Biochemical characteristics and quality of goat milk Jaubert G. in

in

Morand-Fehr P. (ed.).

Recent advances in goat research Zaragoza : CIHEAM

Cahiers Options Méditerranéennes; n. 25 1997

pages 71-74

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--- Jaubert G. B ioch emical ch aracteristics an d qu ality of goat milk. In : Morand-Fehr P. (ed.). Recent advances in goat research. Zaragoza : CIHEAM, 1997. p. 71-74 (Cahiers Options Méditerranéennes;

n. 25)

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OF GOAT

G.

- -

Goat milk quality depends

on

of lactation, health status) and the conditions of diet, system),

and has a on the quality of subsequent goat milk A

milk effect of (age, stage of lactation and

yield) and, to a extent, the type of feeding.

Lipase activity and-spontaneous lipolysis play a in in goat milk.

The volatil fatty

have been found the the of 4-

methyloctanoïc acid have also been found following the action of on milk fat. The

of milk ; heat stability) is

affected by the state of the casein micelles and the changes they of the milk the

of and aS2-caseins @e

existence of 2 et al. 1990) and 3 of aS2-casein.

out in the last of aS1-casein by

6 classes of and associated with levels of synthesis.

Nowadays, it is of animals at using the tools of

up of

of the technological quality of goat milk.

: Goat caseine, technilogical quality

The quality of goat milk may be defined as its potential to in a

lives up to the expectations in value), safety (hygienic

Thus, the quality of the milk

which its technological capacities based. quality depends on a of which to both the animal of lactation, health status) and the conditions of

diet, system), and has a on the quality of subsequent goat

is a

of in the quality of lhked to both its physico-chemical

The physico-chemical of goat milk

; and 1986) have been out in ; some

of these

et al. 1988 ; Chandan et al. 1992).

; et al. 1993 ; et al. 1993 ;

et al. of goat milk (at least

equivalent to that of cow's milk), making it a valuable food inclusion in the diet of

Among the of goat milk, is one quality component of to the

cheese Although a goaty is of

to the type of i.e. soft white cheese

milk, and slight nil goat milk to be drunk as such.

The in of goat milk has been

1965 ; Skjevdal 1979 ; et al. 1985 ; et al. unpublished data) who noted a . significant

effect of (age, stage

of lactation and yield) and, to a extent, the type of feeding.

The of the of goat milk is closely linked to 'the of the

constituents in the milk, and also to biochemical and enzymatic The depènd on the milk in of its constituents. Lipase activity and spontaneous lipolysis play a in the development of in goat milk 1982a, 1982b) and the effect of the fatty acids content has been established (Skjevdal 1979 ; et al. 1985).

et al. (1993a and 1993b) used gas techniques to identify the main the of milk obtained the cow, goat, ewe and

to the

of goat milk, the the milk of ewes 'and cows by the of

amounts of phenylacetaldehyde and benzaldehyde and the absence of phenylethanol.

of indole, in cow's

milk.

et al. (1995) used gaz to

of cheese. The volatil fatty acids, and fatty acids (4-methyloctanoïc and 4-ethyloctanoïc), have been found the

compounds the goat of 4-methyloctanoïc acid have also been

found following the action of milk fat

a of goat milk in

intensive system, with that of cow's milk. The physico-chemical of goat milk -especially its low casein content and the specific of casein micelles - account its

making

fact, the of ; heat

stability) is affected by the state of the

of the milk of

- 1). A study of the and

composition of 'casein micelles as a function of

bovine micelles. although the of

4 types of casein in the et al. 1984 ; and

Addeo 1984), quantitative and qualitative as well as the effect of casein on the cheese-making of goat milk (Law and Tziboula 1992 ; et al. 1992 ; 1993 ; et a2. 1994).

Chianese et al. (1993) analyzed 800 individual milk samples and identified 3 of ß-casein

by of in the peptide chain. the of a nul

allele suggested by et al. by

out on individual milk samples devoid of

with of ß-casein (Chianese et a2. 1993).

of and aS2-caseins the

existence of 2 Luccia et al. 1990) and 3 of as2-casein et al.

1987 ; Chianese et al. 1992 ; et al.

asl-casein by et al. (1994) : this is

by in 6 classes of and associated with

levels of synthesis. Thus, a high level of asl-casein A, and C : 3.6 g/l/allele), a E : 1,6 g/l/allele), a low and F : 0,6 g/l/allele) and finally a nul level (allele O) can be is a of about 6 g of asl-casein between the m i l k s two homozygous goats with high low of a,l-caseine synthesis.

of goat milks containing high and low levels of asl-casein ; et al. 1994 ; Vassal et al. 1994) have shown that genotype has a significant effect on casein content, fat and

a high level of asl-casein shows a

aptitude to coagulate and gives a

(+

+

%). A significant effect is also noted in of and : milk with

72

a high asl-casein content is and inclined to 1993 ; Vassal et al. 1994).

Nowadays, it is possible to of @ais et al. 1993), and also to

milk,

in of,goat milk.

and qualitative analysis of milk caseins is a means of and

assessing the technological quality of This to

milk suitable of

T.A., Acta Agric. Scand. 35 : 315-320.

A., F., 16 : 157-75.

C., G., C. (1994). Anim. Genet. 25 : 173-77.

V on

2, pp 399-420.

L., G.,

U., LAEZZA, F., A., (1993).

Lait 73 : 533-47.

L., N., L., F. (1992). J. Dairy 59 :

Luit 62 : 1-31.

Lait 62 : 126-54.

N. F. (1984). Verguro 11 : 17-24.

S . , Sci. Tec. Latt. Casearia 40 : 24-8.

J.F. (1993). Lait 73 : 573-80.

A., L., L., F. (1990). Sci. Tec.

L&.-

C., J., Y., A., (1993). Lait : 581-92.

C., J., (1988). C'ah. Diet. 23 : 367-74.

F., G., Genet. Sel.

F., G., F., VASSAL, L., J.

J. Dairy Sci. 76 : 677-90.

W., J.F.,

G., (1993). Lait 73 : 593-9.

299-305.

Casearia 41 : 305-14.

19 : 399-411.

(1994). Aniin. 7 : 3-19.

F. (1993). Lait 73 : 559-65.

J. Dairy Sci. 63 : 1605-30.

47 : 558-62.

C., Y., JANSA, (1993). of lactation in animals

F. (1993). 25 : 403-8.

(1993). Lait 73 : 511-32.

L., J., F. (1993a). J. Dairy 60 : 199-213.

L., F. (1993b). J. Dairy 60 : 215-22.

A., O., F., J.

,

O., N., A.,

F. of V on 2, pp. 374-

F. (1993). Lait 73 : 549-57.

(1965). Acta Agric. Scand. 15 : 301-42.

Bull. 202 : 54-67.

A., J.F. (1993). Lait 73 : 601-11.

81.

E., A., A. (1992).

Anim. 88A : 13-22.

T. (1979). 6 : 397-405.

VASSAL, L., A., J. (1994). 74 : 89-103.

Thesis,

milk J,

on the J, COLLECT

J,

on

J, J, 72°C ; 30-60 sec

J, J,

to 20-24°C Of

(mesophilic : 1-2 %

,

of

to 8 ml 100 1

: 15 to 60 min : 16

moulds) : 4,3 to 4,5

J,

moulds l 8 to 22°C ; 16

of moulds

J, J, J,

J,

J,

: 1 to 2 %

24 to 72 ; 10-12°C 75-80 %

J,

8 to 12 days ; 10-12°C

J,

J, J, 90-95 %

4°C

1. of St soft cheese)