My lunch with Ponzy: Culinary chemistry

Lu weighing the merits of cantaloupes at the Freshgrocer Photo by Daniel R. Burke

Budding chemists often get their start playing with their foodtesting pH levels with liquefied cabbage, determining the density of Hostess Twinkies and replicating the classic experiment demonstrating the triboluminescence of wintergreen Life Savers.

Professor of Chemistry Ponzy Lu has never forgotten his kitchen roots.

Last semester he offered a preceptorial called Biology and the Chemistry of Cooking for 15 students (150 had applied), but instead of Food 101, in three 90-minute sessions they explored the physiology of taste, the importance of Maillard reactions in creating a perfect sauce espagnole, and the role of a steroidal pheromone in the ability of pigs to locate truffles.

Preceptorials are small non-credit courses created and organized by students and offered by faculty each semester. Lus class, one observer recalled, was five parts food and two parts science.

That proportion seemed just right during a recent lunch at Nan, the elegant little Asian-French fusion restaurant at 40th and Chestnut streets presided over by chef Kamol Phutlek, one of the creators of the Philadelphia restaurant renaissance. Between bites, Lu talked a little bit about science and a lot about his lifelong interest in good eating.

The French say chacun à son gouteach to his own tastebut Lu says when it comes to cooking, you have to know what you are shooting forso taste the best. Thats why the reading material for the preceptorial included rapturous descriptions of the restaurant Troisgros in France, Calvin Trillins paean of praise to Arthur Bryants barbecue in Kansas CityLu keeps a stash of the famous sauce in his basementand last summers search for the perfect Philly cheesesteak led by Inquirer restaurant critic Craig LaBan. Even the Thai chopped salad appetizer at Nan sparked a taste memory. Everyones stolen this salad from Wolfgang Puck, Lu reported. His first restaurant, Chinois on Main, is one of my favorites, and I try to get there whenever Im in LA.

For one session, Lu created an experiment that required knowledge of three areas of basic science for its successthe physiology of the tongue designed to detect basic tastes (sweet, sour, bitter, salty, astringent), the Maillard browning reactions involving simple sugars, amino acids and simple peptides, and the molecular biology of the 1,000 preprogrammed smell receptors in the human brain. He created rich stock made from eight pounds of browned meat bones and trimmings thickened with a roux of butter and flour. The resulting homemade sauce was tested on steak sandwiches against four commercial varieties. Which was best? Mine was, said Lu. The others were too salty.

The last class featured a truffle taste-off. Brillat-Savarin, the 18th-century gastronome, thought that truffles had aphrodisiacal properties. The musk-like scent of this fungus is produced by a steroid that is the major constituent of the pheromone of the boar, explained Lu. Thats why farmers use pigs to search for this delicacy. Italian white truffles costing $1,500 a pound were compared to $350-per-pound French black truffles, $35-per-pound Chinese truffles and morels, a highly prized mushroom. The students voted for the French variety served in scrambled eggs.

Lu declared the crab cake that he had for lunch too salty. But it did remind him of the George Perriers lighter-than-air crab cakes, a mainstay of the luncheon menu at LeBec-Fin. Using the scientific method, Lu said, I experimented with his recipe and changed the order of the ingredients and I think Ive improved it.