Derya Koçak Yanık

Volatiles of Fresh and Commercial Sweet Red Pepper Pastes: Processing Methods and Microwave Assisted Extraction

Microwave-assisted hexane or water extraction was used to extract flavor compounds from fresh red pepper fruit and also from traditionally and industrially made pepper pastes. The composition of the volatile components from each extract was analyzed using comprehensive two-dimensional gas chromatography with time of flight mass spectrometry. In total, 79 compounds were determined including 15 alcohols, 14 terpenes, 13 aldehydes, 12 ketones, 7 fatty acids, 6 fatty acid esters, and 6 browning reaction products. The major common compounds of fresh pepper and the pastes were 2-pentanone, 3-hexanol, acetic acid, oleic acid, and linoleic acid. The compounds (E)-2-undecenal, farnesol, 2-pentadecyn-1-ol, linolenic acid, and squalene were found only in the fresh pepper samples. Browning reaction products were observed in both of the pastes. However, their concentration was much higher in the industrially made one. Microwave-assisted hexane extraction from the traditionally made pepper paste gave the highest number of volatiles. Many volatiles considered to possess pleasant aroma characteristics were observed only in the traditionally made paste.

Valorization of Olive Pomace Oil with Enzymatic Synthesis of 2-Monoacylglycerol

2-Monoacylglycerols (2-MAG) with a high content of oleic acid at sn-2 position was synthesized by enzymatic ethanolysis of refined olive pomace oil, which is a byproduct of olive oil processing. Six lipases from different microbial sources were used in the synthesis of 2-MAG. Immobilized lipase from Candida antarctica gave the highest product yield among the selected lipases. Response surface methodology was applied to optimize reaction conditions; time (4 to 10 h), temperature (45 to 60 °C), enzyme load (10 to 18 wt%), and ethanol:oil molar ratio (30:1 to 60:1). The predicted highest 2-MAG yield (84.83%) was obtained at 45 °C using 10 (wt%) enzyme load and 50:1 ethanol:oil molar ratio for 5 h reaction time. Experiments to confirm the predicted results at optimum conditions presented a 2-MAG yield of 82.54%. The purification yield (g 2-MAG extracted/100 g of total product) was 80.10 and 69.00 for solvent extraction and low-temperature crystallization, respectively. The purity of the synthesized 2-MAG was found to be higher than 96%.

Optimisation of Microwave-Assisted Extraction of Pomegranate (Punica granatum L.) Seed Oil and Evaluation of Its Physicochemical and Bioactive Properties

Pomegranate seed oil was extracted in a closed-vessel high-pressure microwave system. The characteristics of the obtained oil, such as fatty acid composition, free fatty acidity, total phenolic content, antioxidant activity and colour, were compared to those of the oil obtained by cold solvent extraction. Response surface methodology was applied to optimise extraction conditions: power (176-300 W), time (5-20 min), particle size (d=0.125-0.800 mm) and solvent to sample ratio (2:1, 6:1 and 10:1, by mass). The predicted highest extraction yield (35.19%) was obtained using microwave power of 220 W, particle size in the range of d=0.125-0.450 mm and solvent-to-sample ratio of 10:1 (by mass) in 5 min extraction time. Microwave-assisted solvent extraction (MASE) resulted in higher extraction yield than that of Soxhlet (34.70% in 8 h) or cold (17.50% in 8 h) extraction. The dominant fatty acid of pomegranate seed oil was punicic acid (86%) irrespective of the extraction method. Oil obtained by MASE had better physicochemical properties, total phenolic content and antioxidant activity than the oil obtained by cold solvent extraction.