Spray lipids oxidation

Dried whole milk is prepared by conventional spray or roller drying, with some modifications of the preheat treatment of the milk. The product is usually stored under nitrogen to delay lipid oxidation and off-flavor development. In spite of the processing changes, flavor defects and short storage life have limited the markets for dried whole milk most of it is used in the confectionery and baking industries. Federal and FAO standards require a minimum of 20% but less than 40% milk fat and a maximum of 5% moisture. 

Water Activity The role of water activity in determining shelf life of the spray-dried powders is of interest. It is well documented in the literature that lipid oxidation is slowest at the monolayer (water activity ca. 0.2) and will increase on either side of the monolayer. Anker and Reineccius [86] found that shelf life of orange peel oil encapsulated in gum Arabic increased with water activity within the range of water... 

Boneless beef roasts Fresh dried plum juice concentrate, spray dried plum powder Reduce lipid oxidation warmed-over flavor Nunez de Gonzalez et al., 2008b... 

A second possibility to increase the functionality of spray-dried emulsions is to build up a specific structure with desired functionality at the oil-water interface. Enzymatic cross-linking of proteins at the oil-water interface can increase the stability of emulsions. Cross-linking of a-lactalbumin at the interface of an emulsion increased the physical stability [28]. Kellerby et al. [29] investigated the influence of network formation through transglutaminase on the oxidation stability of caseinate-based fish oil emulsions. The authors showed that cross-linking increases the cohesiveness of the proteins at the interface but not lipid oxidation in liquid emulsions. Data from our own research showed that also in spray-dried microcapsules transglutaminase cross-linked proteins do not act as additional barrier (data not published). 

The use of freeze-drying avoids an inherent disadvantage of spray drying, i.e., the elevated processing temperature, which accelerates the oxidation of polyunsaturated lipids. 

The lipid peroxidation inhibitory activities of EOs are assessed by the P-carotene bleaching tests (Yadegarinia et al., 2006). In this method, the ability to minimize the coupled oxidation of P -carotene and linoleic acid is measured with a photospectrometer. The reaction with radicals shows a change in this orange color. The P-carotene bleaching test shows better results than the DPPH assay because it is more specialized in lipophilic compounds. The test is important in the food industry because the test medium is an emulsion, which is near to the situation in food, therefore allowable alternatives to synthetic antioxidants can be found. An only qualitative assertion uses the TLC procedure. A sample of the EOs is applied onto a TLC plate and is sprayed with P-carotene and linoleic acid. Afterwards, the plate is abandoned to the daylight for 45 min. Zones with constant yellow colors show an antioxidative activity of the component (Guerrini et al., 2006). 

Oxidation of Lipids Encapsulated in Spray-Dried Particles... 

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