Coffee Production Wastes: Potentials and Perspectives

Review Article

Austin Food Sci. 2016; 1(3): 1014.

Coffee Production Wastes: Potentials and Perspectives

Figueroa GA1, Homann T2 and Rawel HM3*

1Regional School of Sanitary Engineering of Water Resources, University of San Carlos of Guatemala, Guatemala

2Institute of Nutritional Science, University of Potsdam, Germany

3Instrumental Analysis in Nutritional Science, University of Potsdam, Germany

*Corresponding author: Harshadrai M Rawel, Instrumental Analysis in Nutritional Science, Institute of Nutritional Science, University of Potsdam, Germany

Received: May 17, 2016; Accepted: July 05, 2016; Published: July 06, 2016

Abstract

There has been a significant amount of research activity in the area of coffee by-products and coffee wastewater during the last few years. Most of the work is directed towards the potential uses of coffee residues, like utilization of pulp, husk and coffee silver skin as a starting material for production of enzymes and secondary metabolites including acquisition of bioactive compounds, antioxidants or food additives, on the other hand the pollution caused by coffee wastewater has also been a concern in many coffee producing countries due to the high content of organic matter and acid content resulting from the fermentation processes involved in the mucilage. This paper comments on the various research efforts for the management and treatment of coffee byproducts with focus on coffee wastewater. It is surely not exhaustive, but serves as a starting point for further research in this highly topical research field.

Keywords: Coffee by-products; Coffee waste water; Organic matter; Mucilage; Bioactive compounds; Phenolic compound; Proteins

Introduction

The forthcoming increase in world population demands for more efficient ways to achieve sustainable development and use of renewable sources. Rising concern on environmental issues drives ahead the improvement of sustainability by closing production cycles underlying the increased need to develop policies and solutions to solve these problems. This trend is also witnessed by a growing amount of research focused towards improving both environmental and economic benefits through efficient reuse of resources [1]. One of the key subjects has recently been reviewed and deals with the extraction of high value-added compounds from agri-food residues by means of supercritical technology [1]. Coffee is the most important food commodity worldwide and ranks second, after crude oil, among all commodities [2]. A recent compilation of the available information focuses in this context on the functional properties of coffee, coffee beans and by-products in terms of the associated potential health benefits [2]. A further review also considers different aspects of coffee by-products utilization and management giving a more detailed focus on the utilization for the purpose of value addition [3]. While trying to attain sustainability non-food applications are also providing economically viable alternatives [3,4]. The criterion for coffee by-products utilization to be industrially favorable is its costeffectiveness and eco-friendly nature, where the major determining factor is defined in the terms of the availability and quality of the substrates while considering the development for efficient processing in the food and non-food sectors [3].

Coffee waste product utilization

Coffee preparation proceeds in the first step by the elimination of the husks adhering to the beans and can be performed by a dry or a wet process. Coffee cherry husks thus obtained represents about 12% of the berry on dry-weight basis [3]. The dry process, also termed as “unwashed”, is the oldest practiced method, where the entire cherry after harvest is first cleaned and then placed in the sun to dry in thin layers or on patios. The wet method is called wet process or washed coffee and in this case the coffee cherries are immersed in water.

Unripe fruits will float and the good ripe ones will sink. The skin of the cherry and some of the pulp is removed by pressing the fruit in water through a screen by a machine, generating “coffee pulp juice”. The coffee pulp represents 29% dry-weight of the whole berry [3]. The beans are then put in a fermentation tank with a water stream and allowed to ferment to degrade a hygroscopic mucilaginous layer which is an obstacle to the drying. In addition this process generates wastewater which contains organic matter and also involves mucilage removal with high levels of environmental pollutants. Figure 1 shows exemplary a typical small scale factory where such waste water is generated. Both these approaches of coffee preparation are well described [3]. Coffee silver skin is an integument of coffee bean obtained as a by-product of the roasting process [3]. Finally, the fourth main coffee by-product results from the processing of soluble “instant” coffee preparation and is termed as “spent coffee” [5].

Citation: Figueroa GA, Homann T and Rawel HM. Coffee Production Wastes: Potentials and Perspectives. Austin Food Sci. 2016; 1(3): 1014.