Changes in nitrogen content and amino acid composition of navel oranges during ripening
1988
Tadeo, J.L. | Ortiz, J.M. | Martin, B. | Estelles, A.
Nitrogen content and composition of amino acids in juice and rind of navel oranges were studied. The compared varieties were 'Navelina', 'Washington Navel' and 'Navelate', early, mid-season and late types, respectively. Total N content in juice increased during the season with values from about 60 to near 100 mg 100 ml(-1) in 'Navelina' and 'Washington Navel' and from 60 to about 80 mg 100 ml(-1) in 'Navelate'; amino N increased from 30 to 60 mg 100 ml(-1) approximately in the three varieties. The total N content in rind was quite similar in all cases, with values that decreased with time from 1 to around 0.6 g 100 g(-1) dry weight (DW), 50-60% corresponding to the protein N. The main free amino acids in juice and rind at different maturity stages are tabulated. Proline represents at maturity around 50% of the total free amino acids in rind, with values near to 1.5 mmol 100 ml(-1) in juice and over 5.0 mmol 100 g(-1) DW in rind. Total protein amino acids in rind decreased during maturation, reaching final values of about 20 mmol 100 g(-1) DW. Differences in composition among the three studied varieties are discussed.
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