Black raspberries a contender for best antioxidant fruit, says study
The research looked at the content of phenolics and anthocyanins in black raspberries, red raspberries and blackberries, assessing their antioxidant potential and health promoting properties.
Until now, the properties of black raspberries have been relatively unknown, overshadowed by the appearance and taste of the cultivated blackberries. They are also smaller than blackberries and have a less pleasant smell than red raspberries.
“The interest in health promoting food products becomes more global nowadays, especially in the developed countries,” lead author Dr Anna Małgorzata Kostecka-Gugała told us.
“We hope that the latest worldwide studies on the black raspberry will be helpful in terms of popularisation of this exceptional species.”
The study, which took place at the University of Agriculture in Krakow, discovered the amount of antioxidants in black raspberries was three times higher than the other fruits investigated.
One discovery of note was the black raspberries’ anthocyanines content, which was found to be approximately 1000% more than the raspberry and blackberry.
Interestingly, black raspberries also contained a higher content of secondary metabolites, which have been proved equally beneficial for human health.
“Among the black raspberry secondary metabolites two classes of phenolic compounds seem to play the essential role for human health: anthocyanins and ellagitannins,” said Kostecka-Gugała.
“In black raspberries the derivatives of cyanidin (3-glucoside, 3-sambubioside, 3-rutinoside, and 3-xylosylrutinoside) as well as pelargonidin 3-rutinoside have been identified and their concentrations are extraordinary.
“The second group of phenolics, ellagitannins and their derivative, ellagic acid, found in black raspberries and revealing strong beneficial action to human health, are distinctive only for Rosaceae family.”
The health benefits of anthocyanidins and its derivatives have been well-documented and add to an ever growing body of science to support the potential heart health benefits of black raspberries, with the bioactives proposed to be anthocyanins, flavonols, resveratrol, ellagitannin and tannins.
An investigation last month into supplements containing a dried powder extract from black raspberry suggested they may improve blood pressure and help support cardiovascular health.
Likewise, a study last month revealed consumption of pomegranate juice may reduce biochemical markers of damage caused by exercise. Pomegranate is a rich source of ellagitannin compounds like punicalagins and punicalins, which are strongly linked to improved heart health, prostate health and joint health.
In this latest study, the researchers led by Kostecka-Gugała, began looking at red raspberries, black raspberries and blackberries grown in central Europe during two successive vegetation periods.
The content of phenolic compounds, including anthocyanins, as well as antioxidant properties of fruit extracts were analysed using a number of methods including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity involving both colorimetric and EPR spectrometric measurements.
Among the tested fruits, black raspberries had the largest antioxidant capacity according to all the methods used. These berries were also the most abundant in phenolic and anthocyanin compounds.
Blackberries were characterised by larger antioxidant capacity than red raspberry fruits which were accompanied by higher content of total phenolics and anthocyanins.
The research contributes to further characterisation of central European berry fruits.
“The common mechanism of these berries’ antioxidative action is attributed to the hydroxy groups that serve as electron donors to the molecule of a free radical, reactive oxygen species (ROS) or many biologically important molecules, e.g. enzymes,” said Kostecka-Gugała.
“They may exert anticancer activity by various mechanisms, including deactivation of carcinogenic compounds, modulation of cancer cell signalling or cell cycle progression, induction of apoptosis, and modulation of activity of several enzymes, including those involved in carcinogenesis.”
Kostecka-Gugała added that there were additional individual compounds that acted in various tissues with specific molecular targets that differed in function as well as biological availability.
“These interactions between particular antioxidants and also between these bioactive substances and other berry fruit constituents are still unclear. This as well as several other factors complicates the understanding of the mechanisms and biological effects of polyphenols in humans.”
Source: Open Chemistry
Volume 13, Issue 1, DOI: 10.1515/chem-2015-0143
“Antioxidant properties of fruits of raspberry and blackberry grown in central Europe.”
Authors: A. Kostecka-Gugała, I. Ledwożyw-Smoleń, J. Augustynowicz, G. Wyżgolik, M. Kruczek, P. Kaszycki