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The content of lipophilic vitamins A and E was determined in samples of sheep and goat milk of different breeds coming from 9 farms in central, eastern, and southern Bohemia. Samples were collected throughout the period of lactation (from April to September). Vitamins A and E were determined by HPLC using DAD and FLD detectors. Vitamin A was determined in all samples but only α-tocopherol (out of various forms of vitamin E) was detected in all samples. The total average content of vitamins A and E in raw milk of all sheep breeds during lactation was 0.93 ± 0.07 and 2.93 ± 0.87 mg/kg, levels of these vitamins in goat milk were 0.79 ± 0.08 and 1.29 ± 0.35 mg/kg, respectively. The results showed a significantly medium and strong correlation between the content of vitamin A and E and the content of fat (R2 = 0.57 and 0.75, respectively). The year did not have any statistically significant influence on the content of monitored vitamins. The content of both vitamins is dependent on the phase of lactation. The levels of vitamins A and E were significantly lower in the early phase and significantly higher in the late phase of lactation. The amount of monitored vitamins slightly decreased during pasteurisation. A strong decrease in the content of both vitamins was observed during the first two weeks after milk storage in a freezing box at the temperature of -20°C (about 11-55%).
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58
Food Analysis, Food Quality and Nutrition Czech J. Food Sci., 33, 2015 (1): 58–65
doi: 10.17221/149/2014-CJFS
Ruminant milk and milk products have formed an
inseparable element of human diet since the earli-
est domestication of livestock. Although the milk
dominating in the dairy industry in many countries
is cow milk, other farm animals such as sheep and
goats are used for milk production increasingly. Goat
and sheep milk products have interesting properties
(C et al. 1999), including hypoallergenicity,
compared to those made of cow milk (E-A
2007). The goat milk is much easier to digest than
the cow milk as the protein composition is differ-
ent. Better digestibility of goat milk ensures that the
fat it contains is dispersed in the smaller fat beads
(J 1996). Due to the better digestibility of milk
proteins the goat milk is an important part of the diet
of people suffering from allergies (H 2002, V
et al. 2012). In addition, the breeding of sheep and
goats in the public eye is associated with a friendlier
attitude towards animals and nature, so that their
milk is considered as organic and ecological. With
the increasingly growing network of farmers markets
it is much easier to get these products and for these
both reasons the consumption of sheep and goat milk
constantly grows. Goat milk is consumed in its raw
liquid form and in the form of dairy products, while
sheep milk is mainly used to make cheese.
Milk contains relatively low amounts of vitaminsA
and E. However, due to its frequent consumption in
Supported by the Ministry of Education, Youth and Sports of the Czech Republic, Project No. MSMT 2B08072
and an institutional support of the Ministry of Agriculture of the Czech Republic, Project No. RO0511.
Factors Influencing the Content of Vitamins A and E
inSheep and Goat Milk
T MICHLOVÁ1, H DRAGOUNO2, Š HORNÍČKOVÁ1
and A HEJTMÁNKOVÁ1
1Department of Chemistry, Faculty of Agrobiology, Food and Natural Resources,
Czech University of Life Sciences Prague, Czech Republic; 2Dairy Research Institute Ltd.,
Prague, Czech Republic
Abstract
M T., D H., H Š., H A. (2015): Factors influencing the content of
vitamins A and E in sheep and goat milk. Czech J. Food Sci., 33: 58–65.
The content of lipophilic vitamins A and E was determined in samples of sheep and goat milk of different breeds com-
ing from 9 farms in central, eastern, and southern Bohemia. Samples were collected throughout the period of lactation
(from April to September). Vitamins A and E were determined by HPLC using DAD and FLD detectors. Vitamin A
was determined in all samples but only α-tocopherol (out of various forms of vitamin E) was detected in all samples.
The total average content of vitamins A and E in raw milk of all sheep breeds during lactation was 0.93 ± 0.07 and
2.93 ± 0.87 mg/kg, levels of these vitamins in goat milk were 0.79 ± 0.08 and 1.29 ± 0.35 mg/kg, respectively. The re-
sults showed a significantly medium and strong correlation between the content of vitamin A and E and the content
of fat (R2 = 0.57 and 0.75, respectively). The year did not have any statistically significant influence on the content of
monitored vitamins. The content of both vitamins is dependent on the phase of lactation. The levels of vitamins A
and E were significantly lower in the early phase and significantly higher in the late phase of lactation. The amount of
monitored vitamins slightly decreased during pasteurisation. A strong decrease in the content of both vitamins was
observed during the first two weeks after milk storage in a freezing box at the temperature of –20°C (about 11–55%).
Keywords: retinol; tocoferols; goat; sheep; storage; pasteurisation; lactation period
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Czech J. Food Sci., 33, 2015 (1): 58–65 Food Analysis, Food Quality and Nutrition
doi: 10.17221/149/2014-CJFS
various forms, it represents an important dietary
source of these vitamins. Vitamin A plays a substantial
role in the biochemical processes related to visual
perception, it is important for bone development,
affects the growth, differentiation, and maturation of
gametes and is also important for foetal development
(D et al. 2005). Vitamin A is also an effective
antioxidant. It plays a role in the synthesis of proteins,
nucleic acids, and lipoproteins. VitaminA deficiency
is associated with vision disturbances (night blind-
ness), inhibition of growth and deformities of bones
and reproductive organs. High doses of vitamin A
result in increased hepatic reserve (H 1996;
M et al. 1998). The recommended daily dose for
adults ranges from 0.8 mg to 1 mg (2600–3300 IU) and
for children from 0.4 mg to 0.6 mg (1300–2000IU)
(C & C 2006).
Vitamin E is a very important antioxidant, it has an
irreplaceable function in protecting the body against
free oxygen radicals which can lead to DNA damage,
and inhibits mutagens in the gastrointestinal tract. It
is also a factor that slows down the aging of the body
and plays a role in the prevention of cardiovascular
diseases and cancer (E & J 2004).
The recommended daily dose of vitamin E is from
10 mg to 15 mg for adults and from 5 mg to 8 mg
for children (M 2000).
Vitamin E deficiency is often associated with dis-
orders of fat absorption or distribution or cystic
fibrosis (P 2011).
The content of the vitamins in raw milk is influenced
by many factors. These include species of animal,
breed, stage of lactation, and the individual health
status. According to M-F et al. (2007)
and Z and T (2011) the nutrition
of the animal and specific character of the farming
(e.g. indoor vs. pasture farming system) are other
important aspects. The content of these vitamins
is also influenced by technological processing and
heat treatment of milk.
There are not many studies focused on how other
factors influence the vitamin content in sheep and
goat milk, especially in real life. R-L
et al. (2008) indicated the content of vitamin A in
goat and sheep milk 0.4 and 0.8 mg/kg, respectively.
For vitamin E these values are 0.4 and 1.1 mg/kg,
respectively. An extensive monograph devoted to
sheep and goats (P et al. 2007) specified a value
for vitamin A (185 IU for goat milk, 146 IU for sheep
milk) but not for vitamin E. These studies also do
not distinguish between different breeds.
The aim of this study was to determine and com-
pare the content of fat-soluble vitamins A and E in
sheep and goat milk from private farms in the Czech
Republic and to assess the effect of heat treatment
and storage in a freezing box on the content of these
vitamins.
MATERIAL AND METHODS
Experimental material. Levels of vitamins A and
E were determined in goat and sheep pool samples
taken from 9 different farms (F1–F9) of central,
southern and eastern Bohemia. Samples had been
collected repeatedly once a month during the period
of lactation from April to September (6 times a year)
in the years 2012–2013. Samples were collected to
the clean plastic sampling flasks of 100 ml volume,
cooled to 4–6°C, and transferred in thermo boxes
to the laboratory. To ensure the homogeneity of the
sample the sampling flasks were thoroughly shaken
for 2 min prior to the measurement.
Farm characteristics
Farm F1: family farm, herd of 100 heads, White
shorthaired goat; feeding: full-day pasture, hay, silage,
pressed barley, BIOSAXON mineral licks.
Farm F2: small family farm, herd of 50 heads, Brown
shorthaired goat; feeding: full-day pasture, hay, silage,
pressed barley, branches of pine, oak, beech, birch,
pine branches dominance, ALMAGEROL mineral
licks and salt licks.
Farm F3: small family farm, herd of 40 heads,
Anglo-Nubian goat; feeding: full-day pasture, hay,
silage, pressed barley, oats, MILLAPHOS Z-V min-
eral licks.
Farm F4: small family farm, flock of 65 heads,
Lacaune sheep; feeding: full-day pasture, hay, silage,
pressed grains, molasses, SANO mineral licks.
Farm F5: big commercial farm, flock of 380 heads of
East Friesian sheep, 330 heads of White shorthaired
goat, and 120 heads of Brown shorthaired goat; feed-
ing: full-day pasture, hay, silage, pressed grains, maize,
mineral licks: RUMIHERB, NATURMIX.
Farm F6: big family farm, flock of 130 heads, Ro-
manov sheep; feeding: full-day pasture, hay, lucerne
silage, scrap lupine, pressed grains, mineral licks:
MILLAPHOS and BIOSAXON.
Farm F7: small family farm, herd of 18 heads, Brown
shorthaired goat; feeding: full-day pasture, hay, silage,
oats, mineral licks SCHAUMANN LECKSTEIN.
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Food Analysis, Food Quality and Nutrition Czech J. Food Sci., 33, 2015 (1): 58–65
doi: 10.17221/149/2014-CJFS
Farm F8: family farm, herd of 85 heads, Lacaune
sheep; feeding: full-day pasture, hay, silage, pressed
barley, maize, wheat, SANO mineral licks.
Farm F9: small family farm, herd of 30 heads,East
Friesian sheep; feeding: full-day pasture, hay, silage,
pressed barley, mineral licks RUMIHERB, NATUR-
MIX.
Chemicals. For the preparation of analytical sam-
ples the following standards and chemicals were used:
retinol, > 99% (Sigma-Aldrich, Darmstadt, Germany),
tocol and tocopherol set -α-tocopherol 98.2% (both
Calbiochem, Canada), pyrocatechol, > 99.5% (Sigma-
Aldrich, Darmstadt, Germany), potassium hydroxide,
p.a. (Lachema, Brno, Czech Republic), methanol, p.a.
(Lach-Ner, Neratovice, Czech Republic), hexane p.a.
(Penta, Prague, Czech Republic), methanol, super
gradient, content min. 99.9% (Lach-Ner, Neratovice,
Czech Republic), treated distilled water (Milipore,
Molsheim, France).
Measurement of vitamins A and E content in
milk samples. The content of both vitamins was
extracted by the method of S-M et
al. (2006) with minor modifications. Approx. 1 g of
homogenised sample was weighed in a plastic tube
with a lid. 200 µl of methanolic pyrocatechol (0.2 g/ml)
and 5 ml 1 M KOH were added to the sample. The
mixture was vortexed for 20 s, saponified for 10 min
in the presence of ultrasound and vortexed again for
20 seconds. Then 5 ml of hexane and 1 ml of distilled
water were added to the mixture and it was again
vortexed for 1 minute. Subsequently 3 ml from the
upper hexane layer were taken and evaporated until
dry using a Büchi rotovapor R-215 rotary evaporator
(Büchi Labortechnik GmbH, Essen, Germany). The
residue was dissolved in 0.5 ml of methanol and an
aliquot was transferred through a nylon filter into
1ml Eppendorf tube, which was placed in the freezer
(–20ºC) for 30 minutes. The sample was centrifuged
for 2 min (Eppendorf miniSpin plus microcentrifuge,
by 14.4 rpm) and drained off into a dark vial. The
analysis was carried out using an Ultimate 3000 High
Performance Liquid Chromatograph (Thermo Fisher
Scientific, Dionex, Sunnyvale, USA) with a quaternary
pump, refrigerated autosampler, column heater and
FLD and DAD detectors. Tocols and tocopherols in the
sample were determined by HPLC-FLD under the fol-
lowing conditions: analytical column Develosil 5µm
RP AQUEOUS (250 × 4.6 mm) (Phenomenex, Tor-
rance, USA); precolumn Develosil 5 µm C30 UG-100A
(10 × 4 mm) (Phenomenex, Torrance, USA); mo-
bile phase methanol : deionised water (93 : 3, v/v),
HPLC super gradient methanol (Lach-Ner, Nera-
tovice, Czech Republic) and Milli-Q water, isocratic
elution; flow rate 1 ml/min; injection 10 µl, column
temperature 30°C; detection FLD (excitation 292nm,
emission 330 nm). Retinol was determined under
the same chromatographic conditions using DAD
detector (λ = 325 nm). The detection limits for to-
copherol (T), tocotrienol (TKT), and vitamin A,
expressed as a ratio of three times the value of the
signal-to-noise ratio, were as follows: δ-TKT and δ-T
0.01µg/ml β-TKT, TKT γ-, β-T, and γ-T 0.025µg/ml,
α-TKT and α-T 0.05 µg/ml, vitamin A 0.025 µg/ml.
All results were expressed in mg/kg of milk as the
mean value of three replications.
Statistical analysis was done in the Statistica
Version 9 programme (2009). The measured values
were processed by the analysis of variance (ANOVA),
using post-hoc Tukey’s test, two-side t-test and cor-
relation and regression for more detailed evaluation.
Measurement of fat content. e milk samples were
heated to 40°C and measured by using a MilcoScan FT1
milk analyser (FOSS Analytical A/S, Hillerød, Denmark).
Pasteurisation. The milk samples were treated by
heating by the method of short-time pasteurisation
(HTST), i.e. to 72–74°C for 15–40 s, then cooled to
4–6°C (done on the farms) and transported to the
laboratory.
RESULTS AND DISCUSSION
Monitoring of vitamin A and vitamin E content in
sheep and goat milk. Only the content of α-tocopherol
out of the eight forms of vitamin E was above the limit
of detection. The higher content of vitamin E compared
to vitamin A was observed in most samples of sheep and
goat milk. The measured mean levels of vitamins A and
E in sheep milk were 0.93 ± 0.07 and 2.93 ± 0.87 mg/kg,
respectively, and in goat milk 0.79 ± 0.08 and 1.29±
0.35 mg/kg, respectively (Table 1). These results with
the exception of vitamin A in goat milk are higher
than those published by R-L et al.
(2008), levels of vitamin E are consistent with the
values reported by this author. A consistent value
was also reported by K et al. (2012). Average
values measured in goat and sheep milk were higher
than the values determined by P et al. (2007)
but lower than the values by M-F et al.
(2007). These authors reported very high values of
both vitamins (up to 11 mg/kg of vitamin E and up to
6 mg/kg of vitamin A) depending on the farming and
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Czech J. Food Sci., 33, 2015 (1): 58–65 Food Analysis, Food Quality and Nutrition
doi: 10.17221/149/2014-CJFS
feeding system. Determined levels of vitamins A andE
in sheep milk varied from 0.44 mg/kg to 1.80 mg/kg
and from 0.45 mg/kg to 9.61 mg/kg, respectively. The
content of both vitamins in goat milk ranged from
0.30 mg/kg to 1.36 mg/kg and from 0.33 mg/kg to
2.56 mg/kg, respectively. Variability of the content
of vitamin E in the milk of small ruminants from all
the farms included in the study was 52.9%, which
was more than twice higher than the variability in
the content of vitamin A (23.6%).
The highest average content of vitamin A was
found in milk from farm F3 (1.18 ± 0.18 mg/kg
Anglo-Nubian goat) and in milk from farm F6 (1.13 ±
0.36mg/kg – Romanov sheep). The highest content
of vitamin E was found in milk from farm F6 (4.22 ±
1.75 mg/kg – Romanov sheep), followed by the value
in milk from farm F9 (3.45 ± 1.50 mg/kg – East Frie-
sian sheep). No statistical difference in the content
of vitamin A in milk between the particular farms
was determined, but the difference was found in the
Table 1. Total amounts of vitamin A and vitamin E (mg/kg) in sheep and goat milk from monitored farms (n = 18)
Farm Breed Year Range Average Median St. dev. Fat (%)
Vitamin A
F1 White short haired goat 2012 0.45–0.75 0.60a0.58 0.10 3.28
2013 0.30–0.71 0.56a0.63 0.14 3.24
F2 Brown short haired goat 2012 0.47–0.85 0.70ab 0.75 0.13 3.95
F3 Anglonubian goat 2012 0.491.55 1.09d1.13 0.37 5.31
2013 0.75–1.36 1.18d1.24 0.18 5.06
F4 Lacaune sheep 2012 0.52–0.96 0.77b0.78 0.12 8.11
F5
East Friesian sheep 2012 0.44–1.10 0.67b0.64 0.20 6.39
2013 0.74–1.20 0.96b0.93 0.13 6.62
Brown short haired goat 2013 0.45–1.02 0.68b0.68 0.18 3.46
White short haired goat 2013 0.41–1.00 0.75b0.78 0.22 2.98
F6 Romanov sheep 2012 0.60–1.32 0.98cd 1.03 0.22 8.29
2013 0.55–1.80 1.13cd 1.18 0.36 7.69
F7 Brown short haired goat 2013 0.62–1.04 0.75b0.73 0.15 3.31
F8 Lacaune sheep 2013 0.64–1.34 0.99cd 1.06 0.21 7.81
F9 East Friesian sheep 2013 0.75–1.33 1.00c0.93 0.18 5.85
Vitamin B
F1 White short haired goat 2012 0.33–1.96 1.13a1.18 0.46 3.28
2013 0.45–1.15 0.88a1.03 0.25 3.24
F2 Brown short haired goat 2012 0.79–2.56 2.05bc 2.29 0.55 3.95
F3 Anglonubian goat 2012 0.61–2.39 1.55ab 1.74 0.63 5.31
2013 0.96–2.34 1.37ab 1.22 0.43 5.06
F4 Lacaune sheep 2012 0.92–3.73 2.29c2.25 0.80 8.11
F5
East Friesian sheep 2012 1.82–3.49 2.44bc 2.45 0.48 6.39
2013 1.47–3.52 2.57bc 2.66 0.64 6.62
Brown short haired goat 2013 0.55–1.45 0.96bc 0.91 0.27 3.46
White short haired goat 2013 0.63–1.75 1.04bc 1.03 0.36 2.98
F6 Romanov sheep 2012 0.93–7.16 4.22e4.59 1.75 8.29
2013 1.07–9.61 3.93e3.53 2.61 7.69
F7 Brown short haired goat 2013 0.50–2.04 1.30ab 1.40 0.53 3.31
F8 Lacaune sheep 2013 0.45–3.19 1.62abc 1.55 0.73 7.81
F9 East Friesian sheep 2013 2.64–6.57 3.45d2.64 1.50 5.85
a–d values in the same line marked with different letters differ significantly (P ≤ 0.05); Fat (%) – average fat content for the
entire lactation period
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Food Analysis, Food Quality and Nutrition Czech J. Food Sci., 33, 2015 (1): 58–65
doi: 10.17221/149/2014-CJFS
content of vitamin E in milk. It was not possible to
divide the farms strictly according to the content of
vitamins in milk into two groups, namely into sheep
and goat farms. However, a correlation was observed
between the monitored vitamins and fat content. The
correlation coefficient R2 = 0.57 corresponds to the
medium strong relationship between the content
of vitamin A in milk and the percentage of milk fat.
In addition, the strong relationship (R2= 0.75) was
found between the content of vitamin E in milk and
the percentage of milk fat. It seems that the percent-
age of milk fat is a significant factor influencing the
content of vitamin A and especially the content of
vitamin E in milk.
To determine the influence of breed on the content
of vitamins A and E in milk of small ruminants, the
milk of White shorthaired goat, Brown shorthaired
goat and East Friesian sheep coming from the same
farm (F5) in the year 2013 was used (Table 1). No
statistical difference (P < 0.05) between the two goat
breeds was found. The statistically significant higher
content of both vitamins was found in the milk of
East Friesian sheep. The detected statistical difference
between goat breeds and sheep breed was apparently
associated with a higher fat content in sheep milk.
It is in good accordance with an assumption of the
mutual relationship between the content of fat and
the contents of both lipophilic vitamins in milk.
K et al. (2012) showed a difference between
two sheep breeds and one goat breed. According to
this author the mean content of vitamin A was sig-
nificantly higher in sheep milk of Boutsiko than in
Karamaniko breed, while no significant differences
were found in vitamin E content between milks of
the two sheep breeds. Goat milk had a lower content
of vitamins A and E than sheep milk of both breeds.
To monitor the effect of a specific character of indi-
vidual farms, sheep and goat milk of the same breed from
different farms was used, specifically White shorthaired
goat (farms F1, F5), Brown shorthaired goat (farms F7,
F5) and East Friesian sheep (farms F5, F9) (Table 1).
A statistically significant difference (P < 0.05) in the
content of both vitamins was recorded between sheep
farms F5 and F9. On the farms where goats were kept,
a statistically significant difference (P < 0.05) in the
content of vitamin A and E was found between farms
F1 and F5 (White shorthaired goat) but not between
F5 and F7 (Brown shorthaired goat). us, the vitamin
content reflected the specifics of breeding.
The milk samples from two goat breeds, namely
Anglo-Nubian goat (farm F6) and White shorthaired
goat (farm F1), and two sheep breeds, namely East
Friesian sheep (farm F5) and Romanov sheep (farm
F6), were collected in 2012 and 2013 to determine the
influence of the year. The year was found to have no
statistically significant influence (P < 0.05) on the con-
tent of vitamins A and E in either sheep or goat milk.
Changes during lactation period. The influence
of the lactation phase on vitamin A and E content in
sheep and goat milk was also monitored. The samples
of milk were taken once a month during lactation
from April to September on all farms. The results
are expressed as averages of the vitamin contents in
milk from all sheep breeds and from all goat breeds
in each month. It was found that the content of both
vitamins in sheep and goat milk at the beginning
of lactation period was statistically significantly
different (P < 0.05) from the content at the end of
this period (Figure 1). The contents of vitamins
in the mid-lactation period were not statistically
significantly different but there were some nuances
between them. The differences in the content of
aab,cb,c
a,b
c
A
BB
CC
D
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
April May Juny JulyAugSept
Vitamin A (mg/kg)
Month
aabbbb
AB
BBB
C
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
April May JunyJulyAugSept
Vitamin E (mg/kg)
Month
goats
sheep
Figure 1. Average content of (A) vitamin A and (B) vitamin E in sheep and goat milk during lactation
e values marked with different letters (a-b for goat) and (A-C for sheep) differ significantly (P ≤ 0.05)
(A) (B)
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Czech J. Food Sci., 33, 2015 (1): 58–65 Food Analysis, Food Quality and Nutrition
doi: 10.17221/149/2014-CJFS
vitamin E in the milk at the beginning and at the
end of lactation period were significantly larger,
especially in the sheep milk, than the differences
in the content of vitamin A. The milk yield during
the lactation period may change, especially of sheep
milk. At the end of lactation period the milk yield
was reduced 4 times compared with the beginning
of lactation, which led to an increase in the percent-
age of the main milk compounds including fat. The
content of lipophilic vitamins related to 1 kg of milk
was increased as well. Related to the total amount
of milk produced the content of vitamin A slightly
decreased while the content of vitamin E slightly
increased. The increase in the content of vitamins
in milk at the end of lactation period corresponds
very well with a higher percentage of fat in milk that
occurs right at the end of lactation period (Z &
E 1996; P & S 2002; K
& S 2003; K et al. 2008).
Effect of pasteurisation on the content of vita-
mins in milk. It is generally known that the con-
tent of vitamins decreases during processing and
technological processes. To determine a difference
between the levels of the observed vitamins in raw
and pasteurised milk, the milk of Anglo-Nubian goats
and East Friesian sheep was used. The decrease of
both vitamins in sheep and goat milk treated with
the most frequently used high-temperature short-
time (HTST) pasteurisation varied to a large extent.
The decrease of vitamin A content ranged from 4%
to 27% in goat milk and from 1% to 57% in sheep
milk, an average loss of vitamin A was 13% and 14%,
respectively (Table 2). The decrease of vitamin E in
pasteurised milk varied from 1% to 70% in sheep milk
and from 6% to 31% in goat milk, an average loss of
vitamin E was 23 and 14%, respectively (Table 2).
Almost 50% of the observed decline was an order of
magnitude higher than the decline of both vitamins
during pasteurisation described in the literature.
H (1995) reported the vitamin A decrease of
about 6% during pasteurisation. According to P
and G (1990) pasteurisation had even no effect
on the content of vitamin A. Ö et al. (1997) re-
ported the vitamin E loss of 5% due to pasteurisation.
However, this study showed that in the second half
of lactation period the losses of both vitamins were
significantly reduced and those in sheep milk were
even lower than described by H (1995) and Ö
et al. (1997). These high losses could be caused by
the fact that in farm conditions the procedure of milk
pasteurisation was not always exactly adhered to the
standard procedure applied in a big dairy (e.g. milk
after pasteurisation is not cooled quickly enough,
the heating was done at a higher temperature or for
a longer period of time). Even a relatively frequent
rotation of labourers on the farms could probably
play the role because they need some time to get
experience and working habits. In conclusion it could
be stated that if all the steps were exactly adhered to
the default technological process of pasteurisation,
the loss of the contents of both vitamins was in ac-
cordance with literature references.
Table 2. Content of vitamins A and E in raw and pasteurised sheep and goat milk
Content of vitamin (mg/kg)
April May Juny July August September
Vitamin A
Goat raw milk 1.35 1.24 1.28 1.14 0.84 1.23
Goat pasteurised milk 0.99 1.16 0.99 1.00 0.81 1.11
Sheep raw milk 0.77 0.91 1.1 0.89 0.99 1.17
Sheep pasteurised milk 0.68 0.39 1.06 0.88 0.95 1.16
Decrease of vitamin content in goat milk (%) 27 723 13 410
Decrease of vitamin content in sheep milk (%) 12 57 4241
Vitamin E
Goat raw milk 0.97 1.15 1.38 1.24 1.22 2.26
Goat pasteurised milk 0.67 1.05 1.06 1.17 1.12 2.12
Sheep raw milk 1.93 1.56 3.05 2.63 2.78 3.59
Sheep pasteurised milk 1.65 0.47 1.72 2,54 2.75 3.47
Decrease of vitamin content in goat milk (%) 31 923 686
Decrease of vitamin content in sheep milk (%) 15 70 44 313
64
Food Analysis, Food Quality and Nutrition Czech J. Food Sci., 33, 2015 (1): 58–65
doi: 10.17221/149/2014-CJFS
Changes during storage in freezing box. The
observed variations in the content of vitamins also
occurred during the storage of milk. The influence of
annual storage in a freezing box at the temperature
of –20°C on levels of vitamins A and E in raw and
pasteurised (HTST) sheep and goat milk was also
monitored. Milk of East Friesian sheep and Anglo-
Nubian goats was analysed. Initial levels of both
vitamins in pasteurised sheep and goat milk were
always lower in comparison with raw milk.
The content of vitamin A in raw milk decreased
sharply during the first fourteen days (about 34%),
then it stabilised until the 59th day and then it dropped
again. After three months the decline became linear.
The content of vitamin A in pasteurised milk declined
almost linearly throughout the observation period.
In sheep pasteurised milk the decrease was intensive
during the first seven days (about 38%). At the end
of the reporting period, the level of this vitamin in
raw and pasteurised milk was relatively stable. After
a year of milk storage in the freezer, the content of
vitamin A reached approximately 30 and 24% of
the original value in raw and pasteurised goat milk,
respectively, and approximately 16 and 14% of the
original content in raw and pasteurised sheep milk,
respectively (Figure 2).
The downward trend of the vitamin E level in goat
milk was similar to a decline of vitamin A, only the
absolute initial levels of vitamin E were higher (Fig-
ure2). The most significant decrease in raw milk
was recorded during 14-day storage in a freezing
box (about 34%). In pasteurised goat milk an almost
linear decrease was found out as well as in raw and
pasteurised sheep milk. However, in raw sheep milk
after 243 days of storage the sharp decrease (about
78%) was observed. At the end of the entire storage
period the content of vitamin E as well as vitamin A in
measured milk stopped at almost the same value (18%)
of the original content in raw and pasteurised milk.
CONCLUSIONS
Compared with the most frequently consumed cow
milk, goat milk, and sheep milk are comparable or even
better sources of vitamins A and E in human nutrition.
No statistical difference in the content of vitamin A was
established between the farms, while it was found in the
content of vitamin E. It is not possible to distinguish
strictly between goat and sheep milk according to the
content of vitamin E, however, a correlation between
the monitored vitamins and fat content was observed.
For these reasons a higher content of both vitamins can
be expected in sheep milk and milk of Anglo-Nubian
goat, which have a higher fat content.
In general, a higher content of vitamin E in milk
was detected when compared with the content of
vitamin A. A statistically significant difference in
vitamin E content was found in milk of the same
goat and sheep breed kept on different farms. Except
Brown shorthaired goats (F5 and F7) the content
of both monitored vitamins on sheep and also on
goat farms was statistically different. The content
was apparently influenced by specific conditions of
breeding. The year had no statistically significant
influence on the content of vitamins A and E in milk
of these small ruminants. The levels of vitamins A
and E were significantly lower in the early phase and
significantly higher in the late phase of lactation.
When the pasteurisation procedure was performed,
an average loss of vitamin A and vitamin E in sheep
and goat milk was 13 and 14%, respectively, and 23
and 14%, respectively. The content of vitamins A
and E dropped also during the storage of milk in a
freezing box. A sharp decrease was observed dur-
ing the first two weeks of storage. After a year of
milk storage in the freezer (at –20°C) the content
of vitamin E as well as vitamin A in measured milk
stopped at almost the same average value of 18% of
the original content in raw and pasteurised milk.
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Vitamin A (mg/kg)
Days of storage
goat raw
goat pasterised
sheep raw
sheep pasterised
0 7 14 21 28 59 90 120 151 181 212 243 274 304 335 365
0.0
0.5
1.0
1.5
2.0
2.5
Vitamin E (mg/kg)
Days of storage
0 7 14 21 28 59 90 120 151 181 212 243 274 304 335 365
(A) (B)
Figure 2. Changes in (A) vitamin A and (B) vitamin B content in raw and pasteurised sheep and goat milk during
12-month storage in a freezing box
65
Czech J. Food Sci., 33, 2015 (1): 58–65 Food Analysis, Food Quality and Nutrition
doi: 10.17221/149/2014-CJFS
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Received: 2014–03–18
Accepted after corrections: 2014–07–28
Corresponding author:
Ing. T M, Česká zemědělská univerzita v Praze, Fakulta agrobiologie, potravinových a přírodních
zdrojů, Katedra chemie, Kamýcká 129, 165 21 Praha 6-Suchdol, Česká republika; E-mail: michlova@af.czu.cz
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... Both vitamins were extracted using the method of Sánchez-Machado et al. (2006) with minor modifications by Michlová et al. (2015). The analysis was carried out using an Ultimate 3000 High Performance Liquid Chromatograph (Thermo Fisher Scientific, Dionex, Sunnyvale, USA) with a quaternary pump, refrigerated autosampler, column heater and FLD and DAD detectors. ...
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Vitamins play an important role in intermediary metabolism as co-factors in numerous enzymatic reactions or in non-enzymatic physiological functions such as the visual process (vitamin A), as antioxidants (carotenoids, vitamins E, C, and riboflavin), in regulation of calcium metabolism (vitamin D) and in haematopoiesis (vitamin B12, folates and vitamin B6). Although research in the last few decades has in most cases been focused merely on deficiencies in order to establish requirements, development of diagnosis, etc., there is now a renewed interest in the role of vitamins in the maintenance of health. Recognition of the prominent role of some vitamins as antioxidants, in cell proliferation/differentiation, and in immune function has shed new light on the importance of these essential nutrients in the prevention of many chronic diseases, e.g. coronary heart disease, cancer and other immunorelated diseases (van den Berg et al., 1993).
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Chemical and microbiological characteristics of ewe milk of Boutsiko and Karamaniko breeds and goat milk of the indigenous Greek breed (Capra prisca) were determined. No significant differences were observed for fat, protein, lactose, casein and solids-non-fat contents of ewe milk of both breeds. The microbiological quality of ewe milk of both breeds was, generally, better than that of goat milk. The mean content of vitamin A was significantly (P<0.05) higher in ewe milk of Boutsiko than in Karamaniko breed, while no significant differences were found for vitamins E and C contents between the two breeds of ewe milk. Goat milk had lower content of vitamins A and E than ewe milk of both breeds but the vitamin C content was about the same in ewe and goat milk. Oleic acid was the most abundant fatty acid in ewe milk of both breeds while palmitic acid was the major fatty acid in goat milk. Butyric, stearic and conjugated linoleic acid (CLA) contents of ewe milk of Boutsiko breed were higher than those of Karamaniko breed. Goat milk had lower contents of CLA and higher quantities of lauric and stearic acids than ewe milk of both breeds.
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Small ruminants are the most efficient transformers of low quality forage into high quality animal products with distinguished chemical composition and organoleptic characteristics. There is a wide range of sheep and goat farming systems from highly extensive, based on natural grasslands or rangelands, to very intensive ones, based on natural grazing and supplementary feeding. Usually, the systems which are under comparison are those based mainly on pasture vs. the indoor ones. The aim of this paper is to provide an integrated analysis of the major aspects of the nature and composition of small ruminants products, such as milk and meat, and then the effect of feeding systems on chemical composition and quality characteristics of those products (i.e. fatty acid profile, antioxidants, vitamins, muscle:fat ratio, flavour, taste, etc.), since milk and meat quality is constantly evolving, partly in response to the rising concerns of consumers in terms of safety, health, ethical aspects, origin etc. As small ruminants milk is mostly transformed into cheese and its yield depends on milk composition, the main objectives of the dairy sheep and goat breeders are to improve milk quality by increasing the total milk solids output and stabilizing the milk composition (fat and protein) through the appropriate level of nutrition. Factors such as forage:concentrate ratio, dietary fat supplements, pasture, etc. have essential effect on small ruminants milk yield, milk composition and fatty acid (FA) profile. A number of studies have shown that milk from sheep and goats in pasture is enriched in substances of natural origin like phenolic compounds, fat soluble vitamins, flavours terpenes, bioactive lipid components, unsaturated FA and CLA, in addition to being naturally high in medium-chain FA in comparison to those fed conventional concentrate-forage diets. However, there are species differences between sheep and goats as the dietary effects on those parameters concerns, which could be explained by the differences found in mRNA of stearoyl-CoA desaturase of their mammary adipocytes. The feeding system effects on meat quality is more difficult to be identified because lambs and kids of different breed, weaned at different age and live weight or raised on different types of pastures have different growth rate and carcass characteristics like level of fatness, FA profile, flavour, tenderness, taste, etc. It has been demonstrated that lambs and kids raised under a grazing system without any supplementation, present an inferior fatness degree and a higher meat fat concentration of n−3 PUFA and CLA. Lamb meat has higher fat content, higher proportions of SFA and lower MUFA compared to goats, under similar dietary treatment, which make goat meat especially valuable nutritionally and for consumer health. In conclusion, the existing unfavourable properties of small ruminant products can be improved by nutritional intervention to modify their FA profile for the consumer's health benefit.
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The aim of this study is to update the values concerning nutritional components for sheep and goat dairy products. The bibliography examines first the main biochemical constituents of sheep and goat milk products but also the more specific components with potential nutritional impact and lastly it gathers information on the relationship between cheese and milk compositions and the impact of technologies. Since the composition of French small ruminant cheeses is not well established, with composition tables being old and lacking information, recent studies have been conducted in France to investigate the nutritional characteristics of sheep and goat milks and cheeses on a large scale. Goat milk cheese sampling was representative of French production, taking into account the variability linked to geographic origin, dairy or on-farm transformation and type of cheeses. Fresh lactic cheeses made with raw (6 samples) or pasteurised (6) milk, ripened lactic cheeses made with raw (11) or pasteurised (6) milk, spreads (4), soft ripened cheeses (6 “Chèvre Boite or “Brique” type cheeses) and 4 bulk raw milks were sampled twice in a summer–autumn period. These 86 samples were analysed for their nutritional value. The impact of the technological process was assessed with, for example, its effect on mineral and vitamin B content. With respect to sheep, 5 representative samples of milk were collected, just before cheese making, in the 3 main French traditional areas of dairy sheep production. The sampling was carried out 4 times in the year. The objective was to explore the variability of the nutritional characteristics of the original milk. The cheeses made with these milks were analysed after ripening with a double objective: to specify their nutritional content and to assess the relationship between milk and cheese content. Some preliminary results are given concerning fatty acids.
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This paper deals with the effects of farming systems linked to feeding aspects on the composition and quality of ewe and goat milk. When systems based on grazing and indoor systems are compared, the milk components (fat, protein, lactose) appear to be rather less influenced by type of farming system than by level of milk production. Significant differences are observed when ingested energy varies between pasture and indoor systems. Milk production depends on level of intake, and fat content on the indirect effect of dilution, while protein content varies generally like milk production. Goat milk production and its fat content can rise when grass is at an early growth stage. As in cows, fresh grass strongly influences the fatty acid contents of milk by increasing PUFA and CLA percentages. On cultivated pasture, the kind of fodder species, vegetation stage, season, and stocking rate can modify milk composition and quality. Natural pasture based farming systems produce milk rich in fat and in micro-components, which are beneficial to human health (fatty acids, vitamins), and in volatile components (flavour, terpenes). When three feeding systems based on natural pasture in the plain, on hills and on mountains are compared for goats, milk yield is slightly lower on mountain pasture but fat and protein contents and percentages of PUFA are higher, and the terpenes are more numerous in goat milk. Grass of natural pasture at an early stage produces milk richer in CLA. Supply of concentrates up to 0.6kg/day/goat grazing natural pasture does not seem to modify the contents of volatile compounds, terpenes and flavour in milk, but it should reduce retinol content. In intensive indoor systems, a high level of intake due to fodders of good nutritive value or to high supplies of concentrates enables production of milk rich in protein and relatively low in fat. The ratio of fat to protein percentages can be reversed particularly in mid-lactation, when goats are fed diets short of fibre or fat. Consequently, the quality of cheese (granular paste, lack of nice goat taste) is lowered. When supply of concentrates in diets increases to 60% of total dry matter intake, fat content may decrease slowly and linearly, but if concentrate intake reaches 60–80%, fat content may decrease rapidly due to an increasing shortage of fibrosity in the ration. Studies confirm that the milk fat content influences cheese fat content as well as rheological and sensorial qualities. Thus, this is an important factor, which has direct repercussion on cheese quality such as is appreciated by consumers. In the future, the farmer must select farming or feeding systems in accordance with trade conditions, consumers’ demand and socio-economic conditions. If commercialisation of high quality cheeses is possible, farmers will have to define systems, that allow to optimise parameters of quality, even by limiting milk production. In the future, the farmers have to find a balance between the level of intensification and the quality of dairy products.
Article
This study was conducted on three commercial dairy goat farms (A, B, C), on which does were milked using pipeline milking machines, milking buckets and by hand, respectively. Six to eight mastitis-free milking does of Alpine and Nubian breeds were selected from each farm. Composite samples, made of equal volumes of evening and morning milk, were collected monthly throughout the lactation (March–October). Milk samples were analyzed for somatic cell count (SCC), standard plate count (SPC), and percentages of fat, protein, lactose and solids-non-fat (SNF). The overall means were 9.3 × 105 SCC ml−1, 9.1 × 10−2 cfu ml−1 SPC, 4.08% fat, 3.20% protein, 4.41 % lactose and 8.28% SNF, respectively. There was no significant effect of breed or milking method on SCC. Overall monthly mean SCC increased as lactation advanced. During the entire lactation period, 51% of the milk samples contained above 1 million SCC ml−1. However, only traces (under 5 cfu ml−1) of mastitis-related pathogens were found in these high SCC samples. Nubian does produced milk with higher SPC, percent fat, protein and SNF than Alpine does (P < 0.05). Milk by bucket milking had lower SPC than that by pipeline and hand milkings (P < 0.05), although all milk samples were below the limits of the Pasteurized Milk Ordinance for Grade A raw milk. Pooled data showed that SCC had a minor but positive correlation with SPC (r = 0.14, P < 0.05, n = 312).