The proteins of honey. III. Separation of honey amylase by hydrophobic partition chromatography (author's transl)

Previous experiments to separate the amylase and "invertase" of honey by chromatography on sephadex-gels were unsuccesful. It was shown that honey-amylase, -like amylases form other sources -- has hydrophobic properties. Therefore it was possible to separate amylase-activity from other activities by means of hydrophobic affinity chromatography on phenyl-butylamine-Sepharose 4B.     

On the lipoperoxidase-isomerase-system from oat. Experiments for enzyme separation (author's transl)

It was attempted to separate isomerase and lipoperoxidase activity from oat by means of gel and ion exchange chromatography and by isoelectric focusing. The molecular weight of the enzyme fraction tested was found to be of the order of 3 X 10(6) daltons. By ion exchange chromatography and isoelectric focusing the enzyme fraction with lipoperoxidase and isomerase activity could be separated into isoenzymes. These isoenzymes continued to exhibit both enzymatic activities. The lack of success in achieving of separation and the high molecular weight lead to the conclusion of the asistence of a close interrelation between the two enzymes or possibly of a bifunctional enzyme complex.     

Bitter peptides isolated from corn protein zein by hydrolysis with pepsin (author's transl)]

Eight peptides with bitter taste were isolated from a hydrolyzate of the corn protein zein using several chromatographic procedures. The peptides have the following amino acid sequences and taste thresholds (muM/ml): Ala-Ile-Ala (50-100), Ala-Ala-Leu (50-100), Gly-Ala-Leu (50-100), Leu-Glu-Leu (2.5-3.5), Leu-Glu-Leu (8-12), Leu-Val-Leu (1.5-2.5), Leu-Pro-Phe-Asn-Gln-Leu (0.1-0.2), Leu-Pro-Phe-Ser-Gln-Leu (0.1-0.2). The threshold for bitter taste decreases with increasing number of hydrophobic side chains (greater than or equal to C3) in the peptide. It increases in the presence of hydrophilic side chains to their polarity.     

Mercury-content of austrian edible mushrooms and its relation to the protein content of the mushrooms (author's transl)

The mercury content of 16 eatable mushroom species from different geographical areas was determined by flameless atomic absorption spectroscopy. Mercury levels lay between 18 and 14300 ppb related to mushroom dry matter. A great difference in mercury content was found between species. Boletaceae, Lycoperdaceae, Agaricaceae etc. showed constantly high values (greater than 1000 ppb), but in Cantharellaceae a low content (less than 100 ppb) was recorded. Besides other factors the mercury concentration is essentially dependent on the protein content. A highly significant positive correlation between the two characteristics was found.     

Gas-chromatographic-mass-spectral analysis of aroma-compounds of bread (author's transl)

Analysis of aroma compounds of whithe bread by means of a combined gas-chromatographic-mass-spectral method was carried out. 29 organic compounds were identified, 20 of which were reported for the first time in bread aroma. These for the first time reported compounds are: 1, 1-diethoxyisopentane, 2-phenylethylformiate, n-butylformate, 2-isooctenal, 2-octenone-4, sec. nonanol, nonanol-1, 2-nonanone-4, 2-decenone-4, 2-decenone-5, 1-dodecenone-3, 2-dodecenone-4, 2-dodecenone-5, dodecanol, octylacetate, ethylbenzoate, nitrobenzene, pentadecanone-2, heptadecanone-2, tridecadience.     

On characterization of lipoxygenase from barley (author's transl)]

Lipoxygenase from brewing barley of Nordbaden has optimum activity at alkaline pH and predominantly forms 9-hydroperoxy-10-trans, 12-cis-octadecadienoic acid (9-LHPO) from linoleic acid. While at pH 7 90% 9-LHPO is produced, its proportions drops during incubation at more alkaline pH (pH 7,75) to 70%. This positional specifity is not caused by isoenzymes. While linoleic acid methylester is converted only to a lesser degree, trilinolein is not accepted as substrate.     

Flavonols and flavones of vegetables. VIII. Flavones of carrot leaves (author's transl)

The flavonoid constituents of carrot leaves (Daucus carota L. ssp. sativa) were separated by means of cellulose column chromatography, and the following compounds were obtained crystalline and identified by usual procedures: luteolin 7-beta-D-glucoside as the main flavon, luteolin 4'-beta-D-glucoside, luteolin 7-beta-D-glucuronide, apigenin 7-beta-D-glucoside, apigenin 7-rutinoside, chrysoeriol 7-beta-D-glucoside. Luteolin 7-rutinoside also was identified, but could not be obtained crystalline.     

Thermostable basic proteinase inhibitors from potatoes. Isolation and characterization (author's transl)]

Four basic proteinase inhibitors were isolated from potato tubers (var. Maritta) by ammonium sulfate precipitation, heat treatment, chromatography on CM-cellulose and preparative polyacrylamide gel electrophoresis. Their isoelectric points are in the pH range 9.2--9.8. The molecular weights, as estimated by Sephadex gel filtration, were 8500 for inhibitor K 1 and 22000 for the inhibitors K3, K4, and K6. Differences in inhibitors regarding amino acid composition and specific activity against six different proteinases are discussed. Comparisons with previously described inhibitors are given. A correlation between high cystine content and thermostability of the inhibitor proteins is indicated.     

Study of heat-denatured whey protein removal from stainless steel surfaces in clean-in-place systems

The build-up of protein deposits over the inner surfaces of process equipment, particularly heat exchangers, is a common phenomenon in dairy factories, which hinders the normal functioning of such equipment. In this work, we have studied the washing process of stainless steel surfaces stained with heat-denatured whey protein. To do that we have used the bath-substrate-flow (BSF) device, a bench-scale apparatus that simulates clean-in-place systems. Screening tests were performed at low temperature (30 °C) to investigate the effect of the presence of protease, NaOH, ozone and surfactants on cleaning efficiency. The best results were obtained with NaOH (0.5%, w/w), proteases (1 g L⁻¹) and ozone (40 NL h⁻¹, 80 g Nm⁻³). On the other hand, the use of surfactants (either anionic or nonionic) did not improve the washing efficiency significantly. Therefore, ozone and proteases can be used as environmentally friendly cleaning agents to remove protein deposits in the food industry.     

Examination and composition of some legume seeds (author's transl)

The chemical composition of some legume seeds is reviewed. It was found that soy (Glycine soja), field beans (Vicia faba), Vicia sativa and Lens culingris (red seeds) have the highest protein content. There were only minor differences in amino acid composition except for glutamic acid. The lysine content of legume seeds was high. Lysine is the most limiting essential amino acid in cereal proteins, therefore cereal products can be improved nutritionally by addition of legume seed flour. Examination of polar lipids by thin layer chromatography revealed that lecithin, phosphatidyl ethanolamine and phosphatidyl inositol were the major components. However, Lupinus angustifolius contained two unknown polar lipid classes.--In contrary to previous literature the ripe legume seeds contained only a very small amount of galactosyl diglycerides; however legume seeds contain higher amounts of the compounds. The conection between biosynthesis of linolenic acid and the presence of galactosyl diglycerides in higher plants is discussed.     

Microbial removal of Fe(III) impurities from clay using dissimilatory iron reducers

Fe(III) impurities, which detract refractoriness and whiteness from porcelain and pottery, could be biologically removed from low-quality clay by indigenous dissimilatory Fe(III)-reducing microorganisms. Insoluble Fe(III) in clay particles was leached out as soluble Fe(II), and the Fe(III) reduction reaction was coupled to the oxidation of sugars such as glucose, maltose and sucrose. A maximum removal of 44-45% was obtained when the relative amount of sugar was 5% (w/w; sugar/clay). By the microbial treatment, the whiteness of the clay was increased from 63.20 to 79.64, whereas the redness was clearly decreased from 13.47 to 3.55.     

板蓝根多糖的提取与脱蛋白工艺优化

通过Box-Behnken组合实验设计,考察了料液比、提取温度及提取时间对板蓝根多糖提取率的影响。利用响应面分析方法,模拟得到二次多项式回归方程的预测模型,并确定最佳提取条件为:料液比为1∶55,提取温度80℃,提取时间3.5 h。在此条件下,板蓝根多糖的提取率为3.55%。以蛋白脱除率和多糖损失率为指标,比较了Sevag法、三氯乙酸法和胃/胰蛋白酶法对粗多糖中蛋白质的脱除效果。结果表明:采用胃/胰蛋白酶脱蛋白工艺,蛋白脱除率较高,分别可达63.5%和52.9%,多糖损失较少,且操作简便,无污染,是较好的脱蛋白方法。     

Hydroperoxide degradation by oat isomerase. Investigation of the reaction mechanism (author's transl)

Oat isomerase is inhibited by hydroxyoctadecadienoic acids (monohydroxy acids) to a degree comparable with inhibition by linoleic acid hydroperoxides (LHPO). Hydroxy acids seem to combine with the enzyme like LHPO do. In an experiment on LHPO breakdown by isomerase 1-14C-hydroxy acids were added and it was examined whether the epoxyhydroxy acids are formed by an intermolecular or intramolecular mechanism. In this experiment 1-14C-labeled trihydroxy acids were formed; they arise from the hydrolysis of epoxyhydroxyoctadecenoic acids formed on their part by isomerase effected LHPO-breakdown. It was determined that at least 70% of LHPO are converted by intermolecular reaction.     

Determination of sulphydryl and disulphide groups in proteins by amperometric titration. III. Investigation of the specifity of Ag+ ions for protein SH groups (author's transl)]

The specifity of Ag+ ions for protein SH groups has been questioned frequently, even though the amperometric titration with AgNO3 is one of the most common methods for the determination of SH groups in proteins. This is due to the fact, that the formation of silver complexes in the titration of cysteine causes a consumption of AgNO3 which is too high. In order to find out if this may be true in the case of proteins, in the present work select proteins with a well known content of SH and SS groups have been titrated amperometrically in tris buffer pH 7.4 with 0.001 M AgNO3. The proteins used were hemoglobin, bovine serum albumin, ovalbumin, lysozyme, pepsin, myoglobin, and cytochrome c. The direct and the indirect titrations of (a) native, (b) denatured, and (c) NaBH4 reduced proteins showed, that the expected consumption of AgNO3 was in no case exceeded. Therefore under the conditions used AgNO3 may be considered as a specific reagent for protein SH groups. High SH values as a result of the amperometric titration of proteins with silver nitrate, which have been published occasionally, may be due to incorrect estimation of the end point of the titration. The reducibility of SS groups depends on the kind of protein. Lysozyme and pepsin were already completely reduced at 23 degrees C, whereas bovine serum albumin needed 60 degrees C. The direct titration method was useful only in some cases for the detection of all SH groups originally present in the proteins or formed by reduction with NaBH4. On the other hand the indirect titration method gave maximum values, because the slowly reacting SH groups of proteins are also allowed to react and the resulting titration curves may be evaluated correctly.     

On the metabolism of sulphur dioxide in apples (author's transl)

Apples of the two varieties, Boskoop and Brettacher, were exposed to 35S labeled sulphur dioxide. After storage at several conditions the distribution of 35S-activity among the three fractions, sulphite, sulphate and sulphonate was examined. The major portion of the radioactivity was found in the sulphate fraction. The activity decreased remarkably from the peel towards the core. Appreciable differences in distribution patterns were found between the two apples varieties.     

Arsenic(III) oxidation by iron(VI) (ferrate) and subsequent removal of arsenic(V) by iron(III) coagulation

We investigated the stoichiometry, kinetics, and mechanism of arsenite [As(III)] oxidation by ferrate [Fe(VI)] and performed arsenic removal tests using Fe(VI) as both an oxidant and a coagulant. As(III) was oxidized to As(V) (arsenate) by Fe(VI), with a stoichiometry of 3:2 [As(III):Fe(VI)]. Kinetic studies showed that the reaction of As(III) with Fe(VI) was first-order with respect to both reactants, and its observed second-order rate constant at 25 degrees C decreased nonlinearly from (3.54 +/- 0.24) x 10(5) to (1.23 +/- 0.01) x 10(3) M(-1) s(-1) with an increase of pH from 8.4 to 12.9. A reaction mechanism by oxygen transfer has been proposed for the oxidation of As(III) by Fe(VI). Arsenic removal tests with river water showed that, with minimum 2.0 mg L(-1) Fe(VI), the arsenic concentration can be lowered from an initial 517 to below 50 microg L(-1), which is the regulation level for As in Bangladesh. From this result, Fe(VI) was demonstrated to be very effective in the removal of arsenic species from water at a relatively low dose level (2.0 mg L(-1)). In addition, the combined use of a small amount of Fe(VI) (below 0.5 mg L(-1)) and Fe(III) as a major coagulant was found to be a practical and effective method for arsenic removal.     

Lead-content of foodstuffs. 4. Lead-content of infant foods (author's transl)]

The lead contents in more than 120 glass bottles or packages of infant foods were determined. About 75% of the values were below 100 mug Pb/kg of product. The highest value was 238 mug Pb/kg. The weekly intake of a 6 month-old infant (7.2 kg body weight) fed exclusively with commercial baby foods was found to be about 320 mug Pb, or about 45 mug Pb/kg body weight.