Lipid biomarkers for validation of spent coffee grounds as a healthy dietary fiber

Resumen del trabajo presentado a la 22nd International onference Functional Foods and Chronic Diseases: Science and Practice, celbrada en Boston (USA) del 22 al 23 de septiembre de 2017.[Background] Spent coffee grounds (SCG) are considered a source of antioxidant dietary fiber. However, SCG contain lipids ranged from 10 to 20 %. Cholesterol raising properties have been attributed to coffee diterpenes particularly to cafestol composing the fat fraction of SCG. Fatty acids and diterpenic compounds implications in lipid biomarkers when SCG are used as a food ingredient have not been reported.[Objective] To characterize the lipid profile of SCG and to determine their bioaccessibility and impact on lipid biomarkers for the validation of SCG as a healthy dietary fiber.[Methods] Three different samples were analyzed, one SCG from the commercial instant coffee process and two from different local cafeterias. Instant SCG was Robusta while those from cafeterias were a mixture of Arabica/ Robusta (50/50%) submitted to natural roasting, and an Arabica blend containing 80% natural and 20% torrefacto roasted beans. SCG total fat content was quantified gravimetrically after Soxhlet extraction (AOAC 945.16). Instant SCG was selected for further characterization. In vitro bioaccessibility of fatty acids and diterpenes (cafestol and kahweol) composing instant SCG was evaluated mimicking human oral gastrointestinal conditions. Fatty acids and diterpenes in samples and digest products were determined by GC-FID. A pilot repeated dose 28-day oral treatment was carried out using 10 male Wistar rats divided in two groups called as treatment (1 g of instant SCG dissolved in Tween 80/kg of body weight) and control (Tween 80 in H2O). Total fat content and cholesterol in liver were used as biomarkers to evaluate the effect of SCG fat on rat health. Further information on the effect of SCG on rat health was obtained by measuring wet and dry weights and total fat content in rat feces produced during the first 8 hours after the intake of SCG. Data were compared with that for the control group.[Results] Total fat content in SCG samples ranged from 11 to 21% being the highest value found in instant SCG which was selected for further characterization. Palmitic (62.46 mg/g), stearic (14.73 mg/g), oleic (20.34 mg/g), linoleic (87.18 mg/g) and arachidonic (6.66 mg/g) acids were found in the SCG sample being the 56% of the total fatty acids unsaturated. Cafestol (3.09 mg/g) and kahweol (64.15 µg/g) were also detected in the sample. The 77% of unsaturated fatty acids remained bioaccessible after in vitro digestion including linoleic (52.48 mg/g) and oleic acids (15.90 mg/g), as the most abundant, followed by palmitic acid (14.62 mg/g). Low amounts of kahweol (6.97 µg/g) and cafestol (410 µg/g) were bioaccessible. According to these results, most of the unhealthy lipid compounds forming instant SCG may be bound to the dietary fiber and they may be excreted in feces. After 28 days of treatment with instant SCG no significant differences (p>0.05) were found in liver fat content and cholesterol levels between control rats and those treated with SCG. Feces weights (wet and dry) and fat content was significantly increased (p<0.1) in rats treated with SCG when compared to the control group suggesting higher excretion of fat.Peer reviewe

Bioaccesibility, metabolism, and excretion of lipids composing spent coffee grounds

This article belongs to the Special Issue Dietary Lipids and Human Health.The bioaccessibility, metabolism, and excretion of lipids composing spent coffee grounds (SCGs) were investigated. An analysis of mycotoxins and an acute toxicity study in rats were performed for safety evaluation. Total fat, fatty acids, and diterpenes (cafestol and kahweol) were determined in SCGs and their digests obtained in vitro. A pilot repeated intake study was carried out in Wistar rats using a dose of 1 g SCGs/kg b.w. for 28 days. Fat metabolism was evaluated by analysis of total fat, cholesterol, and histology in liver. The dietary fiber effect of SCGs was measured radiographically. The absence of mycotoxins and toxicity was reported in SCGs. A total of 77% of unsaturated fatty acids and low amounts of kahweol (7.09 µg/g) and cafestol (414.39 µg/g) were bioaccessible after in vitro digestion. A significantly lower (p < 0.1) accumulation of lipids in the liver and a higher excretion of these in feces was found in rats treated with SCGs for 28 days. No lipid droplets or liver damage were observed by histology. SCGs acutely accelerated intestinal motility in rats. SCGs might be considered a sustainable, safe, and healthy food ingredient with potential for preventing hepatic steatosis due to their effect as dietary fiber with a high fat-holding capacity.This research was funded by the SUSCOFFEE (AGL2014-57239-R) Project.Peer reviewe