The stability of vitamin C in the rose hip (Rosa canina L.) products and the possibility of valorization of rose hip seed oil

Abstract

The fruits of rose hip (Rosa canina L.) are mainly used for the production of spreads (marmalade) and dried fruits for making tea. In this paper, a certain amount of fruit is dried in the laboratory dehydrator (air temperature of 60 °C for a period of 16 h, then air temperature of 50 °C for a period of 20 h) and on the other side marmalade is made in a traditional way from the remaining amount, with the idea to determine the stability of vitamin C after different heat treatments. Byproduct in the production of marmalade is a large amount of rose hip seeds which is a rich source of oil. The aim of this paper was to determine the content of vitamin C in the products after heat treatment in relation to the content of vitamin C in fresh sample by indirect iodimetry method (iodometry). The content of rose hip seed oil was determined by Soxhlet extraction and also the water activity of all samples. The results showed loses 17.54% (54.06% on a dry basis) of vitamin C during drying in the laboratory dehydrator and in the production of marmalade the loses were 73.68% (81.38% on a dry basis) of the vitamin C in relation to the initial content of the fresh sample. Water activity of the fresh sample was 0.92, of the marmalade was 0.72 and of dried rose hip was 0.60. The oil content in rose hip seeds was 9.2 % on a dry basis.

Plodovi šipurka (Rosa canina L.) se najviše koriste za proizvodnju namaza (marmelada), a osušeni za spravljanje čajeva. U ovom radu, određena količina plodova je sušena u laboratorijskom dehidratoru (temperatura vazduha od 60 °C u trajanju od 16 h, potom temperatura vazduha od 50 °C u trajanju od 20 h), a od druge količine je napravljena marmelada na tradicionalan način sa idejom da se utvrdi stabilnost vitamina C nakon različitih načina termičke obrade. Nusprodukt pri proizvodnji marmelade je velika količina semenki šipurka koje su bogat izvor ulja. Cilj ovog rada je da se metodom indirektne jodimetrije (jodometrije) utvrdi sadržaj vitamina C u proizvodima nakon termičke obrade u odnosu na sadržaj vitamina C u svežem uzorku. Takođe, određeni su sadržaj ulja u semenkama šipurka ekstrakcijom po Soxhlet-u kao i aktivnost vode u svim uzorcima. Rezultati su pokazali da se pri sušenju u laboratorijskom dehidratoru gubi 17,54% vitamina C u odnosu na početni sadržaj u svežem uzorku (54,06% računato na suvu materiju), a pri proizvodnji marmelade gubi se 73,68% ovog vitamina u odnosu na početni sadržaj u svežem uzorku (81,38% računato na suvu materiju). Aktivnost vode u svežem uzorku iznosila je 0,92, u marmeladi 0,72, a u osušenom šipurku 0,60. Sadržaj ulja u semenkama šipurka iznosio je 9,2% u odnosu na suvu materiju.