Effect of Slurry Concentration and Inlet Temperature Towards Glass Temperature of Spray Dried Pineapple Powder

Abstract

Spray drying of fruit juices represents another alternative way to improve the physicochemical stability and increase their shelf life. Samples of pineapple powder was produced using the spray drying method to investigate the effect of inlet temperature and slurry concentrations towards the glass transition temperature of the pineapple powder. The spray dryer model used was a laboratory scale dryer and samples were run at different inlet temperatures of 130˚C, 140˚C, and 150˚C. Maltodextrin was used as a carrier agent at different concentrations of 15%, 20%, and 25% (wt/wt). The resulting powders were then analysed for glass transition temperature, moisture content, pigmentation, pH value, and particle morphology. Results showed that at higher inlet temperatures and increment of maltodextrin content, the moisture content of pineapple powder decreased. The glass transition temperature of the powders increased as the inlet drying temperature increased. A similar trend in the glass transition temperature was also observed with the addition of maltodextrin concentration. The pH value of the pineapple fruit juice increased with addition of maltodextrin, the same trend was also observed in the reconstituted pineapple juice. The particle size of the pineapple powders decreased with increasing maltodextrin content and at higher inlet temperatures. The highest yield of powder was produced at spray drying conditions of 130˚C with a maltodextrin content of 25%. The pineapple juice with high ratio of water obtained low glass temperature. Furthermore, the result also shows that the higher amount of pineapple juice and maltodextrin increase had produced more pineapple powder. From the studies it is shows that the best processing condition to obtain a free flowing and least hygroscopic pineapple powder is the sample of 900g of pineapple juice used with 200g of water with the present of 25% maltodextrin.