Fatty acid profiles and antioxidant properties of raw and dried walnuts

Abstract

Background: Walnuts consumption produces beneficial effects on human health. Health-promoting benefits are dedicated to its desirable fatty acid profile and high content of antioxidants. Heat treatment of walnuts may alter their fatty acid composition and antioxidant capacity. Aim: In general the aim of this work was to compare fatty acids profiles and antioxidative properties of raw and dried walnuts at 60 °C for 12 hours. Methodology and results: FA profiles were analyzed using gas chromatography. Antioxidative capacities of walnut samples were determined by DPPH and ABTS tests. There were no significant differences in fatty acid profiles comparing dried and raw walnuts. The most abundant fatty acid was linoleic with mean content of 61.38 ± 1.11% in raw and 62.40 ± 0.99% in dried walnuts. Walnuts oil contained 10.64 ± 0.46% and 10.49 ± 0.81% of a-linolenic acid (ALA) in raw and dried walnuts, respectively. Antioxidative capacity of methanolic extracts showed no difference comparing raw and dried walnut by DPPH and ABTS test. Heat treatment at 60 °C for 12h induced no change in fatty acid profiles of walnuts and led to minor decrease in antioxidative capacity measured only by ABTS test. Conclusion: We suggest that drying process in our experiment did not decreased nutritional capacity which is mostly mediated by conservation of fatty acids content in walnuts.

Dijetarni unos oraha povezuje se sa brojnim pozitivnim efektima na zdravlje. Svoj efekat na zdravlje orasi ostvaruju zahvaljujući povoljnom masnokiselinskom sastavu i visokom sadržaju antioksidanasa. Zagrevanje oraha moglo bi dovesti do promena u masnokiselinskom sastavu i uticati na antioksidativni kapacitet. Cilj ovog rada bio je da se uporede masnokiselinski profili i antioksidativni status svežih i oraha sušenih na 60 °C u trajanju od 12 sati. Masnokiselinski sastav analiziran je gasnom hromatografijom. Antioksidativni kapaciteti uzoraka oraha odreðivani su DPPH i ABTS testovima. Utvrðeno je da nije bilo promena u masnokiselinskim profilima posle sušenja oraha na 60 °C u trajanju od 12 sati. Najzastupljenija masna kiselina bila je linolna sa sadržajem od 61.38 ± 1.11% u sirovim i 62.40 ± 0.99% kod sušenih oraha. Ulje oraha sadržalo je 10.64 ± 0.46% i 10.49 ± 0.81% a-linolenske kiseline (ALA) u svežim i sušenim orasima, respektivno. DPPH testom nije utvrđeno da postoje razlike u antioksidativnom potencijalu metanolnih ekstrakata oraha sušenih u odnosu na sveže kao ni sa ABTS testom. Naš eksperimet je pokazao da proces sušenja oraha nije smanjio njihov nutritivni kapacitet što je verovatno posredovano očuvanjem sadržaja masnih kiselina.