Minimization processes

The catalytic vapor-phase oxidation of propylene is generally carried out in a fixed-bed multitube reactor at near atmospheric pressures and elevated temperatures (ca 350°C) molten salt is used for temperature control. Air is commonly used as the oxygen source and steam is added to suppress the formation of flammable gas mixtures. Operation can be single pass or a recycle stream may be employed. Recent interest has focused on improving process efficiency and minimizing process wastes by defining process improvements that use recycle of process gas streams and/or use of new reaction diluents (20-24). 

Approximately half of all the food products ia the United States are fresh or minimally processed. Eresh food products include meats, vegetables, and fmits that are unprocessed except for removal from the original environment and limited trimming and cleaning. Eresh foods are handled to retard deterioration, which is relatively rapid at ambient or higher temperature. Meats are chilled rapidly to below 10°C (50°E) and most vegetables and fmits are generally reduced to below 4.4°C (40°E) by low temperature air, water, or ice. 

Partially Processed Food Products. Partially processed food products have received more than minimal processing but stiU requite refrigeration. 

Natural resins have been collected by hand throughout recorded history and used with minimal processing. They are reported to have been used in the arts, both in paints and for polishing sculptures, as early as 350 BC. Amber, the hardest of these resins, has been used as a gemstone from early Greek history to modem times. The electrical properties of amber were first recorded about 300 BC. Following is a description of commercial natural resins that are available in the United States. 

A drop of water that is placed on a hillside will roll down the slope, following the surface curvature, until it ends up in the valley at the bottom of the hill. This is a natural minimization process by which the drop minimizes its potential energy until it reaches a local minimum. Minimization algorithms are the analogous computational procedures that find minima for a given function. Because these procedures are downhill methods that are unable to cross energy barriers, they end up in local minima close to the point from which the minimization process started (Fig. 3a). It is very rare that a direct minimization method... 

Figure 6-51. Recycle trip configured to minimize process disturbances.

Means to minimize processes 1 and 2 have already been discussed. Processes 3-5 can be minimized or at least delayed through the choice of suitable antioxidants. 

The term process intensification is used synonymously with minimization. Process intensification is also often used more specifically to describe new technologies which reduce the size of unit operations equipment, particularly reactors. Innovative process intensification techniques are receiving more and more attention. Interesting possibilities for a range of unit operations, including reaction, gas-liq-... 

An alternate approach to the above is to provide parallel relief valve-rupture disc systems. The valve will have a setting slightly above the normal operating pressure with the rupture disc at about a 10% higher setting. The relief valve should control minor pressure excursions, can vent material and then reseat to minimize process losses. The rupture disc would provide the ultimate safety protection. 

Natural antimicrobials for the minimal processing offoods (ISBN 1 85573 669 1)... 

Azevedo-Meleiro, C.H. and Rodriguez-Amaya, D.B., Carotenoid composition of kale as influenced by maturity, season and minimal processing, J. Sci. Food Agric., 85, 591, 2005. 

Butot, S., Putallaz, T., Amoroso, R., and Sanchez, G. (2009). Inactivation of enteric viruses in minimally processed berries and herbs. Appl. Environ. Microbiol. 75,4155 161. 

MiUy, P. J., Toledo, R. T., Chen, J., and Kazem, B. (2007). Hydrodynamic cavitation to improve bulk fluid to surface mass transfer in a nonimmersed ultraviolet system for minimal processing of opaque and transparent fluid foods. /. Food Sci. 72, M407-M413. 

Optimizing flow, load, and configuration to run shorter columns at maximum flow and thereby minimize processing time... 

Selected raw materials, which may have organisms at the point of purchase. This is especially the case with natural raw materials produced with minimal processing to meet marketing claims ... 

Table II demonstrates how NPV would be calculated for a hypothetical LIMS, purchased as a package with negligible site preparation and with installation costs included in the purchase. It is to be acquired for a service laboratory primarily supporting R D activities but with some minimal process monitoring responsibilities. The IRR for this project could be found by trial and error determination of the yearly discount rate which results in a zero NPV. A succinct discussion of these financial management analysis tools can be found in two works by Weston and Brigham. The first (9) presents theoretical and detailed analytical expositions the second OO) is a more practical, applications oriented presentation.

Pathogen contamination can occur at every stage of the whole production chain from field-to-fork (Table 19.1). Nevertheless, besides other components of infection, manures derived from livestock are considered to be an important potential preharvest contamination source (Fig. 19.1). Several disease outbreaks have been associated with raw fruits and vegetables and unpasteurised products some have been traced back to livestock (Pell, 1997), but in the majority of the outbreaks associated with fresh produce, minimally processed products and unpasteurised products, the source of contamination remains unknown (de Roever, 1998). 

Nguyen-the C and Carlin F (1994), The microbiology of minimally processed fresh fruits and vegetables , Critical Reviews in Food Science and Nutrition, 34, 371-401. 

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