Heat,
pH, and light are the most common causes of colour modification. All these
factors occurs with different extent in a typical Italian pasta sauce called pesto,
which is essentially made of finely minced basil leaves, pine nuts, cheese,
olive oil, garlic and salt. Small quantities of organic acids are generally
used by industries to improve pesto stability, and the product is often
pasteurized to extend shelf life and prevent microbial spoilage. The result is
a coarse cream with a green hue.
However,
the effects of these practices are not negligible: the colour of pesto could
vary from the pale green of the homemade fresh product, which is very attractive
to the consumer, to a dark brownish green of the pasteurized one, which
conversely does not give the idea of a fresh and appetizing food. This
modifications are mainly due to the varying content of the fresh basil pigments,
i.e., chlorophylls (Chls) and carotenoids, as well as to the content of
products of Chls degradation; i.e., pheophytins (Phts), pheophorbids, and
pyropheophitins. A further important contribution is due to content of cheese
and pine nuts that make the product colour lighter.
…
From
an analytical standpoint, pesto is a typical multicomponent and multiphase
matrix, which is characterized by a solid phase (basil leaves, pine nuts, and
garlic), and a liquid phase (oil) partially emulsified with cheese and water
from basil leaves. In addition, the products have a variable quantity of oil
freely floating on the surface of the sauce.
Masino, F., Ulrici, A., & Antonelli, A. (2008).
Extraction and quantification of main pigments in pesto sauces. European
Food Research and Technology = Zeitschrift Für Lebensmittel-Untersuchung Und
-Forschung.A, 226(3), 569-575.
doi:http://dx.doi.org/10.1007/s00217-007-0572-5
No comments:
Post a Comment