I. Sodini et al., USE OF AN IMMOBILIZED CELL BIOREACTOR FOR THE CONTINUOUS INOCULATION OF MILK IN FRESH CHEESE MANUFACTURING, Journal of industrial microbiology & biotechnology, 18(1), 1997, pp. 56-61
A system was developed to continuously acidify and inoculate skim milk
for the production of fresh cheese. Four strains of mesophilic lactic
acid bacteria were entrapped separately in K-carrageenan/locust bean
gum gel beads and used in a stirred bioreactor operated at 26 degrees
C with a 25% (v/v) gel load. The pH in the reactor was controlled at 6
.0 by adding fresh milk using proportional integrated derived regulati
on. The bioreactor was operated during 8-h daily cycles for up to 7 we
eks with different milks (heat treatment, dry matter content) and diff
ering starting procedures. The heat treatment of the milk was an impor
tant factor for process performance: a dilution rate increase of 57% a
nd an inoculation level decrease of 63% were observed with sterilized
UHT skim milk (142 degrees C - 7.5 s) compared with pasteurized skim m
ilk (72 degrees C - 15 s). The dry matter content of the milk (8-13% w
/w) had no detectable effect on these parameters. A convenient startin
g procedure of the system was tested; steady-state was reached in less
than 40 min following an interruption period of 16-60 h. These result
s combined with our published data on process performance show the fea
sibility of using an integrated immobilized cell bioreactor for milk p
refermentation in cheese manufacture.