When do you say no thanks? Odour determines whether chicken goes in the pan or the bin

Fresh chicken fillets can begin to smell different before their use-by date has passed, but the stated shelf life may also be shorter than necessary.

New research led by food research institute Nofima shows that both the bacteria in the fillet and the storage temperature influence when consumers decide to reject the product.

Not all bacteria produce the same odour

The study shows that odour is not determined solely by the number of bacteria in the package. It also depends on which bacteria have developed and how the chicken has been stored.

“Different bacteria can produce different odours. As a result, consumers may perceive two products with broadly similar total bacterial counts very differently,” says Solveig Langsrud, a senior scientist at Nofima. She led the study and also heads the EU project MICROORC.

Researchers tracked chicken fillets from producers in Norway, Portugal, and Hungary during storage. They mapped the bacteria using both laboratory cultivation and DNA analysis.

The bacterial communities differed. In Norway, lactic acid bacteria dominated. In Hungary, Photobacterium dominated, while in Portugal, Brochothrix and bacteria from the Yersiniaceae family were dominant.

These bacteria produce unpleasant odours when they reach certain numbers, but they will not make people ill.

A total of 365 consumers smelled samples from their own country. They were asked whether they would cook and eat the fillet or throw it away.

Participants rejected the Hungarian samples after the shortest storage time. At that point, bacterial levels were lower than in the Norwegian and Portuguese samples.

Temperature matters

The researchers stored some packs at 4 °C throughout the study. Others were first stored at 4 °C and then moved to 8 °C. This was designed to reflect situations that may arise in shops, on the journey home, or in the refrigerator.

“The results were clear. At 8 °C, bacteria grew faster and the bacterial communities changed. This demonstrates the importance of temperature control. Chicken retains its quality best when it's transferred promptly to a cold refrigerator,” Langsrud points out.

The study examines when consumers perceive chicken as no longer meeting their expected quality. It does not determine whether the food is safe to eat.

Raw chicken should always be handled hygienically and cooked thoroughly, irrespective of what the date label or odour may indicate.

The date should suit the product

There are clear limits for bacteria that can make you sick.

For bacteria that primarily cause unpleasant odours and reduced quality, food producers often use a single general threshold for the total amount of bacteria.

“This may be too broad an approach. Our study shows that the use-by date should be based on the bacteria present in the product, how it is stored, and when consumers react to the odour,” says Langsrud.

The aim is not for consumers to assess shelf life on their own. The aim is to give producers a better basis for setting the date on the package. This would allow the date to more closely reflect how the product is actually perceived at home in the kitchen.

How the study was conducted

The researchers followed chicken breast fillets from three producers for up to 27 days. They measured how many living bacteria grew in the meat and identified which bacteria were dominant.

Conventional lab methods count bacteria that can grow on specific culture media. The researchers therefore also used DNA analysis, which can detect bacteria that standard methods do not capture.

A total of 365 consumers assessed the odour of raw chicken in a laboratory setting. Each participant smelled 11 chicken samples stored at 4 °C and 8 °C for up to 27 days and answered one question: Would they cook and eat the fillet, or throw it away?

The test provides a useful picture of the relationship between odour, bacterial growth, and consumer acceptance. But it does not fully recplicate the situation at home.

Participants assessed small samples without date labels, packaging, or visual cues. Such factors can also influence the choices people make.

Reference:

Langsrud et al. Using consumer acceptance to guide microbial thresholds for the shelf life of fresh chicken breasts, Food Microbiology, 2026. DOI: 10.1016/j.fm.2026.105226

About the research

• The studies involved Nofima in Norway, the University of Veterinary Medicine Budapest in Hungary, and Universidade Católica Portuguesa in Portugal.

• The research was carried out through the MICROORC and MicroPack projects.

• Funding was provided by the EU Horizon Europe programme, the Norwegian Research Levy on Agricultural Products, and Portugal’s Fundação para a Ciência e Tecnologia.

• The study involved 365 consumers in Norway, Portugal, and Hungary. The scientists stored chicken samples at 4 °C, or at 4 °C before moving them to 8 °C, for up to 27 days.

This content is paid for and presented by Nofima The Norwegian Institute of Food, Fisheries and Aquaculture Research

This content is created by Nofima's communication staff, who use this platform to communicate science and share results from research with the public. Nofima is one of more than 80 owners of ScienceNorway.no. Read more here.

More content from Nofima:

• 

  Study: People who track their food waste throw away less food

• 

  Food texture affects both what and how much you eat

• 

  How healthy are blackcurrants?

• 

  This light reads the quality of raw materials from fish

• 

  Red algae grown in wastewater from fish-farming facilities could become sustainable salmon feed

• 

  Pumpkins are good for more than just Halloween decorations