Pengaruh pengeringan semprot terhadap ketahanan Enterobacter sakazakii (Cronobacter spp.) dalam susu skim bubuk

Abstract

Enterobacter sakazakii (Cronobacter spp.) which was associated with meningitis and necrotizing enterocolitis (NEC) in preterm neonates, infant, and low weight birth has been isolated in PIF in Indonesia. PIF can be contaminated by Enterobacter sakazakii (Cronobacter spp.) because it is not a sterile product. During PIF production, pasteurization is a step aimed to kill Enterobacter sakazakii (Cronobacter spp.) and other vegetative pathogens. However, processing steps after pasteurization may introduce the pathogens to the products. Therefore the effect of drying on the survival of Enterobacter sakazakii (Cronobacter spp.) need to be evaluated. The objective of this study is to evaluate the effect of spray drying on the survival of several of Enterobacter sakazakii (Cronobacter spp.) strains. This study consist of preliminary and main study. Preliminary studies aimed to determine the best inlet temperature for drying, quality of the resulted powdered skim milk and two most heat resistant strains by rapid screening of six Enterobacter sakazakii (Cronobacter spp.) strains (DESb7a, DES b7b, DESb10, DES c3, DES c13, and DES d3) at 54°C for 32 minutes. The main study was conducted on the two most heat resistant strains (DES b7a and DESb10), YRc3a, and ATCC51329. The bacterial culture was inoculated into ±40% reconstituted skim milk at 107 – 108 cfu/g and dried in a Buchi Mini Spray Drier at 160°C, 170°C, and 180°C inlet temperature and 82°C outlet temperature. The resulting skim milk powder was subsequently analyzed for the Enterobacter sakazakii (Cronobacter spp.) survival. Spray drying at the studied temperatures killed substantial numbers of Enterobacter sakazakii (Cronobacter spp.) but did not yield Enterobacter sakazakii (Cronobacter spp.)–free powder at the levels of contamination used. At an inlet temperature of 160°C, log reduction of Enterobacter sakazakii (Cronobacter spp.) ranged from 2,54 to 3,07 depending upon Enterobacter sakazakii (Cronobacter spp.) strains. Survival of Enterobacter sakazakii (Cronobacter spp.) decreased as spray drying temperature increased. The log reduction of Enterobacter sakazakii (Cronobacter spp.) at inlet temperature of 170°C ranged from 2,77 to 3,25 while at inlet temperature of 180°C, the log reduction ranged from 3,24 to 3,55 of the four strains. YRc3a was the most heat tolerant Enterobacter sakazakii (Cronobacter spp.) strain during spray drying.