Cocoa bitterness

Roasting cocoa beans results in the production of volatile and non-volatile compounds which contribute to the total flavor complex. 5-Methyl-2-phenyl-2-hexenal, which exhibited a deep bitter persistant cocoa note, was reported in the volatile fraction (53). It was postulated to be the result of aldol condensation of phenylacetaldehyde and isovaleraldehyde with the subsequent loss of water. The two aldehydes were the principal products of Strecker degradation products of phenylalanine and leucine, respectively. Non-volatiles contained diketopiperazines (dipeptide anhydride) which interact with theobromine and develop the typical bitterness of cocoa (54). Theobromine has a relatively stable metallic bitterness, but cocoa bitterness is rapidly noticed and disappears quickly. 

The natural moisture of the cocoa bean combined with the heat of roasting cause many chemical reactions other than flavor changes. Some of these reactions remove unpleasant volatile acids and astringent compounds, partially break down sugars, modify tannins and other nonvolatile compounds with a reduction in bitterness, and convert proteins to amino acids that react with sugars to form flavor compounds, particularly pyrazines (4). To date, over 300 different compounds, many of them formed during roasting, have been identified in the chocolate flavor (5). 

Theobromine was determined by GC in various foods (bitter chocolate, milk chocolate, chocolate cake, cocoa powder, chocolate milk), and results are given in graphs and tables.27 Homogenized samples were boiled in alkaline aqueous media, then fat was extracted with n-hexane. The aqueous layer was acidified with diluted HC1 and NaCl was added. Theobromine was extracted from this treated aqueous solution with dichloromethane and the extract was evaporated to dryness. The residue was redissolved in dichloromethane containing an internal standard. GC analysis was performed on a column packed with 1% cyclohexane dimethanol succinate on Gaschrom Q, with FID. Average recoveries were 99 to 101%, coefficient of variation was less than 3% and the limit of detection for theobromine in foods was about 0.005%. 

Chocolate liquor is the solid or semiplastic food prepared by finely grinding the nib of the cacao bean. It is commonly called baking chocolate, unsweetened chocolate, or bitter chocolate and, in Europe, is frequently referred to as chocolate mass or cocoa paste. Chocolate liquor is essentially the starting point from which all chocolate products are produced. Table 5 lists the theobromine and caffeine content of 22 various chocolate liquor samples determined by high pressure liquid chromatography (HPLC). The liquors averaged 1.22% theobromine and 0.214% caffeine.27- 28 The ratio of theobromine to caffeine ranged from 2.5 1 to 23.0 1. 

Alkaloids are compounds that contain nitrogen in a heterocyclic ring and are commonly found in about 15-20% of all vascular plants. Alkaloids are subclassified on the basis of the chemical type of their nitrogen-containing ring. They are formed as secondary metabolites from amino acids and usually present a bitter taste accompanied by toxicity that should help to repel insects and herbivores. Alkaloids are found in seeds, leaves, and roots of plants such as coffee beans, guarana seeds, cocoa beans, mate tea leaves, peppermint leaves, coca leaves, and many other plant sources. The most common alkaloids are caffeine, theophylline, nicotine, codeine, and indole... 

It is not known how long vanilla has been used as a spice, but it dates back at least 1,000 years. The first known cultivators of vanilla were the Totonac people in the Veracruz region of Mexico, who regarded vanilla as a sacred plant and used it as a deodorant. The use of vanilla was acquired by the Aztecs after their invasion and interaction with the Totonacs. The Aztecs called vanilla tlibcochitl, which translates as black flower, a reference to the dark brown-black color of the dried pods after curing. Aztec royalty used vanilla to sweeten the bitter taste of their cocoa drink xocolatl and for medicinal purposes. The Spanish explorer Hernando Cortez... 

I have always liked chocolate. I grew up on it. Every morning my mother blended a heaping spoonful of cocoa powder with a little milk, some sugar, and a touch of salt (to decrease the bitterness). Then she stirred the mix into gently boiling... 

There are many phenolic substances in plants and thus in foods. Rich dietary sources of phenolics include fruits, tea, coffee, cocoa, and processed foods derived from these, such as wine. At high levels, and in particular when sugar levels are low, phenols impart an astrin-gency, bitterness, and color to foods. In red wine, unsweetened tea, and chocolate products, the taste is heavily influenced by the presence of phenolics. Therefore, an assessment of phenolic content in food is of great importance. 

JS Bonvehi, FV Coll. Evaluation of bitterness and astringency of polyphenolic compounds in cocoa powder. Food Chem 60 365-370, 1997. 

Chocolate is a solid-in-oil (S/O) suspension of non-fat partides (of about 10-100 (im diameter) of sugar and cocoa (cacao) in a continuous phase of cocoa butter, which is the natural fat from the cocoa bean [215]. When cocoa beans are cleaned, roasted, cracked and ground, chocolate liquor results, a suspension of cocoa powder in cocoa butter. Depending on how much cocoa butter is removed (by pressing) one can make, in decreasing order of cocoa butter content bitter, unsweetened, baking... 

Theobromine was isolated from the seeds of the cacao tree and then shortly afterward was synthesized from xanthine by Fischer.132 Theobromine is the primary bitter-tasting alkaloid found in cocoa and chocolate chocolate contains 0.5—2.7% theobromine. Theobromine is water insoluble and is an isomer of theophylline as well as paraxanthine. Theobromine is categorized as 3,7-dimethylxanthine while theophylline is 1,3-dimethyl-7f/-purine-2,6-dione and paraxanthine is 1,7-dimethylxanthine. Theophylline is known to be a bitter-tasting principle of green tea. Theobromine is used as a vasodilator (a blood vessel widener), as an aid in urination, and... 

Van Houten developed two processes, one in 1928 in order to separate physically, cocoa butter and cocoa solids (which were then transformed to make the famous cocoa powder) the other is the alkali treatment of chocolate to remove bitterness ... 

A glutamic acid-rich oligopeptides fraction was found to be effective in masking bitter taste (37). The addition of these peptides to the bitter medicinal drugs and drinks (summer orange and vegetable juices, and cocoa) seems to decrease or mask the bitterness of the products. 

Proteases degrade the proteins to free amino acids and oligopeptides, thus imparting sweet, sour and mainly a bitter taste to the product. Further reactions lead to the corresponding Strecker aldehydes 2-methylbutanal and 3-methylbutanal with a pungent, malty, cocoa note. 

Plain or bitter chocolate is a mixture of ground cocoa nibs with sucrose, cocoa butter and flavouring. Milk chocolate contains in addition milk powder. A bar of chocolate contains about 6 mg of caffeine and a cup of cocoa about 13 mg. 

Cocoa beans have a bitter principle which is somewhat reduced by a fermentation process. The quality of the cocoa made from the beans depends to a considerable extent upon the success of this fermentation. The cocoa beans grow in bunches of thirty to forty,1 surrounded by a soft husk or shell. The beans are collected and placed in fermentation boxes with proper air vents. The sweet outer covering of the beans begins to ferment immediately. This mucous lining of... 

Some species of psilocybian mushrooms have a not-disagreeable flavor and may be eaten neat, but the majority of species have a strong acrid taste which, while not bitter, some find to be revolting and quite as difficult to tolerate as the taste oip otl. To overcome this, epicurean consumers blend smoothies with raw or dried psilocybian mushrooms, using strong-flavored fruit or chocolate to kill the taste. Hot cocoa in water or milk is a common vehicle, providing good flavor as well as his-... 

Chocolate is a food product that is native to Central America and Mexico. The Aztec ruler Montezuma served the bitter cocoa-bean drink to Hernan Cortez in 1519. Cortez took the cocoa beans and the recipe for the chocolate beverage to Spain where it became a very popular, but expensive beverage. Chocolate remained a food product for the wealthy until the mid-nineteenth century, when the price of chocolate became affordable and processing techniques improved. The chocolate served today bears little resemblance to the chocolate served in Montezuma s court. Processing techniques as well as additives create the smooth, sweet, delightful treat that you enjoy today. 

The dipeptide sweetener a-L-aspartyl-L-phenylalanine methyl ester (a-APM), also know as aspartame or NutraSweet brand sweetener, is currently used in over 5,000 food products. It has a sweetness potency of approximately 200 times sucrose and is unstable under alkaline conditions. This instability is due to the well known, irreversible cyclization that a-APM undergoes to form 3-(S.)-benzyl-6-(S,)-carboxymethyl-2,5-diketopiperazine or DKP, with the release of methanol. This has serious implications when attempting to utilize a-APM in certain food applications where alkaline pH is required. In addition to loosing sweetness, this DKP as well as other DKPs isolated from cocoa are reported to be bitter, and thus could compromise the flavor of certain foods. Therefore, detection and quantitation of DKP is of interest. 

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