Inhibitory effect of fermented avocado seed extract (Persea americana Mill. cv. Hass) on polyphenol oxidase and its application as anti-browning agent in avocado, apple, and banana pulps

Antioxidant components of avocado seed can be used to prevent browning caused by polyphenol oxidase (PPO). This research evaluated the inhibitory effect of avocado seed extract obtained through solid state fermentation on PPO and assessed the anti-browning performance of this extract on avocado, banana, and apple pulp in comparison to ascorbic acid and L-Cysteine. The Km and Vmax kinetic parameters of avocado PPO, using catechol as substrate, were 0.1627 g/L and 0.6577 Abs/min, respectively. The fermented extract completely inhibited the enzyme at 60 % v/v, likewise, the type of competitive inhibition of the fermented extract was determined by the Lineweaver-Burk method. Additionally, fermented extract effectively delayed browning in avocado, and banana at 0.5 % v/v and 1.0 % v/v in apple, the effect is linked to the presence of bioactive compounds as potential inhibitors capable of retarding the darkening. Mathematical modeling of enzyme inhibition was performed and it was found self-inhibition is present in most cases. In conclusion, fermented avocado seed extract is a potential product to protect other foodstuffs from oxidation in the food industry.