Brookfield rv dv 2 viscometer

A single-strain starter culture of Lb. plantarum NDC75017, the commercial starter-culture YC-X100, and the combination of these were separately used to make yogurts. The 3 types of starter cultures were inoculated separately in sterilized reconstituted skim milk and incubated at 36°C. Inocula of 10 8 cfu/mL from each starter culture were used. When the pH reached 4.5, the samples were rapidly cooled to 4 to 6°C in an ice-bath and stored at 4°C for 12 h. The pH of each sample was determined using a pH meter (Corning 120 pH meter, Corning Inc., Corning, NY). Then, acetaldehyde and diacetyl concentrations were determined by gas chromatography (Agilent, Santa Clara, CA) as described by Pourahmad et al. (2011) . Water-holding capacity (WHC) was determined by the procedure described by Keogh and O'Kennedy (1998) . Before measuring yogurt consistency, previously incubated samples at 4°C were adapted to 25°C for 30 min according to Xanthopoulos et al. (2012) , using a Brookfield RVDV-II+ Viscometer (Brookfield Engineering Laboratories Inc., Middleboro, MA).