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Avocado leaves, typically considered as pruning residues, possess a significant amount of bioactive compounds. This research aimed to optimize the extraction of phenolic compounds from Hass avocado leaves using microwave-assisted extraction (MAE) and response surface method (RSM). The extraction yield and total phenolic content (TPC) were maximized by determining the optimal process conditions, which were found to be 47°C for 5 minutes and a solid/solvent ratio of 1.13 g dry leaf/100 mL, respectively. The predicted values of all models were found to be statistically significant (p <0.001). The aqueous extracts' antidiabetic and antioxidant activities were 64.59% and 235.6 mg TE/100 g, respectively. The amount of TPC was 591.76 μg GAE/g extract, and chlorogenic acid was the main phenolic component. These results indicated that MAE proved efficient with low energy consumption, yielding phenolic-rich avocado leaf extracts, which possess high antioxidant and antidiabetic activities. [ABSTRACT FROM AUTHOR]

This study covered the phenolic compounds extraction from tomato peels using microwave assisted extraction (MAE) system and their microencapsulation by spray drying technique. For this purpose, MAE conditions (microwave power: 250-500 W and extraction time: 1-60 min) for maximum recovery were optimized by response surface methodology. The highest values for total phenolic content (TPC) (3.58 mg GAE/g) and antioxidant capacity (29.85 mmol TE/g) were obtained at the point where the microwave power was 310 W and the extraction time was 35 min. Phenolic extracts produced under optimum conditions were mixed with maltodextrin (the ratio of soluble solids in the extracts to maltodextrin: 1/1 w/w) and converted into powder form using spray drying technique. The success of the microencapsulation process was confirmed by fourier transform infrared spectroscopy (FTIR). Powder yield, moisture content, water activity and solubility values for microcapsules were determined as 63.45%, 4.18, 0.19 and 92.34%, respectively. The antioxidant capacity of the final powder products was investigated by TFM (3.17 mg GAE/g), DPPH (23.10 mmol TE/g), ABTS (75.83 mmol TE/g) and FRAP (13.95 mmol TE/g) methods. The results show that it is not a reasonable approach to dispose of waste materials or use them in field with low economic value. On the contrary, they have the potential to transform value-added products. [ABSTRACT FROM AUTHOR]

In this study, bioactive compounds (phenolics) from carob pod were extracted by using microwave assisted extraction method. Spray drying technique was performed for the conversion of the resulting extract into powder form. Microwave assisted extraction and spray drying steps were optimized using response surface methodology. In the extraction stage, the effect of solvent temperature and extraction time on the total phenolic content was evaluated. Optimum extraction conditions (total phenolic content: 84.48 mg GAE/g) were determined as 55 °C and 26 min. For the final powder production, the maximum process yield (48.00%) was obtained at the point where the spray dryer inlet temperature was 184 °C and the flow rate was 8 mL/min. The presence of phenolic structures in final product was verified by FTIR spectroscopy. Total phenolic content (15.37 mg GAE/g) and antioxidative behavior (DPPH: 0.63 mmol TE/g, ABTS: 0.30 mmol TE/g, FRAP: 0.06 mmol TE/g, CUPRAC: 0.05 mmol TE)/g) of carob powders were evaluated. [ABSTRACT FROM AUTHOR]