Characteristics of citrus fruits in relation to granulation

A study was conducted in different citrus cultivars to observe the incidence and degree of granulation, and to measure polyphenol oxidase (PPO) activity and phenolic content pattern in relation to granulation. Standard procedures were followed to observe the incidence and degree of granulation, phenolic content pattern, PPO activity and pheno-physicochemical fruit characteristics of citrus fruits. Across all citrus cultivars studied, 25% of the fruit were affected by granulation to the degree of about 10%. In general, granulated fruit were larger in size than normal fruit, and were inferior in quality characteristics. Among different citrus cultivars, ‘Kaula’ mandarin had highest incidence of granulation (62.5%), followed by ‘Mosambi’ sweet orange (43.6%) and the least in ‘Kagzi’ lime (12.2%). Phenolic content and polyphenol oxidase activity also varied widely among different citrus types, and were significantly higher in normal fruit than granulated fruit. Thus, it appears from the study that PPO plays some role in the occurrence of granulation in citrus.