Scientists at Reading Scientific Services (RSSL) food laboratory are getting sniffy about the work they do for food manufacturers in analysing what gives food its particular flavour. They are literally sniffing the flavour compounds in foods as they are being chemically analysed in order to speed up the process of finding which compounds matter to the flavour and which ones don’t.
Gas chromatography (GC) is widely used to separate out and measure the volatile organic compounds (VOCs) that give food and drinks their flavour, says RSSL. But food companies can then spend a lot of time and money using human sensory panels to identify which of the VOCs in a GC analysis are important to a particular flavour.
So RSSL has been using an ‘odour port’ to sniff the VOCs as they are being analysed. This enables scientists to quickly zone in on the ones that appear to contribute most to a food’s flavour.
Mike Geary, flavour and trace scientist at RSSL, says the technique enables RSSL to give a chemical description and measurement to the VOCs that give food its flavour. And it can allow companies to modify flavours themselves instead of relying totally on flavour houses.
“We would be able to say to a company that the reason its product only scores one out of 10 for a nutty flavour, say, is because you only have this amount of this compound in it. And the reason that that one scores seven out of 10 for nutty is because you have seven times as much of that compound in it.”
This means the company’s food technologists can calculate how to make the flavour more or less nutty without having to use a human taste panel each time, he says.
RSSL is now hoping to extend its food flavour work by investing in new equipment that can measure the amounts of VOCs released as you chew a piece of food. Current GC instruments tend to measure the total amounts of VOCs released over a period of time, says Geary. But what he is looking at is the latest proton-transfer-reaction mass spectrometer equipment which produces real- time results.
“It sucks the air out of a person’s nose while they are eating the food and analyses it to see what’s actually being released while they are chewing or drinking.” It probably wouldn’t replace taste panels altogether, says Geary, but it could show how the rate at which a VOC was released, or its persistence in the mouth, was related to the character of a particular flavour.
Geary has been looking at equipment installed at Cork University and Warwick University and correlating their results with taste panels back at RSSL. He hopes to get a decision on whether to invest in a machine by the end of the year.
Contact: michael.geary@rssl.com
Putting the spotlight on spoilage
Infrared light beamed on to meat can spot spoilage organisms within seconds, say scientists at Manchester University, opening the way for a revolution in food safety testing. They have developed an infrared spectroscopy technique that picks up infrared light reflected from the surface of meat and produces biochemical fingerprints of any micro-organisms on the surface, rapidly estimating their number.
As a result, the bacteria on meat responsible for food poisoning can be detected and measured within seconds, says Dr David Ellis who has been leading the work. Conventional laboratory techniques for growing and identifying spoilage bacteria can take hours, he says.
In work on chicken breasts which had been left to spoil at room temperature, Ellis used Fourier transform infrared (FT-IR) spectroscopy to take measurements every hour directly from the surface of the meat. By comparing the results of the FT-IR instrument with counts of viable organisms obtained by conventional laboratory plating methods, Ellis was able to show that FT-IR could acquire a metabolic snapshot and quantify the microbes in chicken in about 60 seconds. The technique has also proved successful on beef.
“There are more than 40 different methods available to detect and measure bacteria growing in meats,” says Ellis. “However, even the most rapid takes several hours, so results are always retrospective which means that infected meat could go into the food chain. We believe our equipment can be built into production lines. It doesn’t involve touching the food; it’s relatively cheap; and results are available in seconds and can be read by a machine. It makes it ideal for on-line meat inspection.”
Contact: d.ellis@manchester.ac.uk