A fast and cheap device for determining the freshness of food developed in Estonia

An Estonian research group at the country’s University of Life Sciences has developed a cheap and simple device to test the freshness of fish and meat; the appliance could be used by large retail chains or households.

This article is published in collaboration with Research in Estonia. By Sven Paulus

The freshness of meat or fish is important in the preparation of a good meal. As the methods used to determine their freshness are mostly expensive and time consuming, a research group at the Estonian University of Life Sciences developed a cheap and simple device to do the testing.

Figuring out freshness very quickly

A research group, led by professor Tõnu Püssa, worked to find a simple method of determining the freshness of fish and meat – in particular, calculating the time that has passed since slaughtering the animal or catching the fish.

The standard microbiological methods allow to determine freshness of food when some time has elapsed and something biochemically significant has happened – or the colour has changed, or the smell is no longer quite right. “Our method allows to determine freshness very quickly – from the first minute onwards, and it can be done very cheaply,” Püssa said.

Usually, the freshness of meat and fish is often determined organoleptically. There are so-called electronic noses that do a quick, but a relatively inaccurate analysis of how old the food could be. The new method, however, already recognises very minor changes in the composition of the water extract of meat or fish.

Commercial opportunities

The initial idea for developing the novel device to do the testing and the supporting software came from an Estonian company, Ldiamon – a research and development company specialising in optical sensors and measurement equipment development and manufacturing.

The principle for determining freshness is simple: as soon as a living cell dies, it breaks down the synthesis of the substance’s energy carrier adenosine triphosphate (ATP). The ATP will continue to degrade, and as a result, the initial molecular weight of the substance ATP will decrease. “The device is simple and cheap, it produces quite accurate results – and our action is now devoted to laying down the method and to scientific proof,” Püssa said.

According to Dr Artur Kuznetsov, representing Ldiamon, the company has now developed a second prototype that could already be sold. “We’re not selling yet, because there’s still extra work going on and the device needs to be certified,” he said.

The testing device.

Kuznetsov added that the use of the device does not require any previous knowledge. “Initially, it can be used by larger companies and retail chains that are interested in the quality of meat or fish products, which is obviously very important to them. It can also be used in households by people who are very sensitive to the ageing of meat,” he said.

The research group is also studying better food preservation

In addition, Püssa’s research group also studies how to use sustainable plant supplements to produce healthier meat products and how to prevent meat from going off.

In the international project, “Sustainable plant ingredients for healthier meat – proof of concepts”, Püssa and his colleagues researched which plant additives could be used for food preservation. The aim of the study was to try to replace conventional food additives already used in the industry and added to meat in order to reduce the aging.

A meat prepared in Estonia. Photo by Aron Urb.

There are two basic processes that can occur with meat, especially when dealing with chopped or minced meat. The aging processes are particularly rapid, with bacterial processes starting first, as meat production is not carried out under sterile conditions. Another process is the oxidation of certain fatty acids in meat, which is also a process of degradation. “In this project, we wanted to find good vegetable materials that would slow the meat aging. The idea is that we can both inhibit bacterial growth and all kinds of oxidation with the same material at the same time,” Püssa said.

International cooperation

The entire initiative is a cooperation project between Estonia, Finland, Sweden, Denmark and Latvia. Each research team searched for the best plants – and as a result, many joint articles have already been published. “Cooperation is particularly good with the Latvians, with whom we have several joint articles. We found certain materials that are not ideal, but have both antioxidant and antibacterial effects,” Püssa explained.

In the scientific process, the mix of rhubarb stems and tomatoes gave pretty good qualities, and the local group added these additives to the meat in the form of freeze-dried powders. “Rhubarb root and blackcurrant leaves are also very interesting materials and we also used dark berries, such as black currants, aronia and edible honeysuckle berries in the study,” the professor said.

According to the scientist, the growth of bacteria was greatly reduced by rhubarb root and tomato, and the acidity of the meat was greatly reduced.

Cover: A fish cooked in Estonia’s Muhu island. Photo by Oliver Moosus.