Value-added products from by-products generated from fruits and vegetables

Fruits and vegetables represent a considerable part of the food chain. When processing fruits and vegetables, there are many by-products generated. Moreover, these by-products might have many nutritional and unique values, and we should not treat them as waste. So, the leftovers can be improved by adding value. This makes the product more marketable and valuable. It also turns waste into useful material through the perspective of a circular economy that can benefit industries, the environment, and consumers.

What are the value-added products from fruit and vegetables?

While processing fruits and vegetables into final products, large amounts of waste/ by-products are generated with high polyphenols and dietary fiber concentrations. The most common “waste” from fruits and vegetable industries can be categorized as plant skin, peels, pulp, seeds, and fiber, which have many bioactive and nutritious compounds.

What is value addition in fruit products?

When considering world-leading fruit products, the world’s citrus production and export have grown steadily over the past three decades, although at a slower pace than competing fruits such as mangoes, avocadoes, and melons (FAO). Among the most commonly cultivated species, oranges account for more than half of world citrus production and are the most widely traded citrus fruit, followed by tangerines, lemons, and grapefruits (FAO). The end products of citrus are commonly fresh pulps or juice. The remaining waste materials after production are peels, pulp, and seeds, which comprise a high portion of the fresh fruit weight. As these wastes are rich in bioactive compounds, many value-added compounds can be produced from them, such as fibers, flavonoids, pectin, and limonene.  

World banana trade has expanded to unprecedented heights recently, with an estimated export volume of 21 million tonnes in 2019 (FAO). When processing banana products, a lot of banana peel waste is generated. So, the banana peels are turned into banana chips and powder through value addition. Additionally, the peels are used in animal feed. These banana peel wastes contain dietary fiber, proteins, and bioactive compounds, such as phenolic compounds with reported antioxidant activities.

The by-products of one of the typical seasonal fruits of mango are peels and kernels while producing mango juices, pickles, purees, and canned products. These by-products are good sources of bioactive compounds. Mango peels comprise functional compounds such as polyphenols, carotenoids, vitamin C, Vitamin E, dietary fibers, and natural antioxidants. In contrast, mango kernels are sources of essential amino acids, phenolic compounds, edible oil, and high amounts of unsaturated fatty acids. Because these wastes have high nutritional value, there is great potential to turn them into valuable products through value addition.

The most non-common waste of Mangosteen production is mangosteen pericarp. It has been reported that 10 kg of harvested mangosteens generates about 6 kilograms of pericarps (Mohammad et al., 2014). These pericarps are bioactive compounds with medicinal properties and are used as dietary supplements. Another by-product is that mangosteen seeds contain 21.18% oil (Ajayi et al., 2006) with essential and non-essential fatty acids (Ajayi et al., 2006). They are beneficial for the heart and liver; hence, they can be used as edible oils.

In the apple processing industry, apple pomace is the main by-product, which makes up 25 – 35% of the total crop waste (Dijlas et al., 2009). The apple pomace waste includes the peels, seeds, stems, core, and soft tissues. These peels are good sources of polyphenols, pectin, protein, and vitamins. The primary utilization of these peel wastes is pectin extraction, which can be co-precipitated from the apple pomace.

What are the examples of value addition in vegetables?

The main waste generated in the tomato processing industry is seeds, peels, and pulp. These wastes are good sources of protein and fats. Furthermore, these wastes are rich in unsaturated fatty acids, making tomato seed oil suitable for use as edible oil. A vital lycopene carotenoid is also present in large amounts in tomato wastes.

The waste of the carrot processing industry is peels and pomace when making carrot juices. These wastes have valuable carotenes, uronic acids, sugars, fibers, and pectin compounds. Studies are being done to recover these fibers from the carrot waste residues, as they have been reported to have cholesterol-lowering effects that can protect against coronary heart diseases. Also, various attempts are being made to incorporate them into the production of functional foods and beverages.

Cabbage is also a vegetable with a high production yield; however, the waste generated is minimal since it is consumed either in raw or fresh form. The primary wastes are their outer leaves, disposed of by the plant. These leaves can be used mainly for the production of biofuels by the anaerobic digestion process.

Value-addition of food by-products to the generated waste through the food processing chain

The generated wastes from the food processing line cannot be directly incorporated into the food chain. That is why the term “food by-products” is gaining popularity—it highlights that these “food wastes” can serve as critical materials for reclaiming functional compounds and creating new products with market value.

For example, the phenols and carotenoids produced from fruit by-products are used as natural food or beverage preservatives since they extend the shelf-life of the products and can delay the formation of off-flavors and rancidity. The extracted pectin from fruit processing waste can be used as a gelling agent in confectionery or as a fat replacement in meat.

Therefore, new aspects concerning the use of these wastes as by-products for further exploitation in producing food additives or supplements with high nutritional value have gained increasing interest because these are high-value products, and their recovery may be economically attractive.

If you want to learn more about value-added products, read our article, The benefits behind fruit and vegetable peels