Effects of chemical surface coating (Rain-Z^TM) on the powder yield of spray-drying: a preliminary approach

Spray-drying is the liquid food drying method where stickiness and wall deposition has most commonly been a major issue. For that reason, the efficacy of chemical surface coating was introduced to reduce stickiness and improve product recovery. The glass drying chamber was coated with a commercially available water repellent product Rain-Z^TM. The drying chamber was homogenously polished twice prior to physico-chemical analysis. The hydrophobicity and morphological properties were determined by means of goniometer, SEM and FTIR, respectively. From the results obtained, the exposure of Rain-Z^TM has increased significantly the product recovery (p<0.05). However, the productivity was decreased as the cycle increased (p<0.05). This was possibly due to thermal degradation. Moreover, the treated glass shows higher contact angle (2.6-fold increase) than the untreated (p<0.05). In fact, the SEM images of the treated glass showed rough surfaces as to indicate its hydrophobicity shifting. Meanwhile, powdered sample determined by FTIR show similar spectra trend detected on each functional group of both samples which suggested that there was no foreign residual left. In summary, we reported that a simple surface modification using commercially available product on the drying chamber has successfully proven to be one of the potential approaches to increase yield and productivity.