Abstract
Browning is one of the most important event occurring during fruit processing. Among the causes of the change in color of fresh-cut-fruits (such as enzymatic browning of the phenols, Maillard reaction, ascorbic acid oxidation, caramelization and formation of browned polymers by oxidized lipids), the most important is the oxidation of the o-diphenols to o-quinones by polyphenoloxidase (PPO). To control PPO activity in fresh cut fruits, dipping treatment are generally used. Briefly, these treatments consist of dipping the cut, peeled and cored fruit in a solution containing a mixture of antioxidants, acidifiers, complexants, proteases or protein inhibitors. Recently, novel processing technique emerged such as those based on pulsed light. These techniques are very promising as they are fast, simple, easily implemented in conveyor belt systems and they do not need for chemicals, contact with the fruit or thermal heat. However, to evaluate the effectiveness of these treatments or to develop new ones, generally, a number of chemical and microbiological assays must be performed simultaneously. As these assays requires also a number of steps (extraction, centrifugation, dilution, reagent addition, etc.), the comparison of treatments on fresh cut fruits is often hampered by the experimental uncertainty. Thus, this work aimed to compare the efficiency of treatments on fresh cut fruits by a novel approach based on microcalorimetry. Microcalorimetry is an emerging technique which measures the thermal power, P (Watt), at constant temperature, of any solid or liquid sample. The results shows that microcalorimetry allows to differentiate the efficiency of dipping treatments based on ascorbic acid, citric acid or mixture of them and those treatments based on pulsed light. The main advantage of this approach is that it allows measuring continuously the reaction occurring in the fresh-cut-fruit sample without the need of any pre-treatment of the samples or the use of chemcals reagents