Fats for Biscuits

Introduction 

In biscuits fat (or margarine) is one of the main ingredients besides flour and sugar - the functional properties of sugar in biscuits.

In the application the fat is called shortening. By coating of the gluten of the flour, the dough will be not so elastic as a bread dough: the dough stays “short”.

Large biscuit manufacturers are buying and storing hot (melted) fat in tanks and apply it as such or first let crystallise in cooling equipment before it is used.

The fat (or margarine) can be supplied in two ways:

• crystallized fat in extruded blocks or bag-in-box
• crystallized fat in pumpable form

The main characteristics of a fat are:

• n-values or SFC (sold fat content)-values give the solid fat content (so crystallised part of the fat) at predefined temperatures like 10-20-30-35°C. Note: SFI (solid fat index) is not the same as SFC.
• the fatty acid composition, such as saturated fatty acids (safa), mono or poly-unsaturated fatty acids (mufa or pufa), trans content.
• triglyceride composition, influencing crystallisation rate and N-values
• taste keepability; also depending on the fatty acid composition

Oil modification techniques 

Oils and fats have their own characteristics. The required characteristics of the fat in various kinds of baked products and biscuits can vary largely.

These characteristics cannot be obtained by the fats as found in nature. Oil modification techniques have been developed to obtain the various characteristics.

There are 3 oil modification techniques:

• Hardening or hydrogenation
  • under high temperature condition and by means of a catalyst, unsaturated bounds in the fatty acid chain are changed into saturated ones by the addition of hydrogen or the cis-unsaturated form is converted in a trans-unsaturated form.
• Fractionation
  • by controlled crystallisation of e.g. Palm oil (PO), followed by a separation of the crystals from the partially crystallised mass, the fat can be divided in two parts:
    • hard fraction called stearin: POs or palm stearin
    • soft or fluid fraction called olein: POf or palm olein
• Interesterification or re-arrangement
  • the chemical interesterification occurs at high temperature and at presence of a catalyst; the fatty acids are statistically re-arranged on the glycerol molecule. If two different oils or fats are used, a completely new composition of triglycerides can be made with other (more desired) properties.

Since trans fats have been banned, more and more interesterified mixtures are used in fatblends to fulfil the requirements for the typical applications in foods.

Example of solids content as function of temperatures for a number of fats

By blending of oils and one or more fatcomponents (from these oil modification techniques) the characteristics, required for a certain application, can be obtained.

Fats in biscuits 

For the application in biscuits the level and the type of fat is important for:

• homogeneous distribution in the dough and possibly the aeration of the dough
• final dough hardness before cutting
• spread in the oven
• hardness of the biscuit
• eating quality; texture and flavour
• shelf life of the biscuit

Main effects can be summarised as follows:

Health issues 
As stated by American Heart Association:

Based on a large body of evidence, it is apparent that the optimal diet for reducing risk of chronic diseases is one in which saturated fatty acids are reduced and trans fatty acids from manufactured fats are virtually eliminated. Because of the growing health benefits recognized for unsaturated fatty acids, it is likely that a mixture of these fatty acids in the diet will give the greatest health benefits within the context of a total fat intake that is considered moderate.

Trans reduction

Since 1993 it became clear that trans fatty acids obtained by partially hardening/hydrogenation were even worse then saturated fatty acids concerning influence on cholesterol level and risk for Coronary Heart Disease.
Fatblends for all kind of margarines and fats for the various foods application were redefined without loosing the characteristics for the application so actually without negative influence on the application. Almost no partially hardened components are used anymore but more fractions and interesterified components 
 

Safa reduction

By taking out trans fatty acids the safa content increased to keep functionality.
The last years there is a new challenge to lower the safa content in applied fats. Some food manufacturers ask already for possibilities of lower safa fats with similar functionality. With new fractions and newly developed interesterified components functionality in the application can be possibly achieved but keeping similar taste keepability (and so shelf life) is more difficult. With less safa and so more unsaturated fatty acids (mufa or pufa) the risk for oxidation so formation of off taste components is higher.

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