Food Microscopy

Nowadays microscopy enables not just visual examination but also detailed chemical analysis of foods and related materials. During 2007, we invested in a state-of-the-art scanning electron microscope (SEM) and associated X-ray analysis system to underpin research, troubleshooting and routine analysis. Three applications of direct relevance to industry illustrate the role of modern microscopy particularly well.

The structure of foods and ingredients plays a major role in determining their functional, textural and sensory properties. A big advantage of the new SEM is that we can examine fresh and wet food samples directly, expanding the range of materials that can be analysed without freezing or freeze-drying, which can introduce artefacts. We can also carry out real-time experiments to study the effect of moisture on food samples - for example, the dispersion of materials such as gums, milk powders and polyphosphates in products such as soups, ready meals, condiments, sauces and desserts. This enables us to answer questions like 'why is this batch of product unsatisfactory when the last batch was fine?' or 'how can we design other, similar products?'

Packaging failures - whether structural or chemical - can seriously compromise product safety. Using the system we can investigate internal or external corrosion of metal cans, delamination in plastic packages, and failure of heat seals in plastic packaging. We can also assess the microtopography of packaging and other food contact services - to help determine, for example, whether a particular finish is too uneven for effective removal of surface deposits or biofilms.

Rapid identification of foreign bodies found in foods enables quick resolution of the problem and helps prevent recurrences. Linked to the SEM, the X-ray analyser enables identification of materials such as glass, metal and stone. For glass fragments, for example, we have amassed a reference collection and database of X-ray analysis profiles of around 700 different types of glass. The profile of any glass sample we are sent can be compared with our database for a definitive identification.