RANCIDITY OF WALNUTS AND ALMONDS AFFECTED BY SHORT TIME HEAT TREATMENTS FOR INSECT CONTROL

Short time heat treatments effectively control insect contamination of nuts containing substantial quantities of polyunsaturated fatty acids susceptible to oxidative rancidity. Walnut kernels contain greater concentrations of polyunsaturated fatty acids than almond kernels. The objectives of this research were to investigate the lipid stability of shelled walnuts and almonds as affected by short time heat treatments and accelerated storage temperatures. Heating treatments were at 55C for 2 min, 55C for 10 min, 60C for 2 min or 60C for 10 min to simulate predetermined deinfestation treatments. Untreated control and heat treated shelled walnut and almond kernels were stored at 25C for 5, 15, 30 and 60 days or 35C for 2, 5, 10 and 20 days to simulate the shelf lives of walnut and almond kernels at 4C for 2 years. Oils extracted from untreated and short time heat treated walnut kernels exhibited higher peroxide values than oils extracted from untreated and short time heat treated almond kernels under equivalent conditions. Oils extracted from untreated walnut kernels exhibited significantly (P ± 0.05) higher peroxide values than oils extracted from short time heat treated walnut kernels after 5, 15, 30, and 60 days of storage at 25C, or after 2, 5, 10, or 20 days of storage at 35C. Oils extracted from untreated almond kernels exhibited higher peroxide values than oils extracted from short time heat treated almond kernels after 5, 15, 30, or 60 days of storage at 25C, or after 2, 5, 10 or 20 days of storage at 35C. Oils extracted from untreated walnut kernels and oils extracted from short time heat treated walnut kernels exhibited higher peroxide values than oils extracted from almond kernels after storage at 25C or 35C. Short time heat treatment does not enhance development of rancidity during accelerated storage of walnut or almond kernels.     

Current and emerging molecular diagnostic technologies applicable to bacterial food safety

There is an increasing need for rapid test methods to certify the quality and safety of food products. Current tests applied for the microbiological assessment of food products are based on standard approved culture-based isolation methods and can take several days to yield results. Nucleic acid diagnostic (NAD) tests for the identification of bacterial foodborne pathogens employing in vitro amplification technologies are capable of sensitive and specific detection of single or multiple pathogens in foods in a shorter timeframe than traditional methods. New developments in molecular biosensors have the potential to provide at-line bioanalysis, whereas microarray-based technologies may in the future be the NAD platforms of choice for multiple pathogen detection and identification. This article reviews current and emerging NAD platforms for foodborne bacterial pathogens that have the potential to impact food safety.     

Thermochemistry of MgAl2O4-Al8/3O4 Defect Spinels

Solution calorimetry of MgAl₂O₄-Al_8/3O₄ solid solutions was performed in a molten 2PbO · B₂O₃ solvent at 975 K. The results indicate small negative heats of mixing, relative to spinel standard states for both end-members. These data were combined with information on the energetics of the α-γ transition in Al₂O₃ and on the MgAl₂O₄-Al_8/3O₄ (MgO-Al₂O₃) subsolidus phase relations to estimate the partial molar entropy of mixing of γ-Al_8/3O₄ in the solid solution. This entropy is much less positive than that calculated from several models for the configurational entropy of mixing of magnesium, aluminum, and vacancies on octahedral and/or tetrahedral sites. The data suggest a good deal of local order to be present in the solid solutions, consistent with negative enthalpies of mixing and entropies of mixing far less than ideal configurational values.     

Neural network identification of critical factors in a dynamic just-in-time kanban environment

Prior research has examined the proper number of kanbans to be used in various just-in-time environments, but relatively little work has been done in exploring which factors internal and external to a shop in a given time period are critical in determining the necessary number of kanbans to be specified for the next period. The research reported here examines the identification of shop factors in a dynamic and stochastic just-in-time environment. In particular, three questions are addressed: does information from a prior period help in setting the kanban level in the current period? If so, which endogenous and exogenous factors considered individually help the most? And finally, what grouping of individual factors is most important in deciding the number of kanbans? The methodology employed is to use artificial neural networks to fit simulated shop data to learn the relationship between prediction factors and overall shop performance. Appropriate non-parametric statistical tests are then used to answer the questions. The answers obtained, although shop specific, may also be generated by firms willing to follow the procedure presented here for conditions specific to their particular operation.     

OPTIMIZATION OF REDUNDANCY IN WATER DISTRIBUTION NETWORKS USING GRAPH THEORETIC PRINCIPLES

An integer goal programming based approach to maximize reliability in water distribution networks is developed. Previous work has shown that graphs which are inherently the most invulnerable to failure have the same number of links incident at each node, i.e. they are regular in degree. The converse of this statement is not true. Regular graphs can contain weaknesses such as bridges, articulation nodes, and even total disconnections. The integer goal programming formulation in this paper is combined with a procedure which recognizes both explicit and implicit articulation points within the water distribution network to ensure that such weaknesses are excluded from the final solution. The integer program component of the approach attempts to maximize regularity within the network. In the goal programming context this is achieved by minimizing the sum of the deviations, at each node, in terms of the number of links incident upon it, from the average number of links incident on a node over the whole network. The integer requirement is imposed to prevent non-integer numbers of links being selected by the model.     

Master production scheduling,customer service and manufacturing flexibility in an assemble-to-order environment

A key element of manufacturing planning and control involves the inter-functional coordination of various manufacturing requirements. This paper reports the results of a simulation experiment that compares alternative master production scheduling (MPS) procedures in an assemble-to-order environment. The MPS procedures are superbills and covering sets. For a given investment in safety stocks the managerial problem is how to construct the MPS in order to minimize the firm's delivery time pressures. The results of the simulation experiment strongly support the use of the superbill techniques over the covering set technique. Moreover, of the experimental factors that influence delivery time performance, the choice of master production scheduling technique has the largest effect. Demand variability has the next greatest effect on delivery time performance. The safely stock level has the third greatest effect and product commonality was fourth. Finally, the managerial implications of the results are discussed in detail.     

A FUZZY ALGORITHMIC APPROACH TO THE CONSTRUCTION OF COMPOSITE INDICES: AN APPLICATION TO A FUNCTIONAL LIMITATION INDEX

This paper presents a fuzzy algorithmic approach to the construction of composite indices. The method uses a fuzzy analytic translation of a linguistic definition of the composite index, where the definition involves more primary concepts for which scales already exist. An application to the construction of a functional limitation index is presented. Comparisons between the fuzzy algorithmic approach and a more standard, tabular approach are also shown. The results suggest that the fuzzy algorithmic approach yields essentially the same index with less effort and some conceptual advantages.     

INACTIVATION of SACCHAROMYCES CEREVISIAE IN APPLE JUICE BY SQUARE-WAVE and EXPONENTIAL-DECAY PULSED ELECTRIC FIELDS

With equivalent electrical energy input, inactivation of microorganisms by pulsed electric fields depends on pulse waveform. Exponential-decay and square-wave pulsed electric fields were selected to treat Saccharomyces cerevisiae suspended in apple juice. A parallel-plate static treatment chamber with 25 ml volume and 0.95 cm electrode gap was used. Peak electric field and pulse electric energy input were 12 kV/cm and 260 Joules per pulse for both waveforms. Both waveforms were found effective in the microbial inactivation. However, inactivation of S. cerevisiae treated with square-wave pulses was greater than yeast treated with exponential-decay pulses. For the purpose of food pasteurization, square-wave pulsed electric fields may result in significant energy savings compared to exponential-decay pulses.