Coffee pulp is a by-product during wet coffee processing that is typically disposed of in the processing units and amounts to 40-50% of the fresh weight of the berries. Their constituent phytochemicals, which include caffeine, tannins and chlorogenic acid, can have a positive impact on human health, such as antioxidant and antidiabetic effects, as has recently confirmed for an aqueous Coffea Arabica L. extract in in vitro and in vivo models. As a holistic approach to exploiting these positive properties a durable and stable consumable coffee pulp puree was developed, with possible applications in smoothies, yogurts, snack fillings and similar products. The puree was thermally and chemically (by the addition of citric acid) stabilized, to obtain an enzymatically and color-stable puree with pH 3.6 and an antioxidant capacity of 87.9 µmolTE/gDM. The puree exhibited a multimodal particle size distribution and shear-thinning behavior as common for fruit purees. The aroma of the puree was dominated by fruity, floral, citrusy and hay-like odor-impressions. Predominant aroma-active compounds as determined by aroma extract dilution analysis (AEDA) with gas chromatography-mass spectrometry/olfactometry (GC-MS/O) analysis were (E)-β-damascenone (apple juice-like, grape juice-like), geraniol (flowery), 4-methylphenol (horse stable-like, fecal), 3-hydroxy-4,5-dimethylfuran-2(5H)-one (lovage-like, celery-like), 4-hydroxy-3-methoxybenzaldehyde (vanilla-like), 3-hydroxy-2-pyrone (lovage-like, seasoning-like), and phenylacetic acid (beeswax-like, honey-like). A comparison with the raw pulp revealed that geraniol and 3-hydroxy-3-pyrone are released or formed during the processing steps. Overall, 55 aroma-active areas were detected during AEDA, of which 45 were identified by means of GC-MS/O being aldehydes, acids and lactones, predominantly. Overall, this work demonstrates the potential of exploiting coffee pulp, as a by-product during coffee processing, for use in novel food applications.

Upcycling of coffee by-products: Exploring the aroma of a coffee pulp puree

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