Fruit and Vegetable Waste: Bioactive Compounds, Their Extraction, and Possible Utilization Narashans Alok Sagar, Sunil Pareek, Sunil Sharma, Elhadi M. Yahia , and Maria Gloria Lobo 2018. Comprehensive reviews in Food Science and Food Safety Vol 00. Available online: https://www.researchgate.net/publication/324170873_Fruit_and_Vegetable_Waste_Bioactive_Compounds_Their_Extraction_and_Possible_Utilization
Years ago when I was completing my PhD on lingonberries I learned quite a lot about fruit processing how even the steam created in the process of making lingonberry sauce was captured and “mined” for a whole host of volatile and aromatic compounds that were packaged and sold for use somewhere else in the food industry. This article is a fascinating review of even more modern techniques being used to extract bioactive compounds from what would otherwise be called food waste. After the apple has been peeled and sliced, there is a tremendous waste stream that includes stems, peels, seeds and pulp that usually ends up in a compost pile or worse- buried in a landfill. “.. Apples generate 10.91% of seed and pulp as by-products, and 89.09% of final products during slicing.” When you think about the tons of apple products made worldwide, that’s a lot of waste from a single fruit! Bananas yield 35% waste through their peel!
“Losses and waste occur during all phases of the supply and handling chain, including during harvesting, transport to packinghouses or markets, classification and grading, storage, marketing, processing, and at home before or after preparation. Losses occur throughout the supply chain from production throughout all postharvest stages before consumption.”
Although this article emphasizes tropical fruits, it is an eye opener as far as what is actually left behind after processing, and the technology being used to capture such things as dietary fiber, phenolic compounds, flavorings, aromas and more. Most fascinating is a list of fruits that are treated with microorganisms to release a whole rainbow of enzymes, organic acids, and proteins that are then packaged and used in other food products as stabilizers, agents to prevent browning in processed products. We often look at the food industry in a poor light, but food chemistry is far more complex than most people realize, and this is a great example of recycling and repurposing that has been happening for many years.
The article also describes methods by which this waste extraction happens. Such exotic processes as microwave-assisted extraction, pulsed electrical field extraction, enzyme assisted and liquid to liquid extraction seem so foreign but are part of a growing technology to harvest everything of value from the waste stream and make it useful. Pretty impressive! Of course, you could eat the entire apple- peels, seeds and all, but even that would not provide the valuable components liberated by the many extraction techniques.