Chemicals extended refrigeration

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

Preservation. Antimicrobial agents, such as methyl paraben, propyl paraben, sodium benzoate, and calcium proprionate are added to many foods to prevent food spoilage caused by mold, bacteria, fungi, or yeast. The use of preservation chemicals extends the shelf lives of many foods and eliminates the need for refrigeration of others. 

Dipping of fresh salmon slices in aqueous solutions of the sodium salts of organic acids (approximately 2.5%) have been shown to maintain chemical quality, and also extend the shelf life of the product with only minor sensory changes during refrigerated storage (Sallam, 2007b). 

Approximately 3 g of benzoyl peroxide are added to 20 kg of wheat flour. This is then easily decomposed to benzoic acid and other substances such as biphenyl and phenylbenzoate (Be-Onishi et al., 2004). Aqueous solutions of 2.5% of the sodium salts of organic acids are adequate to maintain the chemical quality and extend the shelf life of fresh salmon with only minor sensory changes during refrigerated storage (Sallam, 2007b). In carcass surface applications 2% lactic, 1.5% acetic plus 1.5% propionic acids are usually applied (Dubai et al., 2004). 

Irradiation can extend the shelf life of food so that it can be stored for long periods of time without refrigeration, as shown in Figure 21.18. However, people who oppose food irradiation are concerned about what are called unique radiolytic products—URPs, for short. These products result from chemical changes caused by the ionizing effects of radiation. 

The manufacturer s obligation to foresee misuse does not extend to foreseeing abuse. In these situations it is the misuse and not the nature of the warning which causes the harm. For instance, in Collins v Rowe, recovery for carbon monoxide injuries was denied where the refrigerator which emitted the damaging chemical would not have done so if the plaintiff had not tampered with it. 

Battery life can be extended by storing the batteries at a low temperature, as in a refrigerator or freezer, which slows the chemical reactions in the battery. Such storage can extend the life of alkaline batteries by about 5%, while the charge of rechargeable batteries can be extended from a few days up to several months. 

Although l(Mig-term stability (from a few weeks to a few months) has been reported [112], the most frequent drawback of monolayers lies in the poor chemical and thermal stability, leading to sensing elements with a limited shelf-fife and lifetime. Special precautions, such as refrigerated storage, are often required in order to extend the shelf-fife. 

---