Investigation of apricot powder production possibilities with foam-mat drying method

In this study, the possibilities of apricot powder production using the foam-mat drying method were investigated. For this purpose, fresh, sulfur-treated, sun-dried, and halved sun-dried apricots were used in the production of apricot powder. Egg white (EW) and hydroxypropyl methylcellulose (HPMC) were used as foaming agents, and 9-11 DE maltodextrin (MD) was used as a drying aid. The response surface methodology (D-optimal mixture design) was employed to determine the foaming agent/maltodextrin ratios to be used in the study. The apricot content in all produced apricot powders was set at 50% of the dry matter. The optimal ratio of EW was determined as 23.06%, while HPMC was determined as 3.83%, and these ratios were completed to 50% with MD. Using these optimum values, apricot puree were formed and then dried at 65ºC and an air velocity of 1.5 m/s to produce apricot powders. For comparison purposes, purees with an apricot+maltodextrin ratio of 50%+50% in weight percent (DM) were prepared, and apricot powders were produced using the spray drying and freeze drying methods. In the apricot powders, moisture content values ranged from 2.17 to 3.52 g/100 g, water activity (aw) values ranged from 0.108 to 0.127, hygroscopicity values ranged from 37.90 to 42.54 g/100 g, and caking degree values ranged from 0 to 22.70 g/100 g. The bulk density of apricot powders ranged from 0.261 to 0.636 g/cm3, tapped density ranged from 0.490 to 0.815 g/cm3, Carr Index ranged from 6.52 to 53.50%, and Hausner Ratio ranged from 1.20 to 2.15. The total soluble solid (TSS) in apricot powders ranged from 3.55 to 3.81, β-carotene content ranged from 14.31 to 36.30 mg/kg DM, pH values ranged from 4.96 to 6.64, solubility ranged from 84.55% to 93.05%, particle size (D[4.3]) ranged from 33.52 to 149.27 μm, and the glass transition temperature ranged from 62.45 to 70.16ºC. Images obtained with scanning electron microscopy (SEM) revealed an irregular morphology resembling broken glass and flaky structure on the surfaces of the apricot powders obtained from HPMC, EW, and freeze drying. Apricot powders obtained with the spray dryer exhibited round or oval-shaped particles with a smooth surface due to the effect of the spray drying conditions. Sensory analyses revealed that the best results were obtained from apricot powders produced from fresh apricots using freeze drying and the foam drying technique with HPMC as the foaming agent. Based on the results obtained, it was concluded that apricot powder can be successfully produced using the foam-mat drying method.