Heat stabilizers, additive fatty acid

Soon after harvest, tree nuts, because of their high concentrations of unsaturated fatty acids, may undergo development of oxidative rancidity. This leads to the formation of undesirable rancid flavors and a decline in both unsaturated fatty acids (e.g., oleic, linoleic, and linolenic acids) and natural antioxidants (e.g., tocopherols) [63]. The postharvest stability and sensory quality of tree nuts are influenced by several factors such as chemical composition (e.g., fatty acid composition and presence of antioxidants such as tocopherols), moisture content, oxygen concentration, and temperature, among others. There is some evidence that lipid oxidation is at least in part due to the action of oxidative enzymes, such as lipoxygenases. This is supported by the fact that mild to moderate heat treatment of some nuts, such as pecan, retards the development of rancid flavors during storage [64,65]. Nevertheless, mild oxidation is probably necessary for the development of the characteristic volatile flavor components of natural tree nuts [63], In addition to the Upid oxidation volatiles, some other compounds, such as terpenes, lactones, and short-chain volatile acids, may impact the aroma profiles of some types of natural flee nuts. 

Sucrose esters of fatty acids having 12 or more carbon atoms display surface active properties. Most of them are odourless and tasteless (or slightly bitter) allowing them to find applications both in food and personal care products [17]. Sucroesters were approved and freely permitted in Japan for use as food additives in 1959 for both their emulsifying ability and their heat stability. In addition, they are well known to protect food proteins from thermal denaturation and inhibit the growth of Escherichia coli and other bacteria. 

The addition of heat stabilizers improves the thermal stability of polymers. One group of commercially available PVC heat stabilizers are Ca/Zn stabilizers. According to the Erye-Horst mechanism (Thomas 1993), the zinc fatty acid salt reacts with PVC by an esterifying displacement of chlorine. Stabilization arises from substimtion of labile chlorine atoms with more stable carboxylate groups (Scheme 14.2) ... 

Other additives can also greatly affect the susceptibility of a flexible PVC formulation. As is the case of plasticizers, the type of lubricant chosen can affect the microbial susceptibility. The chemical additives that are derived from natural products can provide a rich food source for microorganisms. Microbial attack on these additives can result in a shorter useful life of the product. Some of the most common lubricants employed in plastics are based on fatty acids or fatty acid esters. Parafins are another common lubricant type. The most frequently used heat stabilizers in flexible PVC formulations are mixed metal salts of fatty adds. Large varieties of other minor additives are sometimes used in flexible PVC, such as antistats, and antiblocks. 

In addition to sensory evaluation, some other parameters are suitable to describe the quality of cold-pressed oils. Such characteristic features are oxidative stability (Rancimat test), tocopherol content and composition, amount of trans-fatty acids or stigmastadiene, showing a heat treatment during production, as weU as content of chlorophyll, as a measure not only for the maturity of the raw material, but also as an indicator of improper pressing conditions. 

Lead soaps are made according to methods 1, 2 a and 2 b if neutral. Method 2 is used for the manufacture of alkaline soaps, and also for making complex soaps. A mixture of PbO and PbS04 is reacted with the fatty acid. - Stearic acid and - oleic acid [1120-46-3] are the main reactants. Three types of stearates are important neutral [1072-35-1], monobasic [90459-52-2] and dibasic [56189-09-4]. Main use is as heat stabilizer and lubricant for PVC (->plastics additives). Other uses are as lubricants in pencil manufacture (- inks) and - paper additives. 

Several studies have been conducted on the stability of selected plastics additives for food contact in EU aqueous, fatty and alternate stimulants. Thus, Simoneau and Hannaert [17] showed that bis(2-ethylhxyl)phthalate plasticiser and octadecyl 3-(3,5-di-ter -butyl 4-hydroxy phenyl) propionate antioxidant are quite stable under all heat exposure conditions tested (20-40 °C, 1 h to 10 days) and all food simulents used (15% ethanol, 95% ethanol, 3% acetic acid, olive oil and iso-octanol). In these tests, the amounts of additives remaining in the plastic at the end of the test were between 90% and 107% of the amounts present in the plastic before extraction. 

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