Novel approaches to reduce brown pigment formation and color changes in thermal pasteurized tomato juice

Abstract

The effects of two heat processes mild-temperature pasteurization (MTP: 75 °C, 23 s) and high-temperature pasteurization (HTP: 92 °C, 5 s) on undesirable brown color development and some quality attributes (pH, soluble solids content, and color parameters) of pasteurized tomato juice were evaluated and compared during 94 days of storage at 5 °C. Although both heat treatments combined with refrigeration prevented microbial growth for 64 days, the shelf life regarding acceptable microbial load of HTP-treated sample was higher than 94 days. Both processes produced lesser brown color formation in tomato juices than the commonly adopted thermal treatments although the MTP processing provides better color preservation than the HTP one. No effect of heat treatments on soluble solids content was observed while the HTP processing slightly increased the acidity of pasteurized tomato juice. The good relationship obtained between brown color and total color difference (TCD) suggests that TCD can be used to evaluate the visual color deterioration and browning in thermally processed tomato juice throughout refrigerated storage. Results presented in this study showed that the combination of a mild heat treatment plus refrigeration may help to ensure the microbiological safety and the nutritional value of pasteurized tomato juices.