Extended refrigeration

TABLE 11.52 Chemicals Which Polymerize or Decompose on Extended Refrigeration... 

Eor fresh poultry, a potassium sorbate dip significantly reduces total viable bacteria and doubles the refrigerated shelf life of ice-packed broilers (133). In cooked, uncured, vacuum-packaged turkey and poultry stored at 4°C, 0.2—0.25 wt % potassium sorbate suppresses microbial growth for up to 10 days (134). Sorbic acid at 0.5% in a marinade mixture for chicken dmmmettes extends refrigerator shelf life (135). Country-cured hams sprayed with a 10 wt % potassium sorbate solution showed no mold growth for up to 30 days (136). A review of sorbate use in meat and fish products has been pubHshed (137). 

Figure 6. TBA values above 3 are indicative of off flavor in beef The effect of rosemary and phosphate in extending refrigerated shelf life of ground beef patties is shown.

Fig. 2. Dual-pressure process using extended absorption for NO abatement. RC = refrigerated cooling see Figure 1 for other definitions.

Seafood. Sorbates are used to extend the shelf life of many seafood products, both fresh and processed (103,104). For smoked or dried fish, an instantaneous dip in 5 wt % potassium sorbate or a 10-minute dip in 1.0 wt % potassium sorbate prior to drying or smoking inhibits the development of yeast and mold (105,106). For fresh fish, sorbates can be incorporated at approximately 0.5 wt % into the ice, refrigerated seawater, or ice-water slush in... 

Chloroform was used chiefly as an anesthetic and in pharmaceutical preparations immediately prior to World War II. However, these uses have been banned. Annual output in both the United States and the United Kingdom was between 900 and 1350 metric tons. During the war, chloroform production in the United States tripled, largely to meet the requirement for penicillin manufacture. Demand for chloroform continued to increase in the postwar period as its technical appHcations were extended. Consumption continues to increase at a comparatively rapid rate. Chloroform is now used primarily in the manufacture of HCFC-22, monochlorodifluoromethane, a refrigerant, and as a raw material for polytetrafluoroethylene plastics. 

Improved and redesigned rotors of modem compressors save considerable power. The ethylene fractionator and the propylene refrigeration condensers can be replaced with extended surface tube bundles instead of conventional tube bundles. 

Values calculated from NIST Thermodynamic Properties of Refrigerants and Refrigerant Mixtures Database (REFPROP, Version 5). Thermodynamic properties are from. 32-term MBWR equation of state transport properties are from extended corresponding states model, t = triple point c = critical point. 

Air-cooled condensers are used mostly in air-conditioning and for smaller-refrigeration capacities. The main advantage is avauability of cooling medium (air) but heat-transfer rates for the air side are far below values when water is used as a coohng medium. Condensation always occurs inside tubes, while the air side uses extended surface (fiusy... 

Above this size, the flow of air over the condenser surface will be by forced convection, i.e. fans. The high thermal resistance of the boundary layer on the air side of the heat exchanger leads to the use, in all but the very smallest condensers, of an extended surface. This takes the form of plate fins mechanically bonded onto the refrigerant tubes in most commercial patterns. The ratio of outside to inside surface will be between 5 1 and 10 1. 

Fruits are seasonal in temperate climates, and a good harvest may be followed by a shortage if there is no method of preservation. The hard fruits, apples and pears, have traditionally been stored in cool places and may then last for several months, depending on the variety Refrigeration has extended the storage life, and made this more reliable. 

The submitters recommend that the product be stored in a stoppered brown bottle in a refrigerator. Although the material can be kept at room temperature for several weeks without noticeable decomposition, gradual evolution of carbon dioxide occurs over a period of several months, with the attendant risk of explosion. However, storage in the presence of a small amount of silica gel as a drying agent extends the shelf life of the material to more than a year. 

Solutions 1 and II may be stored in the refrigerator for an extended period. The dipping solution must be employed within 5—10 min of preparation. 

Dipping solution 1 may be stored for an extended period dipping solution and spray solution 11 should be stored in the refrigerator and made up fresh every other day [11]. 

---