DASHA SP. MIHAYLOVA¹*, LANTE ANNA², KRASTANOV I. ALBERT¹
*Corresponding author
1. University of Food Technologies, Department of Biotechnology, 26 Maritza Blvd., Plovdiv, 4002, Bulgaria
2. Università di Padova, Department of Agronomy, Food, Natural Resources, Animals and Environment, Viale dell’Università 16, Agripolis, 35020 Legnaro, Padova, Italy

Abstract

The present paper is focused on antioxidant and antimicrobial activities of pressurized-liquid extracts of Sideritis scardica and Clinopodium vulgare, wide used plants in Bulgarian traditional medicine. The pressurized-liquid technique was applied here as an easy and alternative method to obtain plant extracts. The total phenolic content was assessed and several reliable procedures were carried out to measure the antioxidant capacity of the extracts. In addition, the ability of plant extracts to enhance the oxidative stability of vegetable oils was evaluated by Rancimat test. The established antioxidant activity was in favour of the Cl. vulgare extract. Moreover, antimicrobial activity was performed toward different microorganisms. The results obtained clearly underline the potential of the investigated extracts as natural antioxidant additives to replace synthetic ones in food processing.

INTRODUCTION

In recent years, there has been an increased interest in the use of natural compounds, and questions concerning the safety of synthetic compounds have encouraged more detailed studies on plant resources.
It is well known that bioactive compounds such as polyphenols are constituents of many plants and herbs, and they have attracted a great deal of public and scientific interest because of their health-promoting effects and of their potential applications in foods as antioxidants and antimicrobial agents. Nowadays scientists examined selected plants of interest in traditional diets in order to determine their phenolic composition, antioxidant capacity and antimicrobial activity.
Antioxidants have been used in food as additional compounds for centuries. They are mainly added to delay free radical accumulation, hence strengthening the oxidative stability of food (8, 10). However, research results did not show an antioxidant compound, which could be active in all food products, because antioxidant activity might be the result of many factors, e.g. dissolving ability and activity in lipid systems and stability during the time of pr ...