Characterization of spray-dried Gac aril extract and estimated shelf life of β-carotene and lycopene

BACKGROUND: Fresh Gac (Momordica cochinchinensis) fruit is rich in carotenoids, mainly β-carotene and lycopene, but these compounds are sensitive to degradation. Spray drying is used to encapsulate the sensitive β-carotene and lycopene with different materials. Only a few reports of using highly branched cyclodextrin (HBCD) have been published. Additionally, studies of β-carotene and lycopene losses in Gac powders during storage are limited. Therefore, the encapsulation of β-carotene and lycopene of Gac aril with HBCD by spray drying at different inlet temperatures were compared. The shelf life of β-carotene and lycopene during storage was also calculated. METHODS: The fresh Gac aril was separated and kept frozen before the experiment. Gac aril and water (1:5 w/v) were centrifuged at 8,000 g at 20 °C for 15 min using a high-speed centrifuge (Sorval; Dupont, Wilmington, DE, USA). The supernatant was filtered twice and concentrated until 15° Brix using a rotary evaporator (R-200; Buchi, Flawil, Switzerland). The mixture of concentrated aril extract and highly branched cyclodextrin at 5% (w/v) was dried at three inlet temperatures by a spray dryer (B-290; Buchi, Flawil, Switzerland) with drying air flow rate, compressor air pressure, and feed rate set at 473 L/h, 40 m(3)/h, and 3 mL/min, respectively . The physicochemical qualities, particle image morphology, and estimated storage time of β-carotene and lycopene were determined. RESULTS: Increased inlet temperatures of spray drying decreased the bulk density, β-carotene, and lycopene content of spray-dried powders significantly. The color values of dried powders had significant differences in yellowness (b*) and chroma, but not lightness (L*), redness (a*), and hue when the inlet temperature increased from 160 °C to 180 °C. The maximum reduction of β-carotene and lycopene observed during storage at 55 °C was 90.88% and 91.11% for 33 and 18 days. For β-carotene, the estimated shelf-life (retention of 50% of β-carotene) was 9.9, 48.4, and 91.6 days at 25 °C, 10 °C, and 4 °C. The shelf-life of lycopene was 26, 176, and 357 days at 25 °C, 10 °C, and 4 °C, respectively. HBCD could be potentially used as an encapsulating agent in spray-dried Gac aril, but the shelf-life of β-carotene and lycopene needs to be improved to be useful as a food ingredient.