Preservation storage temperature

The estabhshment of safe thermal processes for preserving food in hermetically sealed containers depends on the slowest heating volume of the container. Heat-treated foods are called commercially sterile. Small numbers of viable, very heat-resistant thermophylic spores may be present even after heat treatment. Thermophylic spores do not germinate at normal storage temperatures. 

The storage temperature of honey should be carefully controlled to preserve its quality. At its best, honey should be consumed within six months following its harvesting. 

Freezing Preservation. The rate of loss of color, flavor, texture, and nutrients, the growth of microbes, and the aclivity of enzymes and other life forms are all functions of temperature Thus lower storage temperatures prolong the useful life of foods. 

Unfiltered and unpreserved groundwater water samples collected for total and dissolved metal analyses arrived to the laboratory in a cooler with ice three days after collection. On the fourth day after collection the laboratory filtered the samples for dissolved metal analysis and preserved all samples with nitric acid. The violation of the preservation requirements (no acid ice instead of ambient storage temperature) had a marginal effect on the concentrations of total metals as the addition of acid dissolved most of the metals that may have precipitated in the sample container. That is why the chemist accepts the total metal results, but qualifies them as estimated data. However, because improper preservation and storage have grossly compromised dissolved metal concentrations, the chemist rejects the dissolved metal results and requests that the water be resampled and reanalyzed. 

Thermal techniques such as isothermal calorimetry (ITC) and differential scanning calorimetry (DSC) have been used in formulation screens to predict the formulation with the greatest stability based on the assumption that excipients that increase the of the protein will stabilize the molecule at the recommended storage temperature. For example, a screen of preservatives performed during formulation development for interleukin-1 receptor found that the for the formulation... 

Several factors may influence the success or failure of a preservative to protect a formulation against microbial contamination. These factors include the interaction of the preservative with surfactants, active substances, other components of the vehicle, sorption by the polymeric packaging materials, and product storage temperature. Although hundreds of chemicals can fimction as germicides, only a few substances have made it to the marketplace. The small list is not based as much on a compound s effectiveness as an antimicrobial agent as on the compound s safety and effectiveness in the final product. 

It has been known for decades that heat is one of the most destructive factors of anthocyanins in berry fruit juices (Jackman et al., 1987a). With strawberry preserves, it was shown as early as 1953 that the half-life time was 1 h at 100°C, 240 h at 38°C and 1300 h at 20°C. In a storage experiment with concentrates and dry powder of elderberry extracts, the stability increased 6-9 times when the temperature was reduced from 20°C to 4°C (Zajac et al., 1992). Anthocyanin degradation in anthocyanin solutions increased from 30% to 60% after 60 days when storage temperatures were increased from 10°C to 23°C (Cabrita et al., 2000). High-temperature short-time processing is recommended for maximum anthocyanin retention of foods containing anthocyanins (Jackman and Smith, 1996). 

Serum is the preferred specimen for gonadotropin measurements hemolyzed, lipemic, or icteric specimens should not be used. Both hormones are stable for 8 days at room temperature and for 2 weeks at 4 °C for longer periods, the serum specimen should be stored frozen at or below -20 C. Because of episodic, circadian, and cyclic variations in the secretion of gonadotropins, a meaningful clinical evaluation of these hormones may require determinations in pooled blood specimens, multiple serial blood specimens, or timed urine specunens. Urine specimens should not contain preservatives storage at or below —20 °C is recommended. 

Increasing storage temperature to 15 and 25°C significantly increased effective inhibition of E. coli 0157 H7 populations by the fumaric acid/ sodium benzoate preservative mixture in apple cider (Chikthimmah, LaBorde, and Beelman, 2003). Yersinia enterocolitica can grow aerobically and anaerobically at temperatures as low as -2°C (Mollaret and Thai, 1974) and at pFI values as low as 4.4. Formic acid is the most effective organic acid for the inhibition of Y. enterocolitica (El-Ziney, De Meyer, and Debevere, 1997). 

Low temperature storage was found to be the most effective treatment for the preservation of cut lettuce (12) and citrus salads (14.). Table II shows the effect of storage temperature on the quality of cut lettuce. 

C) (12) The other preservatives were either ineffective or had detrimental effects on flavor, texture, or appearance. Citrus salads were treated with sodium benzoate or potassium sorbate (12). No extension of shelf life was observed when these chemicals were added at storage temperatures of 50°F and 40°F, but when the additives were present at 30°F storage substantial improvements in shelf life were observed, demonstrating the synergistic effect of chemical additives and low temperature storage. 

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