Identification and seasonal variations of amino acids in birch sap used for syrup production

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