Physical-chemical characteristics and oxidative stability of oil obtained from lyophilized raspberry seed

Abstract

Fresh raspberry (Rubus idaeus), cultivar Willamette, was freeze-dried (lyophilization). A byproduct of lyophilization is "fine dust" of raspberry consisting of finely ground raspberry fruit body and seed. The seeds were separated. The seed oil was isolated and its physical and chemical characteristics were determined. Parameters that characterize the seed and quality of the oil were examined, including fatty acid composition, oxidative stability under different storage conditions, and radical-scavenging activity. The fatty acid composition was determined by GC/FID and the contents of the dominant fatty acids were found as: oleic 16.92%, linoleic 54.95%, and a-linolenic acid 23.97%. The oxidative stability of the oil was poor. The induction period by Rancimat test at 100 °C was 5.2 h. The radical-scavenging activity is similar to that of resveratrol [1,3-benzenediol 5-(1E-2-4-hydroxy-phenyl-ethyl)]. Although this product is used in the candy industry, it would be far more useful if raspberry oil of satisfactory quality could be extracted. This paper demonstrates that sifted lyophilized seeds can be used for the extraction of oils. This process allows for maximal usage of the byproducts, reduces losses and it increases the development of new products. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.