Effects of thick‐layer drying on the bioactive compounds of acerola residues

Abstract

AbstractAcerola (Malpighia emarginata D.C.) is a fruit rich in antioxidants and vitamins, whose processing generates large quantities of residues. This waste is potentially useful due to the presence of important bioactive compounds, but its high moisture level makes it difficult to use. This work evaluates the impact of dehydration in a thick‐layer dryer on the bioactive compounds of acerola residues. The compounds analyzed before and after dehydration were: total phenolics, total flavonoids, and ascorbic acid. The presence of important compounds for the food and pharmaceutical industries was found using nuclear magnetic resonance and gas chromatography–mass spectrometry. The effects of operating variables on the bioactive compounds were quantified. The heterogeneity of the material as a function of the axial bed position was also investigated.Practical applicationsThe acerola is increasingly used in the form of juice, jelly and compote owing to its high levels of ascorbic acid and other important bioactive compounds. The wastes from acerola processing can contain higher amounts of phenolic and other bioactive compounds than the edible fleshy parts. In this study, the effect of convective thick‐layer drying on the main bioactive compounds (phenolics, flavonoids and ascorbic acid) of the acerola residues was investigated. The analysis using nuclear magnetic resonance (NMR) and gas chromatography–mass spectrometry (GC–MS) also allowed the identification the presence of important compounds in dehydrated acerola residues, such as phytosterols, malic and linoleic acids. Results show that these residues are a potentially useful resource to be explored and that the dehydration of acerola residues in a thick‐layer fixed‐bed dryer is an interesting alternative for the possible reuse of this material if performed under adequate operating conditions.