INFLUENCE OF SOME DRYING METHODS ON VOLATILE OIL QUALITY OF PARSLEY (Petroselinum sativum Hoffm.) AND DILL (Anethum graveloens L.) PLANTS.

Abstract

Drying process may contribute to regular supply and facilitate the marketing of plants, because it facilitates the transport and storage.  Two of the most commonly used herbs and cultivated throughout the Mediterranean region are parsley (Petroselinum sativum Hoffm.) and dill (Anethum graveloens L.) plants belongs to Fam. Apiaceae (Umbelliferae) were used in the present work. The present study was carried out at the Experiment Farm of Horticulture Research Station in EL-Kassasen, Ismailia Governorate, Egypt, in two successive winter seasons of 2006/2007 and 2007/2008 to investigate the influence of some drying methods (shade at 20 ±2 °C, oven at 45 °C, sun at 30 ±3 °C and greenhouse at 35 ±5 °C), on the plant dry weight (g / 100g FW), moisture content (%), the volatile oil quality and quantities of parsley and dill plants. The physical and chemical properties of the volatile oil of the two fresh plants viz., specificgravity, refractive index and optical rotation were determined and are included in this study.   The results showed that the shade drying method was the best treatment to produce the highest volatile oils percentage of both plants, while oven drying  gave the highest percentage of volatile oils components. On the other hand, sun drying method was the lowest one since it caused a decrease in the plant quality. The G.L.C. of the parsley volatile oil revealed a total of 10 compounds were      α- and β- pinene, sabinene, limonene, α- and β- phellandren, myrcene, p-cymene, myresticine and apiol. The total identified compounds constituent 74.6, 79.5, 91.1, 86.6 and 72.1 % in the oil of the control, shade, oven, sun and greenhouse drying methods, respectively. While, the G.L.C. of the dill volatile oil revealed a total of 11 compounds were α- and β- pinene, myrcene, limonene, p-cymen, α- and β-phellandren, 3,9- epoxy-p-menthlen, trans - dihydrocarvon, cis- dihydrocarvon and carvon. The total identified compounds constituent 100, 97.7, 98.2, 92.2 and 89.4 % in the oil of the control, shade, oven, sun and greenhouse drying methods, respectively. The method of drying affected the proportion of the oil components in the two plants. The volatile oil % of the total main components (α- and β- pinene, myresticine and apiol) was 34.5, 46.7, 59.4, 45.8 and 36.8 % of parsley plants in the oil of the control, shade, oven, sun and greenhouse drying methods, respectively. While, the volatile oil % of the total main components (α- phellendren and limonene) was 71.2, 71.5, 78.6, 57.9 and 64.8 % of dill plants, in the oil of the control, shade, oven, sun and greenhouse drying methods, respectively. The method of drying included oven dried at 45 °C for 6 hr. was the best procedure to produce parsley and dill dried materials if compared with the other tested methods, since it kept the leaf volatile oils with characterised features increasing yield quantity and quality.