Cocoa gel optimizes texture of whole-fruit chocolate, reveals Swiss study

23 May 2024 --- Swiss researchers at ETH Zurich and industry stakeholders have developed a sweetening gel from cacaofruit that can help replace the need for conventional refined sugar in chocolate. The result is a healthier product with a lower environmental impact than traditional chocolate, the researchers state.

The recipe that uses naturally occurring pectin from the cacao pod is a new approach to whole-fruit chocolate. Whole-fruit chocolate has emerged as a new category in the last five years as a way to reduce waste and use the whole fruit — 70% of which is normally thrown away after the beans are extracted.

“Whole-fruit chocolate [typically] crystallizes the pulp juice into powdered sugar and adds it to the chocolate, but a lot of the juice’s valuable ingredients and aroma might be lost in this process,” says Kim Mishra, lead author of the study.

“This process is also very energy intensive. We are skipping this part with our innovative sweetening gel.”

The research team at ETH worked together with start-up Koa, which supplies cacaofruit pulp powders and juices, and the Swiss chocolate manufacturer Felchlin to develop the process for whole-fruit chocolate, detailed in Nature Food. 

We spoke with the study's lead author Kim Mishra to dive into the innovation and its uses for the chocolate industry.ETH has filed a patent for the recipe so that Koa and Felchlin can license it in the future. 

“The Food Process Engineering group of ETH Zürich is renowned for its chocolate research. We are constantly seeking to improve Chocolate not only as a Swiss ‘flagship’ product but also for the cocoa farmers. KOA and Max Felchlin played a crucial role, also in the ideation phase,” adds Mishra. 

Using gels to trap water
Taste and texture were the key concerns when developing the recipe. Too much fruit juice extracted from the pulp made for a clumpy chocolate, but too little resulted in an insufficiently sweet product. 

“Every chocolatier knows that chocolate and humidity (water) equals disaster,” underscores Mishra.  

“Our main challenge was to overcome this dogma and try to engineer the water ‘availability’ in the chocolate. Adding only the sweet pulp juice to the chocolate led to immediate clumping of the chocolate, the same way Tahini thickens when you add water.” 

After many failed attempts, the team finally understood how to ‘trap’ the water and make great chocolate.

The solution was to utilize the dietary fiber from the cacaofruit endocarp — the inner lining of the fruit shell — to trap free water into a gel matrix. 

The endocarp is first processed into a fine powder that can then be used to gel the juice, yielding optimal chocolate consistency, Mishra adds. 

This process also results in a product that contains more fiber, reduced saturated fat and ultimately less powdered sugar in the chocolate.  

The endocarp and the juice concentrate form a gel, serving as a sweetening agent and improving the nutritional profile. (Credit: Mishra, K., Green, A., Burkard, J. et al. Valorization of cocoa pod side streams improves nutritional and sustainability aspects of chocolate.)

A healthier type of chocolate
By using cocoa gel as a sweetener, whole-fruit chocolate boasts a higher fiber content than the average European dark chocolate (15 g versus 12 g per 100 g). It also contains only 23 g of saturated fat as opposed to the usual 33 g. 

This means that ETH researchers were able to increase the fiber content by around 20% while reducing the saturated fat percentage by around 30%. 

“Fiber is valuable from a physiological perspective because it naturally regulates intestinal activity and prevents blood sugar levels from rising too rapidly when consuming chocolate,” explains Mishra. 

When consumed in excess, saturated fat can also pose a health risk. He adds that there’s a relationship between increased consumption of saturated fats and increased risk of cardiovascular diseases. 

Moreover, these ingredients contain plenty of micro- and phytonutrients. “The endocarp powder from the cocoa pod has a high phenolic and flavonoid content, suggesting antioxidant activity. The pulp juice is also a natural ‘red bull’ loaded with vitamin C and minerals.”

Exploring sweetness
To test the new recipes’ sensory experience, trained panelists from the Bern University of Applied Sciences taste-tested pieces of chocolate weighing 5 g each, with some containing various amounts of powdered sugar and others containing the new variety sweetened with cocoa gel. 

“This allowed us to empirically determine the sweetness of our recipe as expressed in the equivalent amount of powdered sugar,” adds Mishra.

The experiments showed that chocolate may contain up to 20% of the gel, which is equivalent to the sweetness of chocolate with 5–10% powdered sugar.

By comparison, conventional dark chocolate can easily contain between 30–40% powdered sugar.

CaPao was one of the first innovations to come to market using the whole cacaofruit. It upcycles and “snackifies” cacaofruit that would otherwise have gone to waste.

Tangy taste considerations 
The sweetening gel also added some extra notes of dried fruits and acidity. 

“The acidity was commented to counteract the sweetness sensation compared to the chocolate with powdered sugar. Hence, for future studies, such effects have to be balanced out with neutralizing the gels or adding more cocoa butter, for example,” explains Mishra. 

One of the most valuable insights from this research has led Mishra to understand that chocolate sweetness is a multifactorial sensation. 

The researchers are now looking into other applications for the sweetening gel when it come to multilayered confectionery and additive manufacturing. 

“We have promising results showing that we can distribute sweet dots onto the chocolate surface to boost the sweetness sensation over the whole mastication experience,” Mishra enthuses.  

Celebrating cacaofruit sidestreams 
The industry has been dabbling in utilizing the whole cacaofruit as early as 2019 when Nestlé unveiled a no-added-sugar dark chocolate from cacao fruit pulp. 

Later that year, Nestlé Japan launched Cacao Fruit Chocolate in the form of a KitKat. The product was positioned as the first chocolate confectionery to use dried, powdered cacao pulp as a substitute for traditional sugar. 

In 2019, Barry Callebaut debuted the “Cacaofruit Experience,” offering WholeFruit Chocolate made from 100% cacao fruit. The initial launch gave chocolate chefs exclusive access to the nascent ingredient. 

Mondelēz’s innovation and venture hub, SnackFutures, was the first company to introduce the Cacaofruit Experience — now called Cabosse Naturals — in a consumer product under its CaPao brand. In 2021, the product became one of the first to be certified under the Upcycled Food Association’s Upcycled Certification Program. 

Other launches include Switzerland-based Sprüngli’s Grand Cru Absolu in 2020, dubbed the world’s first luxury chocolate made with two ingredients, and Belgian Confiserie Vandenbulcke launched chocolates with a cacao pulp fruit filling at ISM 2022. 

By Missy Green