ALPHA-TOMATINE CONTENT IN TOMATO AND TOMATO PRODUCTS DETERMINED BY HPLC WITH PULSED AMPEROMETRIC DETECTION

Tomato plants (Lycopersicon esculentum) synthesize the glycoalkaloid a-tomatine, possibly as a defense against insects and other pests. As part of an effort to improve the safety of plant foods, the usefulness of a new HPLC pulsed amperometric detection (PAD) method for the direct analysis of cx-tomatine in different parts of the tomato plant; in store-bought and field-grown, including transgenic, tomatoes; in a variety of commercial and home-processed tomato products; and in eggplant and tomatillos was evaluated. The method was found to be useful for analysis of a variety of products including high-tomatine calyxes, flowers, leaves, roots, and stems of the tomato plant (14-130 mg/100 g of fresh weight), low-tomatine red tomatoes (0.03-0.08 mg/100 g), intermediate-tomatine tomatoes (0.1-0.8 mg/100 g), and high-tomatine fresh and processed green, including pickled and fried, tomatoes (0.9-55 mg/100 g). No experimental difficulties were encountered with extraction and analysis of tomatine in complex foods such as tomato juice, ketchup, salsa, sauce, and sun-dried tomatoes. Microwaving and frying did not significantly affect tomatine levels of tomato foods. The tomatine content of fresh market and transgenic delayed-ripening varieties was not different from the range ordinarily seen in tomato. The possible usefulness of the findings to plant science, food safety, and human health is discussed.