2.4. Yoghurt processing
Prior to yoghurt processing, all equipment used was sterilized in
an autoclave after thorough wash cleaning. Heat sensitive materials
such as plastic equipment were placed in boiling water for 30 min
to kill vegetative cells on the material surface.
Prior to yoghurt processing, all equipment used was sterilized in
an autoclave after thorough wash cleaning. Heat sensitive materials
such as plastic equipment were placed in boiling water for 30 min
to kill vegetative cells on the material surface.
Starter preparation: The yoghurt starter culture was inoculated
into fresh milk that was heated at 90 C for 30 min. The inoculate
was incubated at 45 C until pH 4.6 was attained, stored overnight
(4 C) and then was used in the yoghurt processing.
Twelve yoghurt formulations were processed as described by
Ayar et al. (2006). Dry ingredients (gelatin and 4% cane sugar on
milk weight basis) were weighed and separately blended into three
different gelatin stabilizer levels (0.5, 0.6 and 0.7%, w/w). Each dry
ingredient blend was mixed thoroughly with fresh milk, filtered
through cheese cloth and preheated to 50 C to facilitate melting of
gelatin and uniform mixing. The resulting premix was heat treated
for 30 min at 85 C and cooled to 45 C in a 4 C water bath. Then
each of the three premixes was further divided into four equal
portions to which carrot juice (0, 10, 15 and 20%, w/w on milk basis)