Application of pulsed-vacuum on the salt impregnation process of pirarucu fillet.

The influence of the pulsed-vacuum impregnation (PVI) and periodic pulsed-vacuum impregnation (PPVI), and the temperature, on the salting process of pirarucu fillet was studied. For this, the dorsal region of the fish in the slab-shaped (60 mm × 20 mm × 5 mm) and sodium chloride solution (30 g/100 g NaCl) were used. The process was conducted at different temperatures (10 °C - 40 °C) and the following pulsed-vacuum conditions: initial vacuum pulse (5 min at 10 kPa) and alternating periods of vacuum pulse (5 min at 10 kPa) and atmospheric pressure (101 kPa) for 5 min, 10 min and 15 min intermittently. The solid gain (SG) in the fillet was more pronounced in the first two hours of the salting process. The increase of salt content in the product (0.33 ± 0.02 to 0.43 ± 0.04 g/g db) promoted the gradual reduction of moisture (72.99 ± 1.27 to 57.1 ± 2.4 g/100 g) and water activity (1.00 ± 0.03 to 0.78 ± 0.05). PVI and PPVI processes can be used efficiently at room temperature or under refrigeration in the salting process of pirarucu fillet. On the other hand, at higher temperatures (>30 °C), the effect of temperature prevails over the effect of vacuum. Peleg model satisfactorily explains the salting kinetics of the pirarucu fillet.