Sunday, October 28, 2007

Pretzel illogic


Let's get right to it: I have a soft spot for Alton Brown but when he falls, he falls hard. His character is one of the confident science-savvy clever food guy variety, but apparently not one with very good quality control. In his June 20th episode of Good Eats entitled "Pretzel Logic," he points out the importance of treating the surface of dough destined to become soft pretzels with a high pH solution to induce faster browning. He attempts to explain pH as follows: "Okay, here's the deal with pH. If a solution has an equal number of positively and negatively charged hydrogen atoms, it is said to be "neutral", which means that it has a pH of 7". Even the Alton Brown Fan Site could see something was wrong here ( Check out the Fan Site ). Let's start with the obvious: there isn't nor will there ever be a negatively charged hydrogen atom, except for maybe in a nuclear reactor or a particle accelerator. In organic chemistry, we typically abbreviate certain metal or semi-metal hydrides as being synthetic equivalents of a negatively charged hydrogen atom or 'H-minus', but that is just to make it easier to draw organic reaction mechanisms; a full-blown negative charge on a hydrogen atom in the presence of positively charged hydrogen atoms (let alone anything else) is positively obsurd. In fact, positively-charged hydrogen atoms don't exist in water either. Water is as much a base as it is an acid, if we hypothetically placed a positively-charged hydrogen atom in water, a neutral molecule would certainly and instantaneously bond to it to form the hydronium ion (H3O+). However, I think I'm giving our friend Brown too much credit. He naturally meant negatively charged OH ions and the hydronium thing is an honest mistake. For those of you not 'in the know': water, H2O, or two hydrogen atoms bonded to an oxygen atom as such, H-O-H, is constantly breaking apart into ions of the variety '+H3O' (hydronium ion) and '-OH' (hydroxide ion). These two ions when combined chemically produce two neutrally charged molecules of water. To get something straight: water isn't this unstable molecule that just falls apart helter skelter; they don't break apart very easily, but they do to a degree. They are constantly falling apart to make hydronium and hydroxide ions and then recombining to make neutral water molecules. On average about 1 molecule for every 2 billion molecules is broken apart at any given time for a neutral solution of water at room temperature. So Alton was right on one aspect: when the concentration of hydroxide ions equals that of hydronium ions, you have a neutral solution. As you change the pH of a solution by adding base or acid, you upset this balance and you have more of one type of ion. Hydroxide ion is the ion responsible for hydrolyzing polysaccharides and proteins thus at a higher pH (more hydroxide ions) we find that browning occurs faster. Alton displayed cleverness when he employed a lower pH solution (baking soda in water) at a higher temperature (boiling) to do the job that a higher pH solution (sodium hydroxide in water) does at room temperature.

Saturday, October 27, 2007

Operation Bacon Lattice Initiated

Welcome to Bacon Lattice. We are two chemists who are on a mission. The only thing we love more than chemistry is food, more specifically, bacon, more specifically, bacon lattices. Our posts here will hopefully clarify, and in some cases, correct scientific explanations given in popular food media: the Food Network and Cooks Illustrated to name a few. We will also rant about common misconceptions that are continuously perpetuated in the culinary world. And, of course, there will be much discourse on... bacon (and other lattice-worthy cuts of pork).