Acrylamide Formation in Foods during Thermal Processing with a Focus on Frying

This paper summarizes the current state of knowledge on acrylamide formation in foods during thermal processing. The main pathway of acrylamide formation in foods is linked to the Maillard reaction, and in particular, the amino acid asparagine. Effects of several factors related to food composition and processing conditions on the formation levels of acrylamide, and also, other quality characteristics in thermally processed foods are discussed in detail. From a process control point of view, it is also addressed that there is a need to develop viable models for the estimation of acrylamide contents in heated foods during the stages of process design and optimization. Fried potato products, as one of the most encountered category of thermally processed foods, are specifically emphasized for acrylamide formation, potential ways of mitigation, and modeling its formation during frying.     

Putting down roots: Afforestation and bank cohesion of Icelandic Rivers

Riparian vegetation is widely recognized as a critical component of functioning fluvial systems. Human pressures on woody vegetation including riparian areas have had lasting effects, especially at high latitude. In Iceland, prior to human settlement, native downy birch woodlands covered approximately 15%–40% of the land area compared to 1%–2% today. Afforestation efforts include planting seedlings, protecting native forest remnants, and acquiring land areas as national forests. The planted and protected nature of vegetation along rivers within forests provides a unique opportunity to evaluate the various taxa within riparian zones and the channel stabilizing characteristics of the vegetation used in afforestation. We investigated bank properties, sediment textures, and root characteristics within riparian zones along four rivers in forests in Iceland. Bank sediment textures are dominantly sandy loam overlying coarser textures. Undercut banks are common because of erosion of the less cohesive subsurface layer. Quantitative root data indicate that the woody taxa have greater root densities, rooting depths, and more complex root structures than forbs or graminoids. The native downy birch has the highest root densities, with <1 mm roots most abundant. Modeling of added bank cohesion indicates that willow provides up to six times and birch up to four times more added cohesion to the coarse sediment textures comprising stream banks compared to no vegetation. We conclude that planting and protecting the native birch and willow helps to reduce bank erosion, especially where long-term grazing exclusion can be maintained.     

Benin 2025—Balancing Future Water Availability and Demand Using the WEAP ‘Water Evaluation and Planning’ System

In Benin, annual water availability per capita far exceeds the critical threshold of about 1,700 m³, but during the dry season, water scarcity occurs at the local scale. By modeling the water balance of the Ouémé–Bonou catchment with WEAP (Water Evaluation and Planning System), this study aimed at analyzing Benin’s future water situation under different scenarios of socio-economic development and climate change until 2025. The results show that the pressure on Benin’s water resources will increase, leading to greater competition for surface water. Furthermore, financial and technological constraints hinder a satisfactory development, and exploration of groundwater and reservoir resources. However, improvements are most needed, especially in rural areas. Decreasing inflows and groundwater recharge due to climate change aggravate this situation. Even though there are uncertainties and constraints concerning the model and input data, this study shows that the WEAP results offer a solid basis to assist planners in developing recommendations for future water resource management by revealing hot spots of action.     

Assessing road investments: accessibility changes,cost benefit and production effects

Infrastructure investment projects and programmes are generally evaluated by comparing project costs with pertinent benefits. In this paper a series of alternative national road investment programmes in Sweden are examined. Each programme is assessed in terms of expected time savings and reduced accident rates. In addition we make use of a general production function with regionally specific accessibility characteristics as arguments. With this approach, improved accessibility implies an increase of the production potential. The paper compares the value of these production effects with the value of time savings and other benefits in a standard CB-calculation. In the comparisons more than 50 alternative national investment programmes are assessed, and their degree of consistency is estimated.An earlier version of this paper was presented at the European RSA-conference in Moscow, August 1993 and has benefitted from comments during the conference. The authors are grateful for suggestions rendered by two anonymous referees. We also wish to thank R. Jonsson, G. Lindberg and L.-G. Mattsson. Supply of data and research funds from the National Road Administration is acknowledged.     

Modeling,analysis, and screening of cyclic pressure pulsing with nitrogen in hydraulically fractured wells

Cyclic pressure pulsing with nitrogen is studied for hydraulically fractured wells in depleted reservoirs. A compositional simulation model is constructed to represent the hydraulic fractures through local-grid refinement. The process is analyzed from both operational and reservoir/ hydraulic-fracture perspectives. Key sensitivity parameters for the operational component are chosen as the injection rate, lengths of injection and soaking periods and the economic rate limit to shut-in the well. For the reservoir/ hydraulic fracturing components, reservoir permeability, hydraulic fracture permeability, effective thickness and half-length are used. These parameters are varied at five levels. A full-factorial experimental design is utilized to run 1250 cases. The study shows that within the ranges studied, the gas-injection process is applied successfully for a 20-year project period with net present values based on the incremental recoveries greater than zero. It is observed that the cycle rate limit, injection and soaking periods must be optimized to maximize the efficiency. The simulation results are used to develop a neural network based proxy model that can be used as a screening tool for the process. The proxy model is validated with blind-cases with a correlation coefficient of 0.96.     

Antagonistic effect on Listeria monocytogenes and L. innocua of a bacteriocin-like metabolite produced by lactic acid bacteria isolated from sucuk

Two Lactobacilli and four Pediococci strains producing bacteriocin-like metabolities isolated from sucuk were tested with agar spot tests and well diffusion assays for their inhibitory activity against 16 Listeria strains, also isolated from sucuk. The production of organic acids and hydrogen peroxide limited, L. sake Lb 706 (used as a bacteriocin producer strain) and the isolated lactic acid bacteria (LAB) showed inhibitory activity against all of the Listeria strains, while L. sake Lb 706-A (used as a bacteriocin non-producer mutant) had the same effects against only two Listeria monocytogenes strains (51, 52) in agar spot tests. In the well diffusion assays, while L sake Lb 706 and four Pediococci isolates (413, 416, 419, 446) exhibited inhibitory activity against all of the Listeria strains tested, L. sake Lb 706-A and two of the Lactobacilli isolates (77, 116) showed no effect on the Listeria strains tested.     

Sulfur in wheat gluten: In situ analysis by X-ray absorption near edge structure (XANES) spectroscopy

The sulfur containing gluten proteins largely determine the baking quality of wheat. In order to probe the speciation of sulfur, gluten proteins [gliadin, high molecular weight (HMW) and low molecular weight (LMW) subunits of glutenin], stored glutenin subunits as well as flour were investigated in situ by S K-edge X-ray near edge absorption structure (XANES) spectroscopy. The spectra confirmed the existence of disulfide bonds in oxidised (oxygen stream) glutenin subunits, supporting their significance for the formation of gluten networks. Additionally, glutenin subunits, which were stored under ambient air and temperature conditions, predominantly contained sulfur of higher oxidation states (sulfoxide, sulfonic acid). The disulfide state and also sulfoxide and sulfonic acid states were detected after reoxidation of glutenin subunits with potassium bromate.     

Fatty acid composition of M. longissimus lumborum, ultimate muscle pH values and carcass parameters in reindeer (Rangifer tarandus tarandus L) grazed on natural pasture or fed a commercial feed mixture

The effects of feeding regimen on the fatty acid composition of M. longissimus, ultimate pH values in three muscles (Mm. longissimus, triceps brachii and biceps femoris) and carcass quality were studied in15 reindeer bulls. Nine animals came from natural pasture and six had been fed a pelleted commercial feed mixture for two months prior to slaughter. The pellet fed reindeer had significantly better carcass grading scores (EUROP conformation), higher trim fat content, more intramuscular fat and lower ultimate pH values in all three muscles than the group from pasture. The polar and neutral lipid fatty acid composition of the meat was analysed separately. Meat from pasture fed reindeer showed a high content of the fatty acid 18:3 n-3 in the polar lipid fraction. In the same lipid fraction, the fatty acid 18:2 n-6 was dominant in meat from the pellet fed animals. Similar differences in the neutral lipid fraction were found when comparing fatty acid composition between treatment groups, however the abundance of these fatty acids was much less. The present results confirm previous findings that reindeer fed typical pelleted commercial feed mixtures generally have an improved nutritional status.     

Selective sperm binding to pig oviductal epithelium in vitro

The sperm reservoir in the caudal isthmus of the oviduct of a number of species is created by binding of spermatozoa to oviductal epithelium. The sperm reservoir fulfills a number of functions such as control of sperm transport, maintenance of sperm viability and modulation of capacitation. The initial capacities of ejaculated and epididymal boar spermatozoa to bind to oviductal epithelium were investigated using a modified pig oviductal explant assay. The number of spermatozoa that bound to 0.01 mm(2) of explant surface was used as the parameter of binding capacity. Binding of spermatozoa to oviductal epithelial explants was dependent in a linear manner on the number of spermatozoa added (P < or = 0.05). No difference was found in initial sperm binding between isthmic and ampullar explants. There was no effect of the stage of the oestrous cycle or the reproductive status of the female donor. There was a significant effect (P < or = 0.05) of the individual boar on the binding index. The binding index correlated negatively with the percentage of spermatozoa with cytoplasmic droplets and the percentage of morphologically abnormal spermatozoa (P < or = 0.05). Epididymal spermatozoa showed significantly lower initial binding capability than did ejaculated spermatozoa from the same boars (P < or = 0.05); therefore, components of seminal plasma may play a role in the binding process. The individual differences revealed by this study and their relation to morphology and contact of spermatozoa with seminal fluid indicate a selective function of sperm-oviduct binding.