Drying and Shade Effects on Spearmint Oil Yields and Composition

Abstract

<jats:p>‘Native’ spearmint (<jats:italic>Mentha spicata</jats:italic> L.) is one of the two most widely grown spearmints in the United States and in other countries. Recent studies demonstrated the feasibility of growing ‘Native’ spearmint as a cash crop for north–central Wyoming. Transportation and energy costs of commercial mint production can be reduced by drying the spearmint in windrows in the field for a few days after harvest and before oil extraction. This method of drying mint has been a common practice in the traditional mint production regions of the world. However, there is a knowledge gap regarding the effect of this drying method on the yield and composition of ‘Native’ spearmint oil. Field and laboratory experiments were conducted in Wyoming to evaluate the effects of drying duration in days after harvest (DAH: 0, 1, 2, 3, 4, 7, or 11) and drying conditions (shade and sun) on the yield of essential oil (EO) and on the concentrations of different oil constituents (beta-pinene, myrcene, limonene, eucalyptol, cis-sabinene hydrate, 4-terpineol, cis-dihydro carvone, cis-carveol, carvone, iso-dihydro carveol acetate, beta-bourbonene, beta-caryophyllene, alpha-humulene/transbeta-farnesene, and germacrene D). Neither drying duration nor drying condition had a significant effect on oil yield. The average yield of essential oil was 0.25 g of oil per 100 g of fresh weight. Drying duration and drying conditions had a significant effect on the composition of EOs. The concentrations of myrcene and germacrene-D were higher in the EOs from plants dried under shade (3.2% and 2.4%, respectively) than the EOs from plants dried under direct sun (3% and 2.2%, respectively). The concentration of beta-pinene was higher in plants dried under direct sun than under shade (0.92% vs. 0.88%). Carvone ranged from 51% to 53% in the oil and was higher in EOs from plants dried for 1 and 2 DAH and lower in EOs from plants dried for 7 days. Drying of ‘Native’ spearmint under direct sun in Wyoming for up to 11 DAH can be used as an effective tool to reduce transportation and energy costs without affecting oil yields.</jats:p>

Influence of Air-Drying on the Quality Characteristics of Spearmint: Effects of Air Temperature and Velocity

“…; Zheljazkov et al . ), the volatile compounds and sensory characteristics (Diaz‐Maroto et al . ), and phenolic antioxidants (Orphanides et al .…”

“…Previous studies investigated the effect of drying methods on the yield and composition of the essential oil (Antal et al 2011;Zheljazkov et al 2014), the volatile compounds and sensory characteristics (Diaz-Maroto et al 2003), and phenolic antioxidants (Orphanides et al 2013). Although the chemical composition and bioactivity of dried mints are important, the food industry is mainly interested in consumer acceptability and food safety.…”

Non-Isothermal Drying of Medicinal Plants

“…Usually quality of medicinal plant includes moisture content, [30] nutritional value, [27] texture, [31] color, [32] Downloaded by [Selcuk Universitesi] at 17:37 05 February 2015 5 water-soluble proteins, [33] bioactive polyphenols [34] and/or essential oils. [35] Some of quality attributes, such as moisture, texture and color, are measurable in real-time, whereas others are not directly measurable, but could be calculated through relational models. In classical work of Labuza et al [36] it was found that degradation of quality attributes due to non-enzymatic browning, enzymatic activity and lipid oxidation are all non-linear functions of moisture content.…”

Effect of Natural Drying Methods on Flavour Profile of Camphor Rich Ocimum americanum L. from North India

“…The essential oil yield of shade dried Ocimum basilicum, Mentha piperita, Origanum vulgare and Origanum onites was the highest [24][25][26]. However, according to a study from United States, neither drying duration nor drying condition had a significant effect on oil yield of Mentha spicata [27]. These drying studies have revealed that the essential oil composition of Lamiaceae plants varied with varying temperature and humidity conditions.…”