Natural aroma chemicals for use in foods and beverages - Natural Food Additives, Ingredients and Flavourings - page 225

[10.56]

Issues around chirality can be illustrated well with the lactones, especially the
wide-spread gamma -lactones. All the gamma-lactones [10.57] (except the simplest,
gamma -butyrolactone, R = H) have a chiral centre alpha - to the ring oxygen.

[10.57]

Another piece of 'received wisdom' is that all naturally occurring gamma -lactones
are found exclusively in the R -confi guration. Table 10.3 shows that while the
R -form predominates in most though not all sources, with the possible exception
of gamma -dodecalactone, both are found in nature. In the case of the wonderfully

￿ ￿ ￿ ￿ ￿

Table 10.3 Sources of naturally occurring γ -lactones

Source C8 C9 C10 C12 Reference

Apricot 89/11 84/16 94/6 100/0 Bernreuther et al . (1989)

85/15 100/0 100/0 Greger and Schieberle (2007)

Mango 53/47 73/27 66/34 100/0 Bernreuther et al . (1989)

Peach 87/13 85/15 87/13 96/4 Bernreuther et al . (1989)

Passionfruit 55/45- 50/50- 87/13- 99/1- Nitz et al . (1991)

78/22 56/44 93/7 100/0

Raspberry 44/56 28/72 49/51 50/50 Nitz et al . (1991)

Lulo del chocó 23/77 20/80 Morales et al . (2000)