The effect of fruit size and harvesting of Thai tangerine fruit (Citrus reticulata, Blanco) at different growth stages, 8-12 months after fruit set, on the distribution of limonin in whole fruit as well as in the individual fruit parts and extracted juice was investigated. The highest limonin concentration was observed in seed, followed by albedo, flavedo, segment membrane and juice sacs in decreasing order. The limonin concentration in juice as well as in whole fruit was decreased when fruit was harvested 8-12 months of fruit set. Increasing harvesting time from 8 to 12 months showed corresponding decreases in the amount of limonin in flavedo, albedo and seed. There was a decrease in titrable acidity and increase in total soluble solid and total soluble solid/titrable acidity ratio of juice with a later than normal harvesting time. However, fruit size showed no effect on limonin content and other properties of juice extracted from tangerine. Figure 2 Cross-section of tangerine fruit, showing the limonin disribution in each fruit part (n ϭ 5).Flavedo (0.18 Ϯ 0.028 mg limonin/ g sample) Albedo (0.205 Ϯ 0.021 mg limonin/ g sample) Segment membrane (0.1 Ϯ 0.014 mg limonin/ g sample) Juice sacs (0.002 Ϯ 0.001 mg limonin/ g sample) Seed (1.48 Ϯ 0.042 mg limonin/ g sample)along with the juice as pulp or when fruit is eaten fresh (Macintosh et al. 1982). The limonin concentration of the juice vesicle (Fig. 2) was less than the limonin concentration of juice extracted by the laboratory juice extractor because some limonin precursors from other fruit tissues such