Science - October 9, 2018

Oysters feeding on algae have sweeter taste

Tessa Louwerens

Japanese oysters that eat microalgae have a sweeter taste. Not only do people like them better, they are also prepared to pay more for them. This was the conclusion drawn by PhD candidate Jasper van Houcke.

© Shutterstock

‘Compared to France and Ireland, Dutch oysters are pretty cheap, while the quality is the same’, Van Houcke says. He obtained his doctorate from Food Quality and Design on 8 October. ‘We discovered that the value of oysters can be increased by adding microalgae to their diet.’ This refining has already been applied in France for some time; every river mouth there has its own microalgae composition and, as such, a unique oyster culture.

Van Houcke investigated the influence of a microalgae diet on the biological composition, aroma, taste and sensory properties of the Pacific oyster: the most widely cultured oyster in the Netherlands. He did this for two types of microalgae: Rhodomonas baltica and Skeletonema cosatum. The latter also naturally occurs in France. The oysters were fed one type of microalgae for seven weeks.

The oysters were then served to an expert tasting panel. The panel was of the opinion that the oysters fed with Skeletonema algae were sweeter and melted on the tongue more so than the oysters fed Rhodomonas. This was a positive result, as a survey among 85 consumers revealed a preference for a sweeter oyster. Van Houcke did not investigate which microalgae-fed oysters the consumers like better. ‘We did have consumers taste oysters to determine whether they prefer the Pacific or the European flat oyster. If we would have wanted to also test the effect of the microalgae, the people would have had to taste too many oysters, and the differences would become hard to taste at some point. It would be interesting to carry out further studies.’

Traditional oyster pits in Yerseke, Zeeland. © Shutterstock
Traditional oyster pits in Yerseke, Zeeland. © Shutterstock

Pay more
Van Houcke also investigated to what extend people are willing to buy oysters. A survey among 56 consumers revealed that people prefer sweet oysters grown in the Netherlands. Whether the oysters were refined did not matter. But it could also be due to the lack of understanding of refinement. ‘We did explain it in a couple of sentences, but there might be some improvement to be gained through marketing.’ People were also prepared to pay more for a sweeter oyster. Van Houcke: ‘It doesn’t mean they actually will do so in a shop, but it shows that there are a couple of quick wins to be gained in the oyster sector, for example by focusing marketing on the taste profile. And the traditional oyster basins, as currently used in Yerseke, could be made suitable for refining with just a couple of  small adjustments.’

Additional reading (partly in Dutch):