Organic Acid Profiles of Thermally Processed, Stored Spinach Puree

Abstract

— Deaerated spinach puree was packed into TDT tubes, flushed with nitrogen and sealed. The tubes were divided into batches and processed with an Fo = 4.9 at temperatures ranging from 240–300°F with 10°F increments. Analyses were carried out immediately after processing and after storage for 3 months at 75°F in the dark. Organic acids were analyzed by means of an Automatic Organic Acid Analyzer (AOAA) with confirmation by paper chromatography. Oxalic acid showed poor resolution on the AOAA; therefore, a chemical method was used for analysis. pH measurements were taken and color measured on a Hunterlab Model D25 Color Difference Meter. Catalase determinations were done on the stored samples. After processing, the greatest changes were noted at 240°F, with only minor changes above 280°F. Acetic and pyrrolidone‐carboxylic acid (PCA) showed the most change after processing. After storage, the concentration of acids, color and pH was similar for all packs and all proved catalase negative. During storage succinic, PCA and acetic acids showed the greatest increase with the latter two increasing the most at higher temperatures. Also, during storage α‐ketoglutaric acid disappeared and pyruvic, glutaric, oxaloacetic and malonic acids were formed at all processing temperatures.

Food colourants

“…Lin et al . 171 , report that the major organic acids involved in the degradation of chlorophylls are acetic acid and 5-oxopyrrolidinecarboxylic acid. The alkali salts of chlorophyllins are obtained by the saponifi cation of a solvent extract of natural strains of edible plant material, grass, lucerne and nettles.…”