Antioxidant activity of films and microspheres made with shell and kernel pecan walnut extracts
Tutor / directorAlmajano Pablos, María Pilar
Document typeBachelor thesis
Rights accessRestricted access - author's decision
The ban of synthetic antioxidants, because of their potential negative effects on human health, have focused the investigations on extracts from vegetal sources, which contain large concentrations of polyphenols and other antioxidant compounds, in order to prevent lipid autoxidation in food. However, as important as it is the source of antioxidants, it is also important the investigations about controlled antioxidant delivery systems in food, avoiding alter the properties of food while increasing their efficiency preventing autoxidation. This project is focus in the comparison between two different systems of controlled drug delivery of antioxidant species: films (functional food packaging) and microspheres made by a spray drier, while using Pecan walnut as a natural source of antioxidants compounds. The extracts were prepared with 3g of samples (kernel or shell) and 20mL of ethanol, which later was evaporated with a rotavapor. In order to determine the AOC (antioxidant capacity) of the extracts, different assays were performed: TPC (total phenolic compounds assays), DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2–azinobis(3-ethylbenzothiazoline-6-sulfonic acid)) and FRAP (ferric reducing antioxidant power). These results confirm the presence of antioxidants in both extracts. However, shell extract presents highly concentrations in all assays. To be able to compare both delivery systems, it was planned that they must contain the same concentrations and reagents (chitosan 0.5% and maltodextrin 7.5%). Nevertheless, maltodextrin properties made this unviable on films. It was changed to 0.4% of Sorbitol. While preparing the microspheres, three atomizers were considered but at the end, the microcapsules were achieved with the B-290 Buchi mini spray. In order to determine the AOC of these controlled realise systems, it was used veal hamburgers and during 15 days different assays were performed (pH, TBARS, colour, methaemoglobin, DPPH and FRAP). These confirmed the presence of antioxidant compounds capable to prevent the autoxidation of meat. Where microcapsules present the most favourable results, and more specifically kernel microspheres. It is necessary to mention, that the also favourable results of shell microspheres and their implications in ecological and economic levels bring on their viability. Besides, films and their proved capacity to prevent oxidation in food are also a possible substitute of plastic. All these facts confirm their viability and promote their investigations.
DegreeGRAU EN ENGINYERIA QUÍMICA (Pla 2009)
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