Microalgae in ketchup? Scientists have a recipe for that

Researchers added microalgae protein to ketchup, finding moderate amounts increased nutritional value while maintaining acceptable taste

Researchers have used protein extracted from microalgae to increase the nutritional value of ketchup without significantly changing its familiar flavor at lower concentrations.

The study, published in ACS Food Science & Technology, tested ketchup recipes containing protein extracted from Chlorella vulgaris, a microalgae species that researchers are exploring as an alternative source of protein.

“We wanted to improve the nutritional value of a widely consumed condiment using a sustainable protein source,” said Parise Adadi, corresponding author of the study. “Ketchup is familiar, shelf-stable and suitable for incorporating functional ingredients.”

The researchers developed ketchup recipes containing between 1 percent and 13 percent algal protein extract, along with ingredients including plum tomatoes, sugar, salt, vinegar, spices and citric acid. The samples were bottled and pasteurized before being evaluated by a 15-person tasting panel.

Ketchup containing 1 percent and 3 percent added algal protein retained the sweet, tangy and mildly spiced flavor expected of the condiment, with panelists reporting only a subtle algal taste. At concentrations of 5 percent and 13 percent, however, the algal flavor and greenish color became more noticeable, reducing the samples’ acceptability.

The researchers also compared the nutritional content of the enriched ketchup with a version containing no added algae. Samples containing 3 percent and 5 percent algal extracts had two to three times more protein and higher levels of essential amino acids, minerals and antioxidants. Sodium and iron were among the minerals that increased.

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The findings suggest that moderate amounts of algal protein could increase the nutritional value of ketchup while maintaining characteristics acceptable to consumers, although the sensory evaluation involved only 15 people.

“Chlorella vulgaris can be cultivated rapidly throughout the year using comparatively little land and freshwater, making it a potentially more resource-efficient protein source than many terrestrial crops,” Adadi said.

Microalgae proteins have previously been explored for other food applications, including plant-based seafood alternatives. In the ketchup study, researchers sought to determine whether the protein could be incorporated without introducing an algal flavor that would significantly change the condiment.

The researchers said additional work will include larger consumer studies, shelf-life testing and product development at commercial scales.

Read the full study here.