Extração de óleo essencial da casca de laranja "pera" (Citrus sinensis L. Osbeck) por hidrodestilação : caracterização química e atividade antimicrobiana

Abstract

Essential oil is a volatile compound of lipophilic, liquid, and aromatic substances, having a unique scent, color, and flavor. They are extracted from aromatic plants and can be synthesi zed by all plant parts. More than 3000 essential oils are known, where 300 are commercially crucial to food, pharmaceutical, and chemical industries. Brazil is considered a leading essen tial oil producer, one of the four biggest producers worldwide. Among the extraction methods, the major one used in laboratories in Brazil is hydrodistillation. On the other hand, Brazil is the largest orange producer, and the ’Pera’ orange is a kind of common orange, being a criti cal variety among citrus in the country. The orange peel has a variety of phenolic compounds and a high concentration of limonene. Due to the increased production of this fruit in Brazil, a consequently large amount of industrial waste is generated, mainly from the juice industry, which is generally discarded in landfills. Given the above, this work aims to extract essential oil from the orange peel through the hydrodistillation method, evaluate its yield and antimi crobial activity, and characterize the essential oil obtained chemically. The extractions were performed by hydrodistillation using Clevenger. The yield was determined through the ratio between fruit mass used and oil mass obtained, resulting in 1.81%. The orange essential oil was characterized by GC-MS, where the volatile compounds and their chemical composition were analyzed, identifying polar and apolar compounds present. The main volatile compounds found were alpha-limonene, beta-myrcene, decanal, beta-linalool, and alpha-pinene. The antio xidant activity was analyzed using the DPPH free radical scavenging method, defined as 3.43% (a low value compared to the literature). The analysis of phenolic compounds was evaluated using the Folin-Ciocalteu Assay, resulting in 437.51 mg gallic acid.100g−1 . The antimicro bial activity was analyzed by the disk diffusion method and by volatile compounds against gram-positive Staphylococcus aureus and gram-negative Escherichia coli microorganisms. The produced essential oil showed inhibition by volatile compounds against the microorganism E. coli and inhibition by disk diffusion against the gram-positive Staphylococcus aureus. In the present study, it was concluded that essential oil shows significant antimicrobial activity. The high concentration of Limonene and phenolic compounds found influence this activity. The identified compounds are the major components of orange essential oils. They have antimicro bial, anti-inflammatory, and anticarcinogenic activity, which makes viable the possibility for the study and application of the orange peel essential oil as a possible food preservative.