From Milk to Dairy Products 39
microfiltration (see section 9.1
.
). The
rennet clotting time of NPC
reconstituted to 3% from powder is reduced by 53% and the firmness of the
rennet gel after 30 min is improved by 50% compared to raw milk at the
identical casein concentration. Enriching milk with milk microfiltrate (0.1 µm)
can significantly improve cheese yield, especially in the case of hard cheeses.
In addition, the partial removal of soluble proteins that otherwise aggregate on
the surface
of casein micelles on heating, limits the negative effects of heat
treatments on rennet coagulation. These factors have led to the development of
technology for producing medium- or high-heat powder (e.g. Primin
®
), which
has similar or even greater suitability for cheese production compared to raw
milk (Figure 1.17).
Figure 1.17.
Processing diagram for the production of
Primin milk powder (VRF = volume reduction factor)
1.3.4.
Cheese
Cheese making is an ancient way of preserving milk (protein, fat and some
calcium and phosphorus). Its nutritional and sensory
qualities are valued in
almost every part of the world.
40 Handbook of Food Science and Technology 3
The name “cheese” is reserved for a fermented or non-fermented, ripened
or non-ripened product of exclusively dairy origin (milk, partially or fully
skimmed milk, buttermilk) used alone or as a mixture. It is totally or partially
coagulated before draining or after partial removal of water.
Cheese may be
considered a concentration of the major components of milk (protein, fat),
produced by draining curd obtained by acidification and/or enzymatic action
(usually rennet extracted from the stomach of a calf before weaning). Cheese
production involves four phases: milk standardization,
coagulation, draining
and ripening (Figure 1.18).
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