204
ABSTRACTS
milks forewarmed to 95°C. and to 140°C. were 45 and 86
milks-respectively. Milks of excessive acidity coagulated
when subjected to high temperature forewarming, but
normal milks of good quality withstood temperatures
of 150°C. to 160°C. without coagulating. Undesirable
changes in colour and flavour and an increase in acid
intensity were noticed when forowar ming temperatures
above 140°C. were used.
It was observed that milks, falling within the stability
range of 25 to 40 minutes, possessed a commercially
acceptable body. Milks below this range showed a
slight grain or were of excessive viscosity, and those with
a stability greater than 40 minutes were thin at the end
of an 18 minutes sterilization period. The data indicate
that the high forewarming temperature required to
produce an evaporated milk of a certain desired viscosity
may be within limits 2°C. for one milk or within limits
as wide as 60°C. for another milk. The optimum tempe-
rature depends upon the nature of the stability curve for
each milk and hence its estimation presents some diffi-
culties, although it usually falls between 120°C. and
140°C. when a coming up time of 4 seconds and a holding
time of 25 seconds are used. When no clue is available
the safest procedure would be to forewarm the milk to
130—145°C. for 25 seconds.
In the case of mildly aged milks, forewarming to the
proper high temperature was an effective measure of
stabilizing the concentrated milk toward sterilization.
Use of the optimum high forewarming temperatures
brought about, in the milks tested, a greater increase in
heat stability in the evaporated milk than could be
attained by the addition of the optimum quantity of
stabilizing salts to a normally forewarmed milk. The
heat stability and body of evaporated milks could be
controlled without the use of stabilizing salts by steriliz-
ing the proper blend of the normally forewarned and high
temperature forewarmed milks and stable conesntrate
mixture suitable for sterilization could be obtained by
high temperature forewarming some 25 to 50 per cent
of the milk received in the condensory. [C. P. A.]
Spirit blue agar: A medium for the detection of
Lipolytic organisms. STARR. M. P.
1941
Science, 93 (2414), 333
A SENSITIVE differential medium which could not harm
appreciably the growth of the organisms and which
could detect fat splitting organisms is given. Thirty
gm. of agar, 10 gm. of tryptone and 5 gm. of yeast ex-
tract are dissolved in approximately 900 ml. of distilled
water by autoclaving for several minutes. After
complete solution, 25 ml. of 20 per cent cotton seed oil
emulsion [ 100 ml. of fresh cotton seed oil (wesson) 10 gm.
of finely ground gum arabic and 400 ml. of warm dis-
tilled water and 50 ml. of previously filtered 0.3 per
cent alcoholic solution of spirit blue (National Aniline)
are added. The mixture is made up to one litre with
distilled water] and the medium sterilized by autoclaving
for 15 minutes at 15 lb. pressure. Either pour plates
or streak plates are recommended. The medium should
be stored in the cold to prevent oxidation. Refrigerated
sterile plates of spirit blue agar keeps for over 3 months.
Colonies of lipolytic organisms are recognized by the
develop ment of a permanent deep blue colour beneath the
surrounding colony. While examining the growth
characteristics and lipolytic activity of about 200 species
of bacteria, yeast and molds, no inhibition of growth or
lipolysis was noted, Total counts in dairy products and
the number of lipolytic organisms in the same could be
determined with this medium. [E. V, S.]
GIPD—S1—258 ICofAR—25-5-45—520.