Glass transitions for freeze-dried and air-dried tomato

Glass transition temperatures of freeze-dried tomato conditioned at various water activities at 25 °C were determined by differential scanning calorimetry (DSC). Air-dried tomato with and without osmotic pre-treatment in sucrose/NaCl solutions was also analyzed. Thermograms corresponding to the low water activity domain (0.11 ⩽ a_w ⩽ 0.75) revealed the existence of two glass transitions, which were attributed to separated phases formed by sugars and water and other natural macromolecules present in the vegetable. Both transitions were plasticized by water and experimental data could be well correlated by the Gordon-Taylor equation in the low-temperature domain, and by the Kwei model in the high-temperature domain. For higher water activities, the low-temperature glass transition curve exhibited a discontinuity, with suddenly increased glass transition temperatures approaching a constant value that corresponds to the T_g of the maximally freeze-concentrated amorphous matrix. The unfreezable water content was determined through the melting enthalpy dependence on the moisture content.     

Glass transitions of barley starch and protein in the endosperm and isolated from

When studying the glass-to-rubber transition inside natural materials, it is important to take into account not only the moisture content but also the moisture distribution over the components in the material. We measured the T_g of protein and starch isolated from barley at different moisture contents using differential scanning calorimetry (DSC) (heating rate 10 °C/min) and by thermo mechanical compression tests (TMCT) (heating rate 2 °C/min). The measurement of the T_g of partially crystalline materials, such as barley starch, is more difficult using TMCT because the mechanical effect of expansion of these materials is smaller. For both measurement sets the glass transition lines were modeled using the Gordon–Taylor equation. The lines were adapted for the differences in moisture content over the endosperm by using the sorption isotherms of isolated barley starch and protein and whole barley endosperm. The glass transition lines measured by TMCT were closer together than the ones measured by DSC.     

22 years on: the impact and relevance of the UK No Smoking Day

Objectives

To evaluate the impact and relevance of the national awareness day “No Smoking Day” 22 years after it was launched.

Design

Triangulation of data from a variety of sources. Retrospective surveys conducted one week and three months after No Smoking Day, media coverage, website activity, and volume of calls to national smokers'' helplines.

Main outcome measures

Self reports of awareness and smoking behaviour changes one week and three months after No Smoking Day. Volume of media coverage, visits to No Smoking Day website, and volumes of calls to smokers'' helplines.

Results

Follow up at one week indicates awareness of No Smoking Day is lower in 2004 than in 1986 but still high at 70% for all smokers. The decline in participation from 18% of aware smokers in 1994 to 7% in 2001 has been reversed and in 2005 19% quit or reduced their smoking on No Smoking Day. Three months after No Smoking Day awareness was 78% in 2004, lower than in previous studies but still high and equivalent to 9 965 000 smokers when applied to the population estimate of UK smokers. Likewise participation has decreased but at 14% in 2004 is equivalent to an estimated 1 840 000 (1 in 7 of UK smokers) claiming to quit or reduce their consumption on the Day. Among those who participated, 11% were still not smoking more than three months after the Day, equivalent to an estimated 85 000 smokers (0.7% of UK smokers). Media volume has increased even though campaign spend has remained relatively constant and calls to national smokers'' helplines on No Smoking Day are typically four times those received on an average day.

Conclusions

These data suggest that after 22 years No Smoking Day continues to be successful in reaching smokers. With a budget insufficient to pay for advertising, this public awareness campaign supported by local activities appears to be effective in helping smokers to stop.     

Phase transitions of dairy proteins,dextrans and their mixtures as a function of water interactions

The water sorption behaviour and phase transitions of dairy proteins (β-casein and β-lactoglobulin), dextrans (dextran6 and dextran500) and their mixtures were studied at low water content. Freeze-dried polysaccharide samples containing between 20 and 80% dairy protein were equilibrated at different water activities (a_w) between 0.11 and 0.75, at 25 °C. Water sorption isotherms of pure compounds and mixtures, as well as glass transition at different water activities were determined. Crystallization of polysaccharides was also investigated. BET and Gordon and Taylor equations were used to model water adsorption isotherms and glass transition temperature behaviour, respectively. Polysaccharides showed a higher water adsorption capacity than dairy proteins in the range of a_w studied, which decreased with the addition of protein. The addition of β-casein decreased the Tg values of dextran systems. This effect was attributed to water migration from β-casein to the polysaccharide fraction following the formation of β-casein hydrophobic interactions. Likewise, dairy proteins provoked an increase in the temperature of dextran crystallization and a decrease in the enthalpy. This effect did not reflect the increase of dextran molecular mobility in the presence of β-casein but could be masked by other factors, like steric hindrance. The effect of dairy proteins, especially β-casein, on the phase transitions of polysaccharides should be considered for controlling the Maillard reaction, as well as physical and chemical changes that occur during processing and storage of food systems.     

Role of water in the polymorphic transitions of small carbohydrates

Crystallisation of small carbohydrates (hexoses, alditols, and disaccharides) in solution or from the melt is known to provide different polymorphs mainly due to their affinity with water and their molecular flexibility. Food and pharmaceutical applications sometimes require the use of a specific polymorph especially for its compaction and compression properties.     

Research Watch: Lead in peat bogs

Metals.     

Oxidized proteins and their biological impact

Aging is characterized by an increased accumulation of damaged macromolecules and oxidized protein build up is considered to be a hallmark of cellular aging. Advanced glycation end products (AGE) have been analyzed in aging human peripheral blood lymphocytes since such glycoxidative modifications have been reported to increase with age in a variety of cellular and tissular systems and are believed to contribute to the intracellular age‐related accumulation of damaged proteins, a process that has been associated with the cellular functional deficits that occur with age. The pattern of glycated protein has been studied using two dimensional gel electrophoresis followed by Western blotting with an anti‐AGE antibody. The protein silver stain and the immunoblot patterns were not superimposable indicating that glycoxidative modifications are targeting only a restricted set of proteins. Among these preferential protein targets, seven of them exhibited a significant age‐related increased immunoreactivity with the anti‐AGE antibody suggesting that the corresponding modified proteins might serve as biomarkers of aging lymphocytes [ 1 ]. Other age‐related protein modifications such as carbonyl formation and conjugation with the lipid peroxidation product 4‐hydroxy‐2‐nonenal are also currently studied. The age‐related accumulation of altered protein raises the problem of the efficacy of intracellular protein maintenance, in particular the protein degradation and the protein repair systems. Indeed, if these systems that take care of the removal or repair of damaged proteins are affected with aging, they would therefore directly contribute to the increased intracellular load of functionally impaired protein. Since cytosolic oxidized protein degradation and basal protein turnover have been shown to be mostly carried out by the proteasomal system, the fate of proteasome in aging has been addressed and a decline of proteasomal proteolytic activity has been reported [ 2 ]. The impact of aging on human lymphocyte 26S proteasome has been recently investigated and age‐related alterations of proteasome structure and function have been evidenced. Indeed, we observed a decline of 26S proteasome specific activity which is correlated to an increasing yield of post‐translational modifications of proteasome subunits [ 3 ]. In fact, some proteasome subunits and particularly assembly and catalytic subunits are specifically modified with age. According to bidimensional westernblotting, some subunits were found either glycated, conjugated with the lipid peroxidation product 4‐hydroxy‐2‐nonenal or even ubiquitinated. In vitro treatment of the proteasome by glyoxal, that promotes the formation of N?‐carboxymethyllysine adducts, or by the lipid peroxidation product 4‐hydroxy‐2‐nonenal was found to inactivate its peptidase activities although to different extent. In other studies aimed at monitoring the effect of oxidative stress on proteasome structure and function, we have shown on an in vivo rat model that coronary occlusion/reperfusion resulted in inactivation of the proteasome [ 4 ]. This inactivation is associated with selective modification by the lipid peroxidation product 4‐hydroxy‐2‐nonenal of three 20S proteasome α‐subunits. In contrast, the observed inhibition of proteasome upon exposure of human keratinocytes to UV stress was mainly due to the stress‐induced formation of endogeneous inhibitors, including certain oxidatively modified proteins [ 5 ]. In addition, the role of the peptide methionine sulfoxide reductase, one of the very few protein repair enzyme described, and its possible implication in the age‐related decline of protein maintenance has been investigated. The peptide methionine sulfoxide reductase system (Msr A and Msr B) catalyzes the reduction of methionine sulfoxide to methionine within proteins and its activity and the expression of Msr A have been shown to decline in different organs of aged rats [ 6 ] and more recently in senescent human fibroblasts. Moreover, we have recently shown that the peptide methionine sulfoxide reductase Msr A is present both in the cytosol and in the mitochondrial matrix, although under different isoforms [ 7 ]. In conclusion, during aging or in certain oxidative stress situations, impairment of both peptide methionine sulfoxide reductases and proteasome activity appears as a critical factor in the decreased efficacy of intracellular protein maintenance, contributing to the increased intracellular load of modified and functionally impaired proteins that may ultimately lead to a global deterioration of cellular homeostasis.     

Structure of beta-amyloid fibrils and its relevance to their neurotoxicity: implications for the pathogenesis of Alzheimer's disease

Alzheimer's disease and cerebral amyloid angiopathy are characterized by the deposition of beta-amyloid fibrils consisting of 40- and 42-mer peptides (A beta 40 and A beta 42). Since the aggregation (fibrilization) of these peptides is closely related to the pathogenesis of these diseases, numerous structural analyses of A beta 40 and A beta 42 fibrils have been carried out. A beta 42 plays a more important role in the pathogenesis of these diseases since its aggregative ability and neurotoxicity are considerably greater than those of A beta 40. This review summarizes mainly our own recent findings from the structural analysis of A beta 42 fibrils and discusses its relevance to their neurotoxicity in vitro.     

Calibrating the uptake kinetics of semipermeable membrane devices in water: impact of hydrodynamics

The use of lipid-containing semipermeable membrane devices (SPMDs) is becoming commonplace, but the potential effects of environmental variables affecting the accumulation of contaminants into SPMDs had not been characterized sufficiently, yet. To characterize the effect of hydrodynamic conditions on the contaminant uptake kinetics, accumulation of pentachlorobenzene, hexachlorobenzene, and hexachlorocyclohexane isomers from water into SPMD was studied at various water flow rates. The accumulation kinetics of hydrophobic compounds (log Kow > 4) are governed by the aqueous boundary layer in linear flow velocity range from 0.06 to 0.28 cm s(-1) and sensitive to slight changes in flow rate. The effect of flow velocity on the exchange kinetics increases with increasing hydrophobicity. Under faster, but still laminar flow conditions (0.28-1.14 cm s(-1)), the sensitivity to changes in flow decreases to a nonsignificant level for the substances under consideration. The results of this study confirm that the use of the laboratory-derived calibration data for estimation of analyte concentrations in the ambient environment is limited unless flow-sensitive performance reference compounds are used.     

Electrochemistry of free chlorine and monochloramine and its relevance to the presence of Pb in drinking water

The commonly used disinfectants in drinking water are free chlorine (in the form of HOCl/OCl-) and monochloramine (NH2Cl). While free chlorine reacts with natural organic matter in water to produce chlorinated hydrocarbon byproducts, there is also concern that NH2Cl may react with Pbto produce soluble Pb(II) products--leading to elevated Pb levels in drinking water. In this study, electrochemical methods are used to compare the thermodynamics and kinetics of the reduction of these two disinfectants. The standard reduction potential for NH2Cl/Cl- was estimated to be +1.45 V in acidic media and +0.74 V in alkaline media versus NHE using thermodynamic cycles. The kinetics of electroreduction of the two disinfectants was studied using an Au rotating disk electrode. The exchange current densities estimated from Koutecky-Levich plots were 8.2 x 10(-5) and 4.1 x 10(-5) A/cm2, and by low overpotential experiments were 7.5 +/- 0.3 x 10(-5) and 3.7 +/- 0.4 x 10(-5) A/cm2 for free chlorine and NH2Cl, respectively. The rate constantforthe electrochemical reduction of free chlorine at equilibrium is approximately twice as large as that for the reduction of NH2Cl. Equilibrium potential measurements show that free chlorine will oxidize Pb to PbO2 above pH 1.7, whereas NH2Cl will oxidize Pb to PbO2 only above about pH 9.5, if the total dissolved inorganic carbon (DIC) is 18 ppm. Hence, NH2Cl is not capable of producing a passivating PbO2 layer on Pb, and could lead to elevated levels of dissolved Pb in drinking water.     

Binding of atrazine to humic substances from soil,peat and coal related to their structure

Partition coefficients for the binding affinities of atrazine to 16 different humic materials were determined by the ultrafiltration HPLC technique. Sources included humic acids (HA), fulvic acids (FA), and combined humic and fulvic fractions (HF) from soil, peat, and coal humic acid. Each of the humic materials was characterized by elemental composition, molecular weight, and composition of main structural fragments determined by 13C solution-state NMR. The magnitude of K(OC) values varied from 87 to 575 L/kg of C, demonstrating relatively low binding affinity of humic substances (HS) for atrazine. On the basis of the measured K(OC) values, the humic materials can be arranged in the following order: coal HA approximately = gray wooded soil HA > chernozemic soil HA and HF > sod-podzolic soil HA approximately = peat HF > sod-podzolic soil FA > peat dissolved organic matter. The magnitude of the K(OC) values correlated strongly with the percentage of aromatic carbon in HS samples (r = 0.91). The hydrophobic binding was hypothesized as the key interaction underlying the binding of atrazine to HS.     

Occurrence of trace metals in foodstuffs and their health impact

BackgroundUnlike organic pollutants, heavy metals are not created nor are biodegradable materials. They naturally occur in earth crust and many of them reach the environment via anthropogenic activities, which belonged to mining, smelting, production of fertilizers, pesticide applications and others.Scope and approachDue to their water solubility and bioaccumulative tendency in different matrices of the environment, some heavy metals are extremely toxic even at low exposure levels and can be transported into the food chain.Key findings and conclusionsMany criteria are defined to identify heavy metals based on their specific gravity, weight and atomic number, chemical properties and their toxicity, therefore the heavy metals term is still very loose. Dietary exposure is a significant route for trace metals to the humans and constitutes about 90% of exposure. Long term exposure to metals via food consumption, drinking water or other occupational sources leads to serious problems, e.g., hepatotoxicity, kidney failure and neurotoxicity. Analysis of the current situation concluded that the concentrations of heavy metals declined over the years, but they are still hot spots suffering from domestic wastes, agrochemicals like pesticides, fertilizers and industrial wastes. Due to the contamination sources in those hot spots, levels of some metals exceeded the approved permissible limits and become sources of severe problems to humans. Almost comprehensive hazard assessment of these metals is missing due to insufficient data corresponding to body burden for groups potentially exposed to high concentration of metals and their concentrations in foodstuffs.     

Effect of peat decomposition and mass loss on historic mercury records in peat bogs from patagonia

Ombrotrophic peat bogs have been widely used to evaluate long-term records of atmospheric mercury (Hg) deposition. One of the major aims of these investigations is the estimation of the increase in atmospheric Hg fluxes during the industrial age compared to preindustrial fluxes. Comparability of Hg accumulation rates calculated from density, peat accumulation rates, and Hg concentrations requires linearity between these parameters. Peat formation is a dynamic process accompanied by intense mass loss and alteration of the organic material. Our investigations on three peat cores from the Magellanic Moorlands, Chile, indicate that Hg concentrations in peat strongly depend on peat humification. Moreover, differences in mass accumulation rates during peat evolution are not compensated by linear changes in density, peat accumulation, or Hg concentrations. We suggest that Hg accumulation rates be normalized to carbon accumulation rates to achieve comparability of Hg accumulation rates derived from differently altered peat sections. Normalization to the carbon accumulation rates reduces Hg accumulation rates in less degraded peat sections in the upper peat layers by factors of more than 2. Our results suggest that the increase in Hg deposition rates during modern times derived from ombrotrophic peat bogs are potentially overestimated if Hg accumulation rates are not corrected for mass accumulation rates.     

History and environmental impact of mining activity in Celtic Aeduan territory recorded in a peat bog (Morvan, France)

The present study aims to document historical mining and smelting activities by means of geochemical and pollen analyses performed in a peat bog core collected around the Bibracte oppidum (Morvan, France), the largest settlement of the great Aeduan Celtic tribe (ca. 180 B.C. to 25 A.D.). The anthropogenic Pb profile indicates local mining operations starting from the Late Bronze Age, ca. cal. 1300 B.C. Lead inputs peaked at the height of Aeduan civilization and then decreased after the Roman conquest of Gaul, when the site was abandoned. Other phases of mining are recognized from the 11th century to modern times. They have all led to modifications in plant cover, probably related in part to forest clearances necessary to supply energy for mining and smelting. Zn, Sb, Cd, and Cu distributions may result from diffusional and biological processes or from the influence of groundwater and underlying mineral soil, precluding their interpretation for historical reconstruction. The abundance of mineral resources, in addition to the strategic location, might explain why early settlers founded the city of Bibracte at that particular place. About 20% of the anthropogenic lead record was accumulated before our era and about 50% before the 18th century, which constitutes a troublesome heritage. Any attempts to develop control strategies in accumulating environments should take into account past human activities in order to not overestimate the impact of contemporary pollution.     

Glass transition and water effects on sucrose inversion in noncrystalline carbohydrate food systems

The effects of water and glass transition on the hydrolysis of sucrose by invertase in noncrystalline carbohydrate systems were investigated. Maltodextrin/sucrose (2:1) and maltodextrin/lactose/sucrose (1:1:1) were dissolved in distilled water. Invertase (10 mg/17.2 g) was added. Amorphous samples were produced by freeze-drying the solutions. Sorption isotherms were determined gravimetrically at 24 °C over the 0.113–0.763 a_w, and over 0.239–0.764 a_w, the glass transition, T_g was determined using differential scanning calorimetry (DSC). DSC and water sorption results suggested that samples remained noncrystalline. Sucrose inversion was analysed by monitoring glucose content during storage. Sucrose hydrolysis occurred at significant rates at 0.662 and 0.764 a_w. The rate increase was not related to the apparent glass transition of the systems.     

Microencapsulation of bacteria: A review of different technologies and their impact on the probiotic effects

Probiotic based products are associated with many health benefits. However, the main problem is the low survival of these microorganisms in food products and in gastrointestinal tract. Providing probiotics with a physical barrier is an efficient approach to protect microorganisms and to deliver them into the gut. In our opinion, microencapsulation is one of the most efficient methods, and has been under especial consideration and investigation. However, there are still many challenges to overcome with respect to the microencapsulation process. This review focuses mainly on the methodological approach of probiotic encapsulation including materials and results obtained using encapsulated probiotic in food matrices and different pathologies in animal models.Industrial relevanceThe inclusion of probiotics into food matrices is one of the most challenging lines of research in food technology. Probiotics in general, and some strains in particular, have a low resistance to different environmental conditions, such as oxygen, light or temperature. Thus, the protection and isolation of the microorganism from the food matrix and the environmental condition are crucial for the development of new probiotic food. In this sense, microencapsulation has gained an increasing interest, since it has been demonstrated that it could protect the bacteria not only during its production process but also during its incorporation into the food matrix, also with protective effects during storage. In conclusion, microencapsulation is of great interest since it could allow a wider application of probiotics in the food market, actually restricted to fresh or powder products.     

Climate impact on Alternaria moulds and their mycotoxins in fresh produce: The case of the tomato chain

Climate change will affect the presence and concentration of mycotoxin in various foods. Recently, a concern arised on the presence of Alternaria mycotoxins in tomatoes and derived tomato products. The objective of this study was to evaluate the effect of climate change on their growth and mycotoxin production on tomatoes in function of changing temperatures. Therefore, a climate change model “HadGEM2-ES” was applied and downscaling of coarse gridded data was done towards a tomato field surface. After transforming the daily temperature data towards hourly data, the growth model of the Alternaria mould was applied. This leads to an assessment of growth rate and actual growth for three time frames being current (1981–2000), near (2031–2050) and far future (2081–2100). The influence of the harvesting period in a growing season, RCP scenarios and time frames was evaluated and two regions, Spain and Portugal were compared with each other. For Spain there were no significant differences for RCP 2.6 and 4.5. For the more extreme RCP scenarios (6.0 and 8.5) the diameter of the mould was significantly lower for the far future compared with the current time frame. This can be explained by the higher temperatures (18.2–38.2 °C) which become too high for fungal growth. For Poland, there was a significant difference in the different time frames, the diameter of the mould was for the far future > near future > current time frame. This is due to the predicted higher temperatures in the far future (14.2–28.4 °C) which becomes closer to the optimal temperature for the growth of Alternaria spp. compared with the colder temperatures in the present. According to the results, the situation in Poland in the far future (2081–2100) will became similar as the situation in Spain in the present time frame (1981–2000).     

Aflatoxins and food pathogens: impact of biologically active aflatoxins and their control strategies

Globally disease outbreaks as a result of the consumption of contaminated food and feedstuffs are a regular primary problem. The foremost elements contributing to contamination are microorganisms, particularly fungi, which produce low‐molecular weight secondary metabolites, with demonstrated toxic properties that are referred to as mycotoxins. Aflatoxins contaminate agricultural commodities and may cause sickness or fatality in humans and animals. Moreover, poor conditions of storage and a deficiency in regulatory measures in food quality control aggravate the main issue. For that reason, mycotoxin‐related illness of nutrition represents a major health hazard for local populations. Government policies should make regulations aiming to avoid the entry of aflatoxins into food stuffs. For consumer safety, control and management strategies should be developed and implemented by regulatory authorities. There is the need for attention from farmers, scientists, government and collaborative minds throughout the country to ensure aflatoxin‐free food. The present review is informative not only for health‐conscious consumers, but also for relevant authorities with respect to paving the way for future research aiming to fill the existing gaps in our knowledge with regard to mycotoxins and food security. © 2016 Society of Chemical Industry     

Antioxidants in lipid foods and their impact on food quality

This paper reviews the antioxidant properties of tocopherols and ascorbic acid in edible oils, and the impact of interfacial phenomena on their activities in emulsions and the effects of edible oil processing. Tocopherols are the most important natural antioxidants found in vegetable oil-derived foods. These antioxidants can interrupt lipid autoxidation by interfering with either the chain propagation or the decomposition processes. α-Tocopherol at high concentrations inhibits hydroperoxide decomposition but promotes hydroperoxide formation. The effect of antioxidants in inhibiting hydroperoxide decomposition may thus be critical in preserving food quality by reducing rancidity due to aldehyde formation. Ascorbic acid can regenerate α-tocopherol, inactivate metal initiators and reduce hydroperoxides. The activity of natural antioxidants is greatly affected by complex interfacial phenomena in emulsions and multi-component foods. In an oil-in-water emulsion system, the lipophilic antioxidants α-tocopherol and ascorbyl palmitate are more effective than in bulk oil, while the opposite trend is found for the hydrophilic antioxidants Trolox and ascorbic acid. The methodology to evaluate natural antioxidants must be carefully interpreted depending on whether oxidation is carried out in bulk oils or in emulsions, and what method is used to measure lipid oxidation.