Ali Liazid

Ultrasound-assisted extraction of capsaicinoids from peppers

The development of a rapid, reproducible and simple method of extraction of the majority capsaicinoids (nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin and homodihydrocapsaicin) present in hot peppers by the employment of ultrasound-assisted extraction is reported. The study has covered four possible solvents for the extraction (acetonitrile, methanol, ethanol and water), the optimum temperature for extraction (10-60 degrees C), the extraction time (2-25 min), the quantity of sample (0.2-2 g), and the volume of solvent (15-50 mL). Under the optimum conditions of the method developed, methanol is employed as solvent, at a temperature of 50 degrees C and an extraction time of 10 min. The repeatability and reproducibility of the method (R.S.D.<3%) have been determined. The capsaicinoids extracted have been analysed by HPLC with fluorescence detection and using monolithic columns for the chromatographic separation. The method developed has been employed for the quantification of the various capsaicinoids present in different varieties of hot peppers cultivated in Spain.

Evolution of total and individual capsaicinoids in peppers during ripening of the Cayenne pepper plant (Capsicum annuum L.)

The evolution of total capsaicinoids and the individual contents of the five major capsaicinoids: nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin and homodihydrocapsaicin present in the Cayenne pepper (Capsicum annuum L.), during fruit ripening, has been established. Capsaicinoids begin to accumulate gradually in the peppers from the beginning of its development up to a maximum concentration (1,789 μmol/Kg FW). From this time there is initially a sharp decrease in the total capsaicinoid content (32%), followed by a gradual decrease until day 80 of ripening. The two major capsaicinoids present in the Cayenne pepper are capsaicin and dihydrocapsaicin, which represent between 79% and 90%, respectively, of total capsaicinoids depending on fruit ripening. The relative content of capsaicin differs from the evolution of the other four capsaicinoids studied.

Investigation on Ochratoxin A stability using different extraction techniques.

The stability of Ochratoxin A during its extraction using different extraction techniques has been evaluated. Microwave-assisted extraction and pressurised liquid extraction, in addition to two other reference methods of extraction, i.e. ultrasound-assisted and magnetic stirring-assisted extraction, were evaluated. The effect of extraction temperature using the cited techniques was checked. The results show that Ochratoxin A can be extracted using microwave-assisted extraction at temperatures up to 150 degrees C without degradation. Pressurised liquid extraction can be used at temperatures up to 100 degrees C, for extraction times of less than 30min. Further, both ultrasound-assisted extraction and magnetic stirring extraction can be applied at temperatures up to 65 degrees C. High-performance liquid chromatography combined with fluorescence detection using a Chromolith RP-18e column at a flow rate of 5mL min(-1) was used to quantify the Ochratoxin A. The retention time for the Ochratoxin A was 1.3min. The limits of detection (LOD) and of quantification (LOQ) were 0.03 and 0.10microg L(-1), respectively.

Capsaicinoid Contents in Peppers and Pepper-Related Spicy Foods

The quantification of the major capsaicinoids, namely nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin, present in spicy foods made from peppers has been performed. The capsaicin content is directly related to the pungency properties of foods that contain hot peppers. The samples studied included 10 different dried hot peppers, 19 hot sauces, 4 kinds of paprika, and 4 different ketchups. The range of concentrations of capsaicinoids found were as follows: dried hot peppers (554.1–1705.9 mol kg−1), paprikas (582.0–665.0 mol kg−1), spicy ketchups (4.0–12.4 mol kg−1), and hot sauces (4.6–843.8 mol kg−1). Variability in the capsaicinoid content was found, with capsaicin and dihydrocapsaicin present at the highest levels. The capsaicin content was generally higher than the dihydrocapsaicin content.

Stability of anthocyanins from red grape skins under pressurized liquid extraction and ultrasound-assisted extraction conditions.

The stability of anthocyanins from grape skins after applying different extraction techniques has been determined. The following compounds, previously extracted from real samples, were assessed: delphinidin 3-glucoside, cyanidin 3-glucoside, petunidin 3-glucoside, peonidin 3-glucoside, malvidin 3-glucoside, peonidin 3-acetylglucoside, malvidin 3-acetylglucoside, malvidin 3-caffeoylglucoside, petunidin 3-p-coumaroylglucoside and malvidin 3-p-coumaroylglucoside (trans). The techniques used were ultrasound-assisted extraction and pressurized liquid extraction. In ultrasound-assisted extraction, temperatures up to 75 °C can be applied without degradation of the aforementioned compounds. In pressurized liquid extraction the anthocyanins were found to be stable up to 100 °C. The relative stabilities of both the glycosidic and acylated forms were evaluated. Acylated derivatives were more stable than non-acylated forms. The differences between the two groups of compounds became more marked on working at higher temperatures and on using extraction techniques with higher levels of oxygen in the extraction media.

Fast Separation of Capsaicinoids from Peppers by Reversed Phase Ultra-Performance Liquid Chromatography: Comparation with Traditional High-Performance Liquid Chromatography Methods

A new chromatographic method for the separation of major capsaicinoids in peppers has been developed. Nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin have been separated by reversed-phase ultra-performance liquid chromatography. A gradient method has been developed using two solvents: 0.1% acetic acid in water and 0.1% acetic acid in methanol. The developed method allows the full separation of capsaicinoids in less than 3 min, with high reproducibility (relative standard deviation < 4.3%) and repeatability (relative standard deviation < 3.6%). Robustness regarding the total amount of methanol in the sample was determined. Comparison with previous reversed-phase high-performance liquid chromatography methods using both monolithic and conventional columns was also studied. Finally, the method was applied in the determination of major capsaicinoids in 16 hot pepper samples produced in Spain.