Stop Food Waste Day 2022: Waste to Value
Did you know that one third of all food produced globally is either wasted or lost? Fruits and vegetables are amongst the most wasted foods, with up to 50% being discarded1. Of course, some wastage is unavoidable. Inedible parts of fruits and vegetables like peels, seeds, piths, pulp and other fibrous parts of plant foods are often disposed of or used in anaerobic digestion to create fuel and fertilisers.
You may be wondering how all of this is linked to the gut microbiota. Well, emerging research is exploring alternative ways to utilise these nutritious fruit and vegetable by-products to feed our gut microbes!
Prebiotics from Food Waste
Prebiotics are defined as “substrates that are selectively utilised by host microorganisms conferring a health benefit”2. Prebiotics can be found naturally in food, such as Jerusalem artichoke, chicory, leeks, bananas, legumes and beans, but are also becoming more widely available in supplement form or as added ingredients in food. The dietary prebiotics most widely studied are non-digestible oligosaccharides such as fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), as well as inulin, lactulose and resistant starch.
Since fruit and vegetable wastes contain microbe-accessible nutrients like dietary fibre, prebiotics and phenolic compounds, researchers are exploring ways to utilise these by-products to improve organoleptic properties and nutritional value of foods. For example, fruit pomace (rich in dietary fibre and bioactive compounds), a by-product of fruit juice production, can be processed into a powder and used in baked goods to improve texture, colour (natural pigments) and nutritional value. Moreover, some evidence shows that pectin oligosaccharides (POS) derived from pectin-containing food wastes such as potato skins, orange peels, apple pulp etc., may have a prebiotic effect3.
However, the extraction of POS by the conventional hydrothermal treatment process is often neither very environmentally friendly nor efficient, hence newer methods are being are being tested. Currently, researchers in the UK are studying the use of microwave technology to extract POS from fruit and vegetable waste – so far this method has proven to be more energy efficient, less reagent intensive and produces a higher yield of POS4.
Thus, innovative technologies such as these could help our planet by reducing the environmental impact of food waste and at the same time help keep our gut microbes happy and healthy! In the meantime, let’s do our part in minimising food waste and environmental footprint within our own households and local communities.
1. Pop et al. (2021) Dietary fiber and prebiotic compounds in fruits and vegetables food waste. Sustainability, 13(13): p.7219.
2. Gibson et al. (2017) Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nature reviews Gastroenterology & hepatology, 14(8): pp.491-502.
3. Chung et al. (2017) Prebiotic potential of pectin and pectic oligosaccharides to promote anti-inflammatory commensal bacteria in the human colon. FEMS microbiology ecology, 93(11): p.fix127.
4. Arrutia et al. (2020) Development of a continuous-flow system for microwave-assisted extraction of pectin-derived oligosaccharides from food waste. Chemical Engineering Journal, 395: p.125056.