Chemistry Reference
In-Depth Information
to introduce enzymes uniformly into the cheese matrix, they both create problems through
premature curd softening, yield reduction and loss of 'unincluded' enzyme from the curds.
Washed-curd cheeses are brine-salted, rather than dry-salted, and this may appear to offer an
enzyme addition point (E in Fig. 5.1), but researchers can predict that enzyme penetration
from brine into the closed texture of pressed cheese would be very low, ruling out this route,
and making washed-curd cheese very difficult to treat with ripening enzymes.
In dry-salted cheese varieties, such as Cheddar, the addition of enzymes to milled curd
with the salt (point D, immediately before pressing to form cheese blocks) was originally
proposed
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for laboratory-scale cheese making and this was successfully adapted to a 180
L vat scale.
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However, this technique is difficult to adapt and scale up to automated salting
equipment which is used in large throughput cheese plants. Although enzymes can be
granulated with dry salt, this is an expensive process for cheap ingredients and it is not
widely used. An alternative method for enzyme addition was patented recently, involving
mixing curds and enzyme in a vessel to which 'negative pressure' is applied, so that the
enzyme is 'sucked in' to the curd matrix.
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However, it is not clear how the problems of
even distribution and alteration of curd moisture and structure are solved by this invention.
Although Wilkinson and Kilcawley
32
suggested in their review that mechanical injection of
enzymes may offer new solutions to addition at the finished cheese stage, there are no such
efficacious technologies on the market at this stage.
Whatever physical method is employed to place enzymes into cheese curd, some kind of
vehicle is needed to disperse them and this is either water or some other natural constituents
of cheese (salt, fat, etc.).
Thus, this whole area of enzyme addition technology is in urgent need of radical new ideas
from the research base, but researchers also need feedback from cheese technologists and
business economists. For example, there is sufficient know-how in molecular and applied
enzymology to devise matrices and support materials to create microparticulate enzyme
complexes which could both liberate and metabolize amino acids, fatty acids and sugars to
known flavour and aroma compounds. Such expertise has been generated in the fields of low-
water enzymology, immobilized enzyme science, cellular enzymology and membranology,
but as yet there has been no incentive to apply this to cheese-ripening research. This is
understandable in current circumstances, because the logical route to the use of complex
enzyme systems that are easy to put into cheese is
via
whole cell technology - nature has
done the work for us, so why undo it? The simple answer is that nature designed microbial
cells for efficient life processes, not for efficient cheese-ripening technology, and the natural
microbial cell chemistry and architecture need modification to put the (technologically)
right combinations together. Gene technology can do this for us within the whole cell
technology concept but however safe this is made, the tide of media and consumer opinion is
firmly against developments along this route. Nevertheless, whole cell options are available,
some without GM and some with and they are currently favoured by companies involved in
developing cheese-ripening systems.
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5.4.3 Enzyme-modified cheese technology
EMC is not really cheese from the consumer food point of view. It is a highly flavoured
ingredient for processed cheese, cheese-flavoured snack foods and sauces, made by incu-
bating emulsified cheese homogenates with animal or GRAS (generally recognized as safe)
microbial lipases and proteinases. This technology was first approved in the USA in 1969
and its products quickly came into large-scale use in processed cheese in 1970. All of the
major dairy ingredient suppliers now have extensive and relatively sophisticated EMC-based
