Upcycling of black currant pomace for the production of a fermented beverage with Wolfiporia cocos

Abstract

Pomace as a side stream from black currant juice production is mostly discarded, even though it is rich in nutrients like protein, fiber, sugars, anthocyanins, polyphenols, and other secondary metabolites. Fungi from the division of Basidiomycota have a great enzymatic toolbox to recycle these complex mixtures of nutrients. In particular, the edible medicinal fungus Wolfiporia cocos has been described as a suitable biocatalyst to form pleasant aroma compounds in fermentation processes. Therefore, medium optimization, upscaling, and filtration were performed to produce a beverage based on black currant pomace fermented with W. cocos. A trained panel described the beverage as highly pleasant, reminiscent of honey, flowers and berries with a well-balanced sour and sweet taste. The flavor compounds linalool (citrus), geraniol (flowery), phenylacetic acid (honey), methyl phenylacetate (honey), eugenol (clove), and 2-phenylethanol (rose) were produced during fermentation and the concentrations exceeded their respective odor thresholds. The produced beverage was evaluated with 8.0 ± 1.4 from 10 for the question of whether panelists would buy the product. Fungal fermentation with the edible fungus W. cocos enabled the production of a highly pleasant beverage and additionally may reduce waste by using pomace and table sugar as sole ingredients.

Fermentation of Cocoa (Theobroma cacao L.) Pulp by Laetiporus persicinus Yields a Novel Beverage with Tropical Aroma

“…In recent years, the fermentation of various substrates with edible fungi of the division Basidiomycota has gained attention from different research groups due to the potential of the method to form a broad spectrum of aroma compounds. However, to the best of our knowledge, L. persicinus has thus far not been subjected to in-depth aroma analyses [14][15][16][26][27][28][29], and no data are available on the aroma composition of L. persicinus, whether grown in solid-state or in submerged cultures. The present study shows the formation of a highly delicious beverage via the fermentation of cocoa pulp with L. persicinus for the first time.…”

“…The acceptance of taste started with 2.1 out of 5.0 points for the CP-M and increased up to 4.2 points until 48 h and decreased again afterwards. cinus has thus far not been subjected to in-depth aroma analyses [14][15][16][26][27][28][29], and no data are available on the aroma composition of L. persicinus, whether grown in solid-state or in submerged cultures. The present study shows the formation of a highly delicious beverage via the fermentation of cocoa pulp with L. persicinus for the first time.…”

“…An improvement in the overall acceptance of a beverage fermented by basidiomycetes has been shown for other substrates previously. For example, Sommer et al produced a beverage via submerged fermentation of black current pomace with Wolfiporia cocos and the results showed an increase in the overall acceptance of 2.5 to 8.0 out of 10.0 points [27]. Wang et al reported that the fermentation of okara with edible fungi can improve the flavor quality by decreasing the amount of off-flavor compounds and by forming new aromatic compounds [28].…”

“…The enantioselective analysis showed that (R)linalool was present in the sample, with an ee = 98.4%. 5-Butyl-2(5H)-furanone (24), which has a strong coconut and peach-like odor, was present, as was (E)-nerolidol (27) with sweet, popcorn, flowery and woody notes, and they had FD factors of 1024. 2-Nonanone (8) showed an FD factor of 512 with a fruity, musty, herbaceous, spicy, but also cheesy, odor.…”

“…As no odor threshold has been published so far for 5-butyl-2(5H)-furanone, its odor threshold in water was determined for the first time with 62 µg/L. Of the compounds identified and quantified, (R)-linalool (13), 2-phenylethanol (22), 5-butyl-2(5H)-furanone (24) and (E)-nerolidol (27) showed OAVs > 1 and thus most likely contributed to the characteristic aroma of the beverage. 2-Nonanone (8) and 1phenylethyl acetate (15) had OAVs << 1, indicating no or only a minor contribution to the overall aroma.…”