BROWNING BEHAVIOR OF TAURINE AND PROLINE IN MODEL AND DRIED SQUID SYSTEMS

Model systems containing taurine or proline mixed with glucose at pH 6.4 were adjusted for water activity (Aw) to 0.99, 0.90, 0.84, 0.75 and 0.60 with celite. The browning rates measured during 96 h at temperatures between 5° and 45°C increased with increased temperature and reduced water activity. The model system containing taurine had a higher browning rate than that with proline at the same Aw and temperature. The browning rate with taurine at Aw = 0.60 increased 34 times at 45°C and 7 times at 35°C compared to that at 25°C. Decreases in Aw from 0.90 to 0.60 resulted in increased browning rate, 4.1 times at 45°C and 1.3 times at 35°C. The browning rate in model systems with proline followed the same pattern. Temperature had a more pronounced effect on browning rate than Aw. Browning was very slow in model systems at temperatures below 25°C. Evidence is provided that the Maillard reaction occurred in the mantle of squid (Illex argentinus) during air drying at 35°C. Dehydration resulted in loss of 50% of the taurine (from 22.3 to 11.6 mmoles/100g dry mass) and more than 60% of the proline (from 23.4 to 8.9 mmoles/100g dry mass). Total free amino acids remained unchanged when the moisture level was above 50% or Aw = 0.95. The browning intensity of the squid mantle increased 5 fold during drying. Taurine and proline were digested most at water activity above 0.95, while other amino acids were lost at a greater rate in the intermediate water activity range.