Preservation, additives, chemical during storage

The packaging material must not interact with the product either to adsorb substances from the product or to leach chemicals into the product. Plastics contain additives to enhance polymer performance. PVC may contain phthalate diester plasticizer, which can leach into infusion fluids from packaging. Antimicrobial preservatives such as phenylmercuric acetate are known to partition into rubbers and plastics during storage, thus reducing the formulation concentration below effective antimicrobial levels. 

Justification for the preparation of any review for this book series is that it deals with some aspect of the many real problems arising from the presence of any foreign chemical in our surroundings. Thus, manuscripts may encompass case studies from any country. Added plant or animal pest-control chemicals or their metabolites that may persist into food and animal feeds are within this scope. Food additives (substances deliberately added to foods for flavor, odor, appearance, and preservation, as well as those inadvertently added during manufacture, packing, distribution, and storage) are also considered suitable review material. Additionally, chemical contamination in any manner of air, water, soil, or plant or animal life is within these objectives and their purview. 

Chemical preservation. Where permitted by legislation (very limited), fruit juices may be preserved by the addition of sodium benzoate (0.1-0.3%) or sulfur dioxide (0.03-0.08%). In the latter case, there is a gradual loss of SO2 during storage, and in bulk containers it is often necessary to add further quantities of sodium metabisulfite to maintain an adequate level of preservative. Ashurst [15] noted that sulfur dioxide finds its greatest use in the preservation of fruit juice concentrates (1500-2000 mg/kg). 

It is noteworthy that a part of the gel fraction in commercial HA latex cannot be solubilized by transesterification or saponification. " This hard gel has been proposed to be formed by radical reactions between rubber chains and tetra-methylthiuram disulfide (TMTD), which is normally used as a bactericide preservative, in latex together with zinc oxide (ZnO). The addition of TMTD and ZnO into HA and DPNR lattices resulted in a rapid increase in the gel fraction of hard gel, which is insoluble in good solvents even after the enzymatic or chemical treatments. This suggests that TMTD and ZnO can be another way of increasing the gel content during long storage of latex. 

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