Frozen preservation

Copepods may be provided during a sensitive period (Atlantic halibut N 6SS and Lie, 1998) or as a supplement to the traditional feed - (e.g. turbot (Scophthalmus maximus) Stpttrup and Norsker, 1997 Dover sole (Solea solea) Heath and Moore, 1997). In these systems, Artemia nauplii seem to meet energy requirements, while the copepods supplement the diet with essential nutrients for improved growth, survival or higher proportion of normally developed fry. Preserved copepods were also shown to be beneficial as a supplement to traditional live prey for an ornamental fish Amphip-rion clarkia using frozen preserved copepods harvested from the wild (Olivotto et al, 2010). 

Citric acid is used in carbonated beverages to provide tartness, modify and enhance flavors, and chelate trace metals. It is often added to jams and jellies to control pH and provide tartness. It is used in cured and freeze-dried meat products to protect the amino acids (qv) and improve water retention. Bakers use it to improve the flavor of fmit fillings in baked goods. Because citric acid is a good chelator for trace metals, it is used as an antioxidant synergist in fats and oils, and as a preservative in frozen fish and shellfish (7) (see Antioxidaisits). 

Food processing firms producing heat-preserved, frozen, dehydrated, or chemically preserved foods may be classified by their finished products. Companies may be further grouped based on whether they process raw materials into ingredients, such as in poultry and meat processing plants, or whether they take these ingredients and convert them to ready-to-eat consumer products. 

Sucrose helps minimize earthy tastes of vegetables, while enhancing inherent flavors and aromas, and preserving color and texture (37). Addition of sucrose inhibits enzymatic browning of canned and frozen fmits, and prevents loss of color, flavor, and aroma from fmit during processing (38). 

A large amount of water is added to the dehydrated material in order to cause it to swell the swollen structure is preserved when the material is frozen and subsequently dried in vacuo (in the frozen state) to a low moisture content. Some leaching occurs during the treatment with water and this, undoubtedly, further contributes to the increase in the porosity of the solid. Drying of the lyophilized substance can.be completed in a relatively short time in a vacuum oven at an elevated temperature, or at room temperature in the presence of an efficient water adsorbent. 

Recent work (51) on FeCpj irradiated in Fe(CO)5 solutions (to give FeCpj) has shown that the Fe atom can come from the Fe(CO)j molecule. The mechanism is unknown and may well involve exchange or other reactions in solution in addition to hot atom reactions. The results do show, however, that it is not necessary to preserve the Fe-Cp bonding in order to reform FeCpj. In frozen solutions the yield of FeCpj is much lower than in liquid solutions. 

In a society where canned and frozen foods are so prevalent, we tend to take food preservation for granted. It is easy to forget that prevention of spoilage is a major undertaking when food is harvested at one time and place but eaten at another. A contemporary example is the space station, where the astronauts must be supplied with edible food that is preserved without refrigeration for long times. 

RAC samples from a processing study should be handled exactly as RAC samples from a field residue trial. They should be frozen as soon as possible following collection. Once the processing commodities have been created, they should be frozen and shipped to the analytical lab as quickly as possible. Both the RAC samples and processed samples from a processing study must remain frozen throughout the shipment and storage period of the study in order to preserve residue integrity. 

Fresh frozen plasma Plasma that is frozen within hours after donation to preserve clotting factors. 

Monsanto. 1981. Stability study of natural sediments samples preserved by frozen storage with attachment. Monsanto Company, St. Louis, MO. 

Urine, for Trichomoniasis Prepare two films from sediment. Fix in Schaudinn or PVA fixative. Preserve the remainder of sediment in 10% Formalin. Centrifuge. Cover the sediment with sterile saline and send it on ice (not frozen) for direct mounts and culture. 

A study of by Palmer-Toy et al.,12 summarized in Table 19.1, provides further empirical evidence of the utility of techniques coupling heating with efficient protein extraction for the proteomic analysis of FFPE tissue. A specimen from a patient with chronic stenosing external otitis was divided in half and preserved as fresh-frozen tissue or FFPE. Ten micromolar sections of the FFPE tissue were vortexed in heptane to deparaffinize the tissue and were then co-extracted with methanol. The methanol layer was evaporated, and the protein residue was resuspended in 2% SDS/lOOmM ammonium bicarbon-ate/20mM dithiothreitol (DTT), pH 8.5 and heated at 70°C for lh. After tryptic digestion, 123 total confident proteins were identified in the FFPE tissue, compared to 94 proteins identified from the fresh-frozen tissue. Hwang et al. also reported up to a fivefold increase in protein extraction efficiency for samples extracted in a Tris-HCl/2% SDS/1% Triton X-100/1% deoxycholate solution at 94°C for 30 min versus samples extracted in 100 mM ammonium bicarbonate/30% acetonitrile at the same temperature.14... 

Hydrazide-activated proteins are stable to long-term storage at 4°C in the presence of a preservative (0.05 percent sodium azide) or in a frozen or lyophilized state. 

Degobbis [60] studied the storage of seawater samples for ammonia determination. The effects of freezing, filtration, addition of preservatives, and type of container on the concentration of ammonium ions in samples stored for up to a few weeks were investigated. Both rapid and slow freezing were equally effective in stabilising ammonium ion concentration, and the addition of phenol as a preservative was effective in stabilising non-frozen samples for up to two weeks. 

Surface and bottom water samples were collected in 500 ml, 1, or 4 litre polycarbonate bottles. Polycarbonate bottles have been shown to retain 97% of an initial spike of bis(tri-n-butyltin) oxide in seawater at a concentration of 0.5 mg/1 over a weeklong period [104]. Samples were analysed immediately after collection and transported to the laboratory, or were stored frozen at -20 °C and analysed at a later date. Frozen storage has been shown to be effective in preserving sample stability with respect to monobutyltin, dibutyltin, and tributyltin concentrations for a period of at least 100 days. 

---