Coffee is one of the popular beverages of the world and second largest traded commodity after petroleum. Coffee is cultivated in about 80 countries across the globe and entangles huge business worldwide. Coffee dispensation requires an elevated degree of processing know how and produces large amounts of processing by-products such as coffee pulp and husk, which have limited applications such as fertilizer, livestock feed, compost and such others. Biotechnological applications in the field of industrial residues management promote sustainable development of country's economy. The objectives pertaining to food processing by-products, waste and effluents include the recovery of fine chemicals and production of precious metabolites via chemical and biotechnological processes. Pre-treatments, followed by recovery procedures endow value-added products (natural antioxidants, vitamins, enzymes, cellulose, starch, lipids, proteins, pigments) of high significance to the pharmaceutical, cosmetic and food industries. With the background of high crop production in the upcoming years, there is an imperative need to counterpart this production with some utilization and industrial application of coffee by-products since coffee industry emerges enormous amounts of coffee by-products which are thriving nutrient resources. The present review highlights explorations of value addition to coffee by-products which can be achieved with valorization strategy, integration of techniques and applications of bioengineering principles in food processing and waste management and secondly conserve environment with disposal problem accelerating both ecological and economical resources.

Sustainable management of coffee industry by-products and value addition—A review

Bioethanol has been identified as the mostly used biofuel worldwide since it significantly contributes to the reduction of crude oil consumption and environmental pollution. It can be produced from various types of feedstocks such as sucrose, starch, lignocellulosic and algal biomass through fermentation process by microorganisms. Compared to other types of microoganisms, yeasts especially Saccharomyces cerevisiae is the common microbes employed in ethanol production due to its high ethanol productivity, high ethanol tolerance and ability of fermenting wide range of sugars. However, there are some challenges in yeast fermentation which inhibit ethanol production such as high temperature, high ethanol concentration and the ability to ferment pentose sugars. Various types of yeast strains have been used in fermentation for ethanol production including hybrid, recombinant and wild-type yeasts. Yeasts can directly ferment simple sugars into ethanol while other type of feedstocks must be converted to fermentable sugars before it can be fermented to ethanol. The common processes involves in ethanol production are pretreatment, hydrolysis and fermentation. Production of bioethanol during fermentation depends on several factors such as temperature, sugar concentration, pH, fermentation time, agitation rate, and inoculum size. The efficiency and productivity of ethanol can be enhanced by immobilizing the yeast cells. This review highlights the different types of yeast strains, fermentation process, factors affecting bioethanol production and immobilization of yeasts for better bioethanol production.

https://cyberleninka.org/article/n/143136.pdf

Yeasts in sustainable bioethanol production: A review.

Spent coffee grounds (SCG) and coffee silverskin (CS) represent a great pollution hazard if discharged into the environment. Taking this fact into account, the purpose of this study was to evaluate the chemical composition, functional properties, and structural characteristics of these agro-industrial residues in order to identify the characteristics that allow their reutilization in industrial processes. According to the results, SCG and CS are both of lignocellulosic nature. Sugars polymerized to their cellulose and hemicellulose fractions correspond to 51.5 and 40.45 % w/w, respectively; however, the hemicellulose sugars and their composition significantly differ from one residue to another. SCG and CS particles differ in terms of morphology and crystallinity, but both materials have very low porosity and similar melting point. In terms of functional properties, SCG and CS present good water and oil holding capacities, emulsion activity and stability, and antioxidant potential, being therefore great candidates for use on food and pharmaceutical fields.

/pdf/chemical-functional-and-structural-properties-of-spent-3ug3zr5jqk.pdf

Chemical, Functional, and Structural Properties of Spent Coffee Grounds and Coffee Silverskin.

Spent coffee ground (SCG) contains large amounts of organic compounds (i.e. fatty acids, amino acids, polyphenols, minerals and polysaccharides) that justify its valorization. Earlier innovation explored the extraction of specific components such as oil, flavor, terpenes, and alcohols as value-added products. However, by-products of coffee fruit and bean processing can also be considered as potential functional ingredients for the food industry. There is an urgent need for practical and innovative ideas to use this low cost SCG and exploit its full potential increasing the overall sustainability of the coffee agro-industry.

Spent coffee grounds: A review on current research and future prospects

https://repositorium.sdum.uminho.pt/bitstream/1822/16850/1/pp.pdf

Extraction of antioxidant phenolic compounds from spent coffee grounds

Coffee is one of the most consumed beverages in the world and is the second largest traded commodity after petroleum. Due to the great demand of this product, large amounts of residues are generated in the coffee industry, which are toxic and represent serious environmental problems. Coffee silverskin and spent coffee grounds are the main coffee industry residues, obtained during the beans roasting, and the process to prepare “instant coffee”, respectively. Recently, some attempts have been made to use these residues for energy or value-added compounds production, as strategies to reduce their toxicity levels, while adding value to them. The present article provides an overview regarding coffee and its main industrial residues. In a first part, the composition of beans and their processing, as well as data about the coffee world production and exportation, are presented. In the sequence, the characteristics, chemical composition, and application of the main coffee industry residues are reviewed. Based on these data, it was concluded that coffee may be considered as one of the most valuable primary products in world trade, crucial to the economies and politics of many developing countries since its cultivation, processing, trading, transportation, and marketing provide employment for millions of people. As a consequence of this big market, the reuse of the main coffee industry residues is of large importance from environmental and economical viewpoints.

/pdf/production-composition-and-application-of-coffee-and-its-4p8opx28by.pdf

Production, Composition, and Application of Coffee and Its Industrial Residues

http://repositorium.sdum.uminho.pt/bitstream/1822/22490/1/1-s2.0-S0306261911005162-main.pdf

Sugars metabolism and ethanol production by different yeast strains from coffee industry wastes hydrolysates

https://repositorium.sdum.uminho.pt/bitstream/1822/16613/1/pp.pdf

Growth of fungal strains on coffee industry residues with removal of polyphenolic compounds

This work describes a new process for the production of beverages from spent coffee grounds (SCG), as well as the chemical and sensory profiles. The process consisted of the extraction of antioxidant phenolic compounds of SCG, followed by the fermentation of this extract supplemented with sucrose and fermented broth distillation. Thus, two fermented (10.4% and 10.0% of ethanol, by volume) and two distillated (38.1% and 40.2% of ethanol, by volume) beverages were obtained. A total of 45 and 59 volatile compounds (alcohols, esters, aldehydes, terpenes, lactones, pyrazines, norisoprenoids, volatile phenols and acids) identified and quantified by GC-MS characterized the aroma and flavor of the fermented and distilled beverages, respectively. Twenty sensory descriptors define the sensory profile of the two beverages which corroborated the pleasant smell and taste of coffee in the distillate beverage. Therefore, this work demonstrates that the fermented and distilled beverages obtained from spent coffee grounds have acceptable organoleptic qualities that make them suitable for human consumption.

/pdf/increasing-the-sustainability-of-the-coffee-agro-industry-1qza5ny0xf.pdf

Ercília M. S. Machado

Papers

Production, Composition, and Application of Coffee and Its Industrial Residues

Sugars metabolism and ethanol production by different yeast strains from coffee industry wastes hydrolysates

Growth of fungal strains on coffee industry residues with removal of polyphenolic compounds

Increasing the sustainability of the coffee agro-industry: spent coffee grounds as a source of new beverages

Cultivation of fungal strains using coffee industry residues as alternative growth substrates