Chemical and physical changes in milk protein concentrate (MPC80) powder during storage

The solubility and chemical changes due to the Maillard reaction were investigated in milk protein concentrate powder containing 80% protein (MPC80) during storage at temperatures and relative humidities in the ranges of 25-40 °C and 44-84%, respectively. The Maillard reaction was studied by measuring furosine (a product of lactosylated protein after digestion with acid) and free hydroxymethylfurfural (HMF) contents by HPLC and L*, a*, b* values with a color-meter. Furosine, free HMF, and browning in MPC80 increased during storage, whereas the solubility decreased. The correlation between the Maillard reaction and solubility loss was explored in modified MPC80 to which glucose was added to enhance the rate of the Maillard reaction. More furosine and brown pigments were observed in the glucose-containing MPC80 than in MPC80 with added lactose. The opposite trend occurred for solubility, suggesting that the Maillard reaction may be a cause of solubility loss in MPC powder.     

Microbial community structure in forest soils treated with a fire retardant

The influence of a fire retardant (Firesorb, an acrylic–acrylamide copolymer) on the microbial community structure determined by phospholipid fatty acid (PLFA) analysis was examined under laboratory conditions using two different textured soils under pine forest. Firesorb was added to unheated and heated soil samples (350°C for 10 min followed by reinoculation, to mimic a forest fire) at three levels of application (none, usual and three times the usual levels), and measurements were made after 12 weeks of incubation. The relative importance of the three factors considered on the PLFA profiles was as follows: soil heating ≫ soil texture ≈ Firesorb treatment. In the unheated soils, Firesorb had a larger effect than soil texture, while the opposite was found in the heated soils. Soil heating reduced the total PLFAs, while Firesorb tended to increase them in both the unheated and heated soils. Soil heating decreased the PLFAs indicative of gram-positive (G⁺) bacteria and tended to increase the fatty acids associated with gram-negative (G⁻) bacteria and, to a lesser extent, the PLFA 18:2ω6, considered to be predominantly of fungal origin. Firesorb treatment decreased the G⁻/G⁺ bacteria ratio in the heated soils but tended to increase it in the unheated soils, the effect being dose dependent.     

Optimization of a pilot-scale process for producing lupin protein isolates with valuable technological properties and minimum thermal damage

This paper describes a pilot process for obtaining protein isolates from white lupin seed with improved water solubility and technofunctional properties as well as reduced thermal damage. After a careful optimization of the process parameters, two valuable food ingredients were prepared: lupin protein isolate type E, with a useful emulsifying capacity, and lupin protein isolate type F, with a high capability of foam formation and stabilization. The spray-drying process was particularly critical for inducing some thermal damage, but a careful selection of the conditions permitted ingredients having only marginally impaired lysine bioavailability to be obtained. The reproducibility of the protein extraction process was tested on two different lupin varieties.     

The efficacy of three techniques to alleviate soil compaction at a restored sand and gravel quarry

Reinstated soil at restored sites often suffers from severe compaction which can significantly impede root development. Several methods, such as ripping and complete cultivation, are available to alleviate compaction that may occur as a result of soil reinstatement. This paper examines the effectiveness of the industry standard industrial ripper and a prototype modern ripper, the Mega‐Lift, in comparison with the recommended best practice method of complete cultivation. An investigation of the penetration resistance of the soil at a restored sand and gravel quarry was carried out using a cone penetrometer and a ‘lifting driving tool’ (dropping weight penetrometer) 3 years following cultivation. All the cultivation treatments reduced soil compaction to some degree compared with the untreated control. However, the penetration resistance values suggest that rooting would be restricted at relatively shallow depths in the plots cultivated using the industrial and Mega‐Lift ripper; penetration resistance exceeded 2 MPa within the first 0.33 m. Complete cultivation maintained penetration resistance values of less than 2 MPa within the depth limit of the penetrometer of 0.42 m. In addition, the results from the ‘lifting driving tool’ indicate that soils treated using complete cultivation remained significantly looser than those treated with the ripper to a depth of at least 0.80 m. The results demonstrate that complete cultivation remains the most effective method of alleviating soil compaction on restored sites, although it is recognized that its relatively high cost may restrict the uptake of the technique.     

Occurrence of Polycyclic Musks in Sewage Sludge and their Behaviour in Soils and Plants. Part 1: Behaviour of Polycyclic Musks in Sewage Sludge of Different Treatment Plants in Summer and Winter (5 pp)

Background, Aim and Scope   Part 1: Behaviour of Polycyclic Musks in Sewage Sludge of Different Treatment Plants in Summer and Winter Part 2: Investigation of Polycyclic Musks in Soils and Plants -  Preamble. In Part 1 of the study, screening tests were performed to investigate the occurrence of PCMs in sewage sludges. For a preliminary risk assessment, further information is needed about their behaviour in the terrestrial environment. Hence, Part 2 examined the adsorption of PCMs to soil, their dissipation and leaching in soil and their uptake by plants. Background, Aim and Scope   Polycyclic Musks (PCMs) enter the environment via the waste water system. Because of their persistence, they can accumulate in different matrices like sewage sludge or biota. By the use of sewage sludge as a fertilizer, PCMs are transferred to agricultural soils. Therefore, in Part 1 of the study, screening tests were performed to investigate the occurrence of PCMs in sewage sludge. For a preliminary risk assessment, further information is needed about their behaviour in the terrestrial environment. Hence, Part 2 of the study examined the adsorption of PCMs to soil, their dissipation and leaching in soil, and their uptake by plants. Materials and Methods: In the screening study, samples of activated sewage sludge were taken both in summer and in winter at 21 treatment plants. In order to get an overview of the contamination situation, sampling covered different types of treatment plants (in rural, urban, industrial areas). Analytical methods for the determination of HHCB, AHTN, ADBI, ATTN, AHDI and ATII in the sludge samples were developed and applied. Results: The analytical screening of PCMs showed their presence in activated and dried sewage sludge samples. HHCB and AHTN represented about 95% of the PCMs investigated. Their concentrations in the activated sludge samples varied between 2.9 and 10.4 mg/kg dry mass (dm) and 1.1 to 4.2 mg/kg dm, respectively. Although different types of sewage treatment plants were investigated, similar PCM levels were found, showing the widespread input of these compounds into domestic waste water. Discussion: PCM concentrations in activated sludge varied widely. The variation drops substantially when concentrations are related to the varying dry mass. In dehydrated sludge, PCM concentrations were up to 24 mg/kg dm for HHCB and up to 6.9 mg/kg dm for AHTN. These high values are comparable to those obtained in other investigations analysing PCMs. If the degradation of organic mass during anaerobic decomposition is included in the evaluation, the figures obtained are comparable to those for activated sludge. Elimination in sewage sludge was higher in summer than in winter. Therefore, the contamination of the sludges in winter reached higher levels compared to the summer. Conclusions: The results show that PCMs are widespread contaminants in sewage sludge. Recommendations and Perspectives: PCM should be considered in a risk assessment as potential contaminants of sewage sludge destined for agricultural use. Due to the high PCM levels in sewage sludge, further investigations into the degradation and elimination behaviour in sewage sludge have to be carried out, including that involving PCM metabolites such as lactone derivatives.     

Spatial modelling of the fraction of photosynthetically active radiation absorbed by a boreal mixedwood forest using a lidar–hyperspectral approach

The spatial variability of the fraction of photosynthetically active radiation absorbed by the canopy (fPAR) was characterized for a heterogeneous boreal mixedwood forest site located in northern Ontario, Canada, based on relationships found between fPAR and light detection and ranging (lidar) data over different canopy architectures. Estimates of fPAR were derived from radiation measurements made above the canopy at a flux tower and below-canopy radiation was measured across a range of species compositions and canopy architectures. Airborne lidar data were used to characterize spatial variability of canopy structure around the flux tower and a map of mean canopy chlorophyll concentration was derived from airborne hyperspectral imagery. Different volumes of lidar points for the locations directly above each photosynthetically active radiation (PAR) sensor were examined to determine if there is an optimal method of relating lidar returns to estimated fPAR values.The strongest correlations between mean lidar height and fPAR occurred when using points that fell within a theoretical cone which originated at the PAR sensor having a solid angle α = 55°. For diffuse conditions, the correlation (r) between mean lidar height versus fPAR × chlorophyll was stronger than between mean lidar height versus fPAR by 8% for mean daily fPAR and from 10 to 20% for diurnal fPAR, depending on solar zenith angle. For direct light conditions, the relationship was improved by 12% for mean daily fPAR and 12–41% for diurnal relationships.Linear regression models of mean daily fPAR × chlorophyll versus mean lidar height were used in conjunction with gridded lidar data and the canopy chlorophyll map to generate maps of mean daily fPAR for direct and diffuse sunlight conditions. Site average fPAR calculated from these maps was 0.79 for direct light conditions and 0.78 for diffuse conditions. When compared to point estimates of mean daily fPAR calculated on the tower, the average fPAR was significantly lower than the point estimate. Subtracting the direct sunlight fPAR map from the diffuse sunlight fPAR map revealed a distinct spatial pattern showing that areas with open canopies and relatively low chlorophyll (e.g., black spruce patches) have a higher fPAR under direct sunlight conditions, while closed canopies with higher chlorophyll (e.g., deciduous species) absorb more PAR under diffuse conditions. These findings have implications for scaling from point measurements at flux towers to larger resolution satellite imagery and addressing local scale heterogeneity in flux tower footprints.     

The biomass of fungal mycelium in buried paleosols and surface soils of the steppe zone

The contents of fungal mycelium have been studied in paleosols of ancient archeological monuments and in surface soils within the steppe, dry steppe, and desert zones of European Russia, on the Stavropol, Privolzhskaya, and Ergeni uplands. The buried paleosols date back to the Bronze Age (4600–4500 and 4000–3900 BP), the Early Iron Age (1900–1800 BP), and the early 18th century (1719–1721). The fungal mycelium has been found in all these paleosols. The biomass of fungal mycelium varies from 2 to 124 μg/g of soil. The distribution patterns of fungal mycelium in the profiles of buried paleosols and surface soils have been identified. It is shown that the dark-colored mycelium is typical of the ancient paleosols. In some cases, the content of the dark-colored mycelium in them may reach 100% of the total mycelium biomass.     

Stability of copigmented anthocyanins and ascorbic acid in a grape juice model system

The stability of red grape anthocyanins (Vitis vinifera) was evaluated in a model juice system during normal (25 degrees C) and accelerated storage (35 degrees C) in the presence of ascorbic acid. Rosemary polyphenolic cofactors (0, 0.2, and 0.4% v/v) were evaluated as anthocyanin stabilizing agents. Cofactor addition resulted in concentration-dependent hyperchromic (up to 178%) and bathochromic (up to 23 nm) shifts, indicating a more intense red coloration of the models. Anthocyanin and ascorbic acid degradation followed first-order kinetics during storage. Results showed that copigmented treatments underwent a lower conversion of L-ascorbic acid into dehydroascorbic acid during storage when compared to the control, favorably impacting the vitamin retention of these models. Copigmentation did not affect anthocyanin degradation in the absence of ascorbic acid but in its presence aided to retain a higher anthocyanin content than the control. This study indicated that the addition of anthocyanin cofactors could be used to reduce the pigment and vitamin degradation while masking detrimental color changes in anthocyanin containing products.     

Effects of rhodium heterogeneous catalyst and isomerization conditions on linoleic acid conjugation of soybean oil

Rhodium heterogeneous catalyst was used to catalyze isomerization of linoleic acid in soybean oil to conjugated linoleic acid (CLA). A central composite rotatable design with five levels of three variables, namely, reaction temperature, stirring speed, and reaction time, was used to determine the maximum CLA yield. The formation of CLA during isomerization was greatly dependent on the reaction temperature and time. The CLA content of soybean oil increased from 0.63 to 202.42 mg/g oil when isomerization was done at 200 degrees C, with a stirring speed of 200 rpm for 49 min. Analysis of triacylglycerol positions showed that linoleic acid at any position in a triacylglyceride could possibly be isomerized to CLA.     

Influence of storage practices on acrylamide formation during potato frying

A number of parameters linked to storage of potatoes were evaluated with regard to their potential to influence the acrylamide formation in French fries. Acrylamide, which is a potential human carcinogen, is reported to be formed during the frying of potatoes as a result of the reactions between asparagine and reducing sugars. This study was conducted using three potato varieties (Bintje, Ramos, and Saturna) typically used in Belgium, The Netherlands, and the northern part of France for French fry and crisp production. Saturna, mainly used in crisp production, appeared to be the least susceptible for acrylamide formation during frying. Especially storage at low temperatures (4 degrees C) compared to storage at 8 degrees C seemed to enhance acrylamide formation due to a strong increase in reducing sugars caused by low-temperature storage. Because of the reversible nature of this physiological reaction, it was possible to achieve a significant reduction of the reducing sugars after a reconditioning of the cold-stored potatoes for 3 weeks at 15 degrees C. All changes in acrylamide concentrations could mainly be explained by the reducing sugar content of the potato (R2 = 0.84, n = 160). This means that, by ensuring a low reducing sugar content of the potato tuber, the risk for acrylamide formation will largely be reduced. Finally the use of a sprout inhibitor did not influence the composition of the potato, and thus acrylamide formation was not susceptible to this treatment.