How and why do we measure the chilli heat of food?

By Josefine Hammerby - 07 December 2018

Chilli peppers originated in Central America and have been part of the human diet for almost 10,000 years. After the ‘discovery’ of the Americas in the 15th and 16th century, the use of chillies in food and traditional medicine spread rapidly around the globe, particularly to parts of Asia.

Over 35 million tonnes of chilli peppers are produced worldwide each year. Chillies are part of the genus Capsicum which is part of the Solanaceae family that also includes other food plants, including aubergines, tomatoes and potatoes. There are five domesticated species of chilli peppers, which each contain many varieties.

Why are chillies spicy?

Capsaicin, and related compounds known as capsaicinoids, give chilli peppers their heat when they are eaten. The capsaicin in chilli peppers excites pain receptors on your tongues, making chilli taste ‘hot’.

Chillies evolved to contain capsaicinoids as a defence mechanism against destructive microbes, in particular Fusarium semitectum, by discouraging insects that spread the mould from eating chillies. The capsaicinoids also deter hungry mammals, whose stomach acid destroys the chilli seeds. Chilli seeds are spread by birds, which aren’t affected by the chilli heat and don’t digest the seeds.

Why does chilli heat need measuring?

Spices and chillies affect people differently. What could be a barely detectable amount of chilli to one person may bring out a sweat in another. To allow consumers to make informed choices many manufacturers display a graphic on a product’s packaging, with a number of chillies to show consumers how spicy it will be. However, it can be difficult to get consistent results across a range of products.

How is spiciness measured?

Scoville ratings are traditionally used to rate the chilli heat of food. The Scoville method was developed in 1912 by Wilbur Scoville and is a measurement of the pungency of spice, a function of capsaicin concentration. Jalapeno chilli peppers score around 1,000-10,000 on the scale, whereas scotch bonnet peppers can score 100,000-350,000!

The original method for assessing the Scoville rating was the Scoville organoleptic test. This used a panel of five trained testers to detect capsaicinoids (the heat component) in increasingly diluted solutions.

More recently HPLC (high performance liquid chromatography) has been used to measure the Scoville rating of the heat of whole chilli or chilli powder instrumentally. This has allowed chilli pungency to be measured more accurately.

However, when complex products are tested in this way the results may not correlate with the perceived spiciness when the product is consumed. This could mean that manufacturers are inadvertently providing misleading information to consumers.

A new method to measure chilli heat

A new method has been developed to give manufacturers and retailers confidence that they are providing consumers with accurate and consistent information about the chilli strength of their products. The calibrated method uses a highly-trained panel of taste testers to provide retailers and manufacturers with a consistent way to rate their products as mild, medium, hot or very hot.

Ingredients and even the colour and texture of a product will influence the perception of hotness. The new method takes these factors into account to provide a consistent and reliable heat rating for food products. Samples are evaluated individually in sensory booths under coloured light to mask any differences in the colour of the products.

The new method can be used to rate the heat of complex products, such as ready meals and cooking sauces.

Get in touch to find out more about this new method.

This article first appeared in Food Spark.

Josefine Hammerby, Sensory Descriptive Projects Manager
+44(0)1386 842297

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