Antioxidant Benefits in Orange Peel Extracts

Jenn Hoskins
2nd April, 2024

Antioxidant Benefits in Orange Peel Extracts

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Benue State University found citrus peels contain health-promoting compounds
  • The 'Valencia' orange peels showed the strongest antioxidant properties
  • These findings could lead to using citrus waste in food and pharmaceuticals, promoting sustainability
The quest for sustainable solutions to food waste has led researchers at Benue State University to explore the hidden value in what is often discarded during the harvesting of citrus fruits[1]. The study focuses on the peels of three popular citrus varieties, namely 'Valencia', 'Washington', and 'Thompson Navel' oranges. These peels, typically seen as waste, are suspected to harbor a wealth of bioactive compounds that could be harnessed for food and pharmaceutical applications. The study begins by extracting substances from the peels using ethanol and hexane in a device known as a Soxhlet extractor. This process isolates the chemical constituents of the peels for further analysis. The researchers then conduct phytochemical screenings to identify the types of compounds present, which include alkaloids, flavonoids, phenols, phytosterols, diterpenes, tannins, and glycosides. These are important because they are often associated with health benefits, particularly due to their antioxidant properties. Gas Chromatography/Mass Spectrometry (GC/MS) analysis further refines the understanding of the peels' composition, pinpointing approximately 48 compounds in each extract. Among these, limonene, ascorbic acid (vitamin C), stearic acid, linalool, linoleic acid, palmitic acid, and pentadecyclic acid are the most prominent. These substances are known for their potential health benefits, including antioxidant activity. Antioxidants are crucial for protecting the body against oxidative stress, which can damage cells and is linked to various diseases. To measure the antioxidant potential of the citrus peel extracts, the researchers employ several assays: the ferric ion reducing antioxidant power (FRAP), hydrogen peroxide scavenging, and cupric ion reducing antioxidant capacity (CUPRAC) tests. These assays assess how well the extracts can neutralize oxidative agents, which can be indicative of their potential health benefits. The findings reveal that the ethanol and hexane extracts of the 'Valencia' variety show the highest FRAP and CUPRAC values, indicating strong antioxidant properties. Moreover, the ethanol extract of the 'Ibadan sweet' variety (a local name that seems to refer to one of the citrus varieties studied) demonstrates a superior ability to scavenge hydrogen peroxide, another marker of antioxidant activity. These results are in line with previous research[2] that found orange peel extracts, particularly when extracted with certain solvents like acetone, to have high antioxidant activity and to protect against DNA damage in human cells. This suggests that not only do citrus peels contain valuable antioxidants, but also that the method of extraction can influence the potency of these compounds. The broader context of this research is the drive towards a circular economy and "zero waste" in the environment[3]. By finding value in the by-products of the fruit industry, such studies contribute to reducing environmental impact while also creating economic and social value. The current study builds on the understanding that fruit wastes are a treasure trove of bioactive compounds that can be repurposed for health-related applications. Furthermore, this research complements the overarching themes of food chemistry and natural products highlighted in a Special Issue[4], which emphasizes the importance of understanding food components not only for their nutritional value but also for their potential roles in disease prevention and therapy. In conclusion, the study from Benue State University underscores the potential of citrus peels as a rich source of natural antioxidants. The identification and quantification of bioactive compounds in these peels pave the way for their inclusion in food products or pharmaceutical formulations, contributing to the sustainability of the food industry and offering new avenues for health promotion.



Main Study

1) Characterization and antioxidant activity of peel extracts from three varieties of citrus sinensis.

Published 15th April, 2024 (future Journal edition)

Related Studies

2) Antioxidant activity of orange flesh and peel extracted with various solvents.

3) Fruit Wastes as a Valuable Source of Value-Added Compounds: A Collaborative Perspective.

4) Development of Food Chemistry, Natural Products, and Nutrition Research: Targeting New Frontiers.

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