Contents of some bioactive compounds in Norway spruce needles as affected by short-term storage at different conditions and implications for their industrial use

Abstract

The main aim of the research was to evaluate changes in contents of essential oils and pigments in Norway spruce needles as affected by short-term storage under different conditions as well as to assess the potential resources of winter-harvested foliage obtainable from by-products of forest felling as a natural source of these bioactives. One- and two-year-old needles were taken for the analyses fresh (control) and after five-week storage at three different conditions: at 4 °C in fridge, at −24 °C in freezer and in the forest of their origin. Essential oils were isolated from needles by hydrodistillation and analysed by gas chromatography-mass spectrometry. Analyses of chlorophylls and carotenoids were performed spectrophotometrically. The study showed that none of the tested storage conditions of P. abies needles had significant influence on the total amounts of essential oils in them varying from 0.16% to 0.20% per dry matter (v/w) in two- and one-year-old needles, respectively. Bornyl acetate was the main compound identified in the essential oils amounting to 14.47–40.04%. The mean total contents of chlorophylls amounted to 1.10 mg/g in one-year-old needles and to 1.28 mg/g in two-year-old ones measured in fresh weight. Statistically significant differences were established in the levels of all the pigments analysed between fresh material, and stored under controlled, −24 °C and 4 °C, conditions both of 1-year-old and 2-year-old needles. The highest contents of the pigments were obtained after the storage at 4 °C as well as under the natural forest condition. Based on the above data and the national forestry statistics, potential yields of essential oils (6.45 kg), total chlorophylls (9.27 kg) and total carotenoids (1.32 kg) were assessed per hectare of a mature sprucewood stand in Lithuania.