Determination of zeranol in meat (author's transl)]

A qualitative and quantitative method for the determination of zeranol in meat and liver is described. The analysis procedure includes methanol extraction, enzymatic hydrolysis of possibly existing conjugates, and liquid-liquid partition, followed by two-dimensional thin layer chromatography. Zeranol is selectively made visible as a red-violet spot with Fast Blue B salt. The detection limit in meat is found to be 10 ppb. For the quantitative determination zeranol is eluted from the TLC plates and reacted with Fast Blue B salt. A quantitative determination can be performed with a concentration of 0.4 ppm. The application of this method demonstrated the presence of zeranol in 2 out of 18 commercially obtained samples.     

Determination of D-isocitric-acid in currant products (author's transl)]

The determination of D-isocitric-acid in currant products is described Disturbances by ingredients can be eliminated with polyamide. It is suggested that the citric: isocitric acid ratio can be used to detect adulterated products.     

Comparison of chronic toxicity and carcinogenicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in 2-year bioassays in female Sprague-Dawley rats

The cancer bioassay for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) conducted by the Dow Chemical company in the mid 70s has been used extensively for conducting quantitative cancer risk assessments for human exposure to TCDD. More recently the National Toxicology Program (NTP) conducted a cancer bioassay of similar design as part of its evaluation of the dioxin toxic equivalency factor methodology. This report compares the design and the results of these two cancer bioassays. This comparison confirms, in most cases, previously published and widely used carcinogenic response characteristics with respect to dose, time course, organ selectivity, tumor type and maximum intensity of TCDD-induced carcinogenicity and toxicity in the Sprague-Dawley rat. Specifically, increases in the incidences of neoplasms were seen in both studies in the liver, lung and oral mucosa. The most notable difference was the significant increase in the incidence of cholangiocarcinoma of the liver seen in the NTP study but not in the Dow study. The experimental designs for the two studies are similar but some protocol parameters differed, such as vehicle, dosing schedule, diet and rat sub-strain utilized. Differences in the shapes of the dose response curves for several neoplasms were noted between the studies, with the NTP study showing non-linearity for all neoplasms. This may result from differences in the experimental protocols as well as divergence in the biological behavior of the different stocks of Sprague-Dawley rat strains used.     

On the nonexistence of propionic acid in various kinds of breeds (author's transl)]

Analyses of 45 samples of sour dough and various kinds of bread have shown that no appreciable amounts of propionic acid are formed during sour dough fermentation. Bread has no natural propionic acid content.     

On lipoxygenase and enzymes which decompose linoleic acid hydroperoxides in rye (author's transl)]

An enzyme fraction from rye containing lipoxygenase activity was investigated. The molecular weight of lipoxygenase was found to be about 102000. Two bands groups with isoelectric points between 5.1-5.5 and 5.8-6.4 were obtained by isoelectric focusing. Three isoenzymes could be separated by ion exchange chromatography. Lipoxygenase has optimum activity at pH 7.3-7.5 and predominantly forms 13-hydroperoxy-9-cis, 11-trans-octadecadienoic acid (13-LHPO). In rye the 13-LHPO is converted to alpha-ketols by a high molecular protein fraction. This isomerase converts the LHPO formed by rye lipoxygenase predominantly to 12,13-ketohydroxy acids. The Michaelis Constant of isomerase is 3-5 X 10(-5), using LHPO as substrate. At low protein concentrations the reaction velocity of LHPO-conversion increases linearly with protein concentration.     

Determination of GSH-DH activity (E.C.1.8.5.1) presence of the enzyme in different wheat varieties (author's transl)]

2,6-dichlorophenol-indophenol is more stable in 75% ethanol than in aqueous solution and ascorbic acid reacts considerably faster in this media than glutathione. The activity determination of glutathione: dehydroascorbic acid oxidoreductase was based on these observations by a photometric measurement of the ascorbic acid resulting from the catalysis. Extracts from various types of wheat were tested and relatively high enzyme activities were found.     

The amount of L-dehydroascorbic acid on total-vitamin C of vegetable products (author's transl)]

Spectrophotometric determinations of vitamin C were carried out on different kinds of vegetable products in raw state, after steam-cooking and freezedrying. Indicators used were in part 2,6-dichlorophenol-indophenol (DIP) and in part N-bromosuccinimide (NBS) and starch iodide, which at the same time allows a determination of other reducing interfering substances. The amount of L-dehydroascorbic acid (DAS), which together with L-ascorbic acid (AS) becomes vitamin C or total-vitamin C (VC), proved to be of special interest. During homogenisation of the vegetable samples in oxalic oxid solution AS was not oxidized. Other precautions like cooling or on oxygen-free atmosphere were not required. DAS was not found in raw vegetable products or after cooking. A high proportion of interfering substances especially when estimating VC was considered the cause for the normally measured amount of DAS. In freeze-dried samples of vegetable products a small amount DAS could be identified depending on the freezing process.     

Simultaneous, gas-chromatographic determination of ethyleneoxide, ethylenechlorohydrine and ethyleneglycol in grain (author's transl)]

The not comminuted grain (10 g) is extracted for 24 hrs (25 degrees C) with 5 ml methanol (shaking machine), then the fluid phase is separated by centrifugal filtration and directly injected into the GC (10 mu). The GC starting temperature (60 degrees C) is adjusted by cooling the oven with Co2. Yield: EO 73% (concentr. range 25 ppm); ECH 93% (concentr. r. 50 ppm); EG 99% (conc. r. 50 ppm). Standard deviation: EO s = +/- 1,70 ppm (N = 24, conc. r. 10 ppm), ECH s = +/- 1,15 ppm (N = 24, conc. r. 20--30 ppm), EG s = +/- 0,62 ppm, (conc. r. 15--30 ppm, N = 24).     

Investigation on the aroma of roasted onions (author's transl)]

A large number of volatile compounds are formed when onions are heated in butter. More than 120 compounds could be identified with GC-MS-technic. The majority of the substances is not characteristic for the onion aroma. Compounds formed according to a patented production of onion aroma could not be identified.     

Photometric determination of arsenic in biological samples (author's transl)]

A modified method by means of absorption of AsH3 in chloroform with an addition of 0,5% hexamethylene-tetramine is described. The detection limit amounts to 0,5 mug arsenic. Arsenic contents of some higher burdened foodstuff are amended.     

Investigations of fat-quality of maize with special consideration of linoleic acid contents (author's transl)]

In the past years the cultivation of maize in the Federal Republic of Germany has been intensified, and with the processing of localy bred maize a production of maize germ oil from German varieties could be expected. In order to maintain certain essential points about the amplitude of variations in the specimen of fatty acids in the localy bred maize, a greater number of maize samples from cultural practice trials (varieties, locations and fertilizer) were taken for the year 1971 and 1972 and their fatty acid composition was analysed. The following results were obtained: 1. Comparared to maize of foreign origin, processed in the Federal Republic of Germany, in most cases the localy bred, has higher contents of linoleic acid and lower contents of oleic acid. Thus the linoleic acid contents of the Germany maize varies between 54.3 and 68.8% while the foreign maize varies between 39.5 and 58.7%. 2. Great differences in quality exist between the local genotypes (varieties). Also clear, but not so great differences are induced by ecological factors, as locations, weather and nutrient supply. The differences of local environment in the linoleic acid content in case of variety "Inrakorn" varies between 60.8 and 64.5%.     

Natural occurrence of progesterone in commercial milk products (author's transl)]

By means of radioimmunoassay the concentrations of progesterone in commercial milk products were determined. The values range from 1.4 ng/ml (skin milk) to 300 ng/g (butter). The results show a close correlation between progesterone and fat contents in milk products. It is discussed that - due to recent progress in analytical methods - hormones in their natural occurrence in food are now measurable in micro-quantities which were not yet considered to be of biological importance; these findings should provoke a revision of terms like "free of hormones" in the sense of "zero tolerances".     

Simultaneous determination of lysine, lysinoalanine, furosine, and pyridosine in food and feed (author's transl)]

A method for the simultaneous separation and determination of lysinoalanine (LAL), lysine, furosine and pyridosine with an automatic amino acid analyzer using a single Column 4 buffer- and 3 temperature-programme is described. The procedure needs 160 Minutes analysis time and allows a separation and quantitative determination of LAL, when present in amounts of more than 100 ppm (semiquantitative above 10 ppm). All amino acids found in food proteins and all other ninhydrinpositive compounds tested until now do not interfere with the determination.     

Detection of acetamide in the thermal degradation products of chitin (author's transl)]

Thermal degradation of chitin, which is a constituent of some foods, yields as main volatile compound acetamide (9% of dry weight) a fact with possible physiological implications. Thermal analysis shows decomposition beginning at 200 degrees C.     

Co-oxydation of linoleic acid to volatile compounds by lipoxygenase isoenzymes from soya beans (author's transl)]

Lipoxygenase isoenzymes L-1 (optimum pH 9.0) and L-2 (pH 6.5) were incubated with linoleic acid. The extracted volatile compounds were separated by gas-chromatography and analysed by mass spectrometry. The relative amounts of volatile carbonyl compounds, which were formed during catalysis were determined (mole percent). L-1 yielded hexanal (greater than 90% at pH 7 and 70% at pH 8.5). L-2 at pH 7 yielded hexanal (31), two geometric isomers of 2,4-decadienal (40), 2-trans-heptenal (12) and 2-trans-octenal (10).     

Cadmium, lead, and zinc-content of fruits and vegetables from gardens in industrial region (author's transl)]

The contents of Cadmium, lead, and zinc in 136 samples of fruit and vegetable of harvest 1973, taken from gardens in Dortmund, have been analysed by mineralisation, extraction with APDC/MIBK and AAS. 5% of the samples contained more cadmium, 13% more lead and zinc than proposed limits.     

Lipoxygenases from pears, strawberries and gooseberries: partial purification and properties (author's transl)]

Membrane-bound lipoxygenases (EC 1.13.11.12) were partially purified from the fruits by centrifugation and gel chromatography. The enzymes have a pH-optimum at 6.0 (pear) resp. 6.5 (strawberry, gooseberry). Linoleic acid is oxidised to 9- and 13-hydroperoxides in a ratio of 3:7 (pear), 2:8 (strawberry) and 1:1 (gooseberry). The enzymes from gooseberries and from strawberries co-oxidise canthaxanthine with a higher specific activity than the lipoxygenases from pears and apples.     

Detection of H2O2 in uperized milk (author's transl)]

Qualitative determination of H2O2 in uperized milk by means of PERID-test-tablets and quantitative tests by means of lactoperoxidase showed that H2O2 is more or less decomposed depending on the original concentration in the uperized milk. The relationship between H2O2-content, time of storage and ascorbic-acid-content are discussed.     

Spectral-photometric determination of L-ascorbic acid with N-bromsuccinimide and starch iodide (author's transl)

A new spectrophotometric method for the determination of L-ascorbic acid (AS) with N-bromosuccinimide (NBS) and starch iodide as an indicator was developed. The questions of pH-dependence, sensitivity and specificity of the oxidation-reduction process were investigated. The method is suitable for the determination of AS in acid solutions; the best pH was 2.6. The specificity of the method for AS cannot be considered as definitely better than other methods. Its sensitivity, however, is higher than when using 2.6-dichlorophenol-indophenol (DIP). When applied the method usually yielded results close to the DIP method and due to its high sensitivity AS determinations in very dilute and hazy solutions are possible.