Updated: Mar 2
As the most famous beverage withinside the world, the large-scale manufacturing of coffee  has resulted in the creation of large quantities of organic solid waste . This poses serious environmental problems for coffee-producing countries .
What are coffee by-products? What is currently referred to as "coffee by-products" need to be modified in our contemporary sustainable society as they may be re-used in food, beverage, and cosmetics. Coffee by-products consist of the peel, coffee pulp, coffee husk, coffee silverskin, and coffee parchment, the fibrous endocarp that covers the 2 hemispheres of the coffee seed and separates them [4, 5]. These by-products were proven to have outstanding benefits and advantages to be utilized for.
Coffee parchment and metabolic disorders Coffee parchment, one of the least-used by-products of coffee has been proven to be an interesting source of dietary fiber (DF)* . DF has been reported to help regulate blood sugar levels by inhibiting α-amylase. It also delays the digestion of carbohydrates by increasing digestion time and decreasing glucose absorption .
Moreover, it was reported to reduce the absorption of cholesterol in the large intestine . That’s why it would be very interesting to use it as a low-calorie snack ingredient. Additionally, phenolic compounds in parchment reduce oxidative stress. In presence of DF, the complex phenolic compounds-DF reaches the colon intact where it is fermented by microbiota to produce metabolites promoting an antioxidant environment at this level.
Furthermore, they play a key role in reducing cholesterol-associated inflammation via adipogenesis inhibition . This enhances the aforementioned property of “lowering cholesterol absorption” in the large intestine, which confers to it a potential preventive effect against some metabolic diseases, such as coronary heart disease and diabetes .
The rest of the coffee by-products are as interesting as the parchment. For instance, Arabica coffee pulp yielded has a high antibacterial activity against nosocomial bacteria; Staphylococcus Epidermidis and Pseudomonas Aeruginosa . Coffee silverskin can have a relatively high protein about 18 to 22 g/100 g, all essential amino acids are present and due to compounds such as melanoidins, some silverskin can find application as a food coloring .
Coffee by-products and dermatology In dermatology, the antioxidant properties present in all coffee by-products due to the phenolic compounds could provide skin protection against UV light-induced damage, the content of polyphenols could be used for patients with alopecia, acne vulgaris for example . Some of these by-products are traditionally present and used in many countries worldwide such as Yemen and Ethiopia where coffee leaves are used as a tea-like beverage Despite all the advantages, these products are currently not available on the market due to regulations, they are considered novel foods. Therefore, approval from the European Food Safety Authority (EFSA) is required to be commercialized in markets with novel food regulations, such as European countries.
Finally, coffee by-products included in a circular economy would deliver an amazing gain to coffee producers and the environment. There is huge potential for these products, especially in a society like today's modern ecologically oriented society that attaches great importance to sustainability and waste reduction for a better future for our planet.
*Dietary fiber (DF) is the fraction of food that cannot be digested or absorbed by humans in the small intestine but fermented in whole or in part in the large intestine
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