Physical and microscopic studies of flour–water systems

Two flour–water systems were prepared under different conditions. A mixed flour–water system (dough) was prepared by mixing and kneading, and an unmixed (Hydrated, Unmixed Flour=HUF system) flour–water system without mixing and kneading. For preparation of the systems wheat flours of different qualities were used. Characterisation of the systems was done by rheological and microscopic analyses. Rheological measurements were performed at small deformation in dynamic oscillating mode, as well as at large deformation by uniaxial extension. The dough, the HUF system and the gluten from them were also investigated by microscopic technique.The mixed and unmixed systems showed differences in structure causing different physical properties. At small deformations (dynamic oscillating measurements) as well as at large ones (uniaxial extension measurements) HUF systems were firmer than doughs having a higher resistance in uniaxial extension measurements and higher elasticity at the beginning of dynamic measurements. Differences in structure of dehydrated systems were also found by microscopic investigations.Presented in part at 51. Tagung für Getreidechemie, 2000, Detmold, Germany     

Natural-light labeling of tomatoes does not facilitate growth or penetration of Salmonella into the fruit

The survival-growth capacity of Salmonella populations on tomato epidermis labeled by a natural-light labeling system was investigated after persistent fears of such marks serving as possible entryways for the pathogenic organisms, alone and in the presence of Pectobacterium carotovorum subsp. carotovorum, a soft-rot organism. Different treatments involving natural-light labeling, fruit waxing, and a five-strain cocktail of Salmonella were applied to mature green tomato surfaces in different sequences prior to storage at 4, 12, or 25°C. Fruit was sampled every 3 days, and Salmonella was enumerated from all treatments and unlabeled fruit, which served as controls. There were no significant differences between treatments or between treatments and controls throughout. The results indicate that the cuticle and epidermal interruptions caused by natural-light labeling do not facilitate the penetration and colonization of the tomato pericarp. In a separate set of experiments, the capacity of Salmonella to penetrate tomato in the presence of a potential synergism with P. carotovorum subsp. carotovorum was investigated. The addition of P. carotovorum at higher, lower, or equal population densities to Salmonella did not significantly alter the behavior of Salmonella on tomatoes stored at 25°C, regardless of natural-light labeling. The inability of P. carotovorum and Salmonella to colonize natural-light-etched surfaces of tomato fruit indicates that the use of this technology does not adversely compromise the surface of tomatoes.     

Evaluation of rapeseed meals in broiler chicks: Effect of iodine supply and glucosinolate degradation by myrosinase or copper

In rapeseed meals (RSM) of a conventional (c) or a newly bred (n) variety 117 or 44 mmol glucosinolates and glucosinolate degradation products per kg dry matter were detected. Soaking meals in aqueous myrosinase or copper sulphate solution and subsequent drying reduced the content of antinutrients by more than 90%. Broiler chickens were fed (i) a glucosinolate-free diet, or this diet in which half the soybean meal was replaced by RSM of various origins and treatment; (ii) untreated cRSM; (iii) cRSM treated with myrosinase: (iv) cRSM treated with Cu (v) untreated nRSM; or (vi) nRSM treated with myrosinase. These diets were administered with or without supplementary iodine. Chickens receiving the iodine-deficient diets with myrosinase-treated RSM showed growth depression, incomplete feathering, leg injuries and severe goitre. In the serum T⁴ could not be detected. Giving myrosinase-treated RSM plus iodine, or giving other RSM diets irrespective of iodine administration, no growth depression was observed. RSM diets without iodine dosage markedly increased thyroid weight: there were no differences between the RSM variants. In contrast to the treatment with myrosinase, in the sera of the chickens fed on untreated RSM or RSM treated with copper T⁴ could be detected, suggesting that in iodine-deficient conditions differences in serum T⁴ concentration between RSM groups indicate a differing anti-thyroid activity. With iodine supplementation the RSM had a significant effect on thyroid weight. The largest thyroids (five-fold heavier) were in the animals with myrosinase-treated cRSM. The untreated cRSM and the nRSM trebled or doubled the thyroid weight, and the myrosinase-treated nRSM trebled it. The thyroid weight of chicks fed cRSM treated with copper did not differ significantly from the glucosinolate-free control. There was evidence that heating the myrosinase-treated RMS produced anti-thyroid compounds; these should be identified in further investigations.     

Advances in possibilities for protein evaluation

With protein evaluation the changing abilities of food proteins are characterized with regard to their covering the requirements of the organism for protein or amino acids, respectively. The biological value of proteins is influenced by several factors. Measuring the reaction of the whole organism (of man or animal) to the food protein the sum of all influencing factors is covered. Hence, these direct evaluation methods have priority. The general dose-reaction curve demonstrates the direct evaluation methods: The evaluation criteria protein efficiency or minimum protein requirement are presented and the different possibilities of interpretion are compared. Most direct evaluation methods are performed with suboptimal protein supply, therefore values for an optimum protein supply can be derived only with reservation. Improved values for protein evaluation can be obtained from investigations of the protein metabolism. With that the substrat-related evaluation can be more orientated to a organism-related one. Indirect biochemical evaluation methods are less important. That does not concern in-vitro evaluation by amino-acid analysis and/or in-vitro digestibility tests. Possibilities and limits of these methods are discussed.     

Comparative studies on the enzymatic absorption of protein hydrolysates in the small intestine of the rat. 3. The absorption trypsins thermatatic and trypsin-thermatatic hydrolysates of a fava bean protein isolate compared to an equimolar mixture of free amino acids

Tryptic, thermitatic, and tryptic-thermitatic Faba bean protein hydrolyzates as well as their equimolar mixture of amino acids were perfused through proximal and distal parts of the intestine (10 cm length) of non-narcotized rats. The total amino-acid concentration of the perfused solution was 50 mM. The absorption of nitrogen and total amino acids from the tryptic and tryptic-thermitatic hydrolyzates was lower than that from the amino-acid mixture, the absorption from the thermitatic hydrolyzate was in accordance with that from the amino-acid mixture. The absorption pattern of the amino acids which preferably undergo a peptidic absorption is similar with the three hydrolyzates: in the proximal intestinal part this concerns glutamic acid and serine, in the distal intestinal part--methionine, alanine, glycin, and serine. The absorption pattern of the amino acids is different between the three hydrolyzates and the amino-acid mixture. Between the absorption pattern of the amino acids from the three hydrolyzates little differences were evident only in the proximal intestinal part. The coefficients of variation of the tryptic-thermitatic hydrolyzates are in accordance with those of the amino-acid mixture, whereas that of the thermitatic hydrolyzates is significantly lower. In the distal intestinal part all supplied forms are more rapidly absorbed than in the proximal part of the intestine.     

Comparative studies on the enzymatic absorption of protein hydrolysates in the small intestines of the rat. 3. The absorption of trypsin, thermitatic and trypsin thermitatic wheat gluten hydrolysates in comparison with equimolar mixtures of free amino acids

Tryptic, thermitatic, and tryptic-thermitatic wheat-gluten hydrolyzates as well as their equimolar amino-acid mixture were perfused through proximal and distal parts of the intestine (10 cm length) of non-narcotized rats. The total amino-acid concentration of the perfused solution was 50 mM. The tryptic hydrolyzate showed a significantly lower absorption of nitrogen and total amino acids than the amino-acid mixture. Both the supplied forms were very different as to their absorption pattern of the amino acids. The high variability of the percental absorption of the individual amino acids of the tryptic hydrolyzate results in a high coefficient of variation. The absorption of nitrogen and total amino acids from thermitatic and tryptic-thermitatic hydrolyzates is equal to that from the amino-acid mixture. In a peptidic form glutamic acid is more rapidly absorbed from the two hydrolyzates, and methionine from the tryptic-thermitatic hydrolyzate in both the intestinal parts. As to alanine and glycine this concerns only the distal intestinal part for both the hydrolyzates. There are no differences between the absorption patterns of the two hydrolyzates but in comparison with the amino-acid mixture and the tryptic hydrolyzate differences were evident. The coefficients of variation of both the hydrolyzates are significantly lower as compared to those of the tryptic hydrolyzate and the amino-acid mixture. All forms of supply are more rapidly absorbed in the distal than in the proximal part of the intestine.     

同时提取大豆中的油脂和蛋白质的工艺

近几年来 ,国外油脂科技的发展非常迅速 ,特别是在油脂工程的大型化、规模化 ,以及油脂工厂自动控制方面发展尤为迅速 ,同时 ,在油脂、油料蛋白及其功能性的研究方面也取得了不少重要成果。应广大读者的要求 ,《中国油脂》杂志从本期开始增加“国外动态”栏目 ,以期让广大读者了解更多国外新技术的动态。本期我刊选编了由国家粮食储备局西安油脂科学研究设计院武丽荣工程师根据“2 0 0 2年北京国际大豆技术及开发合作研讨会暨展示会 (CISCE2 0 0 2 )”的论文编译了几则有关油脂加工方面的论文 (摘编 ) ,这些论文从不同侧面反映了国外油脂行业的一种信息 ,以促进我国油脂工业的发展 ,进而促进我国油脂行业的科技进步     

Concentration and distribution of heavy metals in urban airborne particulate matter in Frankfurt am Main, Germany

Heavy metal concentrations were measured in airborne dust collected at three sites with different traffic densities from August 2001 to July 2002 in the Frankfurt am Main area. Bulk samples of particulate matter (PM) with an aerodynamic equivalent diameter of <22 microm were collected on cellulose nitrate filters using air filtration devices. Fractionated samples of PM with an aerodynamic equivalent diameter of <10 microm were collected using an eight-stage Andersen impactor. Pb, Cd, Mn, Ni, Zn, V, As, Sb, Cu, Cr, Co, and Ce were determined by inductively coupled plasma sector field mass spectrometry, Pt and Rh were determined by adsorptive voltammetry, and Pd was determined by total reflection X-ray fluorescence analysis. The results show that the highest airborne heavy metal concentrations occurred at the main street with a large volume of traffic. With the exception of Co, V, Ce, and Mn, the heavy metals had an elevated enrichment factor compared to their concentrations in the continental crust. The main street site was especially contaminated with Sb, Zn, Cu, V, and Ni. Motor vehicles are the likely source of emissions. With the exception of Cr, Cu, and Zn, most of the airborne heavy metal concentrations determined for impactor samples deviate slightly from the results for total airborne dust. Heavy metal particle size distributions can be divided into three groups. For metals such as As, Cd, Pb, and V, the main fraction can be found in fine particles with a diameter of <2.1 microm, whereas Ce, Cr, Co, and Ni occur mainly in coarse particles with a diameter of >2.1 microm. Cu, Mn, Sb, Zn, Pt, Pd, and Rh occur in high concentrations in the medium range of the impactor stages (particle diameters of 1.1-4.7 microm). Metal concentrations in fine dust particles are needed to assess the human health risks of their inhalation.     

The impact of different hop compounds on the growth of selected beer spoilage bacteria in beer

Beer spoiling lactic acid bacteria are a major reason for quality complaints in breweries around the world. Spoilage by a variety of these bacteria can result in haze, sediment, slime, off-flavours and acidity. As these bacteria occur frequently in the brewing environment, using certain hop products that inhibit the growth of these spoilers could be a solution to prevent problems. To investigate the impact of seven different hop compounds (α-acids, iso-α-acids, tetrahydro-iso-α-acids, rho-iso-α-acids, xanthohumol, iso-xanthohumol and humulinones) on the growth of six major beer spoilage bacteria (Lactobacillus brevis. L. backi, L. coryniformis, L. lindneri, L. buchneri, Pediococcus damnosous), two concentrations (10 and 25 mg/L) of each hop substance were added to unhopped beer. The potential growth of the spoilage bacteria was investigated over 56 consecutive days. A comparison of the results shows a strong inhibition of growth of all spoilage bacteria at 25 mg/L of tetrahydro-iso-α-acids closely followed by α-acids as the second most inhibitory substance. The results showed a high resistance of L. brevis to all hop compounds as well as an inhibition of L. coryniformis and L. buchneri at low concentrations of most hop components. In comparison with the control sample, L. lindneri showed increased growth in the presence of some hop compounds (rho-iso-α-acids, xanthohumol, iso-xanthohumol, humulinones). © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling     

Das Verhalten von kohlenstoffarmem Stahl bei Wasserstoffbeladung und plastischer Verformung

Verknüpfung der Wasserstoffversprödung des unlegierten Stahls mit der Spaltrißbildung. Vergleich des Einflusses von Spaltrissen, die vor der Verformung vorhanden waren, mit denen, die erst während der Verformung entstehen. Transport des Wasserstoffes während der Verformung bei gleichzeitiger Wasserstoffaufnahme und -abgabe. Einfluß von Kornstruktur, Verformungsgeschwindigkeit, Gesamtverformungsgrad und Verformungsart auf die Wasserstoff-umlagerung bei Verformung.