Temperature-Controlled Texture Analysis of Fats and Oils

Fats and oils perform a key role in defining the sensory characteristics of our favourite prepared foods. They affect the structure, stability, flavour, shelf-life, palatability, mouthfeel and visual appearance of food products.

For manufacturers to obtain the desired performance, it is important to recognise that different applications require a fat or oil product with different physical and organoleptic properties. 

The most critical performance factors of fat and oil products are related mostly to consistency, plasticity, firmness and spreadability. But measuring these accurately as an indication to process or finished product performance can be difficult; fats are prone to 'work softening' and their spreadability and firmness are altered at different temperatures. Analysis techniques developed by Stable Micro Systems take the guesswork out of new fat and oil ingredients development.

Measuring textural properties of spreads

The development of a fat or oil product depends on several factors that varies between manufacturers, such as the equipment used, processing limitations and customer preference. As well as products with a broad general appeal, tailored fat and oil products are now being designed to satisfy specific requirements. From confectionery products to pastries and spreads, fats and oils contribute to the attractive eating qualities that make these foods so appetising.

Performance testing is essential for the development of new products, especially for fats or oils designed for specific formulations or processes.

Butter, margarine and spreads depend on the consistency of the fat content and its spreadability. A wide plastic range and a smooth consistency are essential for roll-in shortenings and margarines that are used for thin layer lamination at refrigerator temperatures. Plasticity is also important for the workability and creaming properties needed in shortenings for the preparation of icings and aerated batters.

Firmness (also known as hardness) is a key characteristic in determining the spreadability of a table spread. As the consumer cuts through a spread, the first impression of the product's texture is that of its firmness.

This type of test has long been simulated by straightforward penetration tests using cone or cylinder probes. Spreadability is the ease with which a spread can be applied in a thin, even layer. Firmness or hardness may be measured by the force required to obtain a given deformation or by the amount of deformation under a given force. Although spreadability is also a deformation under an external load, it is a more dynamic property. Measurements of firmness and spreadability are usually highly correlated, but the relationship is rarely perfect and this is partly a function of 'work softening'. Margarine, for instance, 'work softens' more easily than butter when spread onto bread. This makes it more spreadable even when hardness values are initially equal.

These and many other textural properties can be measured using leading edge texture analysis equipment. The TA.XTplus Texture Analyser was designed for this purpose, along with its accompanying software, Exponent. It gives an objective study into both the ingredient characteristics, and the effects of ingredients and processing variables on end-product quality.

Measuring Spreadability

TTC Spreadability Rig

The spreadability fixture for the TA.XTplus Texture Analyser measures the ease with which a product such as margarine or table spread can be applied in a thin, even layer. It comprises of a male 90° cone probe and five precisely matched female Perspex cone shaped product holders.

The sample is either deposited in the lower cone holders in advance of testing, or is filled with a spatula and the surface then levelled. The sample holders can be stored in refrigerated or frozen environments, or they can be used at room temperature.

During a test, the product is forced to flow outwardly at 45° between the male and female cone surfaces. The ease with which it flows indicates the degree of spreadability. The probe withdrawal also offers some insights into its adhesive behaviour.

Controlling temperature of texture analysis

Peltier Cabinet

Performance results must be reproducible to be of value for comparative purposes. Fat and oil products are highly temperature critical so careful equilibrating and stabilising of testing temperature is of value.

Temperature control units solve these problems by providing a temperature controlled environment over a precise operating range. In the case of the temperature controlled Peltier Cabinet, the cabinet is fixed directly to the base of the Texture Analyser and samples can be allowed to equilibrate to the required temperature before testing.

A double thickness transparent window allows the sample to be seen during testing and is easily removed for sample access. A separate heat exchanger and control unit allows the temperature to be set and displayed and integration with the current software allows a quick temperature change. The user can measure and capture temperature data during the texture analysis test to plot alongside force, distance and time.

Temperature in dairy foods

Temperature control is particularly important in the dairy industry, where measurement of textural characteristics is temperature critical, and almost equally so in the gel and confectionery industries.

The consistency of a product must be measured at a number of different temperatures to determine its plastic range. That is the range of temperatures over which the fat can be moulded or worked. Samples are evaluated to determine the relative firmness at low temperature and softness at high temperature. Products with a wide plastic range are workable at both high and low temperatures. An ideal plastic range would indicate the same penetration at all temperatures.

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We can design and manufacture probes or fixtures for the TA.XTplus texture analyser that are bespoke to your sample and its specific measurement.

Once your measurement is performed, our expertise in its graphical interpretation is unparalleled. Not only can we develop the most suitable and accurate method for the testing of your sample, but we can also prepare analysis procedures that obtain the desired parameters from your curve and drop them into a spreadsheet or report designed around your requirements.

For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.

The TA.XTplus texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is available to measure and analyse the textural properties of a huge range of food products. Our technical experts can also custom design instrument fixtures according to individual specifications.

No-one understands texture analysis like we do!

To discuss your specific test requirements click here...