In summary, the EE, b-carotene and lycopene contents of the
Gac oil were significantly affected by microwave power, microwave
drying time, steaming time and hydraulic pressure. Generally,
increase in the EE, and b-carotene and lycopene contents of
Gac oil samples was found with increasing these parameters.
Microwave and steaming treatments prior to pressing are the most
important steps in the Gac oil processing due to significantly
increasing the EE, b-carotene and lycopene. Finally, results indicated
that the most suitable processing conditions for Gac oil
extraction were the microwave power of 630 W, microwave time
of 65 min, steaming time of 20 min and hydraulic pressure of
170 kg/cm2. Under these conditions, the highest EE of 93% was
achieved and Gac oil contained highest content of b-carotene and
lycopene as 140 and 414 mg/100 mL, respectively. These results
could be useful in encouraging Gac oil processors to use microwave
and steaming treatments before pressing to improve extraction
efficiency and preserve nutrients.