In existing processes, the extraction of steviol glycosides from stevia leaves involves many process steps often including extraction by organic solvents. The purpose of the present study was to develop a process for the effective extraction of steviol glycosides, which can provide a concentrated juice exhibiting a high level of recovery with regard to the target compounds, rebaudioside A and stevioside. Pressurized Hot Water Extraction (PHWE) was first optimized with Response Surface Methodology in terms of maximized rebaudioside-A yield and minimized colour components. PHWE was then combined with pressing in a wine-press, resulting higher efficiency for extracting both steviol glycosides in comparison to the reported methods in the literature. Finally, spray drying was applied for both product stabilization and removal of contaminants.
This study aimed to evaluate the coating effect of methacrylic acid copolymers (MAc) on alginate beads, with respect to protection, survivability, and in vitro release of lactobacilli cells under simulated gut conditions, and to evaluate the effect of oven drying and fluidized bed-spraying as a mean to dry and coat alginate beads with MAc. MAc-coated beads exhibited protective effects for lactobacilli cells against low acidic environment providing higher survivability (71.82–96.11%) compared to uncoated beads (28.67–61.68%), and also higher cell release under sequential gut conditions (P<0.05). Lactobacillus casei BT 1268 showed a high cell release and was thus selected for further analysis using spray coating-drying via fluidized bed. Scanning electron microscopy revealed that fluidized bed-spray drying produced beads with irregular shapes but consistent coating and with lactobacilli cells clearly embedded within the inner matrix. Oven dried and fluidized bed-spray dried MAc-coated beads of L. casei BT 1268 also showed similar cell release, indicating the possible use of fluidized bed-spray as a more economical and less time consuming method for the protection and maintenance of cell viability.
, P. , Rai , G.K. & Mahanta , C. ( 2015 b): Process standardization for development of spray-dried lemon juice powder and optimization of amla-lemon based RTS (ready-to-serve) drink using response surface methodology . J