Iron deficiency up-regulates iron absorption from ferrous sulphate but not ferric pyrophosphate and consequently food fortification with ferrous sulphate has relatively greater efficacy in iron-deficient individuals

Fe absorption from water-soluble forms of Fe is inversely proportional to Fe status in humans. Whether this is true for poorly soluble Fe compounds is uncertain. Our objectives were therefore (1) to compare the up-regulation of Fe absorption at low Fe status from ferrous sulphate (FS) and ferric pyrophosphate (FPP) and (2) to compare the efficacy of FS with FPP in a fortification trial to increase body Fe stores in Fe-deficient children v. Fe-sufficient children. Using stable isotopes in test meals in young women (n 49) selected for low and high Fe status, we compared the absorption of FPP with FS. We analysed data from previous efficacy trials in children (n 258) to determine whether Fe status at baseline predicted response to FS v. FPP as salt fortificants. Plasma ferritin was a strong negative predictor of Fe bioavailability from FS (P <0·0001) but not from FPP. In the efficacy trials, body Fe at baseline was a negative predictor of the change in body Fe for both FPP and FS, but the effect was significantly greater with FS (P <0·01). Because Fe deficiency up-regulates Fe absorption from FS but not from FPP, food fortification with FS may have relatively greater impact in Fe-deficient children. Thus, more soluble Fe compounds not only demonstrate better overall absorption and can be used at lower fortification levels, but they also have the added advantage that, because their absorption is up-regulated in Fe deficiency, they innately ‘target’ Fe-deficient individuals in a populatio

Baseline Experimental Results on the Effect of Oil Temperature on Shrouded Meshed Spur Gear Windage Power Loss

Rotorcraft gearbox efficiencies are reduced at increased surface speeds due to viscous and impingement drag on the gear teeth. This windage power loss can affect overall mission range, payload, and frequency of transmission maintenance. Experimental and analytical studies on shrouding for single gears have shown it be potentially effective in mitigating windage power loss. Efficiency studies on unshrouded meshed gears have shown the effect of speed, oil viscosity, temperature, load, lubrication scheme, etc. on gear windage power loss. The open literature does not cite data on shrouded meshed spur gears. Gear windage power loss test results are presented on shrouded meshed spur gears at elevated oil inlet temperatures and constant oil pressure both with and without shrouding. Shroud effectiveness is compared at four oil inlet temperatures. The results are compared to the available literature and follow-up work is outlined

The Effectiveness of Shrouding on Reducing Meshed Spur Gear Power Loss - Test Results

Gearbox efficiency is reduced at high rotational speeds due to windage drag and viscous effects on rotating, meshed gear components. A goal of NASA aeronautics rotorcraft research is aimed at propulsion technologies that improve efficiency while minimizing vehicle weight. Specifically, reducing power losses to rotorcraft gearboxes would allow gains in areas such as vehicle payload, range, mission type, and fuel consumption. To that end, a gear windage rig has been commissioned at NASA Glenn Research Center to measure windage drag on gears and to test methodologies to mitigate windage power losses. One method used in rotorcraft gearbox design attempts to reduce gear windage power loss by utilizing close clearance walls to enclose the gears in both the axial and radial directions. The close clearance shrouds result in reduced drag on the gear teeth, and reduced power loss. For meshed spur gears, the shrouding takes the form of metal side plates and circumferential metal sectors. Variably positioned axial and radial shrouds are incorporated in the NASA rig to study the effect of shroud clearance on gearbox power loss. A number of researchers have given experimental and analytical results for single spur gears, with and without shrouding. Shrouded meshed spur gear test results are sparse in the literature. Windage tests were run at NASA Glenn using meshed spur gears at four shroud configurations: unshrouded, shrouded (max. axial, max radial), and two intermediate shrouding conditions. Results are compared to available meshed spur gear power loss data analyses as well as single spur gear data/analyses. Recommendations are made for future work

Stability of tryptophan during food processing and storage: 2. A comparison of methods used for the measurement of tryptophan losses in processed foods

1. Tryptophan losses in stored milk powders and in different model systems representing the major reactions of food proteins during processing and storage were determined using four different chemical methods and in a rat assay. 2. Similar tryptophan values were obtained by the three chemical methods which included high pressure liquid chromatography (HPLC) after sodium hydroxide hydrolysis. colorimetric reaction with p-dimethylamino- benzaldehyde (p-DAB) after barium hydroxide hydrolysis, and fluorescence of the Norharman derivative after NaOH hydrolysis. 3. Tryptophan losses in the treated proteins as measured by the alkaline-hydrolysis methods were generally smaller than those determined by the rat assay. Good agreement however was obtained when the chemical value was multiplied by the true nitrogen digestibility. 4. Determination of tryptophan by reaction with p-DAB after papain (EC 3.4.22.2) digestion gave lower values in the processed proteins than the other chemical methods or the rat assay. 5. A method using alkaline-hydrolysis is recommended, preferably combined with HPLC-measurement of the liberated tryptopha

Reactions of proteins with oxidizing lipids: 1. Analytical measurements of lipid oxidation and of amino acid losses in a whey protein-methyl linolenate model system

1. The reactions between protein-bound amino acids and oxidizing lipid were investigated in a whey protein-methyl linolenate (C18.3)-water model system. The extent of fat oxidation was followed by measuring oxygen uptake, hydroperoxide formation and hydrocarbon (ethane and pentane) formation. 2. Significant losses occurred with lysine (up to 71 %), tryptophan (up to 31 %) and histidine (up to 57%). Methionine was extensively oxidized to its sulphoxide but less than 2% was further oxidized to the sulphone. No other amino acids were affected. 3. Increasing storage temperature (20°, 37°, 55°) resulted in an enhancement of fat oxidation reactions and amino acid degradation. 4. Increasing water activity (0.28, 0.65, 0.90) increased losses of lysine and tryptophan but had no influence on the oxidation of methionine, the level of remaining hydroperoxides or 02 uptake. Hydrocarbons were decreased. 5. Limitation of 02 uptake to 1 mol/mol lipid instead of excess 02 (02 uptake about 2.5 mol/mol lipid in 4 weeks) significantly reduced the degradation of lysine and tryptophan but had less influence on the oxidation of methionine. The level of remaining hydroperoxides was increased but hydrocarbons were unaffecte

An analysis of the acoustic cavitation noise spectrum: The role of periodic shock waves

Research on applications of acoustic cavitation is often reported in terms of the features within the spectrum of the emissions gathered during cavitation occurrence. There is, however, limited understanding as to the contribution of specific bubble activity to spectral features, beyond a binary interpretation of stable versus inertial cavitation. In this work, laser-nucleation is used to initiate cavitation within a few millimeters of the tip of a needle hydrophone, calibrated for magnitude and phase from 125 kHz to 20 MHz. The bubble activity, acoustically driven at f0 = 692 kHz, is resolved with high-speed shadowgraphic imaging at 5 × 106 frames per second. A synthetic spectrum is constructed from component signals based on the hydrophone data, deconvolved within the calibration bandwidth, in the time domain. Cross correlation coefficients between the experimental and synthetic spectra of 0.97 for the f 0/2 and f 0/3 regimes indicate that periodic shock waves and scattered driving field predominantly account for all spectral features, including the sub-harmonics and their over-harmonics, and harmonics of f 0

Storage of milk powders under adverse conditions: 2. Influence on the content of water-soluble vitamins

1. Storage of milk powder under unfavourable conditions accelerates the normally slow deterioration in nutritional quality. The effects of such storage on the water-soluble vitamin composition were examined. 2. (a) Spray-dried whole milk containing 25 g water/kg was stored at 60° and 70° and sampled weekly to 9 weeks. (b) Spray-dried whole milk and skimmed milk were adjusted to contain 40 and 100 g water/kg and stored at 37° in nitrogenand in oxygen. Samples were taken for analysis at intervals during storage. 3. The samples were analysed for eight B-complex vitamins and ascorbic acid, and also for total lysine, ‘reactive lysine' and ‘lysine as lactulosyl-lysine'. 4. Storage at 60° caused rapid destruction of folic acid (53% loss at 4 weeks) and slower loss of thiamin, vitamin B6 and pantothenic acid (18% at 8 weeks). There was no change in the content of riboflavin, biotin, nicotinic acid and vitamin B12. At 70° the rate of destruction of the four labile vitamins was much increased; 18% or less survived at 4 weeks. 5. At 37° and 40 g water/kg there was little change in total and ‘reactive' lysine during storage for 57 d. Lactulosyl-lysine was demonstrably present butatlow concentration. There was considerable loss of folate (72%) and ascorbate (91%) during storage for 30 d in O2, but no significant loss in N2. Thiamin fell by approximately 12% in 57 d, equally in O2 and N2. The content of the remaining vitamins was unchanged. At 100 g water/kg there were progressive Maillard changes. During 27 d in N2 the colour changed from cream to palebrown, but in O2 there was no perceptible colour change. Total lysine fell by 20% in 27 d, and ‘reactive lysine' by 30%. Folate was stable during 16 d in N2, but largely (94%) destroyed in O2. Ascorbic acid was also destroyed in N2 as in O2. Thiamin fell by 41% in 27 d, equally in O2 and N2. Vitamin B6 was more labile, especially in N2, falling by 71% in 16d. 6. With skimmed-milk powder containing 100 g water/kg, storage at 37° in O2 and N2 gave much the same results as for the corresponding whole-milk powder. The presence of milk fat had no marked effect on the stability of the water-soluble vitamins. 7. Destruction of vitamins was clearly linked to the progress of Maillard-type reactions and was strongly influenced by time and temperature of storage, moisture content and, in some instances, by the presence of O

Reactions of proteins with oxidizing lipids: 2. Influence on protein quality and on the bioavailability of lysine, methionine, cyst(e)ine and tryptophan as measured in rat assays

1. The consequences of reactions between protein and oxidizing lipids on the nutritional quality of food proteins have been investigated using a whey protein-methyl linolenate-water model system. 2. In rat assays, significant reductions were observed in protein efficiency ratio, net protein ratio, net protein utilization, biological value and true nitrogen digestibility, especially when the reaction had taken place at high moisture content, high temperature and in the presence of excess oxygen. 3. The losses of bioavailable lysine and tryptophan as measured by rat assays followed a similar pattern. The chemical value of each amino acid multiplied by the true N digestibility closely resembled the rat assay value. In general, the reaction products of lysine and tryptophan formed during lipid oxidation were biologically unavailable. 4. The bioavailabilities of methionine and of ‘methionine plus cyst(e)ine' were determined in separate assays. Cyst(e)ine was calculated as ‘methionine plus cyst(e)ine' minus methionine. In whey protein which had reacted with oxidizing methyl linolenate, the bioavailable methionine content was not significantly reduced even though 82% of the methionine residues were present as methionine sulphoxide. In hydrogen peroxide-treated casein in which all methionine residues were oxidized to the sulphoxide, methionine sulphoxide was found to be 96% as utilizable as a methionine source to the rat. Free methionine sulphoxide was 87% utilizable. 5. Cyst(e)ine appeared to be as sensitive as lysine to reactions with lipid oxidation products. In whey protein which had reacted with oxidizing methyl linolenate, the bioavailabilities of cyst(e)ine, lysine, tryptophan and methionine were reduced by 28, 24, 11 and 8% respectively and true N digestibility by 9%. These results are discussed in relation to food product

Storage of milk powders under adverse conditions: 1. Losses of lysine and of other essential amino acids as determined by chemical and microbiological methods

1. Whole-milk powders containing 25 g water/kg were stored for up to 9 weeks in sealed aluminium containers at elevated temperatures. Lysine and other essential amino acids were measured by chemical and microbiological methods. 2. Storage at 60° resulted in the progressive formation of lactulosyl-lysine. After 9 weeks, 30% of the lysine groups were present in this form. The powders still retained their natural colour and the levels of tryptophan, methionine, cyst(e)ine and leucine remained unchanged. 3. Storage at 70° resulted in the formation of lactulosyl-lysine followed by its complete degradation with the development of browning. Available tryptophan, methione, leucine and isoleucine decreased progressively during storage. 4. The different methods for lysine determination gave widely dissimilar results. The direct fluorodinitrobenzene (FDNB) technique and reactive lysine from furosine were considered to be the most reliable methods. The FDNB-difference, dye-binding lysine, Tetrahymena and Pediococcus methods all seriously underestimated reactive or available lysine in heat-damaged milk powders. Tetrahymena and Pediococcus appeared to utilize lactulosyl-lysine as a source of lysine. 5. The results are discussed in relation to storage and distribution of milk powders in hot climate

Protein-polyphenol reactions: 1. Nutritional and metabolic consequences of the reaction between oxidized caffeic acid and the lysine residues of casein

1. Studies were made on the lysine content of casein reacted with caffeic acid oxidized aerobically under alkaline conditions or enzymically with tyrosinase (EC 1.14.18.1). 2. Loss of fluorodinitrobenzene (FDNB)-reactive lysine was rapid at pH 10 and increased with time and the temperature of the reaction, with concentration of caffeic acid and with the oxygenation of the mixture. In presence of the enzyme mushroom tyrosinase, maximum reduction of reactive lysine occurred at pH 7 and was dependent on the reaction time and on the concentration of caffeic acid. 3. Reaction of α-formyl-L-[U- 14C]lysine with caffeic acid at pH 10 showed the rapid formation of five reaction products which appeared to polymerize gradually as the reaction progressed. 4. The nutritionally available lysine content of the casein-caffeic acid mixtures, as assayed with rats, was reduced after both alkaline and enzymic reactions, as were faecal digestibility, net protein ratio and net protein utilization. Biological value however was not reduced. 5. In metabolic studies using goat milk casein labelled with L-[3H]lysine and reacted with caffeic acid in the same way, the lysine-caffeoquinone reaction products were not absorbed by the rat but were excreted directly in the faeces. 6. The importance of the reaction of proteins with caffeoquinone and chlorogenoquinone (formed by the oxidation of caffeic and chlorogenic acids respectively) is discussed in relation to the production of sunflower protein, leaf protein and other vegetable-protein concentrate