Urinary iodine concentrations in mothers and their term newborns in country with sufficient iodine supply.

OBJECTIVE: The main aim of the study was to evaluate maternal and newborn urinary iodine concentrations according to the usage of iodine supplementation during pregnancy. METHODS: Thirty-seven women with singleton uncomplicated pregnancies and their newborns were included in this study. Maternal urine samples were obtained at the time of delivery and on the third day after delivery. Newborn urine samples were obtained on the third day after delivery. Urinary iodine concentrations were determined by the alkaline ashing of urine specimens followed by the Sandell-Kolthoff reaction using brucine as a colorimetric marker. RESULT: The overall rate of the usage of iodine supplementation during pregnancy was 54% (20/37). Women who used the iodine supplementation during the pregnancy did not have different urinary iodine concentrations neither at the time of delivery (p = 0.23), nor on the third day after delivery (p = 0.65) in comparison to women without extra iodine supplementation. Newborns from pregnancies with regular iodine supplementation had higher urine iodine concentrations on the third day after delivery (p = 0.02). When women were split into several subgroups based on the daily dosage of iodine supplementation (200, 150, and 50 µg daily and without iodine supplementation), no differences were found in maternal urine iodine concentrations at the time of delivery (p = 0.51) and on the third day after delivery (p = 0.63). Different levels were found in newborn urine iodine concentrations among the subgroups of newborns from pregnancies with different daily doses of iodine supplementation and from pregnancies without iodine supplementation during pregnancy (p = 0.05). CONCLUSIONS: Iodine supplementation during pregnancy affects newborn urine concentrations but not maternal urine concentrations.

Investigation of the metabolic consequences of impregnating spinach leaves with trehalose and applying a pulsed electric field.

The impregnation of leafy vegetables with cryoprotectants using a combination of vacuum impregnation (VI) and pulsed electric fields (PEF) has been proposed by our research group as a method of improving their freezing tolerance and consequently their general quality after thawing. In this study, we have investigated the metabolic consequences of the combination of these unit operations on spinach. The vacuum impregnated spinach leaves showed a drastic decrease in the porosity of the extracellular space. However, at maximum weight gain, randomly located air pockets remained, which may account for oxygen-consuming pathways in the cells being active after VI. The metabolic activity of the impregnated leaves showed a drastic increase that was further enhanced by the application of PEF to the impregnated tissue. Impregnating the leaves with trehalose by VI led to a significant accumulation of trehalose-6-phosphate (T6P), however, this was not further enhanced by PEF. It is suggested that the accumulation of T6P in the leaves may increase metabolic activity, and increase tissue resistance to abiotic stress.

From diets to foods: using linear programming to formulate a nutritious, minimum-cost porridge mix for children aged 1 to 2 years.

BACKGROUND: Linear programming has been used extensively as a tool for nutritional recommendations. Extending the methodology to food formulation presents new challenges, since not all combinations of nutritious ingredients will produce an acceptable food. Furthermore, it would help in implementation and in ensuring the feasibility of the suggested recommendations. OBJECTIVE: To extend the previously used linear programming methodology from diet optimization to food formulation using consistency constraints. In addition, to exemplify usability using the case of a porridge mix formulation for emergency situations in rural Mozambique. METHODS: The linear programming method was extended with a consistency constraint based on previously published empirical studies on swelling of starch in soft porridges. The new method was exemplified using the formulation of a nutritious, minimum-cost porridge mix for children aged 1 to 2 years for use as a complete relief food, based primarily on local ingredients, in rural Mozambique. RESULTS: A nutritious porridge fulfilling the consistency constraints was found; however, the minimum cost was unfeasible with local ingredients only. This illustrates the challenges in formulating nutritious yet economically feasible foods from local ingredients. The high cost was caused by the high cost of mineral-rich foods. A nutritious, low-cost porridge that fulfills the consistency constraints was obtained by including supplements of zinc and calcium salts as ingredients. CONCLUSIONS: The optimizations were successful in fulfilling all constraints and provided a feasible porridge, showing that the extended constrained linear programming methodology provides a systematic tool for designing nutritious foods.

Straightforward rapid spectrophotometric quantification of total cyanogenic glycosides in fresh and processed cassava products.

In this study, we extend pioneering studies and demonstrate straightforward applicability of the corrin-based chemosensor, aquacyanocobyrinic acid (ACCA), for the instantaneous detection and rapid quantification of endogenous cyanide in fresh and processed cassava roots. Hydrolytically liberated endogenous cyanide from cyanogenic glycosides (CNp) reacts with ACCA to form dicyanocobyrinic acid (DCCA), accompanied by a change of colour from orange to violet. The method was successfully tested on various cassava samples containing between 6 and 200 mg equiv. HCN/kg as verified with isonicotinate/1,3-dimethylbarbiturate as an independent method. The affinity of ACCA sensor to cyanide is high, coordination occurs fast and the colorimetric response can therefore be instantaneously monitored with spectrophotometric methods. Direct applications of the sensor without need of extensive and laborious extraction processes are demonstrated in water-extracted samples, in acid-extracted samples, and directly on juice drops. ACCA showed high precision with a standard deviation (STDV) between 0.03 and 0.06 and high accuracy (93-96%). Overall, the ACCA procedure is straightforward, safe and easily performed. In a proof-of-concept study, rapid screening of ten samples within 20 min has been tested.

Emulsion stabilizing capacity of intact starch granules modified by heat treatment or octenyl succinic anhydride.

Starch granules are an interesting stabilizer candidate for food-grade Pickering emulsions. The stabilizing capacity of seven different intact starch granules for making oil-in-water emulsions has been the topic of this screening study. The starches were from quinoa; rice; maize; waxy varieties of rice, maize, and barley; and high-amylose maize. The starches were studied in their native state, heat treated, and modified by octenyl succinic anhydride (OSA). The effect of varying the continuous phase, both with and without salt in a phosphate buffer, was also studied. Quinoa, which had the smallest granule size, had the best capacity to stabilize oil drops, especially when the granules had been hydrophobically modified by heat treatment or by OSA. The average drop diameter (d 32) in these emulsions varied from 270 to 50 µm, where decreasing drop size and less aggregation was promoted by high starch concentration and absence of salt in the system. Of all the starch varieties studied, quinoa had the best overall emulsifying capacity, and OSA modified quinoa starch in particular. Although the size of the drops was relatively large, the drops themselves were in many instances extremely stable. In the cases where the system could stabilize droplets, even when they were so large that they were visible to the naked eye, they remained stable and the measured droplet sizes after 2 years of storage were essentially unchanged from the initial droplet size. This somewhat surprising result has been attributed to the thickness of the adsorbed starch layer providing steric stabilization. The starch particle-stabilized Pickering emulsion systems studied in this work has potential practical application such as being suitable for encapsulation of ingredients in food and pharmaceutical products.

Quinoa starch granules as stabilizing particles for production of Pickering emulsions.

Intact starch granules isolated from quinoa (Chenopodium quinoa Willd.) were used to stabilize emulsion drops in so-called Pickering emulsions. Miglyol 812 was used as dispersed phase and a phosphate buffer (pH7) with different salt (NaCl) concentrations was used as the continuous phase. The starch granules were hydrophobically modified to different degrees by octenyl succinic anhydride (OSA) or by dry heat treatment at 120 degrees C in order to study the effect on the resulting emulsion drop size. The degree of OSA-modification had a low to moderate impact on drop size. The highest level of modification (4.66%) showed the largest mean drop size, and lowest amount of free starch, which could be an effect of a higher degree of aggregation of the starch granules and, thereby, also the emulsion drops stabilized by them. The heat treated starch granules had a poor stabilizing ability and only the starch heated for the longest time (150 min at 120 degrees C) had a better emulsifying capacity than the un-modified native starch granules. The effect of salt concentration was rather limited. However, an increased concentration of salt slightly increased the mean drop size and the elastic modulus.

Quinoa starch granules: a candidate for stabilising food-grade Pickering emulsions.

BACKGROUND: Particle-stabilised emulsions, so-called Pickering emulsions, are known to possess many beneficial properties, including being extremely stable. Starch granules isolated from quinoa have been used as emulsion stabilising particles. The granules were intact, 1-3 µm in diameter and modified with octenyl succinic anhydride to increase their hydrophobicity. Starch granules, as opposed to most other particles used to generate Pickering emulsions, are edible, abundant and derived from natural sources. RESULTS: Emulsions produced by high shear homogenisation had droplet sizes of 9-70 µm depending on the starch-to-oil ratio. Droplet size decreased with increasing starch-to-oil ratio, but was unaffected by the oil phase volume over a range of 5-33% oil (v/v). Although the drops were large and subject to creaming, their size remained unchanged over a period of 7 days. By adjusting the starch-to-oil ratio drops could be made to be buoyancy neutral to prevent creaming. Rheological characterisation indicated a gel structure with an elastic modulus in the range 200-2000 Pa depending on droplet size. CONCLUSION: This work has demonstrated the successful use of starch granules to stabilise emulsions which may find applications beyond that of food, for example in cosmetics and pharmaceutical formulations.

Metabolomic evaluation of pulsed electric field-induced stress on potato tissue.

Metabolite profiling was used to characterize stress responses of potato tissue subjected to reversible electroporation, providing insights on how potato tissue responds to a physical stimulus such as pulsed electric fields (PEF), which is an artificial stress. Wounded potato tissue was subjected to field strengths ranging from 200 to 400 V/cm, with a single rectangular pulse of 1 ms. Electroporation was demonstrated by propidium iodide staining of the cell nucleae. Metabolic profiling of data obtained through GC/TOF-MS and UPLC/TOF-MS complemented with orthogonal projections to latent structures clustering analysis showed that 24 h after the application of PEF, potato metabolism shows PEF-specific responses characterized by the changes in the hexose pool that may involve starch and ascorbic acid degradation.

Pulsed electric field reduces the permeability of potato cell wall.

The effect of the application of pulsed electric fields to potato tissue on the diffusion of the fluorescent dye FM1-43 through the cell wall was studied. Potato tissue was subjected to field strengths ranging from 30 to 500 V/cm, with one 1 ms rectangular pulse, before application of FM1-43 and microscopic examination. Our results show a slower diffusion of FM1-43 in the electropulsed tissue when compared with that in the non-pulsed tissue, suggesting that the electric field decreased the cell wall permeability. This is a fast response that is already detected within 30 s after the delivery of the electric field. This response was mimicked by exogenous H2O2 and blocked by sodium azide, an inhibitor of the production of H2O2 by peroxidases.

Interactions between EPS-producing Streptococcus thermophilus strains in mixed yoghurt cultures.

Mixed cultures of different EPS-producing Streptococcus thermophilus strains in combination with a Lactobacillus delbrueckii subsp. bulgaricus strain with negligible EPS-production were used for yoghurt production. The yoghurt texture was characterised with respect to sensory, rheological and microstructural properties and the EPS-concentrations were determined. The cultures resulted in yoghurts with highly different texture properties, and positive interactions between certain Streptococcus thermophilus strains were observed. The underlying properties of yoghurt texture are multidimensional, but a number of microstructural characteristics were apparent in the yoghurts with the highest mouth thickness, creaminess and viscosity. A strong protein network, not too dense and with medium size pores containing EPS, seems associated with these properties. The presence of capsular polysaccharides (CPS) also appeared to be beneficial as did a combination of EPS types, which were distributed differently in the protein network (in serum pores, respectively in association with protein). Obviously, a certain concentration of EPS must be present to provide for these effects on yoghurt texture, but other factors than concentration per se seem more important.

Using the Surface Evolver to model droplet formation processes in membrane emulsification.

A model was developed to describe the droplet formation mechanism in membrane emulsification from the point of view of Gibbs free energy with the help of the Surface Evolver, which is an interactive finite element program for the study of interfaces shaped by surface tension. A program to test the model was written and run which allows the user to track the droplet shape as it grows, to identify the point of instability due to free energy, and thus predict droplet size. The inputs of the program are pore geometry, oil-aqueous phase interfacial tension, and contact angle. The model reasonably predicted droplet sizes for oblong-shaped pores under quiescent conditions where the force balance approach is not applicable. The model was validated against experimental conditions from the literature where the average error of the predictions compared to the mean droplet sizes was 8%.

Relationship between the electrical and rheological properties of potato tuber tissue after various forms of processing.

The impedance at frequencies of 1-1000 kHz and dynamic bending storage modulus measured by the vibrating reed method were compared for potato tuber tissue, which had been processed by various methods. Raw potato tuber tissue strips were either heated for 30 min up to 100 degrees C or frozen-thawed. Some samples were osmotically dehydrated in a mannitol solution up to a concentration of 0.7 mol/l. The electrical reactance correlated well with the storage modulus of heated or frozen-thawed potato tissues, but not with the storage modulus of the mannitol-treated tissue. The storage modulus appeared to be strongly dependent on the turgor pressure of the cells which was drastically decreased by the heating, freezing-thawing, and osmotic treatments. The electrical properties reflect the cell integrity, and a large difference was observed between the change in impedance after heating or freezing-thawing, and that after the osmotic treatment. A significant change in the electric properties was also observed for a starch suspension at the gelatinization temperature. However, the contribution due to gelatinization did not appear to play an important role in the change of electrical properties of potato tissue by heating.