The formation of acrylamide in potato crisps was fitted by empirical mathematical models. Potato slices were fried under the same experimental conditions for different times. Besides the content of precursors in the raw potato slices, acrylamide and water content in the potato crisps were quantified after predetermined times (2-6 min). The temperature developments in the surrounding oil and outer cell layer of the potato slices were monitored, giving more insight in the frying process and making future comparisons between studies possible. The pattern found for the formation of acrylamide, which was similar to earlier studies, was fitted to three empirical models. Statistical methods were used to compare the performance of the models, with the "Logistic-Exponential" and "Empirical" model performing equally well. The obtained model parameters were in the range of earlier reported studies, although this comparison is not unequivocal as the experimental conditions differed between studies. The precision of parameter estimates was problematic; this should be improved by better experimental design. Nevertheless, the approach of this study will make it possible to truly compare acrylamide formation patterns and model parameters in the future, with the ability to develop a tool to predict acrylamide formation in potato crisps.
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The objective of this study is to apply a potato model for the Andean Ecoregion and extend this model with Late Blight epidemiology and fungicide spray scheduling in order to evaluate effects (trade-offs) of fungicide applications on potato yield.
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Potato cyst nematodes (PCN) are in the Northern Netherlands and the Weser-Ems Region in Germany a major issue for farmers. The yearly average damage by PCN is about 100 Euros/hectare for farmers. Infestations of potato cyst nematodes can be controlled in a sustainable way by proper potato variety selection. Potato varieties vary in the degree of tolerance and resistance to PCN. However, this knowledge is used by only a small fraction of the farmers. The AGROBIOKON project, which is funded by the INTERREG EDR-region, the Landwirtschaftskammer Niedersachsen and the Dutch farmers association, have developed a decision support system for potato variety selection based upon population dynamic models for PCN: OPTIRas. The scientific principles and the model behind the decision support system will be presented. The model will be applied to PCN field experiments in the Weser-Ems region. Experience of using this decision support system in farmer study groups in the Netherlands and Germany will be shared.
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Three empirical models were used to fit the formation of acrylamide in crisps of three different cold-sweetened potato genotypes, fried under the same experimental conditions. Statistical methods were used to compare the performance of the models, with the "Logistic-Exponential" model performing the best. The obtained model parameters for the formation of acrylamide showed improvement in precision compared to an earlier study, the precision of the parameter estimates for the degradation of acrylamide was still problematic. Nevertheless, the predictive capacity of the "Logistic-Exponential" model was tested, as this model showed a strong correlation between parameter a and the reducing sugar content of the raw potato. The predictions from this model for the formation of acrylamide in potato crisps were close to earlier reported experimental values. Therefore, the use of the "Logistic-Exponential" model as a tool to predict acrylamide in potato crisps seems promising and should be developed further.
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Reducing the use of pesticides by early visual detection of diseases in precision agriculture is important. Because of the color similarity between potato-plant diseases, narrow band hyper-spectral imaging is required. Payload constraints on unmanned aerial vehicles require reduc- tion of spectral bands. Therefore, we present a methodology for per-patch classification combined with hyper-spectral band selection. In controlled experiments performed on a set of individual leaves, we measure the performance of five classifiers and three dimensionality-reduction methods with three patch sizes. With the best-performing classifier an error rate of 1.5% is achieved for distinguishing two important potato-plant diseases.
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Within the framework of Agrobiokon an internet application was developed allowing potatogrowers a simple evaluation of their potato late blight control strategy. The goal of developing this application was to confront the perception of growers regarding the protection level of their crops with an independent calculation of this level. Calculations ofthe daily infection risk allow growers to retrospectively track periods of under- and over protection of their crops. This form of interactive knowledge transfer is hoped to trigger improvements in growers’ potato late blight control strategies with respect to spray timing and fungicide selection.
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Field experiments were carried out in 1991 and 1992 on sandy soil highly infested with the potato cyst nematode Globodera pallida. Half the trial area was fumigated with nematicide to establish two levels of nematode density. Three levels of soil compaction were made by different combinations of artificial compaction and rotary cultivation. Two potato cultivars were used in 1991 and four in 1992. Both high nematode density and soil compaction caused severe yield losses, of all cultivars except cv. Elles which was tolerant of nematode attack. The effects of the two stress factors were generally additive. Analysis of the yield loss showed that nematodes mainly reduced cumulative interception of light while compaction mainly reduced the efficiency with which intercepted light was used to produce biomass. This indicates that nematodes and compaction affect growth via different damage mechanisms. Nematodes reduced light interception by accelerating leaf senescence, by decreasing the specific leaf area and indirectly by reducing overall crop growth rate. Partitioning of biomass between leaves, stems and tubers was not affected by nematode infestation but compaction decreased partitioning to leaves early in the growing season while increasing it during later growth stages. The effects of nematodes and compaction on root length dynamics and nutrient uptake were also additive. This suggests that the commonly observed variation in yield loss caused by nematodes on different soil types is not related to differences in root system expansion between soils of various strength. Cv. Elles, which showed tolerance of nematodes by relatively low yield losses in both experiments, was characterised by high root length density and thick roots. These characteristics did not confer tolerance of soil compaction, since compaction affected root lengths and tuber yields equally in all cultivars. In the first experiment only, high nematode density led to decreased root lengths and lower plant nutrient concentrations. The yield loss which occurred in the second experiment was attributed to the effects of nematodes on other aspects of plant physiology. Copyright © 1995, Wiley Blackwell. All rights reserved
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Microbacterium aurum strain B8.A was isolated from the sludge of a potato starch-processing factory on the basis of its ability to use granular starch as carbon- and energy source. Extracellular enzymes hydrolyzing granular starch were detected in the growth medium of M. aurum B8.A, while the type strain M. aurum DSMZ 8600 produced very little amylase activity, and hence was unable to degrade granular starch. The strain B8.A extracellular enzyme fraction degraded wheat, tapioca and potato starch at 37 °C, well below the gelatinization temperature of these starches. Starch granules of potato were hydrolyzed more slowly than of wheat and tapioca, probably due to structural differences and/or surface area effects. Partial hydrolysis of starch granules by extracellular enzymes of strain B8.A resulted in large holes of irregular sizes in case of wheat and tapioca and many smaller pores of relatively homogeneous size in case of potato. The strain B8.A extracellular amylolytic system produced mainly maltotriose and maltose from both granular and soluble starch substrates; also, larger maltooligosaccharides were formed after growth of strain B8.A in rich medium. Zymogram analysis confirmed that a different set of amylolytic enzymes was present depending on the growth conditions of M. aurum B8.A. Some of these enzymes could be partly purified by binding to starch granules.
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This study provides insights into novel combinations of hydrothermal modifications and mineral enrichment by demonstrating the versatility of this environmentally more benign approach compared to other common chemical starch modifications like crosslinking. Heat-moisture treatment (HMT) (15 % moisture, 100 °C) of native potato starch (NPS) affords granular products that gelatinise at lower temperatures, hold more water as gel, and are more susceptible to enzymatic digestion. Prior mineral enrichment of NPS with sodium, potassium, magnesium and calcium ions yielded significant changes in pasting curves, with monovalent cations increasing peak viscosity, while divalent cations decrease peak viscosity through ionic crosslinking of phosphate groups, allowing further fine tuning of swelling behaviour. Both short and long HMT (4 h and 16 h) triggered partial disruption of crystallinity and an increase in particle size without visible surface damage as evidenced by X-ray diffraction, laser diffraction and scanning electron microscopy. These novel products may find applications where a thickening agent is needed, and high levels of target minerals are desirable like sport nutrition. The viscosity behaviour, available energy and essential minerals may be beneficial to the formulation and nutritional value of energy gels, while adhering to clean-label requirements of today`s food industry.
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