Cheese

This guest article was written by Maxwell Holle from the University of Illinois.

A simple glass of milk holds the potential to become hundreds of different types of cheeses with a variety of different flavours. But with so many diverse flavours and styles, how can we identify an off-flavour?

Image by corinnabarbara from Pixabay.

 

What is cheese?

Cheese is milk that we force into a gel by either acid, heat, or enzymes. While making cheese, we try to remove as much water as possible, which also means losing some milk proteins. The simplest cheeses stop here and are known as fresh cheeses; they have a relatively salty and neutral taste. However, most cheeses take on their characteristic flavours and smells during the ageing and ripening stage, where diverse groups of microorganisms get involved. These microorganisms generate the characteristic flavours of some of our favourite cheeses.

When is a Strawberry No Longer a Strawberry?

You take that first bite, tearing through the cells of the red berry and allowing its fragrance to erupt. Juices ooze, coating your mouth. The sweetness, modulated with a slight bitter hint, hits your tongue and lights up your senses, and the distinctive flavour of the strawberry overflows.

Why do we love strawberries so much?

Why do we love strawberries so much? There’s something alluring about them, something intense and complex in the flavour we experience that is not matched by any other berry – its chemistry.

When we recognise a flavour – the combined experience of taste, mouth feel and (crucially) smell – we are actually recognising the aromatic chemistry of a food, the volatile molecules given off when we bring it close to our nose or after we bite into it. When we understand the molecules that make up the distinct chemical profile of a flavour, we can replicate it by creating those chemicals in a lab and stirring them together. This helps us make artificial banana flavour, artificial vanilla flavour, and artificial fresh grass smell. But strawberries are awkward. Strawberry flavour is made up of a chemical medley of many, many different molecules (more than 350), variation exists strawberry species to strawberry species, and we just don’t know how important each chemical is.

This is in direct contrast to the raspberry, a humble berry that we recognise as 4-(4-hydroxyphenyl)butan-2-one, or “raspberry ketone”. Whilst cranberries and blackberries also contain this odour, they mix it with other chemicals, whilst in the raspberry it is exclusively responsible for the raspberry profile we instantly know.

Raspberry ketone, the molecule behind the smell we know so well. © Things We Don't Know.