Quality and Nutritional Changes in Frozen Breaded Shrimp Stored in Wholesale and Retail Freezers

Chemical, microbiological, and sensory changes were monitored in breaded fantail shrimp held in upright and coffin style freezers at two retail markets and in a large warehouse freezer. Quality and nutritional changes in a test lot of shrimp were followed for 13 months. Significant sensory deterioration can be detected as early as 3 - 4 months after production when shrimp are stored in a retail freezer. Minimum retail freezer temperatures reached ≤-20°C between 1% and 36% of the monitored days and had daily temperature variations of 12 - 18°C. Storage at the wholesale level below -20°C with maximum daily temperature variations of 2 - 3°C proved to be an effective method to maintain the quality of frozen shrimp for at least 13 months of storage.     

Application of HPLC for the Determination of PSP Toxins in Shellfish

A high performance liquid chromatographic (HPLC) procedure for determination of the toxins associated with paralytic shellfish poisoning (PSP) is compared to the standard AOAC mouse bioassay method on 100 shellfish samples representing a variety of species. For those samples with toxin content below the detection limit of the bioassay (35 μg saxitoxin (STX)/100g) HPLC analysis indicated a similar low level with a range of <10 to 56 μg STX/100g (n = 60). A correlation coefficient of 0.92 was determined for the 40 samples exhibiting toxicity in the bioassay (i.e., >35 μg STX/100g). Among the advantages of the HPLC method over the bioassay are significantly better sensitivity, greater sample through-put, and ability to determine the levels of each individual PSP toxin.     

Phase Transitions of Wheat Starch-Water Systems Containing Polydextrose

Equivalent concentrations of polydextrose and sucrose had similar effects on phase transitions of wheat starch-water systems. Onset and peak gelatinization temperatures were increased similarly with the two solutes. This was true with varied water:starch ratios, varied concentrations of solute, and for batters prepared with the two solutes. Acesulfame K, cyclamate, and saccharin at low levels, as might be used in food products, had little effect on phase transitions of starch-water-solute systems.     

RIGHT TO THE SUBURB? RETHINKING LEFEBVRE AND IMMIGRANT ACTIVISM

ABSTRACT: In the face of increasing migration by Latinos to suburbs and multi‐scalar policies criminalizing immigrants, municipalities are increasingly confronting the question, Who has the Right to the Suburb? We seek to better understand how the tensions between suburbanites and Latino immigrants are addressed by municipal governments as immigration enforcement is increasingly rescaled to the local level. Case studies of Maywood and Costa Mesa in Southern California suggest responses are by no means similar and can actually be contrasting, given the city's historical trajectories, socio‐economic status, political leadership, and networks of activists. Suburban struggles are often assumed to be conservative and as a result are undertheorized as sites of liberatory struggle. While the urban realm remains the most visible stage of social movements, this paper suggests immigrant activism is increasingly being generated in suburbs, election‐based organizing can be an effective gateway to municipal level change, and seeking to expand or constrict the Right to the City necessarily entails multi‐scalar efforts.     

A UNIFIED COLLOCATION ALGORITHM FOR PACKED-BED CHEMICAL REACTOR SIMULATION

Mathematical models of packed-bed catalytic reactors are aimed to predict the conversions and temperature profiles in both fluid and solid phases within the reactor. Although very general models can be mathematically formulated, usually several simplifying hypothesis are introduced for the fluid phase and/or the solid phase, in order to overcome computational difficulties

We describe in this paper a computational algorithm based on Orthogonal Collocation Method on finite elements, with elimination of the knot unknown functions, coupled with an integration method for stiff ordinary differential equations. This has been used in the development of a computer code, which allows us to find the transient behavior of the reactor by solving the equation relative to the external field, coupled with those describing the transient behavior in the catalyst particles, for a wide class of reactor models. The most general examined model includes axial dispersion in the external fluid phase, interphase mass and heat transfer resistances, intraphase mass resistance and any given kinetic scheme with complex reaction rate expressions.     

A Planning Model for the Fuerte-Carrizo Irrigation System, Mexico

A methodology is presented for planning the operation of the Fuerte-Carrizo irrigation system in northwest Mexico. The system has two storage dams, two irrigation districts, and water transfer capabilities between both dams. The methodology uses a combination of linear programming (LP) and simulation. The LP model maximizes the net return of the farmers, subject to restrictions of the system, availability of water and land, and water transfer relationships. The simulation model is programmed as a microcomputer interactive package simulating the performance of the system. The methodology has proven to be a useful tool to assist those responsible for the operation of the irrigation system.     

Worker Turnover in the 1920s: The Role of Changing Employment Policies

This paper examines the decline in turnover of manufacturingworkers during the 1920s as a response to new employment policieswhich increased workers' cost of voluntary (and involuntary)separation. Case studies of four firms are used to illustratethat the incentives to change employment procedures were thereduction of costly labor turnover and the motivation of workereffort. Firms' new employment practices reduced labor turnoverthrough the direct effect on their workers and the equilibriumeffect on the aggregate labor market.     

Effect of Hydrogen Peroxide and Phenolic Compounds on Horseradish Peroxidase-Catalyzed Decolorization of Betalain Pigments

The effect of hydrogen peroxide and phenolic compounds on the decolorization of betanin and a betaxanthin preparation by horse-radish peroxidase (HRP) was examined. Betanin was decolorized at a greater rate than the betaxanthm pigments and both reactions were H₂O²-dependent. Betaxanthin was more prone to oxidatic decolorization than betanin. 2,4-Dichlorophenol, resorcinol and o-toluidine stimulated the decolorization of both pigments. Guaiacol enhanced the peroxidatic decolorization of both pigments to a small extent, but inhibited the oxidatic breakdown of betaxanthin. Possible implications of these results are discussed.