Aflatoxins

Foods high ia sucrose, proteia, or starch (qv) tend to biad water less firmly and must be dried to a low moisture content to obtain microbial StabiHty. For example, grain and wheat flour can support mold growth at moisture contents above 15% (wet basis) and thus are stored at moisture contents below 14%. Stored grains and oil seeds must be kept at a water activity below 0.65 because certain molds can release aflatoxias as they grow. Aflatoxins are potent carciaogens (see Food toxicants, naturally occurring). 

Aflatoxins B are fuagal metaboHtes and are produced hyyispergillusflavus. There are several related products all contain a pblorogluciaol segment ia their stmcture and all are extremely toxic and carciaogenic, eg, aflatoxia B (56) (201). 

The cyclopropenoid fatty acids, malvaUc acid and stercuhc acid, exist in hexane-defatted meal at levels of 21—76 ppm (70). In rainbow trout, the cyclopropenoid acids cause cancer of the fiver either alone or by acting synergistically with aflatoxin B. However, similar effects in mammals or humans have not been demonstrated (63). 

Contamination of cottonseed by aflatoxins is a perennial concern. The FDA limits the amount of aflatoxin in cottonseed meal intended for beef catde, swine, and poultry to 300 ppb and for dairy catde the limit is 20 ppb. 

Pea.nuts, The proteins of peanuts are low in lysine, threonine, cystine plus methionine, and tryptophan when compared to the amino acid requirements for children but meet the requirements for adults (see Table 3). Peanut flour can be used to increase the nutritive value of cereals such as cornmeal but further improvement is noted by the addition of lysine (71). The trypsin inhibitor content of raw peanuts is about one-fifth that of raw soybeans, but this concentration is sufficient to cause hypertrophy (enlargement) of the pancreas in rats. The inhibitors of peanuts are largely inactivated by moist heat treatment (48). As for cottonseed, peanuts are prone to contamination by aflatoxin. FDA regulations limit aflatoxin levels of peanuts and meals to 100 ppb for breeding beef catde, breeding swine, or poultry 200 ppb for finishing swine 300 ppb for finishing beef catde 20 ppb for immature animals and dairy animals and 20 ppb for humans. 

Post-column in-line photochemical derivatization permits fluorescence detection of the common aflatoxins Bl, B2, Gl, and G2 (60). Chromatographic evidence indicates that photolysis causes the hydration of the nonfluorescent Bl and Gl components to B2a and G2a components, respectively. Analysis of naturally contaminated com samples show no interfering peaks and permits the deterrnination of 1 and 0.25 ppb for Bl and B2, respectively. 

Biddeford, Maine Biotech Research Lab, Rockville, Maryland and Biokits Ltd., Clwyd, UK), aflatoxin M [6795-23-9] (Neogen Corp., Lansing,... 

Aeruginoic acid — see ThiazoIe-4-carboxyIic acid, 2-o-hydroxyphenyI-Aetiocobalamin, 4, 420 Aflatoxin B biosynthesis, 3, 876 Aflatoxin B, metabolism, 1, 245 toxicity, 1, 136 Aflatoxin G, toxicity, 3, 676 ... 

There have been compared the methods of mycotoxin control in food products with aflatoxin as an example, using both HPLC method with fluorescent detecting on the apparatus Thermo FL 3000 with a column BDS Hypersil C 2.1x150, as well as a chromatodensitometry method on the apparatus CAM AG TLS Scanner 3. 

Test preparation for both methods is similar. It comprises an extraction by a water-acetone mixture with its further degreasing protein isolation and redistribution of aflatoxin B into chloroform, concentrating by means of evaporation of the dissolvent on the rotary evaporator (t = 40°C). 

Both methods allow to realize a medical chemical control of the safety of food products by aflatoxin B at the level of 0.005 mg/kg. 

An aflatoxin is isolated from Aspergillus flavus. Which of the three aflatoxins, Bi, Gi or Mj, is it given the set of NMR experiments 43 ... 

The keto-carbonyl C signal at 5c = 200.9 would only fit the aflatoxins B, and M,. In the C NMR spectrum an enol ether-C// fragment can also be recognised from the chemical shift value of 5c = 145.8 and the typical one-bond coupling constant Jch = 196 Hz the proton involved appears at Sh = 72, as the CH COSY plot shows. The H triplet which belongs to it overlaps with a sing-... 

Further interpretation of the CH COSY / CH COLOC plots allows additional assignments to be made for fragments B and C of aflatoxin B,. 

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