Resumen de Antioxidant properties and applications of pecan (carya illinoinensis)
At the present time, the environmental challenges are the second concern on a global level, and the first one in some countries. This is one of the main reasons behind the recent boost of new methods of production within the agri-food sector. Adopting a circular economy model, for example, means aiming at reducing, reusing and processing wastes. Wastes and food sub-products are a potential source of bioactive compounds, some of which can have antioxidant properties. In recent years, they have become more relevant in the food and drug industry, since they represent a good alternative in the formulation of functional foods, such as additives or even in the production of drugs.
The main focus of this dissertation was on the pecan shell (Carya illinoinensis) and its fruit. Secondly, the roselle flower (Hibiscus sabdariffa) and the cayenne pepper (Capsicum annuum) were also studied as well. These plants or their extract have antioxidant and, to a lesser extent, antibacterial properties on food.
Firstly, the total polyphenols content (TPC) and the antiradical activity were identified and analyzed through several methods. Secondly, the potential synergetic effects of these plants in real food environments, such as oil-in-water emul- sions, fish and beef patties were evaluated.
On the other side, active packaging was also part of the study. Films were created from a basis of gelatine, with extracts of the pecan shell and the fruit. The film was characterized and evaluated both in its interaction with the food (ham- burger), analyzing the delay in the oxidation, and for its mechanical and physic-chemical properties. Also, the film Poly (¿-dodecyl ¿-glutamate) (PAAG-12) was formed by adding ¿-tocopherol (one of the main compounds of the pecan shell) and was compared to the polylactic acid film in similar conditions.
The process of extrusion of the pecan shell was optimized. The extrudate shell was added as a new ingredient to the development of bread and tortilla production. The extruded pecan shell was encapsulated and its antioxidant activity was evaluated in patties of salmon. At the same time, the fermentation of the original pecan shell and extruded shell with Aspergillus oryzae fungus were studied.
Along with the antioxidant analysis, an in vitro evaluation was conducted on the antiproliferative activity of the extract from the fruit and shell of the pecan nut, in cultures of cells derived from tumors.
The results obtained from the pecan shell extract show high levels of TPC and good antiradical activity, similar to the values for the extract of green tea. At the same time, both the fruit and the pecan shell had a positive effect, slowing the formation of hydroperoxides in emulsions.
The synergy between the fruit of the nut and the roselle flower slowed down the fat oxidation in sardine burgers, thus decreasing the formation of reactive compounds to malondialdehyde and volatile compounds. Similar results were achieved in meat, by the addition of the mix of the pecan shell with the roselle flower and the cayenne pepper.
Concerning the two types of film developed, the result was positive both in terms of decrease of compounds, generated from the primary oxidation in emulsions, and the secondary oxidation in meat.
The extrusion of the pecan shell increased significantly the antioxidant properties and up to three times the content of soluble fiber versus the non-extruded pecan shell. The addition of this new ingredient in bread, tortillas and capsules showed favorable results. Moreover, the extracts of both the fruit and the pecan shell showed an anti-proliferative activity in cell cultures derived from tumors.
Taking advantage of residues like the pecan shell in order to obtain products with an added value represents an environmentally conscious option. Moreover, the synergies between different plants increased the antioxidant and antimicrobial activities, and potentially allowing the replacement of synthetics additives in food
