Red Oak (Quercus rubra L.) Fruits as Potential Alternative for Cocoa Powder: Optimization of Roasting Conditions, Antioxidant, and Biological Properties

Cocoa powder is a basic ingredient in the manufacture of chocolate, one of the most appreciated sweet products in the world for its sensory and nutritional properties. Furthermore, it displays a central nervous system stimulant effect. This study aimed to investigate acorn-derived powder as an alternative to cocoa powder, in order to obtain a chocolate that does not contain stimulants of the nervous system. Both the chocolate technological process and acorns roasting process (180 °C/25 min, 200 °C/20 min and 220 °C/15 min) were optimized to obtain acorn powder with an organoleptic profile as close as possible to that of cocoa powder. The chocolate sensory evaluation was performed by means of the hedonic test. Furthermore, the aqueous extracts obtained from the resulting powder were evaluated for total polyphenol content, and in vitro antimicrobial and antiproliferative properties. The results point out a high content of phenolic compounds (500.78–524.01 mg GAE/100 g); protection against microbial contamination based on the ability to inhibit a Gram-positive bacterium (Bacillus cereus) was also noticed. The aqueous acorn extracts were also able to reduce the cell viability of HFL-1 (human fetal lung fibroblast) and DLD-1 (colorectal adenocarcinoma) lines. This study suggests red oak (Quercus rubra) fruits as a potential alternative to cocoa powder in the manufacture of chocolate.