Spray-dried and freeze-dried protein-spinach particles; effect of drying technique and protein type on the bioaccessibility of carotenoids, chlorophylls, and phenolics.

The effects of protein carrier and drying technique on the concentration and bioaccessibility of lipophilic compounds (lutein, ß-carotene, chlorophylls a and b) and hydrophilic flavonoids in freeze-dried (FD) or spray-dried (SD) spinach juice and protein-spinach particles were investigated. Carotenoid and chlorophyll contents were highest in FD spinach juice without protein (147 and 1355 mg/100 g, respectively). For both SD and FD protein-spinach particles, SPI best protected carotenoids and chlorophylls (123 and 1160 mg/g, respectively), although the bioaccessibility of lipophilic compounds in WPI particles was higher than SPI particles (p < 0.05). For flavonoids, the drying technique was more important than the type of carrier, since FD particles had higher total flavonoids than SD. However, SD particles had higher bioaccessibility for most flavonoids (40-90 %) compared to FD (<20 %). The drying method and protein carrier can be designed to produce protein-spinach ingredients with desired concentration of compounds and bioaccessibility.