Oxidative stability, encapsulated orange

This study supports the hypothesis that high DE maltodextrins and syrup solids permit the formation of encapsulated products with excellent stability to oxidation. Different enzyme-hydrolyzed starches yielded encapsulated orange oils which varied in stability amylomaize and potato maltodextrins exhibited the poorest stabilities while normal corn, waxy corn, cassava, rice, and wheat glucose syrup solids yielded the best and approximately equivalent shelf-lives. Based on oil retention during drying, amylomaize, wheat, rice, and cassava yielded satisfactory products. 

Another important aspect of encapsulation efficiency is the resistance to oxidation that the carrier imparts to the flavor oils. The oxidation resistance properties are critical to shelf-life stability of the encapsulated product. Oxidation properties can be measured organoleptically by a taste panel or by gas chromatograph of the recovered oil. Peaks related to oxidation products of orange terpenes obtained from GC analysis can be monitored as the powders are aged for three days at 80 C. The GC was used to measure beta-pinene, an oxidation product of orange terpenes. The results are reported in square inches. The greater the area for the beta-pinene peak, the poorer the oxidation resistance of carrier towards the orange terpenes. The data is presented in TABLE 5 ... 

Effect of Water Activity. A preliminary study was done to determine the a at which encapsulated orange peel oil was the most stable to oxidation. Figure 1 summarizes the results of this study. The formation of the limonene oxidation product, limonene oxide, was the slowest for the powder adjusted over Mg(NO3)2 (a 0.536). While the levels of oxidation product do not follow in exact order of a, it is evident that better storage stability correlates with a higher a of the powder. This relationship was not anticipated. Literature on lipid oxidation (2, 2) indicates that there is an optimum a for product... 

Storage Stability. The formation of limonene oxide at 37 C was measured as a function of time to determine shelf-life of the encapsulated orange peel oil samples. Figure 6 shows the shelf-life results. A value of 2mg limonene oxide/g limonene was used as the end of shelf-life for oxidized encapsulated oil samples ( 3) The sample dried at 160 C and 105 C inlet and exit air temperatures respectively and the smallest temperature differential (55 C). This sample formed limonene oxide much faster than the other five samples. By 23 days, this powder had reached a value of 2mg limonene oxide/g limonene. The sample dried at 280 C and 105 C inlet and exit temperatures respectively did not reach 2 mg limonene oxide/g limonene until after 34 days of storage at 37 C. This sample also had the largest inlet and exit air temperature differential (175 C). The remaining four samples had reached 2mg limonene oxide/g limonene after about 30 days of storage at 37 C. 

Gas Chromatographic Analysis. The contribution of limonene-1, 2-epoxides and carvone to the development of oxidized flavor of encapsulated orange oil has been investigated (5). The concentrations of these two compounds were reported to provide a reliable index of the stability of the encapsulated orange oil. 

Beristain Cl, Azuara E, Vernon-Carter El. 2002. Effect of water activity on the stability to oxidation of spray-dried encapsulated orange peel oil using mesquite gum (Prosopis juliflora) as wall material. Journal of Food Science 67 206-211. 

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