Identification and seasonal variations of amino acids in birch sap used for syrup production
1989
Ahtonen, S. | Kallio, H.
The contents of the main free amino acids of birch sap (Betula pendula Roth and B. pubescens Ehrh.), which will be used for syrup production in Finland, were analysed. Fifteen amino acids were monitored as their pentafluoropropionicanhydrideisopropyl esters with capillary-GC-MS. Glutamine, citrulline and glutamic acid were the main components in each tree studied. Together will isoleucine, valine and asparagine they comprised 92-96% of the amino acid pool. During the flow season their total content varied widely from 100 to 500 mg/litre, showing high deviations. The contents of the six main amino acids increased in April, and they at least doubled during the latter half of the month. The most efficiently increased amino acid was glutamine, which finally comprised abouth 40% of the entire pool. The amino acids take part in Maillard reactions, and thus affect of the sensory properties of the heated syrup.
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