Abstract:
Holy basil (Ocimum sanctum Linn.) essential oil contains various groups of volatile compounds, including monoterpene, monoterpenoid, phenylpropanoid, sesquiterpene and sesquiterpenoid, which are popular and used as characteristic flavorings for foods and beverages. However, most of volatile compounds are not stable during processing or long time storage. Moreover, solubility in water of essential oil is not good. Encapsulation technique using beta-cyclodextrin (β-CD) are claimed that can cause inclusion complex which can increase essential oil stability. The objective of this study was to study the effect of inclusion complex formation between β-CD and holy basil essential oil on its stability during thermal processing and 3 months storage. Firstly, identification of major volatile components in holy basil essential oil was performed by gas chromatographymass spectrometry (GC-MS). β-caryophyllene (19,443 ppm), eugenol (16,280 ppm) and methyl eugenol (8,140 ppm) were identified as the major components. In addition, eugenol (1,662,224), linalool (1,462,500), eucalyptol (527,333), β-caryophyllene (303,797), copaene (139,166), methyl eugenol (119,705) and estragole (115,250) were potent odorants based on odor activity value (OAV) calculation. The appropriate inclusion complex ratio of 1:5 (holy basil essential oil:β-CD) was chosen by physicochemical properties of microcapsule. It was found that the ratio of 1:5 showed highest encapsulation yield (EY) and efficiency (EE), which were 59.72% and 57.01%, respectively. However, loading capacity (LC) was 8.25% and solubility was 20.50%, that was significantly difference when compared with β-CD. Moreover, the physicochemical properties and functional groups on the microcapsules were evaluated by thermo gravimetry analysis (TGA) and fourier-transform infrared spectroscopy (FTIR), respectively. The result showed that the holy basil essential oil was well encapsulated in the cavity of β-CD. Results from scanning electron microscopy (SEM) indicated that the inclusion sample at a ratio of 1:5 showed high quality capsules. The particle size and shape of inclusion complex samples were changed from pure β-CD. In addition, the major volatile compounds that found in inclusion complex were eugenol (1,004 ppm), methyl eugenol (662 ppm) and β-caryophyllene (501 ppm). The potent odorants calculated by OAV were eugenol (102,448), eucalyptol (80,000), linalool (17,500), methyl eugenol (9,735), β-caryophyllene (7,828), estragole (3,500) and copaene (3,500). Besides, the inclusion complex improved thermal stability and showed longer period storage than essential oil. Sensory evaluation indicated that panelists could perceive characteristic of holy basil odor in 3 months storage. the inclusion complex sample. So, the β-CD encapsulation could improve physicochemical properties and stability of holy basil essential oil which can be used in various food industries.