Library

Notes: Radiochemical measurements have been developed for the diagnostics of laser-driven implosion plasmas. The excellent calibration for neutron-yield measurement has been done using β-γ coincidence technique. The multiactivable tracer method has been examined for measuring the pusher areal density by means of a high-purity germanium detector. The first experimental success of the secondary nuclear fusion reaction method is also demonstrated for the direct measurement of the fuel ρR.

Notes: Immunoglobulins and α-lactalbumin of acid whey were concentrated in supernatant and precipitate when FeCl3 was added at pH 4.2 and 2.8, respectively. Optimized conditions of pH 4.2 were preferable because of higher retention of immunochemical activity of immunoglobulins. In acid whey treated with 7.5 mM FeCl3 at pH 4.2 and 4°C, 90% of β-lactoglobulin coprecipitated with serum albumin while 70% of immunoglobulins (92% immunochemically active IgG) and 95% of α-lactalbumin were retained in the supernatant. More than 98% of added iron was subsequently eliminated as precipitate by holding the treated whey at pH 8-9 and 4°C, without losing immunochemical activity of immunoglobulin G, in addition to retained activity of immunoglobulins A and M.

Notes: When the pH of cottage cheese whey was adjusted to 4.5 in the presence of 6.7 mM FeCI3, β-lactoglobulin was eliminated from the whey as a precipitate. However, the majority of immunoglobuhns were also coprecipitated. To recover immunoglobulins together with α-lactalbumin, the whey pH was adjusted to 3.0 in the presence of 4.0 mM FeCI3. After centrifugation of the whey, the supernatant contained exclusively β-lactoglobulin; other whey proteins were found in the precipitate. Excess Fe+++ in the precipitate was removed by ion exchange or by ultrafiltration. This protein concentrate had a protein composition much more similar to that of human milk whey than that of ultrafiltered whey protein concentrate.

Notes: Although the mapping process significantly improved the efficiency of simplex optimization, the procedure subsequent to mapping required manual adjustments. An attempt was made to standardize the optimization procedure so as to avoid subjectivity. A selfinstructive computer program of the standardized procedure was written for a hand-held computer. The program was inexpensive and convenient to apply the mapping simplex optimization to problems in product and process development.

Notes: Four methods (absorbance at 280 nm; the Lowry method; the fluor-escamine method, and the trinitrobenzenesulfonic acid method) for determining hydrolysis of milk proteins were compared. Each method was applied to the trichloracetic acid soluble fraction of milk protein, which had been digested with trypsin for various periods of time. Detectability was measured as the ratio between standard error of estimate and slope calculated from the linear regression analysis of Deming for cases when both variables were subject to error. Although it was nondimensional, the detectability thus calculated was simple and reliable for comparing assay methods which were based on different analytical principles. Detectability as well as the detection limit measured according to Schwerdtfeger showed that, of the methods compared, the fluorescamine method was most reliable and sensitive.

Notes: Nɛ-Protected lysine derivatives and threonine were covalently attached to wheat gluten using 1-ethyl-3-(3-dimethylaminopro-pyl)carbodiimide. Influential reaction factors were studied using fractional factorial experiments. Lysine content increased 4.0-fold and 6.5-fold after reaction of pepsin-hydrolyzed gluten with NE-benzylidene lysine and NE-acetyl lysine respectively, but product yields were low (40–65%). Using unhydrolyzed gluten as the starting material, 1.6-fold and 2.5-fold lysine increases resulted using NC-benzylidene and NE-acetyl lysine, respectively, with 95% yield. At least 4-fold increase in threonine could be obtained from reaction of threonine with pepsin-hydrolyzed gluten, but with only 30–50% product yield. Yields increased to 96% by reacting threonine with unhydrolyzed gluten, with 1.8-fold increase in threonine.

Notes: The interaction between αs1, -casein and K-carrageenan was investigated by sedimentation velocity and sedimentation equilibrium ultra-centrifugation, frontal chromatography, fluorescence polarization, viscosity, and turbidity experiments. Schlieren patterns of αs1-casein-K-carrageenan mixtures during sedimentation velocity ultracentrifugation experiments (pH 6.6, μ= 0.08) revealed a large αs1 -casein containing peak followed by a slower sedimenting peak which was thought to be residual, uncomplexed k-carrageenan. The S2 0, w of the interaction peak was greater than the S2 0, w of αs1 -casein alone under identical conditions. The effects of pH, ionic strength, temperature and 6.OM urea suggested that the interaction observed during sedimentation velocity ultracentrifugation and viscometry of αs1 -casein and K-carrageenan was mediated by hydrogen bonding. Fluorescence polarization, frontal chromatography, and molecular weight distributions calculated from sedimentation equilibrium data, however, showed that αs1 -casein and K-carrageenan did not interact in calcium-free systems (pH 6.6, μ= 0.08). DNS-αs1 -casein and DNS-K-carrageenan were employed as the labelled components during the fluorescence polarization experiments. αs1 -Casein-K-car-rageenan mixtures eluted from a controlled pore glass column (170 Å pore diameter) as the individual components with elution volumes identical to those obtained when αs1 -casein and K-carrageenan were chromatographed separately. The molecular weight distributions of αs1 -casein-K-carrageenan mixtures (pH 6.6, μ= 0.08), subjected to sedimentation equilibrium ultracentrifugation, contained a major peak in the molecular weight range corresponding to unreacted αs1, -casein. Thus the “interaction” revealed by sedimentation velocity and viscosity data was not a chemical interaction but, rather a physical entrapment of αs1 -casein by K-carrageenan. Fluid flow through the capillary during viscosity measurements and the intense gravitational fields generated during sedimentation velocity ultracentrifugation probably induced physical entanglement of the K-carrageenan. Under these conditions, αs1 -casein-K-carrageenan mixtures flowed as a “porous-plug” where αs1 -casein, larger than the pores of the K-carrageenan network, was trapped giving rise to the observed “interaction” peak. Physical entanglement of αs1 -casein within the K-carrageenan system which causes a pseudo-interaction was not detected during frontal chromatography, sedimentation equilibrium, and fluorescence polarization measurements. Thus, αs1 -casein and K-carrageenan do not chemically interact in calcium-free systems.

Notes: Adsorption methods for debittering skim milk hydrolysates were compared in an attempt to develop acid-soluble milk solids for fortification of beverages which appear and taste like the original beverages after fortification of the milk solids up to the level of skim milk. Preliminary studies using casein hydrolysates indicated that the bitter peptides were mostly hydrophobic as they were almost completely eliminated by hydrophobic chromatography on hexylepoxy Sepharose, Activated carbon, talc, and flcyclodextrin were more effective in adsorbing bitter peptides than Sephadex G-10. With skim milk hydrolysate, it was observed that activated carbon, glass powder or fiber, Sephadex LH-20, and phenoxyacetyl cellulose were effective in this order in reducing the bitter flavor of skim milk hydrolysate. 100% carbon vs protein completely eliminated the bitterness of Pronase- or ficin-hydrolyzed skim milk; the carbon requirement was reduced by 70% when Pronase hydrolysates were pretreated with glass fiber. About 60% of the riboflavin and less than 5% of the protein were lost during treatment; no substantial decrease in lactose, calcium or ash content was observed. The essential amino acid pattern compared well with the FAO/WHO (1973) provisional reference pattern except for the total aromatic amino acid content which was 81% that of the reference pattern. Sensory analysis of the product indicated that orange crush, orange juice, and grapefruit soda were not significantly preferred over beverages containing 10% hydrolysate solids, while apple juice was preferred to the fortified juice due to a faint whey-like salty flavor of the fortified juice. No difference in the appearance was detected between the fortified and the original beverages except a slight turbidity developed when clear apple juices were fortified. The two bitter peptides were isolated from the butanol extract of the activated carbon used in debittering Pronase-hydrolyzed skim milk. It is likely that these peptides were derived from casein especially αS1-casein.

Notes: Surface hydrophobicity (So) of crude salt extracts of meat was determined fluorometrically using cis-parinaric acid as a probe. Upon heating the extracts to 70°C, So increased two- to threefold, whereas protein solubility (s) decreased to 20%. Further heating (to 85°C) resulted in slight decreases in both So and s. Backwards stepwise multiple regression equations for prediction of emulsifying activity index (EAI) and emulsifying capacity (EC) were: EAI = 2.658 + 0.0001308 sSo, and EC =−35.30 + 6.459 s + 0.001317 sSo− 0.05463 s2. So was most important for predicting emulsifying properties of samples with high (〉50%) solubility, whereas solubility parameters were more influential for samples with low (〈50%) solubility.

Notes: The carbodiimide condensation reaction was used for covalently binding methionine and tryptophan to soybean protein thereby improving its nutritive value. Various conditions of the carbodiimide reaction were analyzed by a fractional factorial design in an attempt to determine the factors affecting the amino acid binding to soy protein hydrolysate (SPH). Of the factors investigated, pH, SPH concentration, carbodiimide concentration, activation time and reaction time were found to significantly affect the methionine binding efficiency, whereas pH, SPH concentration, carbodiimide concentration, amino acid concentration and reaction temperature were found to significantly influence the tryptophan binding efficiency to SPH. Under the best condition found, the methionine and tryptophan contents of methionine- and tryptophan-bound SPH were increased 7.7-fold and 18.0-fold, respectively. An in vitro pepsin-pancreatin digestion test demonstrated that the bound amino acids were readily released. To improve the protein recovery that was only 16–30% when SPH was used, soy protein isolate without pepsin hydrolysis, instead, was used as the starting material. A product with 95–99% protein recovery was obtained and its methionine or tryptophan content was increased 6.3-fold or 11.3-fold, respectively. High digestibility was still maintained for these products. Gel filtration chromatography demonstrated that the carbodiimide reaction caused an increase in the molecular weights of soy protein fractions; no selective amino acid binding among the different soy protein fractions during the carbodiimide reaction was observed.