The avocado seed has antioxidant components that can be used in the prevention of browning caused by Polyphenol oxidase (PPO). In this research the inhibition of the PPO was evaluated by using an extract obtained through fermentation in the solid state of the avocado seed, in comparison with both ascorbic acid and L-Cysteine, applied to three food matrices: apple, banana and avocado pulp. 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, it was evidenced that the fermented extract effectively delayed browning at concentrations of 0.5% v/v in avocado pulp and banana and 1.0% v/v in apple, effect that 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 that self-inhibition is present in most cases. In conclusion, fermented avocado seed extract may be a potential product to protect other foodstuffs from oxidation in the food industry.