1 repulsion for one another that they have in living muscle. By expanding the space between them, brines draw water back into the meat. Acidic marinades use positively charged hydrogen ions, rather than negative chloride ions,
it can chemically alter (denature) the proteins so much that the flesh takes on a cooked texture. If a ceviche-style prepara,tion is what you're after, then protein denaturation is a good thing;
to do the same job. It may seem counterintuitive
otherwise, it can be undesirable. The threshold at which proteins begin to fall apart, albeit slowly, is
because the natural decline in pH after slaughter
around a pH of 4.8. The lower the pH, the faster
leads to filament collapse, but if the pH continues to decrease, the effect reverses. A surplus of
and more completely this chemical transformation
positively charged hydrogen ions accumulates at the surface of the contractile filaments, and they go from having a negative charge (being spaced apart) to having a neutral charge (being packed
occurs. Of course, the texture that results from "cooking" with acidity is quite distinct from that which results from cooking with heat.
together) to finally having a positive charge (being
One benefit that distinguishes an acidic marinade from a salty brine is that, unlike salt, acids are capable of weakening collagen fibers in
spaced apart again).
the connective tissue that surrounds both muscle
The pH doesn't need to drop too far below 5.5 before it has an easily perceptible effect on the
fibers and bundles of muscle fibers, a process that also occurs during cooking (see illustration on
juiciness of the flesh. That effect does take time to
page 80). By weakening this connective tissue,
occur, however. Just like the ions from salt in brines and cures, hydrogen ions from an acidic marinade diffuse through flesh slowly. Acidity can mimic the
the marinade not only tenderizes a tough cut of meat but also frees the muscle fibers in it to swell further, and they draw in more liquid as they do.
action of salt in another way as well: taken too far,
The meat ends up both juicier and more tender.
In ceviche, an acid makes raw fish flesh look as if it has been cooked (see photo on next page). Raw poultry and mammal meat transform in a similar way when marinated in acid, but this kind of preparation is nowhere near as popular for them as it is for fish and shellfish.
Aprolonged soaking in a mildly acidic marinade will tenderize the collagen in a tough cut of meat. such as the flank steak shown here.
MEAT AND SEAFOOD
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