Modeling and predicting spoilage of cooked, cured meat products by multivariate analysis

A cooked, cured meat product is a perishable product spoiled mainly by lactic acid bacteria (LAB). LAB cause discoloration, slime formation, off-odors and off-flavors as the result of their metabolic activity producing various products. These microbial products in conjunction with the microbial population could be used to assess the degree of spoilage of this type of product. The spoilage evaluation was achieved by following a multivariate approach. Cluster analysis, principal component analysis and partial least square regression were employed to associate spoilage with microbiological and physicochemical parameters. The developed model was capable of giving accurate predictions of spoilage describing the spoilage associations. The study might contribute to the improvement of quality assurance systems of meat enterprises.     

Generation of linalool derivatives in an artificial honey produced from bees fed with linalool-enriched sugar syrup

This paper presents a novel procedure to investigate the bioconversion of nectar components via the ‘intermediate’ honeybee and under the effect of the conditions in the beehive. The procedure was applied with linalool, the major component in the extract of Citrus spp. flowers, in order to investigate its bioconversion to linalool derivatives, the major volatiles of citrus honey. Bees were fed daily with 1 L sugar syrup 1:1 (w/v) containing 1 mL of (±) linalool, while control bees were fed with the same amount of linalool-free syrup. The artificial honey was analysed by means of ultrasound-assisted extraction followed by GC–MS analysis. The results show that the formation of both furan and pyran linalool oxides as well as terpendiol I is favoured, probably catalysed by the enzymes secreted by the bee. On the contrary, important linalool derivatives of citrus honey such as lilac aldehydes, cis- and trans-dehydroxy linalool oxides (E)-2,6-dimethyl-6-hydroxy-2,7-octadienal and (Z)-8-hydroxylinalool were absent in the artificial honey, suggesting the requirement of a plant-derived enzyme for their bioconversion. The same stands for (E)-8-hydroxylinalool, major volatile of citrus honey, although small amounts were present in the artificial honey. From these results, it can be concluded that feeding honeybees with linalool-enriched sugar syrup is not an effective way to produce artificial citrus honey similar to the natural one.     

Comparative study of spontaneously fermented sourdoughs originating from two regions of Greece: Peloponnesus and Thessaly

A total of 167 yeast and 136 lactic acid bacteria strains were isolated from spontaneously fermented wheat sourdoughs from two regions of Greece, namely Thessaly and Peloponnesus. Identification of the isolates exhibited dominance of Torulaspora delbrueckii with sporadic presence of Saccharomyces cerevisiae and, regarding the lactic acid bacteria, dominance of Lactobacillus sanfranciscensis in the sourdoughs from Thessaly and Lb. plantarum subsp. plantarum in the sourdoughs from Peloponnesus. The latter was accompanied by Pediococcus pentosaceus as secondary microbiota. None of the above mentioned strains exhibited amylolytic, lipolytic or proteolytic activities, and none of the lactic acid bacteria strains produced antimicrobial compounds.     

Spotlight on transformer design

This paper presents an integrated artificial intelligence technique to achieve an optimum design of a transformer. AI is used to reach an optimum transformer design solution for the winding material selection problem. To be more precise, decision trees (DTs) and adaptive trained neural networks (ATNNs) are combined with the aim of selecting the appropriate winding material (Cu or Al) to design an optimum distribution transformer. Both methodologies have emerged as important tools for classification     

Solid-phase microextraction/gas-chromatographic/mass spectrometric analysis of p-dichlorobenzene and naphthalene in honey

Protection of honeycombs from the Wax moth, Galleria mellonella, involves the use of physical, biological or chemical control methods. As chemical control may result in residues in the extracted honey, the presence of p-dichlorobenzene and naphthalene residues was investigated by solid-phase microextraction (SPME) coupled to gas-chromatographic/mass spectrometry (GC/MS). The method was linear between 5 and 200 microg kg(-1) honey for p-dichlorobenzene and 1 and 200 microg kg(-1) for naphthalene. Limits of detection were 1 and 0.1 microg kg(-1), respectively, for p-dichlorobenzene and naphthalene, while relative standard deviations were 2.6 and 7.9%, respectively. Application of the method to 90 unifloral Greek honeys revealed that, in 25.6% of the samples, the concentration of either one of the pesticides exceeded the maximum residue level (MRL). Maximum concentrations were 163.03 microg kg(-1) honey for p-dichlorobenzene and 193.74 microg kg(-1) honey for naphthalene. Naphthalene was found in traceable amounts in 78.9% of the samples, but only 5.6% of them contained concentrations above the MRL, which indicates the use of pre-contaminated honeycomb foundations or built combs. Nevertheless, because naphthalene is naturally present in some plant species growing in Greece, the contribution of nectar from such a floral source should not be overlooked.     

Architecture for reliable service discovery and delivery in manets based on power management employing slp extensions

Limited energy resources and mobility issues affect the topology of ad hoc networks and introduce difficulties in service discovery. The high possibility of a link breakdown due to low energy supplies in a ubiquitous computing environment, such as a mobile ad hoc network (MANET), raises service-provider selection issues with regard to achieving the best possible service reliability. Every node requiring a specific service must choose a provider under certain criteria. This article provides an overview of standardized service-discovery and delivery solutions. In addition, a novel architecture is proposed which provides the ability to select a service provider by taking into account metrics such as the power supplies of the service provider and concomitant path towards the destination. The proposed algorithm is decentralized and based on service location protocol version 2 (SLPvZ) extensions     

A Synthesis of Tactical Fleet Planning Models for the Car Rental Industry

Daily tactical planning of the vehicle fleet is critical for a car rental business. In this decision-making process planners have to address the conflicting concerns of field management, namely, assuring adequate vehicle availability to satisfy customer demand while maintaining a high degree of utilization for each car in the fleet; this is achieved by the appropriate fleet deployment among car rental locations. This work was inspired by a series of problems encountered by the decision-makers of a major US car rental company. We first present the formulation of the tactical fleet planning model. Based on its structure, we decompose the model into a fleet deployment model and a transportation model. We develop optimal conditions for both subproblems and then we present a heuristic to reduce the gap from optimality for the complete model. We further present the application of the entire solution methodology via a case analysis for the State of Florida. Finally, we develop three extensions to the fleet deployment model to capture the cost of unsatisfied demand and fleet surplus, the service level, and a general price-demand function. We provide optimal closed-form conditions for all the extensions.     

Conjugated Graetz problems—I: General formalism and a class of solid-fluid problems

Conjugated Graetz problems arise where two (or more) phases, with at least one phase in fully developed flow, exchange energy or mass across an intervening surface. In these problems the temperature or concentration fields are coupled through the conjugating conditions which express the continuity of fluxes and the rate of transfer. A general formalism is presented first for the analysis of these problems, employing a matrix differential operator with respect to the radial variable and following the decomposition technique of [1–3]. The aforementioned operator is shown to be symmetric in its domain, possessing a denumerable set of eigenvalues and a complete set of eigenvectors. A class of solid-fluid problems, involving the removal of heat from a heated solid cylinder by a surrounding annular-flow fluid, is then discussed in detail; analytical solutions are obtained by expansion in terms of the above eigenvectors. These solid-fluid problems may be viewed as extensions of the extended, one-phase, Graetz problem with prescribed wall flux [2].     

Shelf life establishment of a sliced, cooked, cured meat product based on quality and safety determinants

In the present study, the distribution of the shelf life of cooked, cured meat products based on lactic acid bacteria growth and the distribution of the time to cause health risks based on Listeria monocytogenes growth were studied. Growth models, developed and validated on cooked meat products, were used to predict the growth of microorganisms. Temperature data were obtained from retail and home refrigerators. Distribution predictions were conducted by two approaches (time-temperature profiles and Monte Carlo simulation). Time-temperature profiles were more appropriate to be used, because Monte Carlo simulation overestimated the growth of L. monocytogenes. Shelf life was greatly influenced by storage temperature, but initial microbial load had a smaller effect. The expiration date of cooked meat products might be based on only the growth of the spoilage microorganisms, and only when product contamination with L. monocytogenes cell concentrations is high does a product fraction pose health risks for consumers. Sensitivity analysis confirmed that storage temperature and temperature variability were the most important factors for the duration of shelf life. Distributions of shelf life and time to cause health risks give valuable information on the quality and safety of cooked meat products and may be used as practical tools by meat processors.