Coffee as source of fibres, polyphenols and caffeine
Green coffee production worldwide accounted for 8.8 MT none of which grown in EU countries. The gross production value of green coffee in 2014 was about 18 billion USD. The most important EU producer is Brazil followed by Vietnam and Colombia. The vast majority of the worldwide green coffee production is imported by EU countries (about 2.7 MT in 2015).
Coffee producers usually submit the green coffee to a roasting process during which several by-products are produced of which the most relevant is silver skin (estimated to be about 1-4% of the processed green coffee). Silver skin is a fine integument that covers and protects the external layer of the seed, grossly called grain, of green coffee. It is partially taken off in field, during desiccation and removal of coffee seeds from the fruits, and partly during roasting. In 2013, it was estimated a coffee production losses represents about 26,000 tonnes per year in EU.
The chemical composition of the silver skin by-product was determined and consists of 70-79% of dietary fibre (15% soluble fibre), cellulose and hemicellulose (around 15%), in about 5% of fat and important bio-functional molecules such as caffeine (0.9%) and polyphenolic compounds (0.6%). Thus the silver skin may certainly be promising also for the nutritional and cosmetic purposes.