Friday, August 31, 2012

Salt Taste, Part 1

The story of salt will be in multiple parts, due to the importance of the topic, and the complexity.  Salt, a.k.a sodium chloride, a.k.a. NaCl, a.k.a. sodium, is an essential element in the chefs or cooks toolbox to make things taste good. I read somewhere that Heston Blumenthal (one of the high priests of cooking, TV personality) stated salt is the most important ingredient in his kitchen. Why would that be the case? Below I begin the discussion on the many functions that salt has in foods, hopefully giving a clue to why such statements are made. Part 1 does not address the health issues and controversies around salt, just why we, as consumers and cooks, love salt. Also an explanation on terminology, I will use the term salty when referring to the taste we perceive, and NaCl when discussing salt (opps NaCl).
Taste perception is very complex, with highly sophisticated biological systems at work, but it can also be quite simple, put something in your mouth and you experience the taste/flavor of the food.  Salt taste is experienced when the concentration of NaCl in the oral cavity reaches a level that not only activates a taste receptor, but the signal sent from the receptor is strong enough to elicit a salty perception, meaning low concentrations of NaCl may be present in the oral cavity yet not elicit a salty taste.  There are multiple perceptual phases associated with salt taste perception and as the concentration of NaCl increases the detection threshold will be reached, the level at which NaCl in solution may be discriminated from water.  As the concentration of NaCl increases further the recognition threshold is reached, the point at which the quality (e.g., salty) can be identified.  As the concentration of NaCl increases still further, the intensity of saltiness mutually increases to a strongest salty intensity we can experience.  It then starts to activate another sensory system (not taste) and becomes painful.  
Two factors dictate the level of perceived saltiness for a given concentration of NaCl: 1/ an individual’s sensitivity to NaCl (which is highly variable for all tastes), and 2/ the food matrix being consumed. To further explain: 1/ just because you find something too salty does not mean I will, as we have variation in the biology or physiology relating to taste processing.  And 2/, the food matrix will be important, potato chips are a salty food, they have NaCl at the surface of the chip, bread is not a salty food, yet it contains about the same amount of NaCl.  The reason for the difference is that the NaCl in bread is trapped in the bread matrix and unavailable for taste activation.  Therefore a salty food such as potato chips are not necessarily a food high in NaCl.
NaCl adds saltiness to foods, depending on the amount you add, the food matrix and individual taste will depend on the level of saltiness you experience.  This doesn’t adequately explain why NaCl is the most important ingredient in Blumenthal’s toolbox.   That can wait till Part 2.

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