Effect of Pretreatments on Controlling Enzymatic Browning Before Drying of Eggplant Slices

The present study was carried out to investigate polyphenoloxidase inhibition in eggplant slices before drying.
Pretreatments were carried out single or combined from immersion in ascorbic acid, citric acid or sodium chloride
solutions at different concentrations 0.5, 1.0, 1.5, 2.0% and /or steaming for 2,4,6,8 min. Polyphenoloxidase activity
of fresh eggplant slices was 0.65 unit /g/min. Sever inhibition was detected with increasing chemical inhibitors concentration
or steam regardless of chemical inhibitors types .The inhibitory effect of steam pretreatments or various
chemicals inhibitors on eggplant slices was found to decrease in the following order steam treatment > ascorbic acid >
sodium chloride > citric acid at the same concentration level. Combination of chemical inhibitors and steam treatment
(Ascorbic acid, citric acid, sodium chloride at levels 0.5% and steam treatment for 2min) as hurdle technology resulted
most effective inhibition on enzymatic browning. Dried eggplant slices with aforementioned combined pretreatment
at low concentration of chemical inhibitors and steam were less three times of enzymatic browning index than control
treatment (without pretreatment). Also, inhibition of polyphenoloxidase of eggplant slices before drying were higher
maintained bioactive compounds especially phenolic compounds, ascorbic acid and antioxidant activity than control