Uncovering cocoa shell as a safe bioactive food ingredient: Nutritional and toxicological breakthroughs

This work aimed to analyze the chemical composition of the cocoa shell flour (CSF) and aqueous extract (CSE) and conduct acute and sub-chronic toxicity assays to ensure safety. CSF was composed of 59.1 % dietary fiber, primarily insoluble fiber (48.1 %). CSE consisted entirely of soluble fiber (72.8 %), mainly pectic polysaccharides. The amino acid profile revealed CSF's potential as a high-quality plant protein source, whereas CSE was rich in free amino acids, especially leucine, valine, and alanine (59.6–62.5 mg 100 g⁻¹). Higher levels of macroelements, especially potassium, were found in CSE. Silicon was the most abundant microelement, and heavy metal levels were within acceptable limits for both cocoa shell matrices. This study confirmed the bioactive potential of CSF and CSE, enriched in phenolic compounds and methylxanthines, including theobromine, caffeine, gallic acid, (+)-catechin, as well as N-phenylpropenoyl-l-amino acids. The high theobromine content in both matrices, especially in CSE (2605.3 mg 100 g⁻¹), did not harm the mice's health; acute and sub-chronic toxicity studies demonstrated the safety of oral administration of CSF and CSE in mice, showing no lethality or remarkable histopathological changes. This research supports the safe use of CSF and CSE, establishing these ingredients as suitable for incorporation into food products.