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ABSTRACTS AMERICAN DAIRY SCIENCE ASSOCIATION AMERICAN SOCIETY OF ANIMAL SCIENCE
ABSTRACTS
AMERICAN DAIRY SCIENCE ASSOCIATION
AMERICAN SOCIETY OF ANIMAL SCIENCE
July 2831, 1998
Denver, Colorado
* Author Presenting Paper
DAIRY FOODS
1
Light-oxidized avor and stability of Vitamins A, D,
and C in value-added milk exposed to uorescent light in
various blow molded containers. K. W. Chapman*, L. C. Rosen-
berry, D. P. Brown, and K. J. Boor, Cornell University, Ithaca, NY.
The use of unpigmented blow molded plastic milk containers provides
potential for photo-degradation of milk nutrients and development of
light-oxidized avors. Degradation of avor and vitamins was compared
in value-added lowfat milks fortied with vitamins A, D, and C, along
with traditional 2% milk (fortied with vitamins A and D) in unpig-
mented blow molded plastic one gallon containers (standard) and in
containers pigmented with 4% or 8% titanium dioxide (TD). Signi-
cantly less vitamin A degradation occurred in nonfat, 1% and 2% fat
milk in both types of pigmented containers as compared to standard
containers. After 24 h of uorescent light exposure, vitamin A levels in
milk held in pigmented containers were identical to those in unexposed
milk. Vitamin C levels in 1% milk held for 42 h in 4% TD and in non-
fat and 1% milk held for 24 h in 8% TD were comparable to those of
samples held in the dark and were signicantly higher than vitamin C
levels of light-exposed milk in standard containers. Vitamin D levels
were stable in nonfat and 1% milks in 8% TD containers at 24 h. At 8
h for 1% and 32 h for 2% milk, samples held in 4% TD had signicantly
less light-oxidized avor than milk in standard containers. After 24 h,
1% milk held in 8% TD developed signicantly less light-oxidized avor
than milk in standard containers. Light-oxidized avor development did
not dier among the nonfat milk samples, regardless of container. In
summary, milk containers with TD signicantly protected lowfat milk
against development of light-oxidized avor and vitamin degradation.
Key Words: Light-oxidation, Vitamins, Photodegradation
2
Detection and quantication of vitamin D in fortied
milk by solid phase enzyme immunoassay. J. Jean*, C. Tur-
cotte, R. E. Simard, and I. Fliss, Universiti Laval, Canada.
Vitamin D is one of the essential vitamins in the human diet for normal
growth and function. In Canada and USA, fortied milk and milk prod-
ucts are the essential source of vitamin D. The recommended nutrient
intake of vitamin D for Canadian adults is 200 to 400 I.U. per day. Ad-
ditional amounts of vitamin D do not confer benets and may even be
toxic. In contrast, a deciency of vitamin D leads to inadequate absorp-
tion of calcium and phosphorus and faulty mineralisation of bones and
teeth. The actual methods for the quantication of vitamin D in milk
are limited in terms of sensitivity, rapidity and simplicity. The develop-
ment of a more accurate method is then urgently needed. The objective
of this study was to develop a new strategy using an immunological
approach for the quantication of vitamin D in fortied milk.
For this purpose, specic antibodies were raised in rabbits against vi-
tamin D using cationized BSA as a carrier protein. No response was
obtained with vitamin D alone. The IgG fraction was rst puried by a
Protein A/G column chromatography and then by CNBr-cBSA followed
by CNBr-cBSA-vitamin D or directly by an Epoxy Activated-vitamin D
columns chromatography. Puried antibodies were used to develop a di-
rect solid phase enzyme immunoassay (DSP-EIA). Using this DSP-EIA,
nanogram of vitamin D were detected within two hours. The signal ob-
tained was proportional to the amount of vitamin D present in a given
sample. The strategy developed seems to be very promising in terms
of sensitivity, rapidity and simplicity. It oers a great potential for au-
tomation and use on a routine basis.
Key Words: Vitamin D, Polyclonal Antibodies, Milk and Milk Products
J. Anim. Sci. Vol. 76, Suppl. 1/J. Dairy Sci. Vol. 81, Suppl. 1/1998
1 3
Gravity separation of raw bovine milk:
Fat globule
size distributions in milk fractions. Y. Ma* and D. Barbano,
1
Northeast Dairy Foods Research Center, Cornell University. Ithaca,
NY.
Gravity separation is utilized by Italian cheesemakers to partially skim bovine
milk. However, little is known about the resulting milks globule size distri-
butions. The purpose of this project was to employ laser light scattering to
investigate this aspect. Raw, fresh, whole bovine milk (volume: 60 ml; height:
10.5 cm) was gravity separated at two temperatures: 4 or 15 C. Following
incubation periods of 2, 6, 12 and 24 h, the bottom 5-ml (Fl) and top 5-ml
(F2) fractions were drained from separation columns. At both temperatures,
large fat globules moved to the top cream layer (F2) within ca. 2 h. Further
incubation did not increase volume mean diameter signicantly in F2. Higher
temperature resulted in a faster rate of separation. Results of the experiment
were as follows: for 24 h incubated milk, at the temperatures 4 and 15 C
respectively, the fat content in Fl decreased from 3.13% to 0.61% and 0.26%,
while that of F2 increased to 20.12% and 26.55%, thus achieving 53.6% and
70.1% creaming capacity.
For the above same samples, concomitantly, the
particle size distributions changed corresponding to changes of fat levels (see
Table). Such gravity separation produced partially skimmed milk with a dif-
ferent particle size distribution than that of milk separated by mechanical
means. As such, gravity separation possibly has unique applications to the
cheese making industry, and its simplicity can make it an eective procedure
for small scale dairy processors.
volume mean
specic surface
90 percentile
10 percentile
samples
diameter (�m)
area (m
2
/g)
diameter (�m)
diameter (�m)
whole milk
3.13
b
5.39
c
5.97
b
0.45
b
4 C, F1
1.77
c
10.41
b
3.52
c
0.24
c
4 C, F2
3.60
a
4.20
d
6.77
a
0.80
a
15 C, F1
1.12
d
15.12
a
2.52
d
0.19
c
15 C, F2
3.66
a
4.06
d
6.80
a
0.84
a
Within the same column, dierent superscripts indicate signicant dierences
(p<0.05).
Key Words: Bovine milk, Gravity separation, Globule size distribution
4
Determination of the free fatty acids content of cheese
using ion exchange and gas liquid chromatography.
S.
Carpino
1
*, M. Manenti
1
, G. Longombardo
1
, P. Campo
1
, G. Licitra
1
,
and D. M. Barbano
2
,
1
Consorzio Ricerca Filiera Lattiero Casearia, Uni-
versity of Catania, Italy,
2
Cornell University, Ithaca, NY.
Our objective was to compare the performance of the ion exchange bind-
ing method with two other methods. Samples of aged Ragusano cheese
were analyzed in three dierent labs with dierent methods:Contarini
G.et all.1989; C.De Jong,1990; and an acidic diethyl ether ether extrac-
tion plus an ion exchange resin were used to extract free fatty acids
from cheese in our lab. The cheese is mixed with sodium sulfate and
extracted with diethyl ether under acid conditions. Sodium sulfate and
a free fatty acid internal standard (C13:0) were added to each ask. The
neutral lipids and the free fatty acids are extracted by diethyl ether in
two extraction steps.This extract is poured into a silicic acid chromatog-
raphy column to bind phospholipids that will interfere with the binding
of free fatty acids by the resin. All column euent is collected in the
bottle containing the resin (Amberlyst A-26). The column euent is
stirred with the resin overnight. The resin binds the free fatty acids but
not neutral lipids. After this treatment the ether:methanol mixture is
decanted and the resin and the container are rinsed ve times with the
ether:methanol mixture to remove all traces of neutral lipid. At this
point the resin has bound all of the free fatty acids that were present in
the original cheese sample plus the internal standard. The resin is trans-
ferred to a methylation ask containing a C17:0 methyl ester internal
standard.The methylated free fatty acids are injected into a GLC to de-
termine the qualitative and quantitative composition of free fatty acids
per unit weight of cheese.There were no signicant dierences between
estimates of total FFA C4:0, C12:0, C14:0, C16:0, C18:0,and C18:2,
between the three methods, however the resin binding method gave sig-
nicantly higher value (p<0.005)for C6:0, C8:0, C10:0, C14:1, C18:1.
Further evaluation of the methods is being carried out to determine the
source of these dierences.
Key Words: Cheese, FFA, Method
5
Antioxidant activity and protection of SFME cell
death by non-fat dry milk extract. H. D. Jang*, A. Helmrich,
and D. Barnes, Department of Biochemistry and Biophysics, Oregon
State University.
The SFME cell line is a serum-free mouse embryo cell which can grow in
serum-free medium indenitely, maintains a normal karyotype and dif-
ferentiates into neural cell types under appropriate conditions. The cells
are cultured in medium in which serum is replaced with insulin, trans-
ferin, epidermal growth factor (EGF), high density lipoprotein (HDL),
and selenium. Without HDL and selenium, the cells go into an apop-
totic state, and die within 4 days.
The ability of aqueous extract of
non-fat dry milk (NFDM) to protect SFME cells from