Effect of processing treatments on the colour of dokong (Lansium domesticum Corr.) juice

The fruit Lansium domesticum Corr. is commonly known in Malaysia as dokong.This species is from the Meliaceae family. One of the problems faced in the processing of dokong juice is the colour change due to browning reaction. Thus studies were conducted to improve the colour of the dokong juice. Four soaking treatments were selected from preliminary trials for further evaluation viz.soaking the peeled fruits in 1% salt solution followed by steaming for 2.5 min (GS); soaking in 0.2% sodium metabisulphite followed by steaming for 2.5 min (MS); soaking in 0.2% sodium metabisulphite (MET) and soaking in water (W). Canned juices prepared using the four treatments were significantly different in the L*, a* and b* colour values. The juice prepared from peeled fruits soaked in 0.2% sodium metabisulphite followed by steaming (MS) had the lightest colour as reflected by the higher L* values obtained. This was followed by MET, G and W samples in descending order of lightness.