Bioactive and functional compounds in apple pomace from juice and cider manufacturing: Potential use in dermal formulations

Background: Apple stands out as one of the main fruits processed worldwide, generating an immense volume of industrial by-products, collectively known as apple pomace. This material contain important levels of bioactive compounds that could be used in food and pharmaceutical products, answering to current demands regarding the incorporation of natural-based ingredients, generally preferred for their reduced side effects (contrarily to the observed with most artificial components). Scope and approach: The option for industrial by-products as source of bioactive compounds has evident economic advantages, counteracting the typically higher cost of biorefinery processes, when compared with the employment of artificial compounds. In addition, this approach is aligned with current circular economy premises, in the sense of using an industrial waste as the starting material to extract high added value compounds. Key findings and conclusions: Apple pomace remaining from cider and juice production companies is as a striking example of an underutilized industrial by-product. In fact, most bioactive compounds (particularly phenolics) in apple are found in its peels, resulting to be more concentrated in pomace than in whole fruits. The major phenolic compounds in apple pomace (e.g. flavonoids, hydroxycinnamic acids, or di-hydrochalcones) are associated with health promoting activities, mainly based on their antioxidant, anti-inflammatory, and antimicrobial properties. Therefore, these compounds could have different food and/or pharmaceutical (e.g., in novel dermal formulations) applications. Besides bioactive compounds, apple pomace contains high levels of pectin, which could likewise be used (as a natural gelling agent) in newly developed formulations.