Riddet Institute research confirms cherries have a high antioxidant and vitamin profile

Caitlyn Knight, of Palmerston North, enjoys New Zealand cherries that not only taste good but are packed full of nutrients. Photo / Supplied

Cherries grown in New Zealand are officially jam-packed with components essential to human health, according to new research.

Cherries can join the ranks of blueberries and other colourful fruits grown in New Zealand with their impressive antioxidant and vitamin profile, according to work done at the Riddet Institute, at Massey University in Palmerston North.

The research into New Zealand cherries was jointly funded by a grant from the High-Value Nutrition National Science Challenge to Cherri Health and Manufacturing (CH&M) and the Bioresource Processing Alliance with Cherri Global.

Cherri Global, based in Hawke’s Bay, has a business division focused on developing a range of cherry products.

The work was carried out by the scientists at the Riddet Institute and Plant & Food Research over several months late last year.

Riddet Institute lead scientist Dr Ali Rashidinejad says this study is the first of its kind to systematically analyse the nutritional and bioactive (phytochemical) compositions of the main cherry varieties grown in New Zealand. Earlier research has focused on cherries grown overseas.

Cherries contain numerous nutrients such as vitamins A, E, K, C and B, carotenoids, lutein, and zeaxanthin, Rashidinejad says. Cherries have been recognised for providing significant health benefits such as decreasing markers for oxidative stress, inflammation, exercise-induced muscle soreness and loss of strength. They are also thought to improve blood pressure, arthritis, and sleep.

There are 17 main varieties grown in New Zealand. This study focused on six varieties grown in Cherri Global orchards in Otago: Bing, Rainier, Kordia, Lapins, Sweetheart, and Staccato.

The study also compared fresh and packaged cherries to learn if nutrients were lost during processing.

Researchers looked at proteins, carbohydrates, sugars, fats, fibre, fat-soluble vitamins, and water-soluble vitamins.

“Basically, in terms of nutrient profiles, we have explored everything we could. And the same with the bioactive compounds,” Rashidinejad says.

“We concluded that all six varieties were rich sources of different nutrients: minerals, vitamins, amino acids, and phenolic compounds – the antioxidants. These latter compounds, the phenolic compounds, were what most interested us because they are potent antioxidants with numerous scientifically proven health-promoting properties.”

Almost 30 phenolic compounds were studied, in collaboration with Plant & Food Research, using high-pressure liquid chromatography techniques.

Most of these compounds were present in differing amounts, with vitamins A, C, E, B1, B2, B3, B6, B9 (folate) and K also detected and quantified in the fresh, packaged, and frozen cherry samples. High concentrations of vitamin C were confirmed.

Riddet Institute research officer Dr Ali Rashidinejad says cherries contain numerous nutrients such as vitamins A, E, K, C and B, carotenoids, lutein, and zeaxanthin. Photo / Lindsay Keats

The cherry season is quite short, with early varieties ripening in late December and all finished by early February.

The delicate stonefruit are not easy to grow, requiring extensive bird protection, and cherries are labour-intensive to pick and process.

After picking, cherries are washed at pack houses and exported or distributed around the country, either as fresh or frozen product. The comparison between fresh and packaged fruit found processing had varying effects on the nutrients and bioactive compounds of the fruit.

“We found only some minor differences and little effect from the time and the process of washing, drying and packing,” Rashidinejad says. “It’s good news that the transport and packing does not have a major effect on the health-promoting compounds.”

The findings are exciting for future opportunities.

“This has been a comprehensive study. The hypotheses have been confirmed that New Zealand cherries are a great source of antioxidants and nutrients, and that the processing has a little or no impact on their nutritional properties.”

He says future steps would be finding ways to use the waste products produced during cherry processing. It has been estimated that 8000 tonnes of cherry waste are produced in New Zealand every year. Because washing and packaging does not significantly reduce the nutrient profile of the fruit, this could lead to new uses for the waste or the seconds that don’t get to shop shelves.

Waste from cherries could be converted into a high-value ingredient for the food industry. This could be in powdered or frozen form, or as a component in another food product.