Abstract
Methylxanthines present psychostimulant effects. These compounds have low toxicity and their consumption at moderate levels presents some beneficial health effects, whereas some significant risk appears at high levels. Samples of common types of methylxanthine-containing beverages and foods consumed in Spain were analyzed to determine their content. Caffeine was the methylxanthine that was most found in the samples investigated. Instant coffees gave the highest caffeine percentage (18–44 mg·g−1). Green and scented teas were found to have a caffeine dry-weight content (8–26 mg·g−1) equivalent to ground coffees (13–23 mg·g−1), but black and pu-erh teas (18–30 mg·g−1) had a higher caffeine content. The evaluation of the most conventional methods for preparing espresso coffees showed that an espresso contains between 88–116 mg of caffeine. In the case of tea beverages, the amount of caffeine present was 2–3 times smaller than in espresso coffees. Energy drinks showed a similar caffeine content (80–106 mg) as espresso coffees. Chocolates had the lowest caffeine content. It has been found that none of the foods evaluated reach the recommended daily intake limit of 400 mg of caffeine with a single dose. This limit can be reached with 4–5 doses in the case of coffees and energy drinks. In the case of chocolates, the methylxanthine compound detected at large levels was theobromine, with amounts ranging from 4 to 10 mg·g−1 for dark chocolates.
Highlights
Caffeine (1,3,7-trimethylxanthine), theobromine (3,7-dimethylxanthine), and theophylline (1,3-dimethylxanthine) are the most well-known compounds of the family of methylxanthines and are naturally present in tea leaves, yerba mate, coffee beans, cocoa beans, kola nuts and guarana berries.caffeine is probably the most broadly consumed central nervous system stimulant in the world [1,2,3].Over the last few decades, different ingredients have been added to foods and beverages as functional ingredients by many manufacturers
A total of 90 beverage samples were evaluated: 45 samples corresponded to cola soda beverages, 23 to energy drinks, and 22 to bottled or canned teas
The percentage of caffeine extracted in conventional espresso shots ranged from 64–76%, which yielded amounts of caffeine in every espresso ranging from 88 to 116 mg (Figure 4). This agrees with previous studies where median values between 73 and 140 mg caffeine/serving have been found for espresso coffees [47,51,52]. These results indicate that espresso coffees have a higher amount of caffeine than instant coffees and suggest that if no other caffeine beverage or food is consumed, 4–5 espresso coffees per day might be considered as safe given that this quantity provides an amount of caffeine that is below the 400 mg limit proposed by the European Food Safety Authority (EFSA) [21]
Summary
Caffeine (1,3,7-trimethylxanthine), theobromine (3,7-dimethylxanthine), and theophylline (1,3-dimethylxanthine) are the most well-known compounds of the family of methylxanthines and are naturally present in tea leaves, yerba mate, coffee beans, cocoa beans, kola nuts and guarana berries. Over the last few decades, different ingredients have been added to foods and beverages as functional ingredients by many manufacturers. The addition of synthetic additives to beverages is not new as caffeine has long been added to soft drinks, mainly in cola soft drinks as a substitute for kola nut extract. One of the clearest examples of the addition of functional ingredients is the case of “energy drinks”, of which the market has grown exponentially since their commercial introduction at the end of the 20th century to the point where there are hundreds of different brands with added caffeine contents ranging from 85 to
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