Kinetic study of the effect of the osmotic dehydration pre-treatment to the shelf life of frozen cucumber

Quality of frozen cucumber can significantly be improved by means of osmotic dehydration as a pre-freezing treatment. The objective of this work was to study the effect of osmotic pre-treatment with alternative osmotic solutes – oligofructose and a high DE maltodextrin – on the quality and functional properties of frozen cucumber tissue. Colour, texture and sensory characteristics of pre-treated and conventionally frozen samples were comparatively measured at 3 months time, during storage at four different temperatures, − 5, − 8, − 12, − 15 °C. Colour change was kinetically studied, and its temperature dependence was modelled by the Arrhenius equation. Dehydrofrozen samples exhibited significantly improved stability, with the rates of colour change being reduced up to 36.7% for osmotically pre-treated cucumbers, compared to the untreated samples. The results indicate that osmodehydrofrozen compared to conventionally frozen sliced cucumbers show improved firmness for prolonged storage period. Sensory evaluation also showed good organoleptic quality in osmodehydrofrozen cucumber slices.

Industrial relevance

The poor quality of frozen cucumber can significantly be improved by means of the cryoprotection accomplished by a pre-freezing osmotic dehydration step. Osmotic dehydration at mild temperatures can preserve product texture, and enhance flavour and other sensory properties (colour). In this paper, the effect of osmotic pre-treatment on the quality and shelf life of frozen cucumber tissue was investigated. The aim was to develop a method of processing cucumber that maintains palatable product while optimizing quality at the beginning and during frozen storage.     

Peroxidase-active cell free extract from onion solid wastes: biocatalytic properties and putative pathway of ferulic acid oxidation

The exploitation of food residuals can be a major contribution in reducing the polluting load of food industry waste and in developing novel added-value products. Plant food residues including trimmings and peels might contain a range of enzymes capable of transforming bioorganic molecules, and thus they may have potential uses in several biocatalytic processes, including green organic synthesis, modification of food physicochemical properties, bioremediation, etc. Although the use of bacterial and fungal enzymes has gained attention in studies pertaining to biocatalytic applications, plant enzymes have been given less consideration or even disregarded. Therefore, we investigated the use of a crude peroxidase preparation from solid onion by-products for oxidizing ferulic acid, a widespread phenolic acid, various derivatives of which may occur in food wastes. The highest enzyme activity was observed at a pH value of 4, but considerable activity was retained up to a pH value of 6. Favorable temperatures for increased activity varied between 20-40 degrees C, 30 degrees C being the optimal. Liquid chromatography-mass spectrometry analysis of a homogenate/H(2)O(2)-treated ferulic acid solution showed the formation of a dimer as a major oxidation product.     

Hydrocaffeic acid oxidation by a peroxidase homogenate from onion solid wastes

A very large amount of phenol-polluted waters are formed from the production of olive oil (olive mill waste water, OMWW), and the main problem associated with their disposal is a viable means of effective treatment. Biochemical processes used for treating OMWW are generally considered to be of high capital and operating costs with limited efficiency. This is mainly due to particularly high levels of phenolic compounds, which are considered major contributors to the toxicity and antibacterial activity of OMWW, and limit their microbial treatment and/or use as fertilizers. Although the use of bacterial and fungal enzymes has gained interest in studies pertaining to bioremediation applications, plant enzymes have been given less attention or even disregarded. In this view, this study aimed at investigating the use of a crude peroxidase preparation from onion solid by-products for oxidising hydrocaffeic acid, a typical o-diphenol with a structure very similar to various phenolic derivatives that may occur in OMWW. Increased enzyme activity was observed at a pH value of 4, but considerable activity was also retained for pH upto 7. Favourable temperatures for increased activity varied between 30 and 50 °C, 40 °C being the optimal. Liquid chromatography–mass spectrometry analysis of a homogenate/H₂O₂-treated hydrocaffeic acid solution revealed the existence of three major oxidation products, which were identified as dehydrodimers. Based on the data generated, a putative pathway for the formation of the peroxidase-mediated hydrocaffeic dehydrodimers was proposed.     

Estimation of the Water Resources Potential in the Island System of the Aegean Archipelago,Greece

Abstract

The present paper tries to estimate the surface water resources potential in some of the major Aegean islands in an effort to provide a means for the continuous development of the region, and, by extension, for similar areas around the world. The islands have to confront the challenge of surviving in a semiarid environment under the constraints of uneven water resources distribution both in space and time. In addition to these, tourism development, industrialization and highly water consumptive life styles have exacerbated perennial problems in water resources and water resources management. The framework of the present effort has a two-prong emphasis. In the first part, a simulation model is presented, which tries to estimate the potential surface runoff under physical, structural organizational, and institutional constraints. The methodology and the premises of the simulation process are delineated. In the second part, the results of the model's application in distinct cases are demarcated. The final product, namely the model and the resulting runoff coefficients, are presented in the form of a standard, which may provide practitioners in the field as well as decisionmakers the means for an initial reference in pertinent developmental efforts. Finally, the conclusions and recommendations raise the question of ecosystem resilience and point towards the urgent and continuous need for the application of integrated water resources management principles.     

Anchor‐free distance estimation: A new approach to distance estimation for multihop ad hoc wireless networks

In ad hoc wireless networks, devices that normally cannot directly communicate route their messages through intermediate nodes. The number of those nodes is called hop count, a useful metric in estimating the distance between 2 nodes. Current methods usually depend on special nodes, called anchors, that need accurate localization information, in order to calculate an estimate for the average distance traversed per hop. The drawback of this approach is that anchor nodes increase the overall cost and complexity of the system. To address this problem, this letter proposes a novel, anchor node–free algorithm that can achieve a useful estimate for actual distance between 2 nodes, by analytically finding an estimate for the average maximum distance traveled per hop and multiplying with the hop count. The only requirement is the a priori knowledge of the networks' node density and the node range. The performance of our method is compared with a recent anchor node–based method and is shown to yield similar location estimation accuracy, despite the fact that it does not use anchor nodes.     

A convex characterization of distributed control problems in spatially invariant systems with communication constraints

In this paper we consider the problem of distributed controller design in spatially invariant systems for which communication among sites is limited. In particular, the controller is constrained so that information is propagated with a delay that depends on the distance between subsystems—a structure we refer to as “funnel” causality. We show that the problem of optimal design can be cast as a convex problem provided that the plant has a similar funnel-causality structure, and the propagation speeds in the controller are at least as fast as those in the plant. As an example, we consider the case of the wave dynamics with limited propagation speed control.     

AI and human society

This paper considers the impact of the AI R&D programme on human society and the individual human being on the assumption that a full realisation of the engineering objective of AI, namely, construction of human-level, domain-independent intelligent entities, is possible. Our assumption is essentially identical tothe maximum progress scenario of the Office of Technology Assessment, US Congress.Specifically, the first section introduces some of the significant issues on the relational nexus among work, education and the human-machine boundary. In particular, based on a Russellian conception of rationality I briefly argue that we need to change our related conceptions of work, employment and free time, through a new human-centred education. On the human-machine boundary problem, I make a couple of tentative suggestions and put forward some crucial open questions.Section two discusses the impact of the emerging machine intelligence on human nature both as modification of its self-image, keeping human nature itself unchanged, and its potential for altering human nature itself. I briefly argue that: (i) in a certain context, the question of the supremacy or uniqueness of human intelligence loses much, if not all, of its weight; and (ii) appearance of Robot-X species would immortalise the human spirit.     

Effect of plasma TNF-alpha on filgrastim-stimulated hematopoiesis in mice and humans

Marshall syndrome is a rare, autosomal dominant skeletal dysplasia that is phenotypically similar to the more common disorder Stickler syndrome. For a large kindred with Marshall syndrome, we demonstrate a splice-donor-site mutation in the COL11A1 gene that cosegregates with the phenotype. The G+1-->A transition causes in-frame skipping of a 54-bp exon and deletes amino acids 726-743 from the major triple-helical domain of the alpha1(XI) collagen polypeptide. The data support the hypothesis that the alpha1(XI) collagen polypeptide has an important role in skeletal morphogenesis that extends beyond its contribution to structural integrity of the cartilage extracellular matrix. Our results also demonstrate allelism of Marshall syndrome with the subset of Stickler syndrome families associated with COL11A1 mutations.     

On l∞ and l2 robustness of spatially invariant systems

We consider spatiotemporal systems and study their l_∞ and l₂ robustness properties in the presence of spatiotemporal perturbations. In particular, we consider spatially invariant nominal models and provide necessary and sufficient conditions for system robustness for the cases when the underlying perturbations are linear spatiotemporal varying, and nonlinear spatiotemporal invariant, unstructured or structured. It turns out that these conditions are analogous to the scaled small gain condition (which is equivalent to a spectral radius condition and a linear matrix inequality for the l_∞ and l₂ cases, respectively) derived for standard linear time‐invariant models subject to time‐varying linear and time‐invariant nonlinear perturbations. Copyright © 2009 John Wiley & Sons, Ltd.