نوع مقاله : مقالات پژوهشی
نویسندگان
دانشگاه لرستان
چکیده
خشککردن یکی از مهم‌ترین فرآیندهای پس از برداشت گیاهان دارویی است. در این پژوهش بهمنظور بررسی تأثیر روشهای مختلف خشککردن بر گیاه دارویی شمعدانی عطری، آزمایشی بر پایه طرح کاملاً تصادفی با سه تکرار و 12 تیمار اجرا شد. تیمارهای مورد آزمایش شامل خشککردن در ماکروویو (توان 300، 600 و 900 وات)، خشک کردن در آون (دمای 45، 55 و 65 درجه سانتیگراد)، خشک کردن طبیعی (خشککردن در سایه محصور اتاق، سایه هوای آزاد، 5 ساعت آفتاب و سپس انتقال به سایه، 10 ساعت آفتاب و سپس انتقال به سایه، و آفتاب کامل) و نمونه گیاهی تازه (بهعنوان شاهد) بودند. در روشهای مختلف خشککردن، کاهش وزن نمونهها تا رسیدن محتوای رطوبت به 12 درصد (بر پایه ماده خشک گیاهی) ادامه یافت. نتایج تجزیه واریانس نشاندهنده تاثیر معنیدار روشهای مختلف خشککردن بر زمان خشککردن، فنل کل، فلاونوئید کل، فعالیت آنتی‌اکسیدانی با دو روش دی‌پی‌پی‌اچ و اف‌آر‌اِی‌پی و محتوای اسانس بود. کمترین و بیشترین زمان خشککردن (05/4 دقیقه و 6 روز) بهترتیب مربوط به تیمارهای خشککردن با توان 900 وات ماکروویو و خشککردن در سایه هوای آزاد بود. بالاترین محتوای فنل کل (78/14 میلیگرم گالیک اسید در صد گرم ماده خشک) و فلاونوئید کل (83/12 میلیگرم کوئرستین در صدگرم ماده خشک) بهترتیب در تیمار سایه محصور و سایه هوای آزاد و بیشترین ظرفیت آنتی‌اکسیدانی (02/1IC50=) در نمونه تازه مشاهده گردید. همچنین گیاهان خشکشده در آون با دمای 45 درجه نیز از نظر فنل کل، فلاونوئید کل و فعالیت آنتی‌اکسیدانی غنی بودند. در حالیکه نمونه‌های خشکشده در سه توان ماکروویو و نمونه‌های خشکشده در آفتاب کامل کمترین میزان را برای این صفات نشان دادند. بالاترین محتوای اسانس (2/0 درصد وزنی/وزنی بر پایه ماده خشک گیاهی) نیز در تیمار خشککردن در آون با دمای 45 درجه مشاهده گردید. به‌طور کلی می‌توان گفت که خشککردن در دماهای بالای آون و توانهای بالای ماکروویو باعث کاهش میزان ترکیبات فنولی و فلاونوئید، فعالیت آنتی‌اکسیدانی و درصد اسانس شمعدانی عطری گردید. در حالیکه روشهای خشککردن در سایه محصور، سایه هوای آزاد و آون با دمای 45 درجه، کمترین کاهش را در این صفات نسبت به نمونه گیاه تازه نشان دادند.
کلیدواژه‌ها
عنوان مقاله [English]
Effect of Different Drying Methods on Drying Time and some Phytochemical Characteristic of Pelargonium (Pelargonium graveolens)
نویسندگان [English]
- Hassan Mumivand
- Abdolhossein Rezaei Nejad
- Shirin Taghipour
- Kobra Sepahvand
- Behnam Moradi
Lorestan University
چکیده [English]
Introduction: Drying is one of the most important post-harvest techniques for medicinal plants. Pelargonium graveolens (known as geranium) is an important, high-value perennial, aromatic shrub that can reach a height up to 1.3 m and a lateral growth of 1 m. The essential oil of P. graveolens is extensively used in the perfumery and cosmetic industries. Medicinal plants produce antioxidant compounds, which defend cells against degenerative effects of reactive oxygen species produced during oxidative stress and metabolism. Antioxidants are molecules that scavenge free radicals and reduce/prevent their damages. Therefore, the identification of natural antioxidants as preservative agents plays a pivotal role for the food, cosmetic and pharmaceutical industry. This study was conducted to investigate the effect of different drying methods (microwave-drying, oven drying and ambient-drying) on drying time and some phytochemical properties of P. graveolens.
Material and Methods: In order to evaluate the effect of different drying methods on drying time and some phytochemical properties of Pelargonium, an experiment was conducted at the faculty of agriculture of Lorestan University (Khorramabad, Iran) in 2017. The experiment was carried out based on completely randomized design with 12 treatments and three replications. The drying treatments were microwave-drying (300, 600 and 900 watts), oven-drying (45, 55 and 65 °C), ambient-drying (shade-drying at room, shade-drying in the field, sun-drying for five hours and then transfer to the room shade, sun-drying for 10 hours and then transfer to the room shade, and sun-drying) and fresh samples (as control). In all drying methods, the drying process continued until the moisture content of samples reached to 12% based on dry matter.
Results and Discussion: The results of analysis of variance showed the significant effect of drying methods on total phenol and flavonoids contents, antioxidant activity and essential oil content of the plants. The minimum and maximum of drying time (4.05 min and 6 days, respectively) was related to microwave-drying (900 watts) and shade-drying in the field, respectively. The highest total phenol (14.78 mg GA per 100 g dry matter) and flavonoid (12.83 mg quercetin per 100 g dry matter) contents were observed in plants dried at room shade and field shade, while the highest antioxidant capacity (IC50=1.02) was related to the fresh samples. The plants dried in the oven (45 °C) also had a notable phenol and flavonoid contents with high antioxidant activity. On the contrary, the samples dried in the microwave and sunshine showed the lowest amount of phenol and flavonoid contents and antioxidant activity. The highest essential oil content was obtained from oven-drying at 45 °C (0.2 %w/w based on dry mater), followed by shade-drying in the field (0.17 %w/w based on dry mater), and oven-drying at 55 °C (0.15 %w/w based on dry mater). While, the lowest essential oil content occurred with microwave-drying at 900 W (0.04 w/w based on dry mater). In this study, the amount of essential oil in the microwave-drying plants was significantly reduced by increasing the power of the microwave. The decrease in essential oil content with increasing oven temperature was also observed. The decrease in essential oil content with increasing oven temperature has also been reported in other species such as peppermint, dill, tarragon and sage and could be due to evaporation of the essential oil along with moisture losing during drying process. The results of Hamrouni Sellami et al. (2012) showed that drying in microwave at 800 w increased total phenol and flavonoid levels of sage (Salvia officinalis L.). Their results showed that as the microwave power increased from 600 to 800 watts, the total phenol content increased significantly. In research by Arslan et al., (2010), the lowest total phenol content was observed in the oven dried samples, whereas the highest total phenol content was obtained from the oven-microwave treatment and sun drying. The researchers explained that this increase was probably due to the release of phenolic compounds during drying and the reason for the decrease in phenolic compounds in the oven was attributed to the high temperature. Besbes et al., (2004) also reported that with increasing drying temperature, the amount of total phenolic compounds decreases, which may be due to the destructive effect of high temperatures on phenolic compounds. In general, it could be concluded that drying in high temperature of oven and high power of microwave reduces the amount of phenolic and flavonoid compounds, antioxidant activity and essential oil content of P. graveolens. While, shade-drying and oven-drying at 45 °C showed the least reduction in these traits compared to the fresh samples.
Conclusion: It can be concluded that shade-drying at room, shade-drying in the field and oven-drying at 45°C are more suitable for the P. graveolens .While drying treatments in the microwave and sunshine are not suitable for the species. In addition, the results showed that there was a significant relationship between total phenol content and antioxidant activity in both assays.
کلیدواژه‌ها [English]
- Pelargonium graveolens
- Drying
- Phenolic compounds
- Antioxidant activity
)
ارسال نظر در مورد این مقاله