Spent coffee grounds: A potential commercial source of phytosterols

Advances and Challenges in Plant Sterol Research: Fundamentals, Analysis, Applications and Production

Plant sterols (PS) are cholesterol-like terpenoids widely spread in the kingdom Plantae. Being the target of extensive research for more than a century, PS have topped with evidence of having beneficial effects in healthy subjects and applications in food, cosmetic and pharmaceutical industries. However, many gaps in several fields of PS's research still hinder their widespread practical applications. In fact, many of the mechanisms associated with PS supplementation and their health benefits are still not fully elucidated. Furthermore, compared to cholesterol data, many complex PS chemical structures still need to be fully characterized, especially in oxidized PS. On the other hand, PS molecules have also been the focus of structural modifications for applications in diverse areas, including not only the above-mentioned but also in e.g., drug delivery systems or alternative matrixes for functional foods and fats. All the identified drawbacks are also superimposed by the need of new PS sources and technologies for their isolation and purification, taking into account increased environmental and sustainability concerns. Accordingly, current and future trends in PS research warrant discussion.

Value-Added Products from Coffee Waste: A Review

Coffee waste is often viewed as a problem, but it can be converted into value-added products if managed with clean technologies and long-term waste management strategies. Several compounds, including lipids, lignin, cellulose and hemicelluloses, tannins, antioxidants, caffeine, polyphenols, carotenoids, flavonoids, and biofuel can be extracted or produced through recycling, recovery, or energy valorization. In this review, we will discuss the potential uses of by-products generated from the waste derived from coffee production, including coffee leaves and flowers from cultivation; coffee pulps, husks, and silverskin from coffee processing; and spent coffee grounds (SCGs) from post-consumption. The full utilization of these coffee by-products can be achieved by establishing suitable infrastructure and building networks between scientists, business organizations, and policymakers, thus reducing the economic and environmental burdens of coffee processing in a sustainable manner.

Sustainability issues along the coffee chain: From the field to the cup

The coffee industry is one of the most important commercial value chains worldwide. Nonetheless, it is also associated to several social, economic, and environmental concerns that impair its sustainability. The present review is focused on these main sustainability concerns from the field to the coffee cup, as well as on the strategies that are being developed and/or implemented to attain sustainability and circular economy principles in the different chain segments. In this context, distinct approaches have been applied, such as sustainable certifications (e.g., voluntary sustainability standards), corporate sustainability initiatives, direct trade, relationship coffee concepts, geographical indication, legislations, waste management, and byproducts valorization, among others. These strategies are addressed and discussed throughout this review, as well as their recognized advantages and limitations. Overall, there is still a long way to go to attain the much-desired sustainability in the coffee chain, being essential to join the efforts of all actors and entities directly or indirectly involved, namely, producers, retailers, roasters, governments, educational institutions (such as universities and scientific research institutes), and organizations.

Targeted and Non-Targeted HPLC Analysis of Coffee-Based Products as Effective Tools for Evaluating the Coffee Authenticity

Coffee is a very popular beverage worldwide. However, its composition and characteristics are affected by a number of factors, such as geographical and botanical origin, harvesting and roasting conditions, and brewing method used. As coffee consumption rises, the demands on its high quality and authenticity naturally grows as well. Unfortunately, at the same time, various tricks of coffee adulteration occur more frequently, with the intention of quick economic profit. Many analytical methods have already been developed to verify the coffee authenticity, in which the high-performance liquid chromatography (HPLC) plays a crucial role, especially thanks to its high selectivity and sensitivity. Thus, this review summarizes the results of targeted and non-targeted HPLC analysis of coffee-based products over the last 10 years as an effective tool for determining coffee composition, which can help to reveal potential forgeries and non-compliance with good manufacturing practice, and subsequently protects consumers from buying overpriced low-quality product. The advantages and drawbacks of the targeted analysis are specified and contrasted with those of the non-targeted HPLC fingerprints, which simply consider the chemical profile of the sample, regardless of the determination of individual compounds present.

Potential Uses of Spent Coffee Grounds in the Food Industry

Current estimates place the amount of spent coffee grounds annually generated worldwide in the 6 million ton figure, with the sources of spent coffee grounds being classified as domestic (i.e., household), commercial (i.e., coffee houses, cafeterias and restaurants), and industrial (i.e., soluble and instant coffee industries). The majority of the produced spent coffee grounds are currently being inappropriately destined for landfills or to a form of energy recovery (e.g., incineration) as a refuse-derived fuel. The disposal of spent coffee in landfills allows for its anaerobic degradation with consequent generation and emission of aggressive greenhouse gases such as methane and CO₂, and energy recovery processes must be considered an end-of-life stage in the lifecycle of spent coffee grounds, as a way of delaying CO₂ emissions and of avoiding emissions of toxic organic volatile compounds generated during combustion of this type of waste. Aside from these environmental issues, an aspect that should be considered is the inappropriate disposal of a product (SCG) that presents unique thermo-mechanical properties and textural characteristics and that is rich in a diversity of classes of compounds, such as polysaccharides, proteins, phenolics, lipids and alkaloids, which could be recovered and used in a diversity of applications, including food-related ones. Therefore, researchers worldwide are invested in studying a variety of possible applications for spent coffee grounds and products thereof, including (but not limited to) biofuels, catalysts, cosmetics, composite materials, feed and food ingredients. Hence, the aim of this essay was to present a comprehensive review of the recent literature on the proposals for utilization of spent coffee grounds in food-related applications, with focus on chemical composition of spent coffee, recovery of bioactive compounds, use as food ingredients and as components in the manufacture of composite materials that can be used in food applications, such as packaging.

Spent coffee grounds: A sustainable approach toward novel perspectives of valorization

Coffee is one of the most popular and preferred drinks in the world, being consumed for its refreshing and energizing properties. As a result, the consumption of coffee generates millions of tons of waste, in particular, spent coffee grounds (SCG). On the contrary, food waste recovery is an incredibly sustainable and convenient solution to the growing need for materials, fuels, and chemicals. SCG has been developed as a precious resource of several high value-added products (oil, proteins, minerals, fatty acids, sterols….). Thus, a transformative pathway to a circular economy that involves the valorization of coffee wastes and by-products is currently attracting the attention of researchers worldwide. The potential growth of scientific papers and publications promotes a comprehensive review to determine the research hotspots, knowledge structure, and to consider future avenues and challenges. Therefore, in this paper, we conducted a systematic review based on 275 indexed papers on the composition and valorization of SCG as a prospective environmental source. PRACTICAL APPLICATIONS: SCG can be applied in agro-food industries.

Coffee silverskin: Characterization of B-vitamins, macronutrients, minerals and phytosterols

The present study assessed the nutritional composition of coffee silverskin (CSS) obtained from arabica roasted coffee. Following validated analytical methods, CSS resulted to be a high source of proteins (14.2 g/100 g) and dietary fibers (51.5 g/100 g). Moreover, the mineral analysis revealed high contents of calcium (1.1 g/100 g) and potassium (1.0 g/100 g). To date, this study provided the widest mineral profile of CSS with 30 minerals targeted including 23 microminerals with high levels of iron (238.0 mg/kg), manganese (46.7 mg/kg), copper (37.9 mg/kg), and zinc (31.9 mg/kg). Moreover, vitamins B₂ (0.18-0.2 mg/kg) and B₃ (2.5-3.1 mg/kg) were studied and reported for the first time in CSS. β-sitosterol (77.1 mg/kg), campesterol, stigmasterol, and Δ5-avenasterol, were also observed from the phytosterol analysis of CSS with a total level of 98.4 mg/kg. This rich nutritional profile highlights the potential values of CSS for innovative reuses in bioactive ingredients development.

Scientometric Overview of Coffee By-Products and Their Applications

As coffee consumption is on the rise, and the global coffee production creates an excess of 23 million tons of waste per year, a revolutionary transition towards a circular economy via the transformation and valorization of the main by-products from its cultivation and preparation (Coffee Husk (CH), Coffee Pulp (CP), Coffee Silverskin (CS), and Spent Coffee Grounds (SCG)) is inspiring researchers around the world. The recent growth of scholarly publications in the field and the emerging applications of coffee by-products published in these scientific papers encourages a systematic review to identify the knowledge structure, research hotspots, and to discuss the challenges and future directions. This paper displays a comprehensive scientometric analysis based on 108 articles with a high level of influence in the field of coffee by-products and their applications. According to our analysis, the research in this field shows an explosive growth since 2017, clustered in five core applications: bioactive compounds, microbial transformation, environmental applications, biofuels from thermochemical processes, and construction materials.

Conversion of spent coffee grounds into vermicompost

The present study was focused on vermicomposting of spent coffee grounds (SCG) and its mixtures with straw pellets. The process was evaluated in terms of biological and physico-chemical properties. The greatest number and biomass of earthworms was found in the treatment with 25% vol. SCG + 75% vol. straw pellets. In this treatment, the upper youngest layer exhibited 1.6-fold and 4.5-fold greater earthworm number and biomass, respectively, than the bottom oldest layer. Earthworm weight decreased in direct proportion to the layer age. The oldest treatment layer was characterized by lesser contents of fungi and six hydrolytic enzymes, compared to the younger layers. Further, the oldest treatment layer had suitable agrochemical properties. Earthworms were able to substantially reduce the caffeine stimulant content, which is considered the most representative pharmaceutically active compound.

Evaluation of secondary metabolites of herbal plant extracts as an antiviral effect on infectious bursal disease virus isolates in embryonated chicken eggs

BACKGROUND AND AIM

Infectious bursal disease attacks the poultry industry, mainly young chickens, causing immunosuppression, and death with high economic losses. This study aimed to evaluate the effects of the monoextract, diextracts, and triextracts of Quercus infectoria (QI), Citrus aurantifolia (CiA), and Coffea arabica (CoA) on infectious bursal disease virus (IBDV) in embryonated chicken eggs (ECEs).

MATERIALS AND METHODS

The experimental design consisted of three sets of ECEs at 11 days of age, and each set included seven groups (G1-G7). The extracts of QI, CiA, and CoA were inoculated to ECEs by the chorioallantoic membrane method before, in concomitant (mixed) with, and after IBDV infection to the first, second, and third sets, respectively. The monoextract, diextracts, and triextracts of QI, CiA, and CoA were given at 1%, 2%, 5%, and 10% concentrations to G1-G3, G4-G6, and G7, respectively. Real-time polymerase chain reaction identified and confirmed the virus in accordance with the pathological changes.

RESULTS

The monoextract (5-10% concentrations) inhibited IBDV and had no effect on viral infection preinoculation, whereas the monoextract (10% concentration) inhibited IBDV during mixed inoculation and post-inoculation. Diextracts (2-10% concentrations) inhibited IBDV and had no effect on viral infection preinoculation, whereas diextracts (5-10% concentrations) inhibited IBDV during mixed inoculation and post-inoculation. Triextracts (1%, 2%, 5%, and 10% concentrations) inhibited IBDV by ameliorating the pathological changes of the virus and preventing the death of ECEs.

CONCLUSION

The inoculation of herbal extracts, particularly triextracts, alleviates the pathological changes in ECEs infected with IBDV. This study recommends the oral route in evaluating plant extracts against IBDV in poultry.

Analysis of Phytosterols Content in Italian-Standard Espresso Coffee

This study aims to assess for the first time the content of phytosterols (PS) in espresso coffee (EC) to deepen the knowledge about the phytochemicals and health potentials of coffee brews. PS were extracted by hot saponification from 14 EC samples produced with coffee originating from 13 coffee-producing countries. PS were identified and quantified by high-performance liquid chromatography (HPLC) after derivatization. Among the detected PS, β-sitosterol (4.1–18.2 mg/L) was the most abundant followed by stigmasterol (1.1–4.9 mg/L), campesterol (0.9–4.7 mg/L), and cycloartenol (0.3–2.0 mg/L). Total PS fraction ranged from 6.5 mg/L to 30.0 mg/L with an average level of 15.7 ± 5.8 mg/L. Therefore, a standard cup of EC (25 mL) could provide 0.4 ± 0.1 mg of PS.

Food Protein Sterylation: Chemical Reactions between Reactive Amino Acids and Sterol Oxidation Products under Food Processing Conditions

Sterols, especially cholesterol and phytosterols, are important components of food lipids. During food processing, such as heating, sterols, like unsaturated fatty acids, can be oxidized. Protein modification by secondary products of lipid peroxidation has recently been demonstrated in food through a process called lipation. Similarly, this study was performed to assess, for the first time, the possibility of reactions between food proteins and sterol oxidation products in conditions relevant for food processing. Therefore, reaction models consisting of oxysterol (cholesterol 5α,6α-epoxide) and reactive amino acids (arginine, lysine, and methionine) were incubated in various conditions of concentration (0–8 mM), time (0–120 min), and temperature (30–180 °C). The identification of lysine adducts through thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) with a diode array detector (DAD), and electrospray ionization (ESI) mass spectrometry (MS) evidenced a reaction with lysine. Moreover, the HPLC-ESI with tandem mass spectrometry (MS/MS) analyses allowed observation of the compound, whose mass to charge ratio m/z 710.5 and fragmentation patterns corresponded to the reaction product [M + H]⁺ between cholesterol-5α,6α-epoxide and the ε-amino-group of N_α-benzoylglycyl-l-lysine. Moreover, kinetic studies between N_α-benzoylglycyl-l-lysine as a model for protein-bound lysine and cholesterol 5α,6α-epoxide were performed, showing that the formation of lysine adducts strongly increases with time, temperature, and oxysterol level. This preliminary study suggests that in conditions commonly reached during food processing, sterol oxidation products could react covalently with protein-bound lysine, causing protein modifications.

Chemical Composition, Antioxidant and Enzyme Inhibitory Properties of Different Extracts Obtained from Spent Coffee Ground and Coffee Silverskin

In a world where an eco-friendlier approach is becoming more and more necessary, it is essential to reduce waste production and to reuse residues of the company’s supply chain. Coffee silverskin (CS) and spent coffee ground (SCG), two by-products of coffee production, are important sources of bioactive compounds and, for this, some authors have proposed their reuse in the nutraceutical, food, and cosmetic sector. However, their potential enzyme inhibitory properties have been poorly investigated. Hence, the objective of the current work was to study the enzymatic inhibitory activities against acetylcholinesterase, butyrylcholinesterase, α-amylase, α-glucosidase, and tyrosinase of different extracts of CS and SCG. Before these in vitro bioassays, the phytochemical composition of each extract was investigated via colorimetric assays and HPLC-MS/MS analysis. In addition, the antioxidant activities were evaluated by different chemical approaches. SCG extracts contained a higher content of bioactive compounds, notably the SCG EtOH:H₂O extract was the richest in caffeine and possessed the highest antioxidant activities. The hydroalcoholic and methanolic extracts were shown to be the most active against all tested enzymes, while the water extracts displayed lower activity. Our results showed a weak correlation between bioactive compounds and enzyme inhibitory effects, proving inhibitory activities likely due to non-phenolic molecules such as alkaloids and terpenoids. Obtained findings could be a starting point to develop novel nutraceuticals from CS and SCG.