Fat is an essential part of any diet. It enables necessary pathways, like vitamin metabolism, to function properly. However, as well as eating excess fat, the type of fat eaten can also have health implications.
Polyunsaturated fats have been deemed to carry a reduced risk of cardiovascular disease compared to saturated fats.1,2 The consumption of saturated fats has been linked to raised levels of LDL cholesterol in the blood, resulting in the formation of plaques, which may narrow or block arteries with destructive effects.
Because unsaturated fats are principally found in plants (for example olive or avocado) and nuts (for example cashew or peanut), vegetable fats are generally utilized instead of animal fats in the preparation of healthier food options.
However, a range of vegetable fats also contain large amounts of saturated fats. These include coconut oil, palm oil and palm kernel oil, with some of the most commonly used vegetable oils having a surprisingly high saturated fat content. In an ideal situation, these fats could be used with no negative impact on health.
Palm oil is one of the main sources of fat globally, largely due to its widespread availability. Palm oil is extracted from the fruit of African palm trees, offering good thermal stability and a tendency to crystallize in the ideal β´ form.3 Fats that have crystals in the β′ form usually offer improved culinary functionality – for example, they are softer and allow creaming.
African palm oil, includes a high proportion of saturated fatty acids, meaning that its use in food products is far from ideal.4,5 Oil from its relative American palm has a far lower saturated fat content, in comparison.
The solid portion of palm oil - palm stearin - is usually combined with other oils to produce products such as margarines and confectionery fats which possess desirable organoleptic properties, such as the presence of essential β’ crystals.6,7
Interesterification – the process by which the fatty acids of triacylglycerides are rearranged to alter physical properties - has been utilized to deliver a mix of palm stearin and palm kernel oil which is well suited to the manufacture of industrial margarines.
Hybrid palm oil, which has been obtained through crossing African oil palm with American oil palm, has begun to enter the food industry, offering a new, healthier alternative to conventional palm oil. These health benefits are largely due to its high oleic fatty acid concentration.
Studies have verified that hybrid palm oil results in a beneficial blood lipid profile which is not linked to increased risk of cardiovascular disease.8
From a practical standpoint, hybrid palm oils offer other advantages in terms of increased resistance to diseases and pests, and extended shelf life, when compared to traditional palm oils.
Despite the health benefits on offer, adoption of hybrid palm oil as a lipid source for industrialized products has been limited. This is due to a lack of physiochemical information on the hybrid palm oil in question.
The majority of studies completed to date have focussed on its nutritional and agronomic properties, while no research has been done on the viability of outright replacing palm oil with hybrid palm oil.
Characterization of hybrid palm oil
The enzymatic interesterification of hybrid palm stearin blended with palm kernel oil has been studied recently, in order to ascertain whether or not it would be suitable as an alternate source of vegetable fat.9 Enzymic interesterification of the mixture was attained in a fixed-bed reactor utilizing lipozyme.
Compositional analysis was performed on the solid portion of the hybrid palm stearin/palm kernel oil mix, and its thermal, physical, rheological, and microscopic properties were evaluated. This was done both before and after enzymic interesterification. Conventional palm stearin was also analyzed for comparison.
Solid fat content was measured every 24 hours using pulsed nuclear magnetic resonance (NMR), employing a Bruker Minispec-mq20 spectrometer operating at a resonance frequency of 20 MHz.
Measurements were taken at 10, 20, 30, 35, and 40 °C before being analyzed with the integrated Bruker Minispec Software. Gas chromatography was used to assess fatty acid composition, and dynamic oscillatory measurements were taken with an MCR 302 rheometer.
The melting and crystallization profiles of the blends were obtained via differential scanning calorimetry, while the crystal microstructure was examined using polarized light microscopy.
Here, the interesterification resulted in hydrolyzed and esterified lauric, oleic and palmitic acids. This reduced the melting and crystallization temperatures by ≈2 °C and allowed faster structuring and/or crystallization.
This process also promoted rapid stabilization of the size and number of crystals formed. The fat crystals’ size was reduced following enzymatic interesterification, preventing the mix becoming overly granular. This novel hybrid mixture exhibited similar properties and consistency to the standard palm stearin/palm kernel oil mix.
Every sample exhibited fluid-like behavior and rheology results which suggested that the interesterified blends of palm stearin and hybrid palm stearin had been able to achieve complete structure and crystallized within a comparable timeframe.
The hybrid oil mix possessed a greater percentage of unsaturated fatty acids than a comparable mixture that used standard palm stearin/palm kernel oil, confirming the availability of a healthier option.
Microstructure and rheological analyses indicated that the enzymatically interesterified hybrid palm stearin/palm kernel oil mix was a strong contender for use in a variety of food products that utilize vegetable fat as an ingredient.
- Nettleton JA, et al. Ann Nutr Metab. 2017;70(1):26–33. https://doi.org/10.1159/000455681
- Hooper L, et al. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database of Systematic Reviews 2015;6 article CD011737. https://doi.org/10.1002/14651858.CD011737.
- Tanaka L, et al. Journal of the American Oil Chemists’ Society 2007;84(5):421–426. https://doi.org/10.1007/s11746-007-1064-2
- WHO/FAO. Joint WHO/FAO Expert Consultation on Diet, Nutrition and the Prevention of Chronic Diseases 2003 Vol. 916.
- Lucci P, et al. Food & Function 2016;7(1):347–354. https://doi.org/:10.1039/c5fo01083g
- Nusantoro B, et al. Journal of the American Oil Chemists’ Society 2016;93:1051–1062. https://doi.org/10.1007/s11746-016-2851-4
- Lai OM, et al. In Palm oil: Production, processing characterization, and uses (pp.). Urbana, IL: AOCS Press 2012, pages 393, 569, 572.
- Ojeda M, et al. European Journal of Lipid Science and Technology 2017;119(2):1600070. https://doi.org/10.1002/ejlt.201600070
- Janin Flores Ruedas R, et al. Journal of Food 2020;18(1):1-10. https://doi.org/10.1080/19476337.2019.1699168
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