Sensory-Guided Decomposition of Red Currant Juice (Ribes rubrum) and Structure Determination of Key Astringent Compounds

Abstract

Sequential application of solvent extraction, gel permeation chromatography, and RP-HPLC in combination with taste dilution analyses, followed by LC-MS and 1D/2D NMR experiments, led to the discovery and structure determination of 25 key astringent compounds of red currant juice. Besides several flavonol glycosides, in particular, 3-carboxymethyl-indole-1-N-beta-D-glucopyranoside, 3-methylcarboxymethyl-indole-1-N-beta-D-glucopyranoside, and a family of previously not identified compounds, namely, 2-(4-hydroxybenzoyloxymethyl)-4-beta-D-glucopyranosyloxy-2(E)-butenenitrile, 2-(4-hydroxy-3-methoxybenzoyloxymethyl)-4-beta-D-glucopyranosyloxy-2(E)-butenenitrile, (E)-6-[3-hydroxy-4-(O-beta-D-glucopyranosyl)phenyl]-5-hexen-2-one named dehydrorubrumin, and (3E,5E)-6-[3-hydroxy-4-(O-beta-D-glucopyranosyl)phenyl]-3,5-hexadien-2-one named rubrumin, have been identified. Determination of the oral astringency thresholds by means of the half-tongue test revealed that the lowest thresholds of 0.3 and 1.0 nmol/L were found for the nitrogen-containing 3-carboxymethyl-indole-1-N-beta-D-glucopyranoside and 3-methylcarboxymethyl-indole-1-N-beta-D-glucopyranoside, which do not belong to the group of plant polyphenols.

The effect of enzymatic treatment on blackcurrant (Ribes nigrum) juice flavour and its stability

“…resulting from the other HCAs by the glucosidase activity of the Macer. Flavonol glycoside and hydroxycinnamic acid contents have been reported to contribute to astringency in blackcurrants and bilberries even at very low concentrations (Laaksonen et al, 2010;Sandell et al, 2009;Schwarz & Hofmann, 2007). The increase of these compounds in the juice can positively affect the nutritional value, but it can simultaneously have an inverse impact on the sensory profile and thereby negatively affect the consumption of the prepared product.…”

“…Various phenolic compounds are mainly located in the skin fraction which is perceived to be very astringent and somewhat bitter, similar to bilberries and crowberries (Laaksonen, Sandell, Järvinen, & Kallio, 2011;Laaksonen, Sandell, & Kallio, 2010). Especially, quercetin-3-O-rutinoside found in blackcurrant in relatively high contents (Sandell et al, 2009), may be perceived as very astringent even in low amounts (Scharbert, Holzmann, & Hofmann, 2004;Schwarz & Hofmann, 2007). Phenolic compounds, especially anthocyanins and flavonols, can be extracted easily and safely from these skin fractions with aqueous ethanol.…”

“…To some extent, these compounds may be added to the juice without significantly altering the sensory characteristics of the juice (Laaksonen et al, 2010). Along with some flavonol glycosides and phenolic acids, many nitrogen containing compounds, such as indoles and nitriles, were found to significantly contribute to astringency in redcurrants (Schwarz & Hofmann, 2007), which could also be the case with blackcurrants.…”

Functional Metabolomics – a Useful Tool to Characterize Stress-Induced Metabolome Alterations Opening New Avenues Towards Tailoring Food Crop Quality

“…Especially, the application of taste dilution analysis followed by dose/activity considerations led to the discovery of many bitter, sweet, umami, pungent, astringent, salty, or sour sensing molecules in several plants, such as carrots [79,80], cocoa [81], asparagus [82][83][84], pepper [85], red currents [86], tea [87], stevia [88] or spinach [89] in the past. Due to the nowadays well-accepted fact that not only a single flavor-impact molecule, but a combinatorial code of multiple odor-and taste-active key compounds, each in its specific concentration, reflect the chemosensory phenotype and trigger the typical flavor profile of food products.…”

Identification of the Key Astringent Compounds in Spinach (Spinacia oleracea) by Means of the Taste Dilution Analysis

“…Aimed at defining the typical taste signature of food products on a molecular level, the so-called taste dilution analysis (TDA) was developed as an efficient screening tool enabling the sensory-directed identification of taste-active non-volatiles in foods (Frank et al 2001). This approach, combining natural product chemistry and analytical sensory analysis, led to the discovery of various previously unknown taste compounds such as thermally generated bitter compounds (Frank et al 2001), cooling compounds in dark malt , bitter off-tastants in carrot products (Czepa and Hofmann 2003), the taste enhancer alapyridaine in beef bouillon (Ottinger and Hofmann 2003), and astringent key taste compounds in black tea infusions (Scharbert et al 2004), roasted cacao nibs (Stark et al 2005), and red currant juice (Schwarz and Hofmann 2007a).…”