Enhanced extraction of procyanidins from avocado processing residues by pulsed electric fields pre-treatment

The waste generated by the global production of avocado (Persea americana Mill), which includes peels, seeds, and pulp, poses environmental challenges. The principles of circular economy offer a sustainable solution by valorizing this waste and transforming it into valuable products. This study investigates the potential of avocado by-products, particularly peels and seeds, as a source of procyanidins. Pulsed electric field (PEF) technology has been shown to increase the extraction yield of valuable compounds from food waste/losses. In our study, we optimized the PEF treatment of avocado peels and seeds for the extraction of procyanidins by using Box-Behnken designs with response surface methodology and desirability functions. The effects evaluated were the frequency (1, 50, 100 Hz), the electric field strength (0.8, 1.1, 1.5 kV/cm) and the number of pulses (100, 150, 200) for avocado peel, while for the avocado seeds were the frequency (50, 100, 150 Hz), the electric field (0.6, 0.7, 0.8 kV/cm) and the total operating time (1, 5, 10 s). Our study showed that the procyanidin content measured by HPLC-FLD significantly increased in PEF-pretreated avocado peel and seeds. The optimized treatment conditions include a frequency of 50 Hz, an electric field strength of 1.31 kV/cm, and 175 electric pulses for the avocado peels, resulting in a procyanidin content of 9798.32 ± 103.83 μg CE/g d.w. For avocado seeds, the optimal conditions include a frequency of 100 Hz, an electric field strength of 0.75 kV/cm, and total operating time of 5.5 s, resulting in a procyanidin content of 21103.12 ± 234.76 μg/g d.w. The precision and validity of the mathematical models confirmed the reliability of these optimal conditions. These results emphasize the potential of PEF technology for the extraction of procyanidin from avocado waste and contribute to environmentally friendly extraction techniques in the food industry.