Developing a new production process for high-porosity lactose particles with high degrees of crystallinity

Spray drying and post-processing production of highly-porous lactose particles using sugars as templating agents

“…2). The steady downward trend in the yield was also observed in our previous work when the citric acid contents of the lactose/citric acid solutions were increased [12], which was connected with an increase in stickiness as explained by Bhandari et al [23]. Increasing the concentration of templating sugars with lower glass-transition temperatures than the glass-transition temperature for lactose decreases the glass-transition of the spray-dried mixture according to the GordonTaylor equation [24] and decreases the sticky-point temperatures, causing an increase in stickiness and powder loss.…”

“…It has been found in our previous studies [12,14] that lactose crystallinity in spray-dried particles increases as the pH of the solution decreases and the acidity increases, which has also been suggested by other researchers [20][21][22]. The lower BET surface areas for the processed particles from ethanol washing of the spray-dried powders at higher citric acid concentrations, and consequently higher degrees of crystallinity, suggested that increasing the lactose crystallinity in the spray-dried powders may have a negative effect on the BET surface areas of the processed powders after ethanol treatment [12].…”

“…The sample and the balance have been placed in a sealed box, where the relative humidity (70-75% RH) and the temperature (24.5-25°C) have been kept constant using a saturated salt solution of sodium chloride and electric light bulbs, respectively. The end of the crystallization process has been determined by the point where the sorption curve reached a plateau region [12]. The free moisture content (dry basis) has been measured by weighing the sample before and after drying in a fan circulated oven (Labec, Australia) at 85°C for 24 h.…”

“…Hence, producing stable crystalline particles with high porosity and surface roughness is the best way to avoid problems associated with unstable amorphous particles. In our previous works [12][13][14], a new production method was proposed, based on a templating concept [15][16][17][18] for producing highly-porous lactose with a high degree of crystallinity using citric acid as a templating agent.…”

“…The lower BET surface areas for the processed particles from ethanol washing of the spray-dried powders at higher citric acid concentrations, and consequently higher degrees of crystallinity, suggested that increasing the lactose crystallinity in the spray-dried powders may have a negative effect on the BET surface areas of the processed powders after ethanol treatment [12]. Citric acid also significantly decreases the yield of the spray-drying process due to an increase in stickiness resulting from its low glass-transition temperature (T g ), so the addition of surface-active material, such as whey protein isolate (WPI), for recovery improvement was necessary [12]. Hence, the search for non-acidic templating materials that have minimum effects on the lactose crystallinity and the yield of the spray-drying process is highly desirable.…”