Foodstuffs, roasted

Commercial products usually do not pose health threats to their consumers. However, botulism cases acquired after consumption of commercially prepared canned foods have been reported. In the U.S., 62 outbreaks occurred in the years 1899 to 1973 (Lynt et al., 1975). Only 7% of outbreaks reported between 1950 and 1996 were linked to commercially processed foods (Centers for Disease Control and Prevention, 1998). The implicated foodstuffs included chopped garlic in soy oil stored in glass bottles at room temperature (Louis et al., 1988), sliced roasted eggplant in oil, yogurt with hazelnuts, stuffed lotus rhizome, bottled caviar, and canned peanuts (Chou et al., 1988 D Argenio et al., 1995). 

Niacin is present in foods mainly as coenzyme NAD and NADP, which are hydrolyzed in the intestine, and it is adsorbed as nicotinamide or nicotinic acid. The free forms, nicotinamide and nicotinic acid, only allowed to be added in fortified foods [403], occur naturally in limited amounts. Instead, niacin occurs as nicotynil ester bonded to polysaccharides, peptides, and glycopeptides. In general, niacin is widespread in foodstuffs (cereals, seeds, meat, and fish). High concentrations are present in roasted coffee beans as a primarily product of the roasting process [417]. 

As for S-containing heterocycles, many N-containing heterocycles are also found in heat-treated foods as secondary flavours as a result of Maillard-type reactions between reducing sugars and amino acids. Pyrazines are N-heterocycles important contributors to the taste and aroma of roasted and toasted foods as well as vegetables and fermented foodstuffs. In cultures of Pseudomonas perolens ATCC 10757, amino acids such as valine, glycine and methionine were shown to... 

There are few data on concentrations of ethylbenzene in foodstuffs. It has been identified as a trace component in the volatiles from honey, jasmine, papaya, olive oil and cheese flavour and in the neutral component of roast beef flavour isolate (Min et al., 1979 Fishbein, 1985). Trace quantities of ethylbenzene have been detected in split peas (13 ig/kg), lentils (5 ig/kg) and beans (mean, 5 pg /kg maximum 11 pg /kg (Lovegren et al., 1979). Concentrations of ethylbenzene in orange peel (23.6 ng/g dry weight) and in parsley leaves (0.257 pg/g dry weight) have been reported (Goma-Binjul etal., 1996). 

More than 700 constituents have been identified in aroma extracts of roasted coffee. Heterocyclic aroma components represent the greatest amount of the steam volatile aroma complex (80 - 85 %) which amounts to 700 -900 ppm in medium roasted Arabica coffees. The concentration of individual components varies depending on coffee varieties and roasting conditions. Typical components are formed by thermal degradation of free and bound amino acid and chlorogenic acid precursors. Compared to other roasted foodstuffs, sulfur containing constituents and phenols are formed in high amounts and contribute to desirable coffee flavor or off-flavor. 

This list of volatile constituents continues to grow as demonstrated by Baltes and coworkers (5 1 Improved analytical instruments and data bases of thousands of mass spectra contributed to the detection of volatile constituents in model reactions as well as in roasted foodstuffs. New food constituents are more and more difficult to locate, isolate and identify. 

Aldoses undergo the Amadori rearrangement and subsequently turn into caramels, the natural brown food colorants, and/or heteroaromatic compounds — derivatives of pyrrole, imidazole, and pyrazine. Ketoses react similarly into ketosylamino acids or ketosylamines, which, in the first step, undergo the Heyns rearrangement (5.17-5.23). These rearrangements are the first steps of either thermal or enzymatic (the Maillard reaction) reactions resulting in the browning of food and the aroma of roasted, baked, or fried foodstuffs. 

It has been claimed that no other class of flavoring compounds is as important in flavoring foods (40). Pyrazines have been detected in many processed foodstuffs and are often associated with "roasted" and "nutty" flavors. Some raw vegetables owe their typical flavor to the presence of certain pyrazines,... 

Recently, Ginz and Engelhardt (1999) studied water-soluble proteins of raw coffee as a source of bitterings. After roasting, by using gel chromatography and HPLC they identified diketopiperazines cyclo(Pro-Pro), cyclo(Pro-Leu), cyclo(Pro-Phe) and isolated cyclo(Pro-Val). These and similar diketopiperazines are known as bitter principles in foodstuffs, but the authors have not yet drawn any conclusions as to the importance of their participation in the bitterness of roasted coffee. 

Identified by Singer and Lijinsky (1976) who gave a concentration of 6 ppm. Neurath et al. (1977) gave concentrations of 7 to 11 ppm for two freeze-dried coffees and one coffee extract, after steam distillation and analysis of the trifluoroacetamides in the neutral fraction. The authors of the two publications were particularly looking for secondary amines in foodstuffs because of the potential carcinogenicity of the nitroso derivatives. Cros et al. (1980) identified pyrrolidine in the headspace of a roasted arabica. 

In the mid-1970s, pyrolysis studies with several amino acids led to the isolation and identification of several additional polycyclic A-heterocyclic compounds which are reported not only to be tumorigenic to mouse skin but also to show inordinately high mutagenicity when tested in the Ames bioassay with Salmonella typhimurium. The impetus for these particular amino acid pyrolysis studies was not the attempt to define the relationship between tobacco leaf precursors and tobacco smoke components but the observation that the extracts of broiled, fried, or roasted foodstuffs (meat, fish, poultry, etc.) were highly mutagenic in the Ames bioassay Salmonella typhimurium). These A-heterocyclic... 

Table lV.B-4 lists several polynuclear (V-heterocyclic amines that exhibit extremely high mutagenicity levels in the Ames bioassay, are amino acid pyrolysis products, and have been identihed in various broiled, fried, or roasted foodstuffs as well as in CSC [Sugimura (3828c)]. On a per microgram basis, B[fl]P in the Ames bioassay with Salmonella typhimu-rium (Strain TA 98) shows about 200 revertants/pg. Several of the amino acid-derived compounds in Table lV.B-4 exceed the B[fl]P effect with the TA 98 strain by factors ranging from about 10 to over 2100. 

PAHs are ubiquitous. They are present in the atmosphere as components of a variety of dusts, soots, tars, oils, engine exhaust gases in water in many commonly consumed foodstuffs, particularly those that are heated, roasted, or broiled... 

These compounds are primarily found in smoked foodstuffs and roasted products including malt and... 

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