Pulsed electric fields using a multiple needle chamber to improve bioactive compounds extraction from unprocessed Opuntia ficus-indica fruits

Abstract

Prickly pear fruit is rich in natural pigments and bioactive compounds that contribute to its antioxidant capacity and health-promoting properties. These compounds can be extracted using pulsed electric fields (PEF), a non-thermal technology that is energy efficient and is being increasingly used for food processing. For that end, a novel electroporation chamber was designed and optimum pulse parameters were selected maximizing juice yield and bioactive compounds extraction. The chamber consists of 5 rows of 10 parallel needles, and the optimum pulse parameters were: Sixty 100 μs long pulses of 1200 V/cm at a frequency of 10 Hz. The average energy input was 11.44 kJ/kg (temperature rise below 10 °C). When comparing PEF-treated samples with untreated ones, juice yield increased 3.3 times, and betalain extraction 1.48 times. Also, the juice extracted had a significantly higher total polyphenol content (1.4 times), and antioxidant capacity (1.4–1.5 times increase, measured by three techniques). This chamber and procedure could be scaled for industrial applications since large samples can be treated without the need of adding conductive medium or peeling the fruits, simplifying the procedure and reducing costs. PEF treatment of prickly pear fruits can effectively provide juice rich in natural colorants and with higher nutritional properties.