engleski

Influence of particle size and process conditions on the extraction yield and antioxidant capacity of nettle extracts (Urtica dioica L.)

Cultivation and use of medicinal herbs is well documented throughout history. Nowadays, their popularity is once again increasing due to the existence of solid scientific evidence on their antibacterial, antifungal, antiviral, anticancer and anti-inflammatory properties. Since the production of nutritively highly valuable food products is a major trend of the global food industry, exploitation of bioactive phytochemicals from medicinal herbs is of great interest and should conform to the economically feasible production conditions. With respect to that, this study aims to define the optimal solid-liquid extraction conditions of bioactive compounds from nettle (Urtica dioica L.), as one of the most widely spread and used medicinal plant in Europe. Nettle is often used to treat urinary, gastrointestinal and cardiovascular disorders, while new scientific evidences have revealed a myriad of bioactive phytochemicals that exert potent biological activity in vitro and in vivo. In order to obtain the highest possible amount of bioactives from nettle, in the present study the influence of particle size, temperature, mixing speed and process duration on extraction yield and antioxidant capacity was investigated, with the use of Taguchi orthogonal array experiment design method. Extraction yield was expressed as dry matter content (g/g) and bioactives content was analyzed as total polyphenols (mg GAE/ g of plant dry matter) and antioxidant capacity by ABTS, DPPH and FRAP methods. The highest extraction yield (1.0639 g/g dry matter) was obtained for the < 100 µm particle size fraction for a 30 min extraction at 90 °C and 500 rpm. As for the chemical components, the highest concentration of extracted bioactives was obtained for the following experimental conditions: particle size fraction 280 – 450 µm, 60 min, 80 °C and 750 rpm. Based on the results of this study, temperature, duration, particle size and mixing speed have a concurrent influence of the extraction process.

Nettle; bioactive compounds; extraction; particle size

Ovaj rad doprinos je projektu „Primjena mikroreaktora u praćenju antioksidacijske aktivnosti samoniklog bilja (MICRO-AA)“, projektni broj HR.3.2.01-0069, koji je financiran iz Europskog socijalnog fonda (ESF) putem Operativnog programa Razvoj ljudskih potencijala.