Orange, lemon and lime juices were extracted from their ripe fruits and subjected to different temperatures and pressures followed by determination of their ascorbic acid (vitamin C) contents. Each fruit juice was heated at 50°C, 75°C and 100°C at atmospheric pressure for 1 hour. The process was repeated on fresh samples at 50°C and 75°C at reduced pressure. The ascorbic acid in orange juice decreased from 52.3mg/100ml for the fresh sample to 42.7mg/100ml and 34.1mg/100ml for the sample heated at atmospheric pressure at 50°C and 75°C respectively. The orange juice samples treated similarly at reduced pressure yielded ascorbic acid values of 45.3mg/100ml and 36.2mg/100ml respectively. A similar pattern was observed for lemon and lime juices. The results suggest that treatment of fruit juices at reduced pressures, as is often the case when producing concentrated juices, does not offer much protection from ascorbic acid loss.

Effect of temperature and pressure on the stability of ascorbic acid in citrus fruit juices

256th National Meeting (2018)

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