Impact of the spray drying conditions and residence time distribution on lysine loss in spray dried infant formula

Abstract

The essential amino acid lysine plays an important role for the nutritional quality of infant formula. Unfortunately, it is easily damaged during spray drying which is usually used to produce infant formula powders. In this study, we showed that the extent of lysine loss can be controlled by adjusting the air inlet temperature and the air-to-liquid ratio. Depending on the spray drying conditions, 10.4±2.9% lysine loss down to no lysine loss was determined after spray drying in laboratory scale and in pilot scale. A main impact on lysine loss could be attributed to the particle residence time which was shown to be longer for the short-form, pilot-scale spray dryer than for the tall-form, laboratory-scale spray dryer. Median particle residence time was 6 s in the laboratory scale dryer and 17 s in the pilot scale dryer. The air-to-liquid ratio of the spray dryer proved to be a good parameter to compare different types of spray dryers. The extent of lysine loss during storage of the spray dried powders was independent of the extent of lysine loss during spray drying. Lysine loss during storage can be reduced by low storage temperatures and low water contents of the powder. Coupling kinetics of lysine loss that take into account the physical state of lactose, i.e., glassy, rubbery, or crystalline, with the processing conditions and particle residence time during spray drying was shown to be a promising tool to improve the nutritional quality of spray dried infant formula.

Physicochemical and functional properties of protein isolate produced from Australian chia seeds

“…This can be attributed to the lower degree of denaturation of CPI during spray drying as the outlet temperature (80 o C) was lower than the denaturation temperature(T d = 97.2 o C) of CPI (Timilsena et al, 2016b). The spray drying process is very fast and the residence time of CPI inside the drying chamber was very short (6 s in laboratory scale spray dryer and 17 s in the pilot scale spray dryer) (Schmitz-Schug et al, 2013). Furthermore, the moisture evaporation flux in the spray drying process is very high, which results in strong evaporative cooling.…”

Microencapsulation of chia seed oil using chia seed protein isolate⿿chia seed gum complex coacervates

“…The results of the accelerated oxidation test of non-encapsulated and encapsulated chia seed oil in the case of spray-dried powders are presented in Fig. 4 [39]. Secondly, the porous, irregular, and flake-like structure of the freeze-dried powder allows diffusion of oxygen more easily which accelerates oxidation of the lipid [30].…”

Comparison of a Novel Miniaturized Screening Device with Büchi B290 Mini Spray-Dryer for the Development of Spray-Dried Solid Dispersions (SDSDs)

“…Density (ρ) values of DCM (ρ DCM(25 • C) = 1.33 g/mL), air (ρ air(25 • C-1013.25 mbar) = 1.184 kg/m 3 ), and nitrogen (ρ N2 (25 • C-1013.25 mbar) = 1.145 kg/m 3 ) were used to convert the volumetric flow rate of feed solution and atomizing airflow (mL/min and L/min, respectively) into mass flow rate (g/min). This dimensionless parameter allows correlating the atomization conditions to the droplet size and comparing the process atomization characteristics of spray-drying operating at different scales [23,24].…”

“…According to Kemp et al (2013), if the atomizing-gas-to-liquid ratio exceeds 6, a particle size of 2-3 µm can be generated [25]. However, this dimensionless parameter does not include the nozzle geometry/diameter, gas velocity, and feed solution concentration that also impacts the particle size distribution (PSD) in addition [23]. Herein, air was used as a drying and atomizing gas while nitrogen was generally applied at laboratory scale.…”