Date Published: November 15, 2018
Publisher: Public Library of Science
Author(s): Renata Zawirska-Wojtasiak, Paulina Piechowska, Elżbieta Wojtowicz, Krzysztof Przygoński, Sylwia Mildner-Szkudlarz, David A Lightfoot.
Epidemiological studies have suggested that coffee consumption is negatively correlated with the incidence of Parkinson’s disease. Coffee contains relatively high levels of β-carbolines, which have been ascribed neuroactive effects in humans however the positive or negative effect has not been confirmed yet. Two ingredients with applications as coffee substitutes—chicory, which is traditionally used in this way, and artichoke—were considered in this study both from the neuroactive point of view but also in relation to the other bioactive compounds that result from their thermal processing. These thermal products are of concern because of their possible toxic properties. The estimated concentration of β-carbolines was high in both materials (1.8 μg/g and 2.5 μg/g harman and 2.9 μg/g and 3.1 μg/g norharman in chicory and artichoke, respectively). Artichoke had more β-carbolines than chicory, and also more all the toxic compounds examined here–acrylamide, carboxymethyllysine, and furans, which were detected in significantly higher concentrations in artichoke, particularly acrylamide. Chicory and artichoke also contain phenolic compounds that possess high antioxidant activity, on a similar level. Artichoke, a new proposed ingredient in coffee substitutes, appears to be a richer source of β-carbolines than the traditionally chicory. Both materials contained high level of undesirable components, such as furan and its derivatives, carboxymethyllysine and particularly acrylamide, much higher in artichoke.
Coffee is the third most popular beverage, after water and tea. Annual coffee consumption is estimated at 400 billion cups, and it is drunk by 40% of the human population. Its popularity is associated with its unique aroma and stimulating properties. Epidemiological studies suggest that coffee consumption is negatively correlated with the incidence of Parkinson’s disease, and that its regular consumption may protect to a certain degree against neurodegenerative diseases. This protective effect is ascribed to the presence of β-carboline compounds [1, 2]. The first report on the identification, quantification and formation of β-carboline compounds was published by Herraiz , who pointed out coffee as the highest dietary source of these compounds. Other studies report that elevated levels of harman and norharman occur in the cerebrospinal fluid of patients suffering from Parkinson’s disease . Also later papers mention the possible neurotoxity of β-carbolines [5, 6].
Neuroactive β-carbolines in food are recently the subject of many studies consideration, so on the basis of our previous research , chicory was chosen from among the traditionally used ingredients of coffee substitutes as the one with the highest carboline content; artichoke was chosen from the few newly proposed ingredients using the same criterion. It worth to note chicory is the main component of coffee substitute and sometime used as only one. When roasted, and in the three roasted mixtures (containing 10%, 20%, and 30% artichoke), these materials were characterized through aroma profile analysis of prepared beverages in order to control possibility of applying this material from sensory point of view. A graphical representation of the sensory data is given in Fig 1. The greatest difference was observed between chicory and artichoke, with the artichoke being bitterer in taste. The mixtures with 10% and 20% additions of artichoke were rather similar to chicory: Mix III, with 30% was more distant. On the basis of this experiment, it seems that more than 30% artichoke might not be acceptable.
Chicory and artichoke contained high levels of β-carbolines. Artichoke, a new proposed ingredient in coffee substitutes, appears to be a richer source of β-carbolines than the traditionally chicory, and its addition increases the concentration of β-carbolines. Both materials contained high level of undesirable components, such as furan and its derivatives, CML and particularly acrylamide, much higher in artichoke. This observation might be extended to all cases when looking for any new bioactive raw materials. Together with desirable substance some harmful components may be introduced even on unexpected high level.