. Starter culture
The starter culture was prepared as described by Magarinos,
Selaive, Costa, Flores, and Pizarro (2007). Each strain of La-05 or
Bb-12 (1 g) was cultured in 100 mL of sterilized skimmed milk (10 w/
v). To facilitate the activation of these cultures, 0.05% (wt/vol) L-CysHCI
was added to the milk in order to diminish the redox potential of
the medium and thereby stimulate micro-organism growth. Glucose
(2%; wt/vol) and yeast extract (1%; wt/vol) were also added to the
mixture. The incubation was carried out under aerobic condition in
the water bath (42 C; Julabo, Model Sw-21c or Haake Model SWD