Evaluation of six drying treatments with respect to essential oil yield, composition and color characteristics of Thymys daenensis subsp. daenensis. Celak leaves

Rahimmalek, Mehdi; Goli, Sayed Amir Hossein

doi:10.1016/j.indcrop.2012.06.012

Cited by 177 publications

(128 citation statements)

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“…In others works [9] it was found that the best drying temperature for increasing the antioxidant capacity of Thymus vulgaris L was 70ºC. It has been reported [10] the effect of six different drying treatments on the essential oil components and found that a temperature of 70 ºC led to an increase in the content of the major constituents of Thymus daenensis subsp. Daenensis, thymol/carvacrol.…”

Section: Introductionmentioning

confidence: 95%

“…The optimum leaf surface temperature was assumed to be 70 ºC; this hypothesis is supported by several authors [8,9] . At this temperature it is increased the content ophenolic monoterpenes, such as thymol and carvacrol, which contribute significantly to the total antioxidant capacity [10,33] , and, on the other hand, the effect of the high temperature on enzymatic reaction (monooxygenases) favors the conversion of p-cymene to thymol, which is negligible at low temperatures [33] .Thus in order to prevent any damage or degradation of compounds Compared with processes during which the heat is continuously supplied at lower air temperatures, the application of an air temperature of 80 ºC during the first step could reduce the total drying time (t), therefore improving energy efficiency [15] . To asses this assumption the energy necessary to heat the drying air was estimated; table 3 shows the equations used for that purpose.…”

Section: Drying Strategymentioning

confidence: 99%

“…Different research has reported the effect of drying methods on the essential oil compounds present in thyme and their antioxidant properties [7][8][9][10] . Considering two drying methods, freeze-drying and oven drying at two temperatures (30 °C and 60 °C), Venskutonis [8] noticed an increase in antioxidant capacity while drying at 60 ºC examining the effect of the drying method on the essential oil composition of Thymus vulgaris [8] .…”

Section: Introductionmentioning

confidence: 99%

“…Because in the initial drying steps product temperature is lower due to water evaporation, it seems of interest to attain a surface temperature of around 70 ºC quickly [9,10] by increasing drying air temperature. Since it is difficult to measure thyme leaf surface temperature inside a bed, modeling would be an interesting means of approaching the thyme-varying temperature on the product surface inside the bed.…”

Section: Introductionmentioning

confidence: 99%

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Management of Surface Drying Temperature to Increase Antioxidant Capacity of Thyme Leaf Extracts (Thymus vulgarisL.)

et al. 2014

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Thyme leaves are an important source of essential oils with antioxidant activity; these compounds are located in trichomes on the leaf surface. The drying conditions affect not only the drying time but also the antioxidant activity. In the literature, a drying temperature of 70 ºC appears to be the best for drying thyme leaves according to their antioxidant capacity. Considering drying periods at different temperature also could be quality beneficial. From these considerations, the goal of this work was to establish a drying strategy with which to manage a drying temperature on the leaf surface which will enable the drying time to be shortened and improve the antioxidant capacity (AC) of the extract of dried thyme leaves. The drying strategy consisted of two consecutive drying periods in order to manage the drying temperature on the leaf surface. The first drying period was carried out at 80°C (T a1 ) until the sample surface reached a temperature of 70 ºC, which then immediately being set to 70, 60, 50 and 40 °C (second drying period (T a2 )), at a different air velocity (v) (1 and 2 m s -1 ). Compared with constant drying conditions, two consecutive drying periods were found to improve the drying kinetics, the AC increased from 10.5% to 27.4 % while reducing the drying time by 14.5% to 39.2 %. The use of this drying strategy was found to be an interesting means of intensifying the convective drying of thyme leaves and its application should be considered when drying similar materials with bioactive compounds on the surface.

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Section: Introductionmentioning

confidence: 95%

Section: Drying Strategymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Management of Surface Drying Temperature to Increase Antioxidant Capacity of Thyme Leaf Extracts (Thymus vulgarisL.)

et al. 2014

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“…Estudos da literatura indicam, no entanto, que, mesmo que os OE estejam armazenados em células internas, a análise de métodos alternativos de secagem deve ser realizada (COSTA et al, 2005;PIMENTEL et al, 2012;RAHIMMALEK;GOLI, 2013). Costa et al (2005) relataram o uso do desumidificador como método eficiente para a secagem do material vegetal antes da Diferentes letras maiúsculas indicam diferenças significativas de rendimento entre os grupos e diferentes letras minúsculas indicam diferenças significativas entre os rendimentos dentro do mesmo grupo, pelo teste de Tukey (P<0,05).…”

Section: Al 2015)unclassified

ANÁLISE DO EFEITO DA SAZONALIDADE SOBRE O RENDIMENTO DO ÓLEO ESSENCIAL DAS FOLHAS DE Nectandra grandiflora Nees1

et al. 2015

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RESUMO -Este estudo teve por objetivos avaliar o efeito da sazonalidade sobre o teor de óleo essencial (OE) presente nas folhas de Nectandra grandiflora Nees e determinar se a secagem do material vegetal à temperatura ambiente influencia o rendimento do OE. Para tanto, foi coletado material vegetal de 12 indivíduos ao longo de um ano, e o OE foi extraído separadamente de folhas frescas e folhas secas, pelo método de hidrodestilação. Paralelamente, 20 g de folhas frescas foram levados à estufa a 40 °C até peso constante, para determinação do teor de umidade, procedimento esse realizado para cada coleta, individualmente. O rendimento de OE das folhas (% m/m) foi calculado para o material vegetal fresco com base em massa de matéria seca, determinado considerando o teor de umidade, bem como para o material seco à temperatura ambiente. Os dados de rendimento foram analisados através do teste de Tukey (P<0,05). Os resultados mostraram que o teor de OE das folhas da espécie apresentou variabilidade sazonal, com a maior produção detectada na primavera (0,75 ± 0,06%). Esse valor foi estatisticamente diferente dos rendimentos encontrados nas outras estações do ano, sendo o menor rendimento obtido no inverno (0,39 ± 0,02%). Desse modo, indicase que a coleta de folhas de N. grandiflora seja realizada durante a primavera, visando obter maior teor de OE. Adicionalmente, verificou-se que não há perda de teor OE durante o processo de secagem à temperatura ambiente e, dessa forma, esse procedimento pós-colheita poderá vir a ser adotado sem comprometer o rendimento do extrativo.Palavras-chave: Extrativos vegetais; Lauraceae; Produtos florestais não madeireiros. ANALYSIS OF THE SEASONALITY EFFECT ON THE ESSENTIAL OIL YIELD OF LEAVES OF Nectandra grandiflora NeesABSTRACT -This study aimed to evaluate the effect of seasonal variability on the yield of essential oil (EO) present in leaves of Nectandra grandiflora Nees and as well as to determine whether the drying process at room temperature of the plant material influences the yield of this EO. Plant material was collected from 12 individuals over a year and EO was extracted by hydrodestillation separately from fresh and dried leaves. Simultaneously, 20 g of fresh leaves was taken to stove at 40 ºC to constant weight for determination of moisture content. This procedure was performed for each collection individually. The yield of EO in leaves (% w/w) was calculated for fresh plant material based on dry matter, determined by considering the moisture content, as well as for the material dried at room temperature. The yields were analyzed by Tukey test (P<0.05). Results

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Essential Oil and Bioactive Compounds Variation in Myrtle (Myrtus communis L.) as Affected by Seasonal Variation and Salt Stress

Shoshtari

Rahimmalek

Hosseini³

2017

Chemistry & Biodiversity

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The effect of different NaCl concentrations (control, 2, 4 and 6 dS/m) and three harvesting times in different seasons including spring (9 April), summer (5 July), and fall (23 September) was evaluated on essential oil (EO) yield, composition, phenolic, flavonoid content, and antioxidant activity of myrtle. Essential oil yield ranged from 0.2% in control and fall to 1.6% in moderate salinity (4 dS/m) and spring season. The main constituents obtained from gas chromatography/mass spectrometry analysis were α-pinene, 1,8-cineole, limonene, linalool, α-terpineol, and linalyl acetate in which α-pinene ranged from 11.70% in moderate and fall to 30.99% in low salinity (2 dS/m) and spring, while 1,8-cineole varied from 7.42% in high salinity (6 dS/m) and summer to 15.45% in low salinity and spring, respectively. Salt stress also resulted in an increase in total phenolic, flavonoid content, and antioxidant activity. The highest antioxidant activity based on DPPH radical scavenging activity, reducing power (FTC) and β-carotene/linoleic acid model systems was found in plants harvested in spring and summer in high stress condition. The lowest IC values obtained in 6 dS/m in spring (375.23 μg/ml) followed by summer (249.41 μg/ml) and fall (618.38 μg/ml). Eight major phenolic and flavonoid compounds were determined in three harvesting times using high performance liquid chromatography analysis. In overall, late harvesting time of myrtle in fall can lead to reduce the most of major EO components, while it can improve the amount of phenolic acids.

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Evaluation of six drying treatments with respect to essential oil yield, composition and color characteristics of Thymys daenensis subsp. daenensis. Celak leaves

Cited by 177 publications

References 28 publications

Management of Surface Drying Temperature to Increase Antioxidant Capacity of Thyme Leaf Extracts (Thymus vulgarisL.)

Management of Surface Drying Temperature to Increase Antioxidant Capacity of Thyme Leaf Extracts (Thymus vulgarisL.)

ANÁLISE DO EFEITO DA SAZONALIDADE SOBRE O RENDIMENTO DO ÓLEO ESSENCIAL DAS FOLHAS DE Nectandra grandiflora Nees1

Essential Oil and Bioactive Compounds Variation in Myrtle (Myrtus communis L.) as Affected by Seasonal Variation and Salt Stress

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