Pectin from fruit waste: a sustainable approach to waste management

Sanoli Perera

Food technologist with experience in food processing industry

4 min read
Pectin from fruit waste: a sustainable approach to waste management

The production of processed fruit items is rising, leading to a significant increase in the volume of fruit waste generated. Managing this surplus waste without harming the environment has become a pressing issue. However, one promising approach to tackle this challenge is to explore innovative methods for repurposing these fruit leftovers into valuable products, thereby mitigating the environmental impact of their disposal.

What is Pectin?

Pectin is a complex polysaccharide from a family of galacturonic acid-rich polysaccharides found in plant cell walls. Galacturonic acid comprises approximately 70% of pectin. Pectin constitutes 35% of primary walls in dicots and non-graminaceous monocots, 2-10% of grass and other commelinoid primary walls, and up to 5% of walls in woody tissue. The complexity of structure provides an assortment of structural epitopes that impart unique functions.

The quality for various uses depends on specific characteristics, such as the amount of anhydrogalacturonic acid, methoxyl content, degree of esterification, and acetyl value. Therefore, it is essential to thoroughly analyze the biochemical properties of each pectin before its application. Pectin is extracted from various sources by boiling them with water and acids to explore these properties. The vital biochemical properties of extracted pectins include the percentage of anhydrogalacturonic acid, methoxyl content, gel strength, and acetyl value.

Natural Pectin Sources: Waste and Extraction Methods

Pectin can be extracted from the waste of mango peel, jackfruit, banana peel, nutmeg rind, pomelo peel, passion fruit rind, lime peel, mangosteen rind, apple pomace, and others. There are a few ways to do it, such as using chemicals or enzymes. One of the oldest and simplest methods is using hot water. This method works by dissolving the pectin in the plant tissues, making it easier to separate from the rest of the plant. It's a simple but effective way to extract pectin from fruits and other plants.

When is extracted from fruit peel waste, the yield varies depending on the type of fruit. Researchers have examined citrus, mango, apple pomace, and banana peel to determine their pectin content. According to one study, citrus peels had the highest pectin content, around 24.5%. Therefore, citrus peel is a vibrant source compared to other fruit peels.

 Pectin Extraction Techniques: Traditional vs. Emerging Green Methods

Pectin extraction methods fall into two categories: conventional and emerging green nonconventional. Traditional techniques often involve heating with acidic catalysts to dissolve protopectin. In contrast, emerging nonconventional methods focus on improving heat and mass transfer, sometimes without acids. Both approaches have their place in pectin extraction as scientists seek more efficient and eco-friendly processes.

Conventional Extraction Process

This process involves three main steps. First is pretreatment, where the fruit material is washed, blanched, or dried to deactivate enzymes and microbes, ensuring a stable raw material that prevents pectin from breaking down. Then, in the extraction stage, acid (either mineral or organic) is added to the fruit material, typically at a pH of 1.5 to 3, and heated to 75-100 °C for 1-3 hours to dissolve protopectin. After extraction, the pectin solution is filtered and concentrated. This concentrated solution is then mixed with double the volume of ethanol to precipitate the pectin, which is washed to remove acids and impurities. The ethanol used in this process is recycled through distillation. Finally, the washed pectin is dried and ground into a fine powder.

Emerging Green Nonconventional Methods

In recent literature, innovative green technologies have emerged to improve the shortcomings of traditional acid-based pectin extraction processes. These methods explore alternative extraction techniques that show promise for commercial use. Among these methods are microwave-assisted extraction, subcritical extraction, ultrasound-assisted extraction, enzymatic extraction, and hybrid extraction approaches. These technologies aim to make pectin extraction more efficient, environmentally friendly, and economically viable.

Benefits and Applications 

Pectin functions as a gelling and stabilizing polymer in various foods. It positively affects human well-being by lowering cholesterol and serum glucose levels, reducing cancer risk, and stimulating the immune response. It has multiple biomedical uses. Pectin also produces specialty products, including edible and biodegradable films, adhesives, paper substitutes, foams and plasticizers, surface modifiers for medical devices, material for biomedical implantation, and drug delivery.

Pectin extracted from fruit wastes offers numerous environmental and economic benefits, and it helps reduce waste disposal costs and environmental pollution associated with landfilling by valorizing fruit wastes. Additionally, it provides an alternative source, reducing reliance on conventional sources such as citrus peels and apple pomace. Moreover, derived from fruit wastes, it exhibits functionality similar to commercial pectin, making it suitable for various food, pharmaceutical, and cosmetic applications. It can be used as a gelling agent in jams, jellies, and fruit spreads, a thickener in dairy products and sauces, and a stabilizer in beverages and confectionery.

Pectin extraction from fruit wastes presents a promising avenue for waste valorization and resource optimization in the fruit processing industry. By harnessing the potential of fruit wastes, we can mitigate environmental pollution and create value-added products with diverse industrial applications. With continued research and innovation, pectin extraction from fruit wastes has the potential to contribute to a more sustainable and circular economy.

Sanoli Perera
Food technologist with experience in food processing industry

More from Sanoli Perera

View more articles