A study by Erdem et al. in the LWT – Food Science and Technology journal found that probiotic strain Bacillus indicus HU36 combined with maltodextrin and lemon fiber in dark chocolate demonstrated high probiotic survival rates and did not adversely impact taste, color or texture.
The findings could lead to a new type of digestive health probiotic bitter chocolate.
The research was carried out by scientists at Istanbul Technical University in Turkey and Royal Holloway University of London in the UK.
Choosing the fibers
The researchers used 100g dark chocolate (50% cocoa) samples supplied by Nestlé Turkey.
Before adding the probiotic strain, they conducted a pre-study to determine which dietary fibers would be best to use in combination with the probiotic, based on consumer acceptability.
Six fibers (maltodextrin, carboxymethylcellulose, inulin, lemon fiber, apple fiber and wheat fiber) and a control with no fibers were tested for acceptability in chocolate by 10 voluntary panelists, who were given basic training in sensory analysis.
The panelists ranked maltodextrin and lemon fiber as the most acceptable in chocolate, so these two fibers were chosen to see if they worked with the probiotic strain.
High probiotic survival rates
The researchers then studied the survival rate of Bacillus indicus HU36 in dark chocolate when maltodextrin and lemon fiber were added together.
They found the highest probiotic survival rate (91%) came when using 3.5 g of maltodextrin and 5.5 g of lemon fiber.
Sensory analysis of the fortified samples was also positive.
“Descriptive sensory analysis showed that dietary fiber addition didn’t show negative effects, such as off-flavor, unwanted aroma or taste, on color and organoleptic properties of samples. Among fibers, maltodextrin and lemon fiber addition had positive effects on the sensory characteristics.”
The positive effects were noted as improved sweetness, firmness and adherence.
The researchers concluded that lemon fiber concentration should be kept at 1.5 g per 100 g while maltodextrin should be kept between 3.20 and 3.91 (g/100 g) to ensure the best sensory characteristics. They found that this concentration guaranteed a probiotic survival rate of around 89.18%.
The probiotic strain
Earlier research by Possemier et al. said that chocolate was a better probiotc carrier than dairy products for intestinal delivery because survival rates were four times higher than milk- containing products.
Lactobacillus and Bifidobacteria are the two most popular probiotic species used in consumer products. Bacillus indicus HU36 is a subset of the Baccilus species. According to researchers in the present study, it is a spore-forming bacteria characterized for its safety as probiotic supplements and high carotenoid content.
The EU nutrition and health claims regulation (NHCR) last year considered the term ‘probiotic’ an implied health claim, banned for product labels. However, ‘probiotic’ claims can still be made in the US.
LWT - Food Science and Technology (2013)
‘Development of a novel synbiotic dark chocolate enriched with Bacillus indicus HU36, maltodextrin and lemon fiber: Optimization by response surface methodology’
Authors: Erdem, Ö., et al.