360 Chapter 14
through the use of EPS - producing strains
in starter cultures. Hassan (2008) has
extensively reviewed the possibilities and
challenges of applying exopolysaccharide -
producing LAB in dairy foods.
Flavor enhancement of cottage cheese is
another area in which cultures are used to
improve quality. In the United States, a fairly
high level of diacetyl is desired in the cream
dressing of cottage cheese. Babel and Mather
(1961) described a process using Leuconostoc
mesenteroides ssp. cremoris to boost the
diacetyl content in cream dressing for cottage
cheese: A mixture of skim milk and cream is
heat - treated, cooled to 21 ° C to 25 ° C (69.8 ° F
to 77 ° F), and inoculated with 1% to 2% of a
culture of Leuconostoc mesenteroides ssp.
cremoris (strain 91414). The inoculated
mixture is incubated at the same temperature
range for 24 to 48 hours to suffi ciently
increase the numbers of the inoculum. At the
end of incubation, the pH of the mixture is
adjusted to about 4.3 with sterile citric acid.
The lowered pH value promotes diacetyl syn-
thesis by enabling the rapid uptake of citrate.
The acidulant used to adjust the pH is also
the precursor for diacetyl. Furthermore, the
pH is conducive for the diacetyl synthesis to
proceed optimally. To promote diacetyl syn-
thesis, the pH adjusted - mixture is further
incubated at 21 ° C to 25 ° C (69.8 ° F to 77 ° F)for
24 hours, and immediately chilled. The chill-
ing arrests the reduction of diacetyl to not - so -
fl avorful acetoin. The chilled mixture is
ready for application on dry cottage cheese
curd. A patent based on this procedure was
awarded to Babel and Mather (1961) , and the
process has been in use commercially for
many years.
Gilliland et al. (1970) described the pro-
duction of concentrated cultures of Leuco-
nostoc citrovorum, which may be supplied to
processors in frozen form. The use of con-
centrated culture obviates the need for the
initial 24 to 48 hours of incubation of the
creaming mixture to build up the fl avor bac-
terial population. The measured dosage of theThe starter populations among cheeses
were not signifi cantly different. The test for
cheese melting functionality showed that the
cheeses made with Pairing C displayed the
highest melt distance (12.5 cm) vs. pairings
A (10.4 cm), D (9.3 cm), and B (8.8 cm).
From these observations it was concluded
that the exopolysaccharide - producing strains
improved the melting functionality of the
cheese, as well as the yields. However, the
researchers noted that the cheese made with
the Pairing C (containing the EPS^ +^ ) strain
was sticky, soft, and diffi cult to shred.
The whey from cheese made with Pairing
C was viscous and diffi cult to process through
ultrafi ltration equipment. On the other hand,
the cheese of Pairing A, containing the Cps^ +^
strain, did not have these drawbacks. Hence,
strain MR - 1C (Cps^ +^ ) was recommended for
use in producing low - fat mozzarella cheese
with good melting functionality, higher yields,
and whey with good downstream processing
qualities. ST strain MR - 1C is commercially
available for cheese manufacturers.
Hassan et al. (2004) reported on the
favorable modifi cation of body and texture
of Karish cheese through the use of EPS -
producing LAB starter, in this case Lacto-
bacillus delbrueckii ssp. bulgaricus CHCC
- It was paired with ST strain CHCC
- Karish cheese is a soft Egyptian cheese
made from skim milk and acid coagulation.
Due to the lack of fat and high density of the
protein matrix, the cheese has a dense, fi rm,
brick - like texture that is not cherished by
consumers. Hassan et al. (2004) made Karish
cheese using a non - exopolysaccharide - pro-
ducing combination consisting of ST 5843
and Lactobacillus delbrueckii ssp. bulgaricus
(a non - EPS mutant of CHCC 769) in one vat.
Cheese was made in a parallel vat with inocu-
lated CHCC 769/ST strain CHCC 3534. The
cheeses were analyzed for moisture, micro-
structure by cryoscanning electron micros-
copy, and rheological properties. The overall
data showed that the body and texture of
Karish cheese could be favorably modifi ed