IMPORTANCE OF LACTONES IN FOOD FLAVORS - STRUCTURE, DISTRIBUTION, SENSORY PROPERTIES AND BIOSYNTHESIS

Lactones are widely distributed in foods and beverages. Their presence in the aromas of more than 120 foodstuffs (fruit, meat, dairy product s, beverages), and their relative importance as flavour impact compoun ds are reviewed. Their sensory properties, i.e. odour quality, intensi ty, tenacity and odour threshold, are presented in relation to their s tructure (4- and 5-olide, molecular weight, length of the side chain, unsaturation) and chirality. The lactone enantiomers are separated eit her after derivatization (formation of ester diastereoisomers, e.g. Mo sher esters) or by direct chiral GC analysis on capillary substituted cyclodextrin columns. Recent data on the relative abundance of R and S enantiomers of lactones present in fruit and dairy products are given . Current knowledge on the biosynthesis and chirality of natural lacto nes and their link with the lipid metabolism are discussed. Oxo- and t he corresponding reduced compounds, i.e. hydroxy fatty acids are likel y precursors of lactones. The latter would be subsequently generated f rom the former through a shortening or, on the contrary, a lengthening of the carbon chain.