Testiranje stabilnosti hidrolatov rmana (Achillea sp.) in pravega ingverja (Zingiber officinale)

Turk, John Paul (author), Kočevar Glavač, Nina (mentor), Schoss, Katja (comentor)

Hidrolati kot sekundarni produkti destilacije eteričnih olj vsebujejo hlapne organske spojine, ki jim dajejo biološko aktivnost – protimikrobno, protivnetno in antioksidativno. V zadnjih letih jih vedno bolj uporabljamo v kozmetični in prehrambni industriji, zanimanje zanje pa narašča tudi v farmacevtski industriji. Njihova kemijska sestava je slabo raziskana, sistematičnih analiz o njihovi stabilnosti in dejavnikih, ki vplivajo na stabilnost, pa praktično ni. V magistrski nalogi smo ugotavljali vpliv temperature, materiala vsebnika in UV-svetlobe na stabilnost hidrolatov. Z vodno destilacijo smo pripravili dva hidrolata navadnega rmana in en hidrolat pravega ingverja. Iz njih smo pripravili serije vzorcev, ki smo jih shranjevali v vsebnikih iz stekla, aluminija, polietilena (PE) in polietilena visoke gostote (HDPE) pri 4 °C, 25 °C in 40 °C, v temi in na svetlobi. Kemijsko sestavo smo spremljali pet mesecev po destilaciji s plinsko kromatografijo, sklopljeno z masno spektrometrijo (GC-MS), pH pa smo merili potenciometrično. Sveži hidrolati so vsebovali 0,080–0,500 mg/mL hlapnih spojin. Kemijska sestava hidrolatov se je na splošno najbolje ohranila pri 4 °C, v temnih steklenih vsebnikih (zaščitena pred svetlobo), kjer se je ohranilo > 80 % izhodnih spojin v hidrolatu ingverja in > 90 % izhodnih spojin v hidrolatu rmana. Najpomembnejši dejavnik pri ohranjanju izhodnih spojin je bil material vsebnika. V vsebnikih iz HDPE se je skupna koncentracija izhodnih hlapnih spojin po petih mesecih znižala za 40–90 %. pH hidrolatov je bil najstabilnejši v vsebnikih iz HDPE, najmanj pa v steklenih vsebnikih in na svetlobi, kjer je naraščal. Najobčutljivejša spojina je bil citral, ki se je pojavil v hidrolatu ingverja. Glavni razpadni produkta v tem hidrolatu je bil cis-(-)-1,2-epoksi-p-ment-8-en (do ⁓ 0,218 mg/mL), ki je nastajal pri povišani temperaturi in pod vplivom UV-svetlobe, verjetno iz citrala. Raziskave v prihodnosti bi lahko proučevale stabilnost hidrolatov z dodanimi stabilizatorji (konzervansi, antioksidanti, pufri) in stabilnost posameznih hlapnih spojin hidrolatov.

• Language: Slovenian
• Keywords: hidrolat, hlapne organske spojine, navadni rman (Achillea millefolium), pravi ingver (Zingiber officinale), stabilnost
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FFA - Faculty of Pharmacy
• Year: 2025
• PID: 20.500.12556/RUL-175188
• COBISS.SI-ID: 254394627
• Publication date in RUL: 21.10.2025

Secondary language

• Language: English
• Title: Stability testing of yarrow (Achillea sp.) and ginger (Zingiber officinale) hydrolates

Abstract

Hydrolates, as secondary products of essential oil distillation, contain volatile organic compounds, which give them unique biological properties—antimicrobial, anti-inflammatory, and antioxidant activity. In recent years, the usage of hydrolates in the food and cosmetics industries has increased, with growing interest in the pharmaceutical industry as well. Their chemical composition is poorly understood, and there are practically no studies on their stability and factors that affect it. The aim of our research was to uncover the role of temperature, packaging material, and exposure to UV light in the stability of hydrolates. Using hydrodistillation, we prepared one ginger and two yarrow hydrolates. These were then divided into samples, which were stored in glass, aluminium, polyethylene (PE) and high-density polyethylene (HDPE) containers at 4°C, 25°C, and 40°C, protected from and exposed to UV light. Their chemical composition was analysed throughout a period of 5 months following distillation with gas chromatography coupled with mass spectrometry (GC-MS), and their pH was measured potentiometrically. The fresh hydrolates contained 0.080–0.500 mg/mL of volatile compounds. The chemical composition of the hydrolates was generally most stable at 4°C, in glass containers, and protected from sunlight, where > 80% and > 90% of the initial compounds were retained in the ginger and yarrow hydrolates, respectively. The most important factor in retaining the initial compounds was packaging material. In HDPE containers, the total concentration of the initial compounds after five months decreased by 40–90%. The pH of the hydrolates was most stable in HDPE containers and least stable in glass containers and when exposed to UV light, where it increased over time. The most sensitive compound was citral, which occurred in the ginger hydrolate. The main product of degradation was cis-(-)-1,2-epoxy-p-ment-8-en (up to ⁓ 0.218 mg/mL), which formed at higher temperatures as well as under exposure to UV light, probably from citral. Future studies could focus on the stability of hydrolates with added stabilisers (preservatives, antioxidants, and buffers) and the stability of the individual volatile compounds found in hydrolates.

• Keywords: ginger (Zingiber officinale), hydrolate, stability, volatile organic compounds, yarrow (Achillea millefolium)