Prevention of browning in plantain products using anti-browning agents was evaluated. Plantain pulps were sliced and treated with different concentrations of ascorbic acid and citric acid (1-5%) for 10 min and in 1.25% sodium metabisulphite for 15 min which was used as control 1. The slices were blanched in hot water for 15 min which served as control 2. Samples were drained and dried in an oven at 60°C for 24 h and milled to obtain plantain flour. The flour was reconstituted to obtain plantain "amala". Analysis were carried out on the browning index, polyphenol oxidase and peroxidase activity of fresh plantain, plantain flour and plantain "amala". Result revealed that control 2 samples had the highest level of browning index of 0.420 and the lowest value of 0.008 was obtained from control 1 samples. Control 1 samples had the lowest values of 0.026 (fresh), 0.023 (flour) and 0.003 "amala" for polyphenol oxidase activity and 0.016, 0.013 and 0.010 for fresh, flour and "amala" plantain products, respectively for peroxidase activity. Citric acid was also effective in inhibiting polyphenol oxidase activity from 0.157 and reduced to 0.046 for fresh plantain and 0.013 for plantain "amala" at 5% concentration. However, the lowest values of 0.026, 0.023 and 0.003 were observed when using 1.25% sodium metabisulphite for fresh plantain, flour and plantain "amala", respectively. This concentration (5%) was also found to reduce peroxidase activity to 0.033 for fresh plantain and the plantain products, whereas 1.25% sodium metabisulphite was able to reduce peroxidase activity to 0.016, 0.013 and 0.010 for fresh plantain, flour and plantain "amala", respectively. Blanching in hot water was not effective in preventing browning index, peroxidase activity and polyphenol oxidase. The results revealed that browning index, peroxidase and polyphenol oxidase activities were reduced as the concentration of ascorbic and citric acids increases.
Producing plantain flour and plantain "amala" using the organic acids such as ascorbic and citric acids as anti-browning agents at different concentrations will help to prevent browning reactions associated with the activities of enzymes (polyphenol oxidase and peroxidase), thereby improving the colour and acceptability of the final products. Thus, providing recommendation to the manufacturers on the concentrations of these acids that will be comparable to the known standard of 1.25% sodium metabisulphite solutions.
Browning Prevention, Chemical Treatments, Plantain Products.