Anna Tsukui

Microwave-assisted extraction of green coffee oil and quantification of diterpenes by HPLC

The microwave-assisted extraction (MAE) of 13 different green coffee beans (Coffea arabica L.) was compared to Soxhlet extraction for oil obtention. The full factorial design applied to the microwave-assisted extraction (MAE), related to time and temperature parameters, allowed to develop a powerful fast and smooth methodology (10 min at 45°C) compared to a 4h Soxhlet extraction. The quantification of cafestol and kahweol diterpenes present in the coffee oil was monitored by HPLC/UV and showed satisfactory linearity (R(2)=0.9979), precision (CV 3.7%), recovery (<93%), limit of detection (0.0130 mg/mL), and limit of quantification (0.0406 mg/mL). The space-time yield calculated on the diterpenes content for sample AT1 (Arabica green coffee) showed a six times higher value compared to the traditional Soxhlet method.

Café: Aspectos Gerais e seu Aproveitamento para além da Bebida

The study of coffee seed reaches different areas of research. Its stimulating effect besides other biological activities, in addition to more than 1,000 volatile chemicals formed during roasting from chemical transformations of its fixed constituents like caffeine, trigoneline, chlorogenic acid, carbohydrate, lipid constituents, including diterpenes and fatty acids (free and esterified), among others, add value to coffee and residues generated until reach its warm beverage. Several by-products are generated during wet and the dry processing, and also by soluble coffee industries. Such by-products can be a source of raw materials for the food, pharmaceutical and cosmetics, and are often used in power generation in boilers for mechanical dryers and fertilizer. Therefore, this review aims to show the diversity of chemical compounds that can be availabed from by-products generated in the coffee process.

Floral Scent and Nectar Sugar Composition of Temnadenia odorifera (Apocynoideae, Apocynaceae)

Temnadenia odorifera is an endemic species from the Brazilian Atlantic Forest. This study was developed in order to identify the volatile compounds emitted by the living flowers and nectar, to evaluate the temporal pattern of scent emission, and the sugars composition of its nectar. Analyses of the flower scent by dynamic headspace in vivo, of nectar sugar composition and studies on floral biology were performed. Twenty-three volatile compounds were identified in the flowers scent. The total amount of odor emitted by flowers varied significantly throughout anthesis, ranging from 10232.7 ng g (9 to 12 h) to 620.2 ng g (15 to 18 h). 2-Phenylethanol and (E)-cinnamyl alcohol were the major compounds. Concentration ratio between disaccharides and the sum of hexoses ranged from 2.3 to 3.04, which can be correlated to the physiological needs inherent to big bees, the most frequent insects in T. odorifera. Analysis of the chemical composition of T. odorifera flowers provided a broader understanding of the mechanisms responsible for plant-insect interactions.

Generation of Volatile Compounds from Carotenoids of Dunaliella bardawil Algae by Water Bath Heating and Microwave Irradiation

The volatile compounds formed by thermal degradation of the carotenoids present in Dunaliella bardawil were investigated by microwave irradiation (MW) and water bath heating (WB) in different conditions of temperature and time using central composite design. Volatiles extraction by solid phase microextraction (SPME) was optimized and performed at 40 °C for 15 minutes, and those in greater amount were quantified by a validated method of gas chromatography coupled to a quadrupole mass spectrometer (GC-qMS). Employing WB, 10, 12 and 120 ng mL-1 of β-cyclocitral, α-ionone e β-ionone, respectively, were obtained between 60 and 87 °C for 30-75 min, while by MW, 5, 5, 50 ng mL-1 were obtained between 75-107 °C for 1.5-2.8 min. Considering the shorter time of MW, it can be concluded that if the time necessary to obtain the best yield by WB is employed in multiple MW cycles, an amount 10 times greater of those compounds would be obtained by MW than by WB. The results suggest a new biotechnology application for the carotenoids of the microalgae of the Dunaliella genus.