Safe processing method and storage time threshold for consuming of powdered-infant formula based on total plate count test

Abstract

Powdered-infant formula (PIF) is theoretically suggested as a substitution for breast-milk. The presence of PIF has brought several problems related to its contamination, handling, and processing. Our study aimed to provide the evidence related to determine the safe processing method, between using hot water (HW) or boiled water (BW), and storage time threshold after PIF was left at room temperature for acertain period of time. We obtained PIF, cow milk-based, from supermarket and made it as suspension. Bacterial growth assessment was performedusing total plate agar, total plate count test, while several tests including the use of agar, blood and McConkey agar, and biochemical reactions were used to determine the bacterial species. We provided formula suspension in different amount of dilution (10⁻¹, 10²,10³, and 10⁻⁴), furthermore observation of bacterial colonies for 3-8 hours was done. The study was carried out at Department of Microbiology, Faculty of Medicine, Universitas Sumatera Utara in October 2017. We obtained a significant number of bacterial colonies at the first time of observation in HW and using BW was safer than HW regardless of its nutritional value, based on total plate count tests. Meanwhile, safe storage time threshold for consuming after it was left at room temperature was no more than one hour. We identified Bacillus subtilis and Klebsiella sp. as contaminants during the observation. Thus, less contamination also reduces infection rate among infantsby performing appropriate handling.