Food Biochemistry and Food Processing (2 edition)

BLBS102-c26 BLBS102-Simpson March 21, 2012 13:51 Trim: 276mm X 219mm Printer Name: Yet to Come

26 Equid Milk: Chemistry, Biochemistry and Processing 519

Bovine milk, skim and

pasteurise at 70oC

x 30 min

Cool part to 26oC,

inoculate with

yeast culture (e.g.

To r u la spp.)

Cool part to

40 oC, inoculate

with lactic culture

(e.g. L. delbrueckii

subsp. bulgaricus)

Plug with cotton

wool, mix and

Plug and mix, hold for

6–7 h at 35–37oC

hold for 15–18 h at

28–30oC

Mother culture

Mix and pour into double-walled starter

vat with agitator through cover. Add

fresh mares’ milk continuously at

30 oC, to acidity of ~0.7% lactic acid.

Agitate for 15 min & ripen at 26–28oC.

Allow to ferment for 3–4 days to

~1.4% lactic acid

Bulk starter

Fresh mares’ milk at 26–28oC in

double-walled vat. Inoculate at a rate

of 30% bulk starter to 0.5% lactic acid,

incubate and mix for ~60 min to 0.6%

lactic acid.

Bottle and cap, hold for 1–2 h at 18–20oC.

Store for 12–24 h at 4–6oC

Koumiss

Figure 26.6.Schematic for the production of koumiss. (Based on

Berlin 1962.)

koumiss production. Methods have been developed, with vary-

ing degrees of success, where a single constituent of bovine milk

has been altered to resemble that of equine milk, for example the

carbohydrate content has been increased or the protein content

reduced but, until recently both had not been altered simulta-

neously. Koumiss of reasonable quality has been produced suc-

cessfully from whole or skimmed bovine milk containing added

sucrose using a mixture ofLb. acidophilus,Lb.delbrueckiissp.

bulgaricusandKluyveromyces marxianusvar.marxianusor var.

lactisas starter culture (Kuc ̈ukcetin et al. 2003). Koumiss has ̈

also been made from diluted bovine milk supplemented with

lactose and, more successfully, from bovine milk mixed with

concentrated whey using a starter culture ofKluyveromyces lac-

tis(AT CC 56498),Lb. delbrueckiisubsp.bulgaricusandLb.

acidophilus. Starter cultures for koumiss manufacture from

bovine milk may also include Saccharomyces lactis (high

antimicrobial activity againstMycobacterium tuberculosis)in

order to retain the ‘anti-tuberculosis image’ of equine milk

(Kuc ̈ukcetin et al. 2003). More recently, bovine milk has been ̈

modified to approximate the composition of mares’ milk us-

ing a series of membrane filtration steps and a starter culture

(Kluyveromyces lactis,Lb. delbrueckiisubsp.bulgaricusand

Lb. acidophilus) that ensures consistent fermentation; the re-

sulting product was found to be very similar to koumiss with

respect to pH, titratable acidity, ethanol content, proteolytic ac-

tivity, apparent viscosity and microbial composition, both when

fresh or stored (15 days at 4◦C) (K ̈uc ̈ukcetin et al. 2003).

The physico-chemical and microbiological properties of asi-

nine milk, similar to equine milk, such as low microbiological

load and high Lyz make it a good substrate for the production of

fermented products with probioticLactobacillusstrains. Cop-

pola et al. (2002) incubated asinine milk with the probioticLb.

rhamnosus(AT 194, GTI/1, GT 1/3) and found that the strain is

unaffected by the high Lyz activity in the milk and remained vi-

able after 15 days at 4◦C and pH 3.7–3.8.Lb. rhamnosusinhibits

the growth of most harmful bacteria in the intestine and acts as

a natural preservative in yoghurt-type products, considerably

extending shelf life. Chiavari et al. (2005) produced fermented

beverages from asinine milk using a mixed culture ofLb. rham-

nosus(AT 194, CLT 2.2) andLb. casei(LC 88) and in all cases

found a high level of viable bacteria after 30 days storage. Some

sensory differences were recorded for the fermented drinks and

those made with theLb. caseistrain developed a more accept-

able and balanced aroma than the boiled vegetable/acidic taste

and aroma of the products made withLb.rhamnosus.

Other Products from Equid Milk

As sales of equine milk have increased considerably in recent

years, research is now focused on the development of new fer-

mented products or new methods for extending the shelf life of

existing products, while maintaining some of the unique compo-

nents of equine milk. The ability of milk to withstand relatively

high processing temperatures is very important from a techno-

logical point of view. The whey proteins in equine milk are much

more thermostable than those of bovine milk. Heat treatment at

80 ◦C×80 s causes only a 10–15% decrease in non-casein

nitrogen, with a marked decrease evident only when the tem-

perature is increased above 100◦C (Bonomi et al. 1994). Lf and

equine BSA are the most heat-sensitive but are not completely

denatured until the temperature reaches 130◦C x 10 min.β-Lg

andα-La are almost completely denatured at temperatures over

130 ◦C and Lyz at temperatures greater than 110◦C (68% residual

Lyz activity after heating at 82◦C for 15 minutes (Jauregui-Adell

1975).