Preconditions for industrial use of foliage as felling by-product of Scots pine for essential oil production

Abstract

The aim of the study was to analyse some preconditions for the industrial production of Scots pine (Pinus sylvestris L.) essential oils including effects of storage temperatures of harvested foliage on the percentages of essential oils, α- and β-pinenes, and an estimate of potential resources of the foliage obtained from by-products of forest felling. The hypothesis was tested whether uncommon winter temperatures could provide favourable storage conditions of pine foliage to produce essential oils without a loss of yield. The study revealed that neither of the tested storage conditions of pine foliage (one month at +4°C, and one month at −24°C) had adverse effects on the total yield of essential oils if compared to the freshly collected foliage. The essential oil yield varied within 0.43–0.64%, showing the highest amount after storage at +4°C. Percentages of α and β isomers of pinene, the main compound of the essential oils, did not change significantly after the storage at both temperatures. Independently of the storage conditions, the (1R)-(+)-α-pinene was more prevalent than (1S)-(−)-α-pinene: the chiral analysis showed that (+) enantiomer was 3.1–5.8 times more abundant than (−) enantiomer. The tested storage temperatures span over the common temperatures of winter time in the region, when forest felling is being performed, and occur more notably with the climate change. Nevertheless, this provide favourable preconditions to produce essential oils without a loss from a pine foliage which could be obtained in large amounts from by-products of forest felling. The equations developed by different authors for the estimation of pine foliage biomass in the study area were used, and it was estimated that a mature 1-m3-stem-volume pine tree produces at least 10kg of fresh foliage biomass. Considering that the rate of the final felling of mature pinewoods in Lithuania remains at the current level of 700,000m3 of stem wood a year, the total estimated harvest of foliage is 7000t. This amount of foliage contains at least 35t of essential oils or 17.4kg of essential oils per hectare of mature pinewood on average. The resources of such magnitude are available on a yearly basis.