Factors affecting the formation of delayed bitterness in sweet orange (Citrus sinensis (L.) Osbeck) juice

Formation of delayed bitterness is an intractable problem in the processing of citrus juice. This study analyzed the distribution of main bitter-causing substances in sweet orange and the effect of heat treatment, storage temperature, clarification, and homogenization on the limonin content in sweet orange juice. The segment membrane accounted for 34-42% of limonin in the fruit and 21-45% of limonoate A-ring lactone (LARL). Heat treatment accelerated the formation of limonin in juice. Pectinase treatment appeared to facilitate the formation of limonin by reducing the pH of juice. In addition, refrigeration at 4 °C was found to restrain the formation of limonin in juice by inhibiting the activity of limonin D-ring lactone hydrolase (LDLH). In conclusion, segment membrane may have a great contribution to the delayed bitterness of sweet orange juice due to its abundant LARL. These results may provide some guidance for citrus processing and bitterness removal.