Abstract:

Parthenocissus tricuspidata red pigment powder was prepared through sequential steps of extraction with aqueous acid solution, vacuum concentration and spray drying. In the present study, the vacuum concentration process was optimized using orthogonal array design for obtaining maximum pigment concentration, and subsequently the optimal spray-drying process was investigated using uniform design for reaching a good compromise moisture among content, dissolving rate, water dissolubility and moisture absorption capacity of pigment powder. Results showed that the optimum conditions for vacuum concentration in a rotary evaporator were as follows: temperature (40 ± 1) ℃, rotation speed (40 ± 2) r/min and time 30 min; the optimum spray-drying process was that after being adjusted to 10%－ 13% of soluble solid content by adding 2% (g/g) soluble starch, the pigment concentrate was spray dried under the following conditions: feeding rate 3 mL/min, input air temperature 175 －180 ℃, output air temperature 60－70 ℃, air flow 0.35－0.37 m3/min, and atomizing pressure 100 kPa. Under such conditions, no wall sticking phenomenon was observed during spray drying process, and the quality of red pigment powder completely reached the desired goal.

Key words: Parthenocissus tricuspidata, red pigment powder, vacuum concentration, spray-drying process, orthogonal design