From Milk to Dairy Products 49
whereas 0.1 µm microfiltration results in the total
retention of caseins and
the transmission of whey proteins to the permeate (transmission rate
between 60 and 80%); as a result, 0.1 µm microfiltration is mainly carried out
when the cheese manufacturer also looks for a high-quality permeate, which in
this case is a “true whey” (absence of phospholipids, casein fines and any
particles).
Figure 1.22.
Manufacturing process of fresh cheese
52 Handbook of Food Science and Technology 3
Figure 1.25.
Manufacturing process of Beaufort
The ultrafiltration of milk
results in a liquid pre-cheese, which has the
composition of drained cheese [MAU 69]. This process eliminates drainage
after coagulation and therefore allows,
in some cases, molding directly into
the containers for retail; it reduces the weight difference due to molding of the
curd, increases yield (by 10 – 20% through whey protein retention in the
cheese) and decreases rennet consumption (added after filtration). It has,
however, the disadvantage of yielding cheeses with high lactate and lactic acid
From Milk to Dairy Products 53
contents, due to the high buffering capacity of pre-cheeses resulting from the
concentration of calcium phosphate associated with casein. To overcome these
problems, it is possible to pre-acidify and salt the milk to solubilize some of
the colloidal calcium phosphates, which
are then removed during
ultrafiltration. This method is limited, however, since pre-acidified milk is
thermally less stable and it is more difficult to add value to the permeate.
1.3.4.4.
Ripening
Ripening involves the enzymatic digestion of the protein and lipid
components in the curd. It is a complex biochemical
process for several
reasons:
– the cheese matrix resulting from the coagulation and drainage of milk has
a very high level of physicochemical heterogeneity;
– enzymes involved in ripening have several origins: they could be
endogenous milk enzymes (plasmin, lipase, etc.), added to milk during
manufacturing (coagulating enzymes, microorganisms)
or produced during
ripening by microbial synthesis (bacteria, yeasts, moulds).
The curd and biological agents constitute a complex ecosystem and a
heterogeneous bioreactor, the parameters of which are not always well
defined. Ripening is dominated by three major biochemical phenomena:
– the fermentation of residual lactose and
the degradation of lactate;
– the hydrolysis of fat and proteins;
– the production of aroma from fatty acids and amino acids.
These transformations give the cheese its characteristics; they modify its
appearance,
composition and consistency, while at the same time flavor,
aroma and texture develop.
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