Validación de subproductos de café como ingredientes alimentarios para una nutrición y salud sostenible

Resumen

The term “sustainable health” means “a healthy and active aging avoiding the risk of diseases”. The fast-growing population, the increasing need for nutritionally correct diets and the depletion of food sources suppose an immense challenge for the global food system. In order to increase the eco-sustainability of the food processing industry, it is necessary to exploit co-products before they become wastes. The coffee industry is responsible for the generation of large amounts of residues that represent a pollution hazard if discharged into the environment. Dealing with these coffee waste recovery is of great importance to combat hunger, raise income and improve food security in the world’s poorest countries. The aim of the present PhD thesis was to validate the feasibility of coffee by-products (husk, parchment, silverskin and spent coffee grounds) as novel food ingredients for a sustainable nutrition and health following the Regulation (EU) 2015/2283. The nutritional composition and safety of coffee cherry by-products generated in producing countries (husk and parchment) were addressed. Further characterization, safety, nutritional value and health implications of ingredients from coffee by-products obtained worldwide (coffee silverskin and spent coffee grounds) were studied. The health-promoting properties of isolated biomolecules from the latter were also evaluated. By-products from coffee cherry processing were submitted to aqueous extraction, which is sustainable and easy to scale-up, for generating ingredients avoiding new wastes. Husk and silverskin were proposed as a source of two food ingredients: an aqueous extract enriched in phytochemicals and antioxidant dietary fiber. In contrast, parchment was proposed as a single source of antioxidant dietary fiber. Husk, parchment and silverskin resulted safe since the absence of pesticides, mycotoxins and lethal effects was observed in rats treated with by-products at 2000 mg/kg b.w. Coffee silverskin extract (CSE) did not show cytotoxicity or genotoxicity. It also showed preventive effects against induced oxidative DNA damage. Results from the nutritional characterization of CSE showed that it might be considered a source of proteins (16 %), low in fat (0.44 %) and high in fiber (22 %). It can also be considered source of potassium, magnesium, calcium and vitamin C. Oral administration of CSE at a dose of 1 g/kg for a period of 28 days was not toxic to rats. Diet supplementation with CSE had no negative effects in hormone secretion, antioxidant or anti-inflammatory biomarkers. Total short chain fatty acids (SCFAs) derived from CSE fiber fermentation were significantly higher (p < 0.05) in male rats compared to male control rats. The absence of mycotoxins and toxicity was also reported in spent coffee grounds (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 them 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. Multifunctional biomolecules for food industry, a fraction enriched in melanoidins, were isolated from CSE and SCGs and they showed antioxidant properties against induced oxidative stress in human colon cell lines. In addition, the fiber effect of melanoidins isolated from CSE was studied in vivo in healthy male Wistar rats. The isolation process was effective in obtaining a high molecular weight fraction, composed mainly of dietary fiber, including melanoidins. This fraction was administered to animals in the drinking water at a dose of 1 g/kg and after 28 days, no signs of toxicity were observed and gastrointestinal motility was significantly accelerated (p < 0.05) compared to the control group. In conclusion, findings derived from the present PhD thesis confirmed the feasibility of using coffee by-products as novel food ingredients. The most preferred application for coffee husk and silverskin is as two food ingredients for human consumption. However, parchment is proposed to be used directly for plastic replacement in intelligent food packaging. The high molecular weight fraction enriched in melanoidins isolated from coffee silverskin can be used for technological (natural colorant) or for nutritional and health (dietary fiber effect) purposes. The most efficient use of instant SCGs seems to be as a food ingredient high in dietary fiber. Crucial data for the application of the Novel Food Authorization for husk, CSE and SCGs to the European Commission have been obtained. The present investigation represents a significant contribution to the coffee industry and to achieve a sustainable nutrition and health.