Levente L. Diosady

Stability of Iodine in Iodized Salt Used for Correction of Iodine-Deficiency Disorders. II

The purpose of this study was to assess the effect of humidity and packaging materials on the stability of iodine in typical salt samples from countries with tropical and subtropical climates under controlled climatic conditions. Initially we examined eight samples. In the second phase we expanded the study to salts from 18 sources and attempted to correlate the observed stability with salt impurities naturally present in these samples. High humidity resulted in rapid loss of iodine from salt iodized with potassium iodate ranging from 30% to 98% of the original iodine content. Solid low-density polyethylene packaging protected the iodine to a great extent. High losses were observed from woven high-density polyethylene bags which are often the packaging material of choice in tropical countries. Impurities that provided moisture at the salt surface had the most deleterious effect. Although clear correlations were not obtained the presence of reducing agents hygroscopic compounds of magnesium and so forth seemed to have the most adverse effects on the stability of iodine. Surprisingly carbonates had little effect on stability over the range present in the samples. Packaging salt in low-density polyethylene bags which provided a good moisture barrier significantly reduced iodine losses and in most cases the iodine content remained relatively stable for six months to a year. The findings from this study indicate that iodine can be highly unstable and in order to ensure the effectiveness of local salt-iodization programmes countries should determine iodine losses from local iodized salt under local conditions of production climate packaging and storage. (authors)This paper operationalizes household food security and links it to household food consumption patterns in rural Nepal. Food security has long been used as a macro-level indicator of agricultural stability by both agricultural and economic researchers. However, little work has been done to operationalize it at the household level. We view household food security as reflecting three different dimensions: past food supply, current food stores, and future supply of food adequate to meet the needs of all household members. A key method is the construction of scales that capture these different aspects of household food security. When operationalized in this way, household food security is associated with increased consumption of non-staple foods in this setting. Past household food security is associated with increased frequency of meat consumption and increased variety of food consumed. Current household food security predicts a higher frequency of meat and dairy intake and greater dietary variety. Future household food security is associated with increased total dietary variety and future consumption of dairy products. We feel that this conceptual approach to assessing household food security, i.e., the use of scales to measure past, current, and future components of food security, can be used as a framework in other settings. Operationalizing household food security in rural Nepal

Removal of phenolic compounds in the production of high-quality canola protein isolates

Abstract Phenolic compounds are a major cause of the dark colour and undesirable taste of canola protein isolates. Based on our previous study of phenolic–protein interactions, a variety of treatments were tested for the removal of phenolic compounds from canola proteins. The combined use of these treatments was able to reduce the phenolic content of the products by 80–90%. Thus modified, the process produced two canola protein isolates, both of high protein content (>85%), low in phenolic acids (∼200 mg/100 g), and essentially free of condensed tannins. Colour measurement and sensory evaluation confirmed that the removal of phenolic compounds improved the colour and taste of canola protein isolates.

Interactions between canola proteins and phenolic compounds in aqueous media

Abstract Proteins and phenolic compounds are readily extractable from canola meal at alkaline pH. In aqueous media they interact to form complexes, thus contributing to the dark colour and undesirable taste of canola protein products recovered from alkaline extracts. The interactions between phenolic compounds and canola proteins were, therefore, studied at pH 12.0 and 3.5 using a novel system that combined a series of chemical treatments with membrane processing to break phenolic–protein complexes and then separate the released phenolic compounds from the proteins. This method was able to classify the extracted phenolic compounds into different fractions according to their bonding mechanisms to canola proteins. In total some 50% of the extracted phenolic compounds in these extracts formed complexes with canola proteins by different mechanisms, among which ionic bonding was predominant. The phenolic fractions bound by hydrophobic interactions, hydrogen bonding, or covalent bonding were relatively small, each constituting less than 10% of the total extractable amount.

Degradation of wheat starch in a twin-screw extruder

Abstract Wheat starch was processed in a Baker-Perkins MPF-50D co-rotating twin-screw extruder, at moisture contents of 25% and 30%, screw speeds of 200 rpm and 300 rpm, feed rate of 30 kg/h, and barrel temperature settings of 100, 120, 140 and 160 °C. High performance size exclusion chromatography was used to determine the extent of degradation of starch along the extruder channel. Starch degradation was found to take place in the cooking zone. The first-order mechanodegradation models, which were developed for a single-screw extruder, were extended to the twin-screw extruder and improved by including a more accurate description of gelatinization in the model. The degradation is described by the equation: χ = 1 − {1 − exp [−k 0 exp (− (ΔE 0 − βτ) (RT) )t]} {1 − exp (−kτt + B)} where τ is the average shear stress, t is the mean residence time of the melt in the active zone of the screw channel, ΔE0 is the activation energy, R is the ideal gas constant, β is the activation volume, k and k0 are experimental constants.

Rapid aqueous extraction of mucilage from whole white mustard seed

Abstract Yellow or white mustard mucilage, present on the surface of Sinapis alba seeds, causes major difficulties in the separation of the oil during aqueous processing due to its effectiveness as an emulsifier. A rapid, efficient aqueous extraction process for the removal of the mucilage from the whole seeds prior to grinding and oil separation has been developed and demonstrated on 1 and 5 l scales. A two-stage extraction process using water with an initial temperature of 45°C at an 8:1 water to seed ratio resulted in over 90% mucilage removal in approximately 3 h. Mucilage removal significantly reduced the water requirement for aqueous oil separation. A three-parameter mathematical model, based upon mass transfer considerations and diminishing mucilage layer thickness, was developed and shown to fit the bulk phase mucilage concentration data during extraction. Concentration data from many different experimental conditions were shown to superimpose when time scaling factors were employed.

Effect of sequestering agents on lipid oxidation in cooked meats

Abstract To retard lipid oxidation, which affects the sensory and nutritional quality of cooked meats, a number of sequestering agents (ortho- and polyphosphates, citric acid, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), salicylic acid, the sodium salts of oxalic, phytic and lactic acids, glycine, cysteine, 8-hydroxy-quinoline and catechol) were added to ground pork prior to cooking. The TBA numbers of meat were evaluated after cooking (day 1) and after 7, 14, 21, 28 and 35 days of storage at 4°C by the 2-thiobarbituric acid (TBA) test. It was found that catechol, EDTA, DTPA, sodium pyrophosphate and, to a lesser extent, sodium tripolyphosphate, substantially lowered the TBA numbers while the other sequestering agents had only a marginal effect. Mixed-chelating systems composed of salicylic acid and either EDTA or DTPA did not show any synergistic effects.

In-line colour and composition monitoring in the extrusion cooking process

Abstract This paper demonstrates the feasibility of using a fiber-optic equipped visible-near-infra-red (Vis-NIR) spectrometer to monitor both colour and composition in an extruder during the extrusion of yellow corn flour. A first series of experiments was conducted without adding any colouring in order to study the changes in colour and composition during the extrusion process. Screw speeds of 40, 50 and 60 rpm and temperatures of 130, 150 and 170°C were used in a 3×3 factorial design to examine the effect of screw speed and temperature. The main effects of these factors and their interaction effect was shown to be highly significant to the L ∗ a ∗ b ∗ colour co-ordinates obtained from the reflectance spectra of the reacting corn flour. The near-infra-red (NIR) spectra were also greatly affected. A second series of experiments involved adding a food colouring (FD&C red 40) to the flour prior to extrusion at different levels. The results showed that difference in food dye concentrations can be detected in-line. Correlation of the colour values obtained in the extruder with chemical composition and with colour of the cooled product as well as development of calibration methods for quantitative interpretation of the composition from the NIR spectra are in progress.

Rapid method for total phenolic acid determination in rapeseed/canola meals

Abstract A procedure for the determination of total phenolic acid content in rapeseed/ canola was developed by combining and modifying two currently used methods. It consists of refluxing the sample with acidic acetone, alkaline hydrolysis of esterified phenolic acids followed by acidification, extraction with ethyl acetate/ ethyl ether, and colormetric measurement using Folin-Denis reagent. The method was tested with canola and casein samples spiked with sinapic acid or sinapine bisulphate standards. Recoveries ranging from 95 to 106% were obtained, and the detection limit was determined to be less than 5 mg sinapic acid equivalents per 100 g sample.

The Production of Chinese Rapeseed Protein Isolates by Membrane Processing

A membrane-based process was developed for the production of Chinese rapeseed protein isolates, which consisted of alkaline extraction of protein at pH 12.0 from CH2OH/NH3/H2O-hexane-extracted Chinese rapeseed meal, isoelectric precipitation at pH 6.5, ultrafiltration followed by diafiltration to concentrate the remaining soluble protein, and freeze-drying. No chemical treatment was required for the removal of phytates from the protein. Three products were obtained with high protein recovery: precipitated and soluble protein isolates, each containing 90 to 100% protein, suitable for animal feed. The two protein isolates were low in phytates, light in color and bland in taste. Chinese rapeseed protein was easier and more economical to treat than canola protein due to the shift of pH for isoelectric precipitation and the elimination of the need for further phytate reduction.

Heterogeneous catalytic hydrogenation of canola oil using palladium

The hydrogenation of canola oil was studied using palladium black as a potential catalyst for producing partially hydrogenated fats with lowtrans-isomer content. Pressure (150\s-750 psig) appeared to have the largest effect ontrans-isomer formation. At 750 psig, 90 C and 560 ppm metal concentration, a maximum of 18.7%trans isomers was obtained at IV 53. A nickel catalyst produces about 50%rans isomers at the same IV. For palladium black, the linolenate and linoleate selectivities were 1.2 and 2.7, respectively. The maximum level oftrans isomers observed ranged from 18.7% to 42.8% (150 psig). Temperature (30\s-90 C) and catalyst concentration (80\s-560 ppm) affected the reaction rate with little effect ontrans-isomer formation and selectivities. At 250 psig and 50 C, supported palladium (5% Pd/C) appeared to be twice as active as palladium black. At 560 ppm Pd, 5% Pd/C produced 30.2%trans (IV 67.5), versus 19.0%trans for palladium black (IV 68.9). Respective linoleate selectivities were 15 and 6.6, while linolenate selectivities were approximately unity. Analysis of the oil samples by neutron activation showedapproximately a 1 ppm, Pdresidue after filtration.