Valorisation of Coffee Roasting By-Products: Recovery of Silverskin Fat By Supercritical CO2 Extraction

Rita Nasti,Luisella Verotta,Stefania Marzorati,Giulia Luisa Bozzano,Andrea Galeazzi,Flavio Manenti,Federica Zaccheria,Nicoletta Ravasio

doi:10.1007/s12649-021-01435-9

Rita Nasti, Luisella Verotta + Show 6 more

Open Access

https://doi.org/10.1007/s12649-021-01435-9

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Abstract

Recovery of agro and food-industrial waste and their valorisation via green technologies can help to outline new concepts of industrial strategies. In this contest, a fat enriched of added-value components was extracted from coffee silverskin by applying a supercritical fluid extraction technique (sc-CO2). An appropriate modulation of process parameters like temperature (T = 35, 50, 60 °C) and pressure (p = 200–300 bar) influences the fat yield and the chemical composition, opening the way for targeted extraction. The extraction time, the organic solvent use and the energy consume were reduced compared to Soxhlet. Moreover, a mathematical model was constructed based on the experimental data collected, employed apparatus, and physico-chemical characteristics of biomass, pointing to a possible industrial scale-up. The experimental results are accompanied by a preliminary cost of manufacturing (COM), highlighting how the high investment for the apparatus is compensated by several benefits.Graphic

Highlights

Within the context of circular economy, a fresh sustainable paradigm has increasingly been followed in many fields, from academia to industries and policymakers
The results showed an effective albeit small increment of the percentage of coffee silverskin (CS) fat yield (3.3 ± 0.3% in Table 1, entry 7) respect to the use of pure supercritical C O2 (sc-CO2) (3.1 ± 0.1% in Table 1 entry 6)
This work demonstrates that silverskin, the only by-product of coffee roasting, can be successfully valorised yielding an added-value semi-solid fat by means of a green extraction technique like supercritical CO2, whose laboratory conditions can be scaled up in industrial plants

Summary

Introduction

Within the context of circular economy, a fresh sustainable paradigm has increasingly been followed in many fields, from academia to industries and policymakers. The traditional extraction techniques already applied to silverskin aiming at obtaining extracts enriched with bioactive compounds, requiring high amounts of solvents, are not more acceptable if the background of green chemistry is becoming relevant in industrial sector For this reason, recently, there has been an increasing demand for innovative and environmentally friendly extraction techniques in accordance with the agenda 2030 for sustainable development of United Nations. The main purpose of this work addresses to silverskin valorisation employing supercritical CO2, optimizing physico-chemical parameters (pressure and temperature) in the absence and presence of a co-solvent (ethanol) and comparing results in terms of yields and composition with conventional extraction methods, like Soxhlet. The CO2 employed for the process was calculated to be 0.6 €/Lgas according to Sapio s.r.l, Italy price and a loss of 2% was considered due to pressurize/depressurize operations This cost can be considered negligible in the case of a specific apparatus for CO2 recovery is present in the industrial implant. The economic cost of CS oil was calculated dividing the total oil extracted per the total raw material processed in 330 days

Results and Discussion

Method

Conclusions