different physical properties compared to the original palm oil. The high-melting-point fraction, palm stearine (MP approximately 55°C), is a hard, waxy solid, while the palm olein fraction is a liquid at room temperature (MP approximately 25°C). Fractionating these fractions again gives additional components with different physical characteristics. Blending the fractions in different proportions generates an unlimited variety of shortenings, matching the functionality of almost any kind of partially hydrogenated vegetable oil.

Palm oil naturally resists oxidation and provides a long shelf life to baked goods and deep-fat-frying operations. It contains no linolenic acid (the most-unstable fatty acid in vegetable oil), and the total content of polyunsaturates is 10%, compared to 60% in soybean oil. The remaining fatty acids are oleic and palmitic acids, both of which are highly stable. Palm oil stability is further increased by the presence of natural antioxidants. Shelf-life and fry stability of all palm oil products are comparable to partially hydrogenated vegetable oil.

When replacing a partially hydrogenated shortening, comparing the solid-fat profile and melting point to the corresponding palm oil product is a useful first step. However, it is not realistic to expect an exact match, because of the large differences in fatty acid compositions. Palm oil, or a slightly harder or softer version of palm oil, is usually a drop-in solution for typical all-purpose shortenings used, for example, in cakes and cookies.

Some applications, including pies, Danish and puff pastries, require a more-sophisticated shortening. Regular palm oil tends to become brittle when cool, and softens excessively as it warms up. These applications need a fat that remains soft at lower temperatures and resists melting at high temperature. For these, appropriate blends of palm fractions provide the temperature tolerance needed for demanding applications.

Gerald P. McNeill, Ph.D., is director of research and development for the oils and fats division of Loders Croklaan NA, Channahon, IL, with responsibility for the roll-out of Loders’ comprehensive line of zero-trans fats and oils products.