In this study the efficiency of horseradish Amorica rusticana leaf, and Levisticum officinale lovage leaf and stem extracts for the stabilisation of rapeseed oil during storage was evaluated. Plant extracts were added to unrefined rapeseed oil in a concentration of 1% by weight, which was chosen based on the results of previous experiments studying the possibilities of the addition of different concentrations of plant extracts for extending the shelf life of the oil. As a control a rapeseed oil sample without extracts was analysed, and for comparison butylated hydroxytoluene (BHT) in the maximum allowed concentration was added to the oil. The efficiency of the extracts in oil was tested in the dark and in the light/dark cycles (day/night regime). For all samples the peroxide value, acid value and DPPH scavenging activity were determined. The oil samples with the added plant extracts stored in the dark oxidised significantly (p < 0.05) slower than the control sample and the sample with BHT. After 24 weeks of storage, the lowest peroxide value was in the sample with the lovage stem extract. The extracts contain compounds that could absorb light (for example chlorophyll) and in the light/dark conditions accelerate oxidation in oil. Among the analysed extracts the lovage stem extract was the most effective oil oxidation inhibitor, but horseradish leaf extract was the most effective DPPH radical scavenger.
Lolita Tomsone, Zanda Kruma, Ruta Galoburda and Thierry Talou
Horseradish is a perennial plant with significant antioxidant properties, and it contains about 0.2% to 1.0% of essential oil, mainly sinigrin, sinigrin-derived allylisothiocyanate and diallylsulphide. The aim of the study was to determine composition of volatile compounds of horseradish (A. rusticana L.) roots depending on the genotype. Volatiles from fresh horseradish roots of nine genotypes were extracted using solid phase microextraction with DVB/Car/PDMS fibre and were further analysed using gas chromatography-mass spectrometry. The volatile compounds were identified by comparing their mass spectra with mass spectral libraries (Nist98) and by calculating linear retention indexes and comparing them with the literature data. The studied horseradish genotypes differed both in the quantitative and qualitative content of aroma compounds. Totally 15 volatile compounds were detected, and their highest amount was found in genotype G12B. The main aroma compound of all horseradish samples was allylisothiocyanate, which formed 64-82% of the total identified volatile compounds. The obtained results were compared with those found in the literature. All horseradish samples contained significant amounts of phenylethylisothiocyanate (4-18%) that is formed from glucosinolate - gluconasturtin. The study revealed that genotype has great influence on the content of volatiles in horseradish roots.
Triticale (× Triticosecale Wittm.) is mainly used for animal feed, but recent studies have shown its possible beneficial effect for human health. The objective of this study was to investigate the nutritional quality of triticale grown under different cropping systems in Latvia. Two winter triticale varieties, ‘Inarta’ and ‘Ruja’, were cultivated in 2014 and 2015 under conventional and organic cropping systems. Protein, starch, and total dietary fibre were determined using standard methods. Ultrasound assisted extraction was used for isolation of phenolic compounds. Total phenol content (TPC) and radical scavenging activity in extracts were determined spectrophotometrically. Overall, the highest content of protein, TPC and ABTS cation scavenging activity occurred in triticale harvested in 2014, due to favourable weather conditions (warm weather and more precipitation in June–July) for accumulation of these compounds during grain filling. Higher starch content in all studied samples harvested in 2015, as compared to 2014, was explained by higher precipitation in July 2015. The type of cropping system had no significant effect (p > 0.05) on protein and starch content, while TPC, DPPH, and ABTS·+ scavenging activity was influenced by cropping system, depending on variety.