Application of electrohydrodynamic‐ultrasonic procedure for extraction of β-carotene from carrot pomace

Nowadays, there is great attention to extract natural colorants and food additives from the by-products of food processing industries. In this research, the β-carotene extraction from carrot pomace was investigated using electrohydrodynamic (EHD) pretreatment and ultrasonic process as an innovative extraction technique. To achieve this purpose, the statistical method of Complete Randomized Design (CRD) was used to estimate the effects of EHD time (at six levels of 2.5, 5, 10, 15, 20 and 25 min) and EHD voltage (at five levels of 0, 14, 16, 18, 20 and 22 kV) on the dependent factors of β-carotene content, antioxidant activity, total phenolic content, and extraction yield of the carrot pomace extracts. The ultrasonic extraction was performed at similar procedure with a temperature of 30 °C, power of 500 W, frequency of 20 kHz, and time of 80 min. It was found that the highest values of β-carotene concentration (415.28 ± 0.56 mg/L; P ≤ 0.01), antioxidant activity (90.42 ± 0.48%; P ≤ 0.001), total phenolic content (151.48 ± 76 mg/L; P ≤ 0.001), and extraction yield (9.15 ± 0.25%; P > 0.05) were achieved at EHD time of 20 min. Moreover, the highest recovery of the β-carotene concentration (433.42 ± 1.86 mg/L; P ≤ 0.001), antioxidant activity (92.35 ± 0.52%; P ≤ 0.001), total phenolic content (155.42 ± 7.73 mg/L; P ≤ 0.001), and extraction yield (9.70 ± 0.10%; P ≤ 0.01) of the extracts were obtained at EHD voltage of 20 kV. Fourier transform infrared (FT-IR) spectroscopy displayed no degradation of functional groups of the carrot pomace extracts during the EHD pretreatment. Therefore, the application of EHD pretreatment method leads to higher levels of β-carotene content, antioxidant activity, total phenolic content, and extraction yield from the carrot pomace extracts.