Researchers from University of Zagreb (Croatia) have developed a chocolate rich in polyphenols derived from raspberry leaves. They report their work in Food Research International and note that raspberry leaves (Rubus idaeus L.) have been used in folk medicine to treat a number of conditions. Many of these potential health benefits are attributed to polyphenolic compounds, especially ellagic acid and ellagitannins, which provide a distinctive flavour of raspberry leaves tea.
In the present study the bioactive content, physical and sensory properties of milk, semisweet and dark chocolates enriched with concentrated (1 and 3%) and freeze dried (1%) red raspberry leaf extract were studied. Researchers found that the addition of 3% concentrated extract reduced the particle size distribution parameter in all chocolates but provided harder product with higher viscosity and rough, coarse product surface, resulting in an unattractive and sensorially unacceptable product. However, the addition of freeze dried extract increased the particle size of all chocolates and did not cause any significant difference in the chocolate surface, and was scored the best in terms of visual, textural and flavour attributes. The addition of 1% of concentrated or 1% of freeze dried extract did not alter the total phenol content (TPC) of enriched chocolate compared to plain samples, while the addition of 3% concentrated extract enhanced the TPC in all chocolates.
Researchers claim that optimal physical, bioactive and sensory properties can be achieved if a freeze-dried concentrate of raspberry leaf is used.