Effects of ascorbic acid and light on reactions in fresh-cut apples by microcalorimetry

During the manufacturing of fresh-cut apples, a number of biochemical events, overall exothermic, con-tribute to increasing the reaction rate of the fruit and the browning of its wounded surface. This workapplied isothermal microcalorimetry to compare the overall effect of such complex events before andafter treatments with ascorbic acid solutions, pulsed lights or UV-C lights. Briefly, apple samples werecut into cylinders and dipped in solutions containing ascorbic acid (0–2.5%) or exposed to high energydoses of light (from 6 to 175 kJ/m2). In general, the heat-flow signal recorded by microcalorimetry wasinversely proportional to the intensity of the applied treatment. In case of treatments with ascorbicacid, the heat-flow signal was empirically deconvoluted in three distinctive signals, respectively, (I) anexponential decay, (II) a gaussian central curve and (III) a final logistical function. The first and the thirdfunctions were constant regardless of the concentration of ascorbic acid used. Only the second Gaussianfunction was correlated with the concentration of ascorbic acid and the area was used to evaluate theefficacy of the process. Overall, this work contributes to the understanding of the heat produced by fruitafter wounding and, from a practical standpoint, can help compare the effects of different treatments onfresh cut fruits.