Lethality within food particles undergoing ohmic heating was investigated using microbiological and chemical marker measurements. Meatballs containing spores of B. stearothermophilus and precursors of chemical markers were thermally processed in a starch solution with 30–40% solids content using a 5 kilowatt (kW) ohmic system. Different temperatures, flow rates, holding tube lengths, and fluid electrical conductivities were used. Lethalities observed under various processing conditions were consistent with predictions. Higher lethality was observed, microbiologically and chemically, at the center of the meatballs rather than near the surface. A good correlation between the marker yield and the bacterial survivor population was obtained under various processing conditions. The results indicate that the chemical markers may be used to evaluate the distribution of lethality among different particles and the contribu‐

A highly sensitive and specific high-performance liquid chromatographic method for the analysis of ascorbic acid in foods and beverages was developed. Ascorbic acid was extracted with O.lM H2S04/ 0.01% EDTA solution, separated on an anion exclusion column and detected amperometrically with a platinum electrode operating at +0.6 V vs. Ag/AgCl reference electrode. Excellent correlation was observed among results obtained by ion exclusion chromatography with either electrochemical or UV detection and by the AOAC 2,6-dichloroindophenol titrimetric method. Ion exclusion chromatography with electrochemical detection was more sensitive and specific for ascorbic acid than the other two methods. INTRODUCTIONTHE CURRENT AOAC (1984) methods for the analysis of ascorbic acid are the 2,&dichloroindophenol titrimetric and the o-phenylenediamine fluorescence methods. These chemical methods lack specificity and are time-consuming; the titration method cannot be used in the presence of sulfite, which is used as a food additive. Numerous high-performance liquid chromatographic (HPLC) methods for ascorbic acid using either UV detection or electrochemical (EC) detection have been published recently (Kissinger and Pachla, 1987;Margolis and Black, 1987;Russel, 1986;Pachla et al., 1985).