Controlling the nutrient profile of fruits and vegetables during prolonged storage prior to processing
Paper in proceedings, 2009
The seasonal nature of fruit and vegetable crops requires either that supply is maintained over a wide geographical distribution range or that produce can be stored relatively long term. We have shown that relatively long term storage of fruit and vegetables can be undertaken with little deterioration in texture and without compromising microbiological safety. Associated experiments, to test produce from different geographical locations have also been undertaken. The availability of fruits and vegetables for processing offers the opportunity to develop novel products, with improved quality and stability for transport and shelf-life. The effect of transport and storage on nutrient profile was studied in carrots, broccoli and tomatoes. Phytochemicals assayed include carotene, lycopene, folate, and ascorbic acid. The plant cell wall composition, free sugars and fibre content have also been determined. In carrot (mg/g dry weight), -carotene was ?0.7mg; ascorbic acid ?0.3mg, sugars ?500mg, and dietary fibre ?300mg. In broccoli, corresponding nutrients were: ascorbic acid up to 8.6mg, folate ?0.005mg, sugars ?250mg, and dietary fibre ?400mg. In tomato, corresponding nutrients were: lycopene ?0,8mg, ascorbic acid ?2.5 mg, sugars ?480mg, and dietary fibre ?400mg. The storage conditions chosen were temperatures of 2-4°C and relative humidity between 70 and 99%, depending on the raw materials. During storage, little change was found in sample compositions post harvest. Fully ripe tomatoes had lost some lycopene but vitamin C in broccoli increased during storage. Although total dietary fibre content did not change during storage there was a noted modification to constituent pectic polysaccharides; shown as a loss of pectic arabinan andgalactan in carrot. The results show that carefully controlled storage conditions were appropriate for the purpose of maintenance or enhancement of nutritional and textural properties. However, shelf life of produce may be compromised by transport conditions. It is therefore recommended to keep transport time short and to ensure that optimum storage conditions can be maintained during transport. Preliminary results indicate that transport rather than storage conditions are the major problem in maintaining product nutrient profile and microbiological quality prior to processing.