Gradient in Sugar and Acid Content among Different Portions of Pulp in the Axial Direction of Several Citrus Fruits at Harvest Season

摘要

Differences in soluble solids content (SSC), titratable acidity and sugar composition (fructose, glucose and sucrose) in the axial direction of pulp in 'Aoshima' satsuma mandarin (C. unshiu Marc.), 'Miyauchi' iyo (C. iyo hort. ex Tanaka), 'Yoshida' ponkan (C. reticulata Blanco) and 'Shiranui' ([C. unshiu Marc, x C. sinensis Osbeck] x C. reticulata Blanco) fruit were determined at harvest season. SSC, sucrose and total sugar content were highest in the stylar end in 'Miyauchi' iyo, 'Yoshida' ponkan and 'Shiranui.' However, there was little difference in sugar composition among different portions in 'Aoshima' satsuma mandarin. Acid content was highest in the mid section in 'Aoshima' satsuma mandarin and 'Miyauchi' iyo, whereas it was highest in the stylar end in 'Yoshida' ponkan and 'Shiranui.' The shape index (diameter/length) of fruit was 1.37, 1.28, 1.08 and 0.98 for 'Aoshima' satsuma mandarin, 'Miyauchi' iyo, 'Yoshida' ponkan and 'Shiranui,' respectively. SSC/acid ratio was highest at the stylarend in 'Aoshima' satsuma mandarin and lowest at the mid section in 'Miyauchi' iyo but there was little difference among portions in 'Yoshida' ponkan and 'Shiranui.' The regression coefficients of SSC and acid content in each portion with their respectivemeans of whole pulp were very high in 'Yoshida' ponkan but low in 'Miyauchi' iyo. Relatively high coefficients were noted in the mid section for both SSC and acid content in 'Aoshima' satsuma mandarin,'Yoshida' ponkan and 'Shiranui.' Therefore, the midsection is a reliable portion for the non-destructive evaluation of fruit quality of these species by using infrared sensors.