Aroma-Active Compounds in Robusta Coffee Pulp Puree-Evaluation of Physicochemical and Sensory Properties.

Nina Buck,Daria Wohlt,Anne Ruth Winter,Eva Ortner

doi:10.3390/molecules26133925

Abstract

Wet coffee processing generates a large amount of coffee pulp waste that is mostly disposed of in the processing units. To reduce this waste and the associated environmental burden, an alternative strategy would be to exploit the coffee pulp to produce a durable and stable consumable product. Accordingly, a puree produced from Robusta coffee pulp was investigated in relation to its physicochemical and sensory properties. After thermal and chemical stabilization, the obtained puree (pH 3.6) was found to exhibit a multimodal particle size distribution, shear-thinning behavior, and lower discoloration, as well as an antioxidant capacity of 87.9 µmolTE/gDM. The flavor of the puree was examined by sensory evaluation and the corresponding analyses of aroma-active volatile compounds, as determined using aroma extract dilution analyses (AEDA) and gas chromatography-mass spectrometry/olfactometry (GC-MS/O). The puree was characterized by dominant fruity (4.4), floral (3.4), citrusy (3.3) and hay-like (3.3) odor impressions. The aroma-active compounds were predominantly aldehydes, acids, and lactones, whereby (E)-β-damascenone, geraniol, 4-methylphenol, 3-hydroxy-4,5-dimethylfuran-2(5H)-one, and 4-hydroxy-3-methoxybenzaldehyde exhibited the highest flavor dilution (FD) factor (1024), thereby indicating their high impact on the overall aroma of the puree. This study demonstrates an approach to stabilize coffee pulp to produce a sweet, fruity puree with comparable physical properties to other fruit purees and that can be used as a new and versatile flavoring ingredient for various food applications.

Highlights

Coffee is one of the most traded commodities in the world
By applying a blanching step and adding citric acid, an enzymatically and color-stable coffee pulp puree was produced with an antioxidant capacity of 87.9 μmolTE /gDM
55 aroma-active areas were detected during aroma extract dilution analyses (AEDA), 45 of which were unequivocally identified by gas chromatographymass spectrometry/olfactometry (GC-MS/O)

Summary

Introduction

Coffee is one of the most traded commodities in the world. The annual world coffee consumption was estimated to be over 10,000 t in 2019/2020 [1]. Coffee processing produces large quantities of by-products, mainly coffee pulp, which is typically disposed of as waste [2]. Coffee pulp amounts to 28.7% of the dry weight [3] and 40–50% of the fresh weight of coffee berries [2]. The coffee fruit is subjected to different processing steps for separating the bean from the fruit [2,4]. The fruits are spread out and sundried, hulled with a peeling machine and cleaned, leaving the coffee husks as by-products.

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