Frying the non-trans way, part 1
To fry with stability in today’s increasingly trans-fat-free world, bakers and snack food makers are turning to oils that are naturally stable. Baking & Snack talked to Gerald P. McNeill, PhD, vice-president of R&D, IOI Loders Croklaan Americas, Channanhon, IL, about how palm oil fits these emerging needs … and why.
Baking & Snack: Which baked products and/or snacks been most successful in making the switch away from frying fats and liquid oils that contain trans fatty acids? Why?
Gerald P. McNeill, PhD: The process of hydrogenation was invented to convert the unstable polyunsaturated fat in soybean oil and other vegetable oils into stable trans fat. The combination of heat and air in fryers causes the polyunsaturated fat in soybean oil to break down quickly when exposed to heat and air, causing rancid flavors to develop. The oil must be replaced frequently and that adds cost to the finished baked goods and snacks.
However, many bakeries and snack food manufacturers have specialized equipment that can overcome the drawbacks of using non-hydrogenated soybean oil, sunflower oil or any other polyunsaturated oils. While heat is essential for baking and frying, air is not. Equipment that is designed to drive out air from the fryer utilizing steam released from the food will prevent degradation of the oil, eliminate off flavors and greatly reduce the frequency of oil replacement.
What must the formulator know about trans-free frying shortenings to ensure their successful use?
If the formulator does not have access to equipment that eliminates air during the frying process, then the use of polyunsaturated oils can be a costly option. In addition to off-flavor development, these oils tend to polymerize, resulting in a thick “gunk” that accumulates in the bottom of the fryer. This requires difficult time consuming cleanouts and loss of oil. In general, consumption of damaged vegetable oil should be avoided because it can have an adverse effect on human health over a long time period.
From a formulation perspective, several alternative oils have emerged as suitable alternatives to partially hydrogenated vegetable oils. All of these oils have one thing in common — a very low content of polyunsaturated fat without the need for hydrogenation.
Palm oil is the most widely produced vegetable oil in the world today, with a polyunsaturated fat content of only 10%. It has already been used extensively around the world for decades, as a very stable, cost effective frying oil for almost any frying application.
Palm oil is naturally a semi-solid fat at room temperature with the texture of butter. As a natural solid it is an excellent candidate for use in products like donuts that require a non-oily texture. Using a special filtration process called fractionation, a liquid component can be squeezed out of the palm oil called palm olein. The liquid palm oil is just as stable as the original palm oil, with all the advantages of a pourable oil. Palm oil and palm olein are very cost effective as they are priced at the low end of the vegetable oil industry. Additional cost savings are realized as the oil does not need to be replaced frequently and does not create polymerized fat.
The advent of genetically engineered varieties of traditional polyunsaturated oils like canola, sunflower and soybean oils has produced seed oils with a low level polyunsaturates that also are stable under frying conditions. Production of these oils is limited resulting in relatively higher costs for the foreseeable future.
What changes are necessary for handling these fats in production plants? Compared with previous choices, will new trans-free fats require different in-plant storage conditions? Filtering frequency? Turnover rates? Temperature ranges?
In the case of palm oil, both solid and liquid forms are available, and due to the physical fractionation process, the texture of almost any existing partially hydrogenated vegetable oil can be matched or tailored made. This means that no changes in handling are required in production plants. The high stability of natural palm oil and its fractions match or exceed the technical requirements of current frying oils and in most cases changes in oil replacement and filtration is not required.
What does the future hold for continuing improvement in frying fats and liquid oils for bakery and snack use?
In the future, demand for vegetable oil in general, and frying oils in particular, is expected to increase exponentially in-step with global population growth. Researchers have predicted that palm oil yield per acre of land has the potential to double in the next 25 years, through a combination of traditional breeding techniques and improved agricultural practices. In the case of seed oils, suitable agricultural land is scarce with only a modest potential for yield growth. Palm oil will likely become the dominant low cost edible oil in the world in the foreseeable future.