Addition of eucalyptus oil and lemon juice to improve the physicochemical properties of Indonesian bay leaf (Syzygium polyanthum) herbal tea

Abstract

Abstract Indonesian bay leaf (Syzygium polyanthum (Wight) Walp.) is one of the medicinal herbs that has been known for its many beneficial health effects. The main problem of bay leaf is its astringent and bitter taste. Therefore, in this research, bay leaf herbal tea was made according to the black tea processing method and added with Eucalyptus oil and lemon juice to improve its physicochemical and sensory properties. This research aimed to determine the optimal brewing temperature and time for bay leaf herbal tea, as well as to identify the suitable concentration of lemon juice and Eucalyptus oil to be added to the bay leaf herbal tea. The brewing temperatures used were 70 °C, 80 °C, and 90 °C, and the brewing times were 10, 20, and 30 minutes. Results showed that bay leaf herbal tea brewed at 90 °C for 30 minutes has the highest antioxidant activity, total phenolics, total flavonoids, and condensed tannins. Afterwards, this selected bay leaf herbal tea was added with Eucalyptus oil in concentrations of 0.05%, 0.10%, and 0.15%, and lemon juice with concentrations of 1%, 2%, and 3%. The addition of 0.15% Eucalyptus oil and 3% lemon into bay leaf herbal tea was the chosen concentration, with lower antioxidant activity, total phenolic and flavonoid contents, compared to bay leaf herbal tea without the addition of lemon juice and Eucalyptus oil. However, the sensory properties of bay leaf herbal tea, in terms of aroma, taste, and astringency, could be potentially increased with the addition of Eucalyptus oil and lemon juice.

Keywords

• Antioxidant
• Brewing
• Phenolic
• S. polyanthum
• Tannin