# Advanced and Potential Methods for Extraction of Bioactive Compounds from Avocado Peel--A Review
## 5 Potential Techniques for Extraction of Bioactive Compounds from Avocado Peel
### Pulsed-Electric Field Extraction (PEF)  
PEF is a non-thermal approach in which the electric potential divides molecules in the cell membrane based on their charge due to the dipole nature of membrane molecules. PEF has increased cell membrane permeability and improved intracellular chemical release from plant tissue [76]. In this technique, materials are treated with PEF electrodes that have brief(s) and high voltage pulses (kV/cm) surrounding them [77, 78]. Plant tissue cell membranes are damaged by PEF treatment at a modest electric field (500 and 1000 V/cm; for 104-102 s) with little temperature increase [79].  
PEFs can be employed for industrial purposes due to various advantages, including a shorter extraction time, higher yield, and low process temperature [80, 81]. In previous decades, the pulsed electric field (PEF) treatment has been acknowledged as effective in improving pressing, extraction, drying, and diffusion processes [77]. PEF destroys the cellular membrane structure to improve mass transfer during extraction, resulting in faster extraction. As a result, PEF can help to prevent heat-sensitive chemicals from degrading. However, the study focusing on extracting avocado peel using PEF still needs to be discovered. Thus, in-depth research on the application of this technique for extracting valuable compounds from the avocado peel is required.  
So far, there are some examples of successful PEF extraction. An earlier report presented that PEF was successfully employed to extract quercetin and ellagic acid from fresh _Emblica officinalis_ juice at 18 to 24 kV/cm with a pulsed time duration of 300 to 1000 s. The best field strength was shown at 22 kV/cm, which resulted in a disintegration index of 0.79 in 500 s. PEF samples demonstrated a nine-fold increase in quercetin and ellagic acid content compared to thermally treated juice [82]. Another study looked at the effects of PEF on the extraction efficiency of fresh spearmint (_Mentha_\(\times\) spicata L.) leaves [83] and found that the conditions that resulted in the maximum disintegration (0.860.02) were 99 pulses, 3 kV/cm field strength, and 4,102,239 J/kg specific energy input PEF extraction of total phenolic content (TPC), antioxidant capacity (AC), and antioxidant activity (AA), was also comparable to heat and microwave pre-treatments, with much higher AA value than freezing/thawing, according to the same study's findings. In addition, compared to untreated samples, the product kept a better color, had a deeper flavor, and had a higher rehydration capacity [84]. PEF also effectively extracts anthocyanin monoglucosides from grape by-products [85]. PEF can also be used as a pre-treatment technique on plant materials before traditional extraction to reduce extraction effort [86]. Before the maceration process, a PEF treatment on the grape skin can shorten the maceration time and improve the stability of bioactive compounds (anthocyanin and polyphenols) during vniification [87]. Another example showed that using PEF to permeabilize Merlot skin resulted in greater extraction of anthocyanins and polyphenols [88].