By: Sarafhana Dollah

Hydrogenation has been the most common approach used to modify the characteristics of liquid oils. However, this process produces the undesirable trans fatty acids. Palm stearin is the solid fraction from palm oil. It is a useful source of natural hard fat and free of trans fatty acids. Blending of palm stearin with liquid vegetable oils produces a good solid fat stock that has desirable characteristics for various food applications. Palm stearin blends are primarily used as an ingredient in bakery and pastry formulations.

Among the food uses of palm stearin are:

CrackersMinor Applications OnlyNot SuitableCake MixesMinor Applications OnlyNot SuitableIcingNot SuitableSuitableInstant NoodlesMinor Applications OnlySuitableNon-Dairy CreamerNot SuitableSuitableBicuitsMinor Applications OnlySuitableDough FatHighly SuitableHighly Suitable

A group of researchers from University Putra Malaysia recently investigated the characteristics of a high oleic seed oil after it was blended and enzymatically interesterified with palm stearin (http://onlinelibrary.wiley.com/doi/10.1002/jsfa.7510/pdf). The original seed oil had very limited applications in food due to its low melting point and lack of plasticity. Three blend ratios were prepared (70:30, 50:50 and 30:70 w/w) and then were enzymatically interesterified up to 24 hours using commercially available lipase enzyme. Lipase-catalysed enzymatic interesterification has been considered as the preferred alternative method for improving the characteristics of oils and fats. These interesterification reactions between a solid fat and liquid oil leads to production of semi-solid fats that contain no trans fatty acid residues.

Results indicated that the interesterified palm stearin blends could meet nutritional needs with improved shelf-life as healthy alternatives to partially hydrogenated products. The research findings were as follows:

Margarine is a water-in-oil emulsion similar to butter in appearance and composition. It is made in several varieties and formulations. The main classes are as follows:

• Table/tub/soft margarine – Used as a spread and in some cake recipes. It is spreadable at refrigerator temperature and sold in tubs.
• All-purpose/industrial margarine – Usually about the consistency of butter and packed into small blocks. It is used for baking, frying and spreading.
• Puff pastry margarine – High melting point fat blend. Its formulation is more specialized for specific uses, for example, for cake fillings in bakeries.

As for shortenings, they were originally formulated to substitute lard. Examples of shortening classifications are:

• Solid shortenings – Are used in the baking and catering industry and also in the household for making biscuits, cakes, pastries, bread and icing. This shortenings melts slowly during baking to trap air bubbles throughout the cooking process to impart a tender quality to baked products.
• Fluid shortenings – Pumpable or pourable shortenings. They are used by large and medium size food factories that are too large to handle shortenings in cartoons. The most common type has the consistency of thick cream.

According to the above study, the 70:30 interestefied blend has melting temperature below body temperature which makes it suitable for the production of soft margarine. Whereas, the interesterified 50:50 and 30:70 blends have higher melting temperature which make them work well for baking and cooking purposes. The experimental soft margarine that was formulated from the 70:30 blend not only meets the important parameters for margarine formulations but also was found to be oxidative stable during storage studies.

This study is an alternative approach to modify the characteristics of a liquid oil to a product with more desirable characteristic for food industry to replace the unhealthy trans fat from hydrogenation. Palm stearin is highly suited as a major component for bakery and pastry fats because of the following attributes:

1. Crystallizes in the beta-prime (β’) form.
2. Natural solid consistency and can be modified further by simple blending and/or interesterification.
3. No need for expensive hydrogenation thus, no trans fat.

Reference:

1. Dollah, S., Abdulkarim, S. M., Ahmad, S. H., Khoramnia, A., & Mohd Ghazali, H. (2015). Physico‐chemical properties of Moringa oleifera seed oil enzymatically interesterified with palm stearin and palm kernel oil and its potential application in food. Journal of the Science of Food and Agriculture.
2. Fauzi S.H., Rashid N.A. and Omar Z. (2013). Effects of chemical interesterification on the physicochemical, microstructural and thermal properties of palm stearin, palm kernel oil and soybean oil blends. Food Chemistry 137:8–17.
3. da Silva R.C., Soares D.F., Lourenço M.B., Soares F.A.S.M., da Silva K.G., Gonçalves M.I.A., et al. (2010). Structured lipids obtained by chemical interesterification of olive oil and palm stearin. LWT – Food Science and Technology 43:752–758.