Full text of DOI:10.1046/j.1471-0307.2001.00006.x

Blackwell Science, Ltd
MILLENNIUM
CONTRIBUTIONS
The typical flavour of goat milk products:
technological aspects
FRANÇOIS MORGAN* and PATRICE GABORIT
Institut Technique des Produits Laitiers Caprins, BP 49, F-17700 Surgères, France
Keywords Dairy technology, Fatty acids, Flavour, Goat milk products, Ripening.
ating influence on the development of the typical
INTRODUCTION
flavour of goat cheeses.6
The production of goat milk at a world-wide level
This paper presents some of our results concern-
is 12 million tonnes,1 a large part of which is used ing: (i) the impact of technological treatments
for direct consumption. In Europe, however, goat and lipase adjunction on the flavour of goat milk;
milk is used principally for cheese production. While (ii) the influence of the sensorial properties of goat
goat cheeses are consumed as traditional products milk on the typical flavour of fresh cheeses; and
in Mediterranean countries, the demand for them is (iii) the contribution of yeasts and moulds to the
on the increase in northern Europe. This new interest development of the typical flavour of mould-ripened
could be partially explained by the unique sensorial soft goat cheeses.
properties of goat milk products, which are charac-
terized by a specific and typical (‘goat’) flavour.This
IMPACT OF TECHNOLOGICAL
specific flavour may be undesirable in milk for direct
PROCESSES ON THE TYPICAL
consumption but for cheese production its presence
FLAVOUR OF GOAT MILK
can be much sought-after.
The goat flavour originates from the lipid fraction,2 The lipolysis level and the sensorial properties of
and several aroma compounds (free fatty acids) goat milk (overall, goat and rancid flavours) have
have been identified (Table 1). Among them, 4- been evaluated before and after skimming, cold
methyloctanoic acid (4-met-C8) and 4-ethyloctanoic storage, mild heat treatment and homogenization.
acid (4-met-C8) have been found to be principally
The results (Table 2) showed that skimmed goat
responsible for the goat flavour, since they are per- milk had a very mild flavour compared to full fat
ceived even at very low concentrations and are present raw milk. Heating (65°C, 1 min) led to a slight
at levels higher than their perception threshold.3 reduction in the overall and goat flavours, and to
The level of these compounds increases during a decrease in the level of lipolysis.
cheese ripening, leading to a flavour improvement.4
On the other hand, some treatments such as cold
These fatty acids, as well as others, are produced storage and homogenization were found to improve
by lipolysis, which can be considered at three dis- the overall and goat flavours of milk, but this was also
tinct levels: (i) initial milk lipolysis (spontaneous accompanied by an increase in the rancid flavour,
lipolysis); (ii) lipolysis induced by milking practices, leading to a flavour defect after homogenization
storage and technological operations; and (iii) micro- (Table 2). Another illustration of these changes might
bial lipolysis, generated notably by ripening strains. be given by evaluation of the free fatty acid concen-
The spontaneous lipolysis is influenced by several trations in milk after cold storage and homogeniza-
genetic and environmental factors,5 which induce tion (Fig. 1). The total content of free fatty acids
important variations of the typical flavour of goat was 40 µg/ml fat in the control milk and it reached
milk at the herd level.
100 and 120 µg/ml fat after cold storage and homog-
*Author for
At the dairy plant level, the typical flavour of goat enization, respectively. The level of almost all the
milk products should be controlled. The industrial free fatty acids increased after these two treatments.
processes applied to goat milk can affect its sensor- However, cold storage induced an important increase
ial properties, and this could have some significant in the content of C8 and C10, whereas homogeni-
consequences for the manufacture of fresh cheeses. zation led to a preferential increase of the C12 and
For ripened cheeses, the surface flora has a domin- C16 concentrations.
correspondence. E-mail:
francois.morgan@
itplc.asso.fr
© 2001 Society of
Dairy Technology
Vol 54, No 1 Feburary 2001 International Journal of Dairy Technology
38

Vol 54, No 1 February 2001
EFFECT OF LIPASES ON
THE TYPICAL FLAVOUR OF
GOAT MILK
Table 1 Fatty acids associated with a typical goat flavour
Perception threshold (µg/l)
Fatty acid
in water
in oil
References
Experiments were carried out in order to evaluate
the impact of lipase adjunction on the sensorial
quality of goat milk.Animal lipases (kid goat, lamb
and pig) and microbial lipases (Rhizopus arrhizus,
Rhizomucor miehei, Aspergillus niger and Penicil-
lium roqueforti) were added (0.05% and 0.1%) to
pasteurized goat milk. The flavour of the milks was
then evaluated by trained panellists. No changes were
observed in the goat flavour, but an important increase
in the rancid flavour was perceived in goat milks
treated with the microbial lipases (results not shown).
However, Kim Ha and Lindsay7 have shown that
microbial lipases produced by Aspergilllus niger,
Penicillium roqueforti and Rhizopus arrhizus were
able to release relatively large amounts of free 4-et-
C8 in goat milk (4.3, 3.4 and 2.1 µg/g fat, respect-
ively). However, the environmental conditions (pH,
temperature and water activity) are determining
factors for the use of lipases as flavouring agents.
Hexanoic
—
—
4, 11
Octanoic
5.8–19
0.02
0.0018
—
10–350
—
0.006–2.4
—
—
3, 4, 12, 13
3, 4, 11, 14
3, 4, 11, 12, 14, 15
4, 11
4-methyl-octanoic
4-ethyl-octanoic
Nonanoic
Decanoic
—
4, 11
Table 2 Impact of technological processes on the sensorial quality of goat milk
Sensorial analysis (score out
of 10)**
Lipolysis
(g OA/100 g)*
Overall
flavour
Goat
flavour
Rancid
flavour
n
Raw milk (control)
Skimmed milk
80
23
0.48
n.d.
6.76 (a)
4.42 (b)
4.14 (a)
0.78 (b)
2.04 (a)
0.26 (b)
Raw milk (control)
Heat-treated milk
20
16
0.27 (a)
0.18 (b)
6.40 (a)
6.24 (b)
4.06 (a)
3.06 (b)
0.86
1.08
Raw milk (control)
Homogenized milk
20
34
0.27 (b)
0.80 (a)
6.40 (b)
7.30 (a)
4.06 (b)
4.90 (a)
0.86 (b)
3.06 (a)***
RELATIONSHIPS BETWEEN THE
FLAVOUR OF GOAT MILK AND
THE SENSORIAL QUALITY OF
FRESH CHEESES
Raw milk (control)
After storage at
6°C for 3 days
After storage at
6°C for 6 days
6
6
8
0.17 (c)
0.24 (b)
0.37 (a)
5.96 (b)
6.76 (a)
6.50 (a)
2.96 (b)
4.68 (a)
4.48 (a)
0.06 (b)
1.00 (a)
1.40 (a)
In a previous study,8 fresh lactic cheeses were
produced with milk having a strong or a weak goat
flavour. Fresh cheeses from milk with a strong goat
flavour were found to have a stronger goat odour
(+23%) and goat flavour (+17%), and a higher
free fatty acid content (+40%) than cheeses from
weakly goat-flavoured milk. These observations
were in agreement with results obtained on white
cheese9 and whey cheese.10
n.d. not determined
(a)(b): homogeneous groups (P < 0.05)
*: lipolysis was determined by the BDI method15 and was expressed as g Oleic Acid
per 100 g fat
**: sensorial analysis was carried out by trained panellists as described previously6
***: perceived as a flavour defect
However, this study also showed that the sensor-
ial properties of ripened cheeses were more strongly
related to the ripening parameters than to the
sensorial properties of the raw material.8 Therefore,
our investigations on the flavour of ripened cheeses
evaluated the influence of the ripening cultures.
IMPACT OF RIPENING STRAINS
ON THE FLAVOUR OF RIPENED
SOFT GOAT CHEESES
The development of the flavour of mould-ripened
soft goat cheeses is mainly due to the lipolytic activity
of the surface flora, underlining the need for a proper
selection of the ripening strains. An illustration of
such a selection strategy was given in a previous
work6 and will be briefly described in this section.
In a first step, a rapid screening was carried out
on goat milk incubated with 30 different cultures
(yeasts and moulds).This survey allowed us to select
some strains that could give rise to an increase in
Figure 1 Concentration of free fatty acids of goat milk
before and after cold storage and homogenization. Lipids
were extracted as described by Le Quéré et al.,4 free fatty
acids were obtained according to Needs et al.17 and the
analysis was carried out by gas chromatography.
International Journal of Dairy Technology
39

Vol 54, No 1 February 2001
2 Skjevdal T (1979) Flavour of goat’s milk: a review of stud-
ies on the sources of its variation. Livestock Production
Science 6 397–405.
3 Brennand C P, Ha J K and Lindsay R C (1989) Aroma
properties and thresholds of some branched-chain and
other minor volatile fatty acids occurring in milkfat and
milk lipids. Journal of Sensory Studies 4 105–120.
4 Le Quéré J L, Pierre A, Riaublanc A and Demaizières D
(1998) Characterization of aroma compounds in the vola-
tile fraction of soft goat cheese during ripening. Lait 78
279–290.
5 Delacroix-Buchet A and Lamberet G (2000) Sensorial
properties and typicity of goat dairy products. In: Pro-
ceedings of the 7th International Conference on Goats,
Poitiers, France, vol. 2, pp. 559–563. Gruner L and
Chabert Y, eds. Paris: Institut de l’Elevage/INRA.
6 Gaborit P, Ménard A and Morgan F (2000) Impact of
ripening strains of the typical flavour of goat cheeses.
International Dairy Journal, in press.
7 Kim Ha J and Lindsay R C (1993) Release of volatile
branched-chain and other fatty acids from ruminant
milk fats by various lipases. Journal of Dairy Science 76
677–690.
Figure 2 Principal ComponentAnalysis of the sensorial data
obtained for soft goat cheeses ripened with various yeasts and
moulds (lactic and Camembert type).6 Correlation plot (left)
and plot of the cheese samples with the corresponding
ripening strains (right).
the goat flavour, without any appearance of flavour
defects. Then, the selected cultures (Penicillium
candidum, PC; Geotrichum candidum, GC; Deba-
ryomyces hansenii, DH; Rhodosporidium infirmo-
miniatum, RI) were used for the manufacture of
lactic and Camembert-type goat cheeses (mould-
ripened soft cheeses).Various combinations of strains
were tested, with P. candidum or G. candidum as
the primary culture, and the others as associated
strains. The obtained results (Fig. 2) showed that
G. candidum was the most suitable strain for the
development of the goat flavour in cheeses.The use
of P. candidum led to less typical products, as well
as to the development of flavour defects in lactic
cheeses and to mushroom and mouldy notes in
Camembert-type cheeses. When these two strains
were used as a coculture, the influence of G. candidum
was stronger in Camembert-type cheeses and the
influence of P. candidum was stronger in lactic
cheeses. The use of D. hansenii or R. infimominiatum,
associated to P. candidum or G. candidum, did not
affect greatly the sensorial properties of goat cheeses.
8 Jaubert G, Bodin J P and Jaubert A (1997) Flavour of goat
farm bulk milk. Cahiers Options Méditérranéennes 25
89–93.
9 Fyksen S and Steinsholt K (1974) Strong or weak flavour
in goat’s milk for making white goat’s milk cheese.
Meieriposten 63 639–649.
10 Bakkene G and Steinsholt K (1975) Milk of high and low
flavour intensity for the manufacture of goat’s milk mysost
(33+ fat in DM). Meieriposten 64 45–55.
11 Le Quéré J L, Septier C, Demaizières D and Salles C
(1996) Identification and sensory evaluation of the
character-impact compounds of goat cheese flavour. In:
Flavour Science: Recent Developments, pp. 325–330.
Taylor A J and Mottram D S, eds. 8th Weurman Flavour
Research Symposium, Reading, UK. Reading: The Royal
Society of Chemistry.
12 Patton S (1964) Flavor threshold of volatile fatty acids.
Journal of Food Science 29 679–680.
13 Urbach G, Stark W and Forss D A (1972) Volatile com-
pounds in butter oil (II): flavour and flavour thresholds
of lactones, fatty acids, phenols, indole and skatole in
deodorized synthetic butter. Journal of Dairy Research 39
35–47.
14 Kim Ha J and Lindsay R C (1991) Contributions of cow,
sheep, and goat milks to characterizing branched-chain
fatty acid and phenolic flavors in varietal cheeses. Journal
of Dairy Science 74 3267–3274.
CONCLUSIONS
The results summarized in this paper illustrate how
the typical flavour of goat milk products can be
controlled. Such technological means could be highly
useful for producers involved in goat milk transfor-
mation, helping them meet emerging and specific
consumer’s needs and add value to goat milk products.
15 Boelens H, Haring H G and De Rijke D (1983) Threshold
values of and human preferences for 4-ethyl octanoic and
3-methyl butanoic acids. Perfumer Flavorist 8 71–74.
16 International Dairy Federation (1991) Determination of
free fatty acids in milk and milk products. IDF Bulletin
no. 265. Brussels: International Dairy Federation.
17 Needs E C, Graeme D, Ford A, Owen J, Tuckley B and
Anderson M (1983) A method for the quantitative deter-
mination of individual free fatty acids by ion exchange
resin adsorption and gas chromatography. Journal of
Dairy Research 50 321–329.
REFERENCES
1 FAOSTAT (1999) Food and Agricultural Organization
Statistical Database.
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International Journal of Dairy Technology