Focus on spoilage – volatile organic compounds (VOCs) in food quality monitoring
Spoilage of highly perishable food products such as fresh fish is typically due to microbial activity that leads to the generation of volatile organic compounds (VOCs). These compounds could be used as spoilage indicators and thus for quality monitoring of the packaged food product. The TERAFOOD project is investigating innovative analytical techniques for the identification and quantification of potential food spoilage indicators.
Food spoilage is a major economic and ecological concern in the modern society. In industrialized countries, more than 40 % of all yearly food losses has been estimated to take place at the retail or consumer level (FAO, 2011). A great part of food waste originates from refrigerated products that have a very short shelf life, such as fresh seafood. In this case, spoilage is usually due to microbial activity and the consequent generation of volatile organic compounds (VOCs) in the package headspace. Even though spoiled food does not necessarily pose an infection risk, offensive off-odors and other unpleasant changes in the sensory quality render the product unfit for consumption. Development of innovative quality monitoring systems thus calls for the identification of VOCs that indicate food spoilage.
The TERAFOOD project, coordinated by the CNRS (Institute of Electronics, Microelectronics and Nanotechnology, Lille) and involving several academic and industrial partners, aims at the development of a compact and low-cost commercial terahertz-sensor that can be used for monitoring the quality of packaged food products by VOC detection (Flanders’ FOOD, 2017; UGent, 2017). Introducing the sensor in food packages allows real-time quality monitoring at any time during storage without opening the package and has thus the potential to greatly reduce food waste. However, every food product has its characteristic spoilage processes that depend on several intrinsic and extrinsic factors. To allow efficient quality monitoring, information is thus needed about VOCs and their concentration levels in different food products as well as under different packaging and storage conditions. Identification and quantification of VOCs that indicate food spoilage is carried out at the Department of Food Safety and Food Quality at Ghent University.
During the first semester of the project, spoilage of Atlantic salmon (Salmo salar) packaged under different gaseous atmospheres was examined (Fig. 1).
Fig. 1. The experimental setup of Atlantic salmon.
Microbiological, chemical and sensory changes were analyzed on a regular basis throughout storage time. VOCs produced in the package headspace were monitored with selected-ion flow-tube mass spectrometry (SIFT-MS) that allowed fast and sensitive quantification of VOCs directly from the actual food packages. The obtained results show that the evolution of the VOC profile and the emerging off-odors depend on the applied storage conditions and that several VOCs can be considered as potential spoilage indicators of Atlantic salmon. For the sensor development, the results provide with essential information about spoilage-related VOCs and highlight the sensitivity levels needed for their detection. During the next semester of the project, advanced multivariate statistical analyses will be carried out to further enhance the characterization of most potential spoilage indicators. Furthermore, the developed experimental setup and methods will be extended to new food products.
- FAO, 2011: http://www.fao.org/docrep/014/mb060e/mb060e00.pdf
- Flanders’ FOOD, 2017: http://www.flandersfood.com/artikel/2017/01/12/ssssst-luister-je-product-nog-vers
- UGent, 2017: https://www.ugent.be/en/research/research-ugent/trackrecord/trackrecord-h2020/interreg/interreg-france-wallonie-vlaanderen-terafood.htm