Brown marking on the thin membranous layer a few cells thick, on the surface of the aril is the main problem encountered with the heat-acid treatment. The degree and intensity of browning vary greatly with treatments. Cultivar differences also play a great role. Another serious problem is pinking and subsequent browning of the fruit aril, which is likely due to stain from the dissolved anthocyanins in the rind under the strong acidic conditions used in the treatment. The present study was an attempt to clarify and identify factors associated with these problems.