Coffee Silverskin Extract: Nutritional Value, Safety and Effect on Key Biological Functions

Abstract

This study aimed to complete the scientific basis for the validation of a coffee silverskin extract (CSE) as a novel food ingredient according to European legislation. Nutritional value, safety, effects on biochemical biomarkers and excretion of short chain fatty acids (SCFAs) in vivo of CSE were assessed. Proteins, amino acids, fat, fatty acids, fiber, simple sugars and micronutrients were analyzed. For the first time, toxicological and physiological effects were evaluated in vivo by a repeated-dose study in healthy Wistar rats. Hormone secretion, antioxidant (enzymatic and no-enzymatic) and anti-inflammatory biomarkers, and dietary fiber fermentability of CSE (analysis of SCFAs in feces) were studied in biological samples. This unique research confirms the feasibility of CSE as a human dietary supplement with several nutrition claims: “source of proteins (16%), potassium, magnesium, calcium and vitamin C, low in fat (0.44%) and high in fiber (22%)”. This is the first report demonstrating that its oral administration (1 g/kg) for 28 days is innocuous. Hormone secretion, antioxidant or anti-inflammatory biomarkers were not affected in heathy animals. Total SCFAs derived from CSE fiber fermentation were significantly higher (p < 0.05) in male treated rats compared to male control rats. All the new information pinpoints CSE as a natural, sustainable and safe food ingredient containing fermentable fiber able to produce SCFAs with beneficial effects on gut microbiota.

Applications of Compounds from Coffee Processing By-Products

“…CGA/g). Antioxidant properties of this extract at 1 mg/mL were also confirmed in human liver cells (HepG2) [ 24 ]. This extract may be a potential agent for the prevention of cellular damage induced by oxidative stress.…”

“…CS preferentially supports bifidobacteria growth in vitro, suggesting that its consumption may have some prebiotic effects [ 35 ]. Studies carried out by our research group have shown the fiber fermentability of CSE in vivo [ 24 ]. Total short chain fatty acids (SCFAs) significantly increased ( p < 0.05) in feces of male Wistar rats treated with CSE (1 g/kg b.w.)…”

“…Regarding additional in vivo toxicity studies, the repeated oral administration of CSE at a dose of 1 g/kg for a period of 28 days was not toxic to male and female Wistar rats [ 24 ]. On the other hand, the repeated intake of SCGs at a dose of 1 g/kg b.w.…”

Effects of Coffee and Its Components on the Gastrointestinal Tract and the Brain–Gut Axis

“…The acute pro-motility effects of SCG demonstrated in that study could be influenced by short chain fatty acids (SCFAs), which have been shown to be released during SCGs fermentation by colon microbiota from medium and dark roasted coffee beans at concentrations higher than 10 mM [ 175 ], and SCFAs (10–200 mM) stimulate colonic motility [ 176 ]. Interestingly, an aqueous extract of coffee silverskin, another coffee by-product, may also display dietary fiber effect since total SCFAs derived from coffee silverskin extract fermentation were higher in feces of rats treated with the extract for 28 days [ 177 ]. Although its precise in vivo effects on gastrointestinal motility still needs to be determined, it might be related with the presence of melanoidins in it (see Section 3.5 ).…”

Occurrence of Antibiotic Resistance Genes in Hermetia illucens Larvae Fed Coffee Silverskin Enriched with Schizochytrium limacinum or Isochrysis galbana Microalgae

“…In the concept of circular economy, the H. illucens larvae were reared on a basal substrate constituted by coffee roasting byproducts (coffee silverskin, Cs) supplemented with increasing percentages of microalgae ( Schizochytrium limacinum or Isochrysis galbana ) as the source of PUFAs such as docosahexaenoic, stearidonic, and α-linolenic acid [ 9 , 24 ]. On the other hand, Cs, rich in polyphenols and mainly composed of dietary fibers (≈55%), proteins (≈19%), carbohydrates (≈6%), and fat (≈2%), has been reported to have prebiotic and antioxidant activities [ 25 ].…”