Valorisation of spent coffee through membrane processing

Evaluation of the Economic, Environmental, and Social Impact of the Valorization of Grape Pomace from the Wine Industry

The increase in the world population has led to intensive food production systems that are generating increasing amounts of solid waste. In this work, the valorization of the most important waste generated during wine production, grape pomace, is evaluated. Eight processes are proposed to approach different types of valorization (production of energy and value-added products), from economic, environmental, and social points of view. The best process depends on the budget available, the production capacity, and the weight of each impact produced by the factory (economic, environmental, or social). For small (less than 0.1 kg/s) or very large (greater than 10 kg/s) capacities, the production of high-value-added products outperforms the other processes in all three impacts and in profitability. For intermediate capacities, combustion and gasification stand out as having the highest greenhouse emissions and intermediate economic benefits. Anaerobic digestion is remarkable for its low greenhouse gas emissions, while tannin production is the best-balanced process from both economic and environmental points of view. Pyrolysis is the worst process of all three impacts.

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.

The wastes of coffee bean processing for utilization in food: a review

A few million cubic tons of waste are generated annually as a result of coffee processing. As a beverage, coffee in itself is a rich source of melanoidins, phenolic compounds, and other phytonutrients which confer a wide range of health benefits. These wastes generated every year are usually discarded as landfill mass, mixed with animal fodder, or incinerated. Coffee wastes, due to their high content of tannins and caffeine, can degrade the soil quality and induce carcinogenicity when mixed with animal fodder. This review aims to identify the potential of coffee silver skin and spent coffee grounds, both generated as a result of the roasting process and instantization processes. Coffee husk and coffee flour are also well-known for their excellent bioactive roles. The proximate composition of coffee silverskin indicates a rich dietary fibre source and finds wide applications in bakery and other allied food products. This process could generate a value-added product and alleviate the disposing quality of remnant spent coffee grounds. Companies are exploring novel ideas of producing coffee flour obtained from drying and milling of coffee cherries for applications in day-to-day food products. Coffee and coffee waste combined with its high concentration of fibre, colorant pigments, and antioxidant compounds, has immense potential as a functional ingredient in food systems and needs to be explored further for its better utilization.

Biorefinery of Dunaliella salina: Sustainable recovery of carotenoids, polar lipids and glycerol

Dunaliella salina is well-known for its high content in carotenoids and glycerol. Nevertheless, Dunaliella salina has also a high content in lipids, including polar lipids, which are suitable for nutraceutical/cosmeceutical applications. This work proposes a sustainable process to maximise the potential of Dunaliella salina for the production of distinct fractions of carotenoids, glycerol, polar lipids and proteins, which may contribute to improve the revenues of the microalgae industry. In this work, extraction with non-hazardous solvents and organic solvent nanofiltration are integrated, in order to obtain added-value products and glycerol. Also, aiming to separate carotenoids from glycerides, a saponification process is proposed. High overall recoveries were obtained for carotenoids (85%), glycerol (86%), polar lipids (94%) and proteins (95%). In order to evaluate the profitability of the proposed biorefinery, an economic assessment was accomplished. Both CAPEX and OPEX (Capital and Operating expenditure) were calculated, likewise the Return of Investment (ROI).

A Membrane-Based Process for the Recovery of Glycyrrhizin and Phenolic Compounds from Licorice Wastewaters

In this work, the use of polymeric ultrafiltration and nanofiltration membranes was investigated in order to recover glycyrrhizin and phenolic compounds from licorice wastewaters. Filtration experiments were performed on a laboratory scale using four polyamide thin-film composite membranes (GK, GH, GE, and DK, from GE Osmonics) with different molecular weight cut-offs (from 150 to 3500 Da). The permeate flux and retention values of glycyrrhizin, the total polyphenols, the caffeic acid, the total carbohydrate, and the total antioxidant activity as a function of the transmembrane pressure (TMP) and weight reduction factor (WRF) were evaluated. In selected operating conditions, the membrane productivity decreased in the order of GK > DK > GH > GE, with a similar trend to that of water permeability. Glycyrrhizin was totally rejected by selected membranes, independently of TMP and WRF. For the other antioxidant compounds, the retention values increased by increasing both of the parameters. According to the experimental results, a combination of membranes in a sequential design was proposed as a viable approach to produce concentrated fractions enriched in bioactive compounds and purified water from licorice wastewater.

Potentialities and Limits of Some Non-thermal Technologies to Improve Sustainability of Food Processing

In the whole food production chain, from the farm to the fork, food manufacturing steps have a large environmental impact. Despite significant efforts made to optimize heat recovery or water consumption, conventional food processing remains poorly efficient in terms of energy requirements and waste management. Therefore, in the few last decades, much research has focused on the development of alternative non-thermal technologies. Some of them, such as membrane separation processes, hydrostatic or dynamic high pressure, dense phase or high-pressure carbon dioxide, and pulsed electric fields (PEFs) have been extensively studied for cold pasteurization, concentration, extraction, or food functionalization. However, it is still difficult to evaluate the actual advantages or limits of these innovative processing technologies to replace conventional processes. Thus, the overall aim of this paper is to present an overview of the most relevant studies dealing with the potentialities and limits of these non-thermal technologies to improve sustainability of food processing. After a brief presentation of the physical principles of these technologies, the paper illustrates how these technologies could play a decisive role for sustainable food preservation or valorization of raw materials and by-products.