Mangosteen rind ups 'cheap chocolate' polyphenols by 50%: Research

By Louisa Richards

- Last updated on GMT

Adding powdered rind of mangosteen improves the polyphenol content by 13% in dark chocolates and 50% in compound chocolates, researchers have found. Photo credits: iStock.com / ieang
Adding powdered rind of mangosteen improves the polyphenol content by 13% in dark chocolates and 50% in compound chocolates, researchers have found. Photo credits: iStock.com / ieang

Related tags: Chocolate

Adding a mangosteen fruit by-product to cheaper low cocoa chocolates could improve their nutritional content without compromising flavour, researchers have discovered. 

The study looked at the use of Mangosteen pericarp, or rind, as powder in graded amounts in dark and ‘compound’ chocolates - chocolates made from a combination of cocoa, vegetable fat and sweeteners. Pericarp powder at a concentration of 3% significantly improved the polyphenol content by 13% in dark chocolates and 50% in compound chocolates without affecting sensory qualities. 

The authors said such low-cost plant polyphenols could enhance the bioactive and flavour profile of chocolates, especially in low-cocoa compound chocolates. 

Unexplored approach 

Cocoa is a source of beneficial polyphenols with phenolic content varying according to cultivar and processing. Higher polyphenol content in cocoa is desirable nutritionally, but can compromise flavour development at the roasting stage. 

The researchers said adding compounds from plant sources such as raspberry leaves, green tea and fruit extracts was a relatively unexplored approach to improving polyphenol content and flavour. Costs can restrict this process however, and taste and acceptability for the consumer must be considered. 

Mangosteen (Garcinia mangostana​ Linn.​) is a tropical fruit commonly grown in Thailand, Malaysia and Indonesia. The pericarp surrounding the edible sweet pulp is often discarded as agricultural waste, however this part of the fruit is rich in bioactive compounds such as anthocyanins, xanthones and procyanidins and has long been used in traditional Thai medicine. 

Increasing nutritional and sensory qualities of compound chocolate is of interest in a market that has seen an increase in cocoa butter prices. Asian and European markets are boosting compound chocolate demand and production. This opportunity motivated the authors to explore the results of adding a low-cost agricultural waste product to chocolates. 

Euromonitor International estimates that global functional chocolate is worth about €280m with Western Europe accounting for about €80m of that.

Study details​ 

Mangosteen pericarp powder was added to chocolate, the phenolic content analysed and sensory qualities evaluated by a trained panel during four sessions spanning two weeks with the chocolates in a randomised counterbalanced order. 

Chocolate was rated by the panel for attributes such as sweetness, bitterness, graininess and aftertaste. 

The scientists found that adding mangosteen pericarp powder improved the phenolic content without affecting sensory qualities. Polyphenols were stable in a simulated chocolate processing setting and the researchers suggested chocolate makers could potentially add the powder during the mixing stage and still preserve the polyphenols. 

As low polyphenol concentration is crucial to flavour development, adding plant polyphenols at a later processing stage maximises both flavour and nutritional properties, said the authors.

“Additionally, non-cocoa polyphenols introduced to pre-roasted cocoa liquor might lead to novel flavour products during roasting,”​ they wrote. 

Asked about comparative health benefits of cocoa-rich chocolate and plant polyphenol enriched chocolate, author of the study and director of clinical nutrition at the Singapore Institute of Clinical Science Professor Christiani Jeyakumar Henry told NutraIngredients: “This has not been evaluated to make a real comparison. But the Mangosteen polyphenols have similar structure to some cocoa polyphenols."

He said that more research is planned on optimising the polyphenol condition during making, and exploring other plant based options. 

 

Source: Food Chemistry​ 

Published online ahead of print, http://dx.doi.org/10.1016/j.foodchem.2015.12.092​ 

“Plant polyphenols to enhance the nutritional and sensory properties of chocolates”

Authors: N.E. Deutz et al.

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