Effect of Ultrasonic Treatment Time and Concentration of Citric Acid and Salt (NaCl) on the activity of Polyphenoloxidase in Avocado Pulp (Persea americana var mill. Hass)

Abstract

Enzymatic browning is a problem in fruit quality of fresh and processed vegetables, being the enzyme polyphenol oxidase (PPO) one of the leading causes of browning in avocado pulp. The inhibition of polyphenol oxidase activity is a constant challenge for agribusiness, which seeks new methods that do not harm the nutrients of the food. This study determined the effect of time (10 min to 30 min) with ultrasound treatment (40 kHz), citric acid concentration (0.5% to 2% w / w) and salt (0.5% to 2% w / w) on the activity of polyphenol oxidase in avocado pulp (Persea americana Mill Hass) using response surface methodology with central rotational composite design (DCCR) totaling 18 trials. It was determined that ultrasound treatment time at the designated power-level had no significant effect, while the concentrations of citric acid and salt did have a significant effect on polyphenol oxidase activity, causing inactivation to reach 96.73 % (14.39 UPFO / g) of PFO at conditions of 20 minutes, 2% of citric acid and 1.25% of salt.