# Upcycled Orange Peel Ingredients: A Scoping Review on Phytochemical Composition, Extraction Techniques, and Biorefinery Strategies

## TL;DR

This review explores how orange peels can be upcycled into valuable bioactive compounds, focusing on extraction methods and biorefinery strategies to reduce food waste and support sustainability.

## Contribution

The study provides a comprehensive scoping review and bibliometric analysis of orange peel valorization research from 2003 to 2023, highlighting trends and gaps in sustainable extraction and biorefinery approaches.

## Key findings

- There has been exponential growth in orange peel research over the past decade, driven by interest in sustainable food waste valorization.
- Polyphenol- and pectin-rich extracts are the primary focus due to their economic and nutritional value, while carotenoids remain underexplored.
- Innovative multi-extraction and zero-waste biorefinery models have emerged but face challenges in standardization and scalability.

## Abstract

Background/Objectives: Orange peels (OP), a major by-product of the juice industry, are rich in bioactive compounds (phenolic compounds, pectin, carotenoids, and essential oils). Its valorization represents a promising route to reduce food waste and foster a circular bioeconomy. This review aimed to map scientific progress in OP upcycling, focusing on the extraction of bioactive ingredients for human nutrition and integrated biorefinery approaches aligned with zero-waste principles. Methods: A bibliometric analysis and a scoping review were conducted covering studies published between 2003 and 2023. Scopus database and VOSviewer was usedto identify research trends, hotspots, and gaps. Conventional and emerging green extraction methods were critically compared, and integrated biorefinery strategies for maximizing OP valorization were systematically assessed. Results: The analysis revealed an exponential rise in OP research over the past decade, reflecting growing interest in sustainable food waste valorization. Polyphenol- and pectin-rich extracts are currently the focus of research and applications, driven by their high economic and nutritional value. Innovative multi-extraction and zero-waste biorefinery models have emerged, yet most remain at low technological readiness levels. Carotenoids and other bioactive compounds remain underexplored, and challenges persist regarding standardization and scalability. Conclusions: OP valorization is shifting towards integrated green extraction and biorefinery frameworks that address clean-label demands, promote circular economy goals, and align with the Sustainable Development Goals. Future research should prioritize (i) standardized protocols, (ii) scalable green extraction technologies, (iii) the inclusion of underutilized compounds such as carotenoids, and (iv) regulatory pathways to accelerate industrial translation.