Nutritional, chemical and antioxidant/pro-oxidant profiles of silverskin, a coffee roasting by-product

Abstract

Coffee silverskin (a coffee roasting by-product) contains high amounts of dietary fibre (49% insoluble and 7% soluble) and protein (19%). Potassium (∼5g/100g), magnesium (2g/100g) and calcium (0.6g/100g) are the major macrominerals. The vitamin E profile of silverskin comprises α-tocopherol, β-tocopherol, ɣ-tocopherol, δ-tocopherol, β-tocotrienol, ɣ-tocotrienol, and δ-tocotrienol. The fatty acid profile is mainly saturated (C16:0 and C22:0), but the total amount of fat is low (2.4%). Caffeine (1.25g/100g), chlorogenic acid (246mg/100g), and 5-hydroxymethylfurfural (5.68mg/100g) are also present in silverskin. Total phenolics and flavonoids are partially responsible for the in vitro antioxidant activity. Silverskin extracts protected erythrocytes from oxidative AAPH- and HO-induced hemolysis, but at high concentrations a pro-oxidant effect on erythrocyte morphology was observed.

Ultrasound‐assisted extraction (UAE) of bioactive compounds from coffee silverskin: Impact on phenolic content, antioxidant activity, and morphological characteristics

“…They showed a wide range TPC from 4.35 mg GAE/g (the coffee blend) to 12.82 mg GAE/g ( coffee robusta ). The results in the present study agreed with those reported by the previous studies (Costa et al, ; Panusa et al, ; Regazzoni et al, ; Toschi et al, ).…”

“…They reported the caffeine content of same CSS variety collected in different batches was from 0.77 to 1.03 g/100 g sample. Costa et al () extracted CSS with 50% ethanol‐water as solvent showing caffeine content of 1.25 g/100 g sample which the highest among their studies, however, was still lower than our result which was 3.67 and 4.29 g/100 g sample treated by water and methanol–water mixture, respectively. The differences of the caffeine content could result from the different methods applied for extraction as well as different coffee varieties and roasting conditions (Hečimović, Belščak‐Cvitanović, Horžić, & Komes, ).…”

“…Many researchers reported CSS extracts had antioxidant activity (Bresciani et al, ; Costa et al, ; Narita & Inouye, ; Panusa et al, ). In present study, two assays, DPPH• scavenging ability and ferric reducing antioxidant power (FRAP), were performed in order to evaluate antioxidant capacity of the CSS extracts under different extraction conditions (solvent, extraction time, and ultrasound intensity).…”

Coffee Silverskin: A Review on Potential Cosmetic Applications

“…During the roasting process, coffee beans expand and this thin layer is detached, becoming the main by-product of coffee roasting industries [1]. CS, compared to other coffee by-products, is a relatively stable product due to its lower moisture content (5-7%) [2,3]. Currently used as fuel, for composting and soil fertilization, CS represents a good source of several bioactive compounds that can be extracted and further used for food, cosmetic and pharmaceutical purposes [4].…”

“…CS is composed by a high amount of dietary fiber (56-62%), especially soluble fiber (~87%) [2,3]. It contains cellulose (18%) and hemicellulose (13%), being this last composed by xylose (4.7%), Table 1.…”