Teknik reka bentuk komposit pusat dalam kaedah gerak balas permukaan (RSM), telah dipilih untuk memeriksa pengaruh parameter-parameter pengeringan sembur terhadap kandungan lembapan dan ketumpatan pukal serbuk buah naga. Pemboleh ubah-pemboleh ubah tak bersandar dengan julat seperti yang disebutkan telah diuji kaji: suhu masukan (156-224°C), kadar aliran suapan (16.6-33.4 ml/min) dan kepekatan maltodextrin (31.6-48.4%). Keputusan menunjukkan bahawa data eksperimen dapat diwakili oleh bentuk polinomial tertib kedua. Bagaimanapun, hanya istilah linear mempunyai pengaruh mutlak terhadap keadaan serbuk. Parameter-parameter terbaik untuk mencapai nilai kandungan lembapan terendah adalah suhu masukan 224°C, kadar aliran suapan 22.9 ml/min dan kepekatan maltodextrin 40%, dengan jangkaan 3.88% kandungan lembapan. Nilai ketumpatan pukal yang maksimum iaitu 0.45 g/ml dicapai pada suhu masukan 156°C, kadar aliran suapan 16.6 ml/min dan kepekatan maltodextrin 48.4%.
Kata kunci: Kaedah gerak balas permukaan; sembur kering; buah naga
Central Composite Design technique from Response Surface Methodology (RSM) was used to investigate the effects of spray drying conditions on red-fleshed pitaya powder moisture content and bulk density. The spray drying independent variables and ranges are inlet air temperature (156-224°C), feed flow rate (16.6-33.4 ml/min) and maltodextrin concentration (31.6-48.4 %). Results showed that the data were adequately fitted to second order polynomial model. However, only linear terms proved to be significant for powder attributes. The best spray drying conditions within the experimental ranges for minimum powder moisture content of 3.88% would be inlet air temperature, feed flow rate and maltodextrin concentration of 224°C, 22.9 ml/min and 40% respectively. The maximum powder bulk density of 0.45 g/ml was obtained at inlet air temperature of 156°C, 16.6 ml/min feed flow rate and 48.4% maltodextrin concentration.
Key words: Response surface methodology; spray-drying; red-fleshed pitaya