Flavour formation in callus cultures of guava (Pridium guajava) fruit

Explants from guava Pridium guajava L fruit, when cultured on Murashige and Skoog media containing different combinations of IAA, NAA, 2,4‐D and kinetin, yielded unorganised callus cultures. Light (>2000 lux) and kinetin (>5 mg litre−1) promoted chlorophyllous callus. However, none of the tested variations yielded organised cultures. Increase in kinetin from 0.2 to 0.8 mg litre−1 resulted in a slight increase in the growth of the callus. There was perceptible guava fruit flavour in all three passages of callus cultures, all of which exhibited a slow growth rate. GC‐MS analysis of the volatile flavour fraction of the callus tissue revealed (Z)hex‐3‐en‐1‐ol, 3‐phenylpropyl acetate, (E)hex‐3‐en‐1‐ol, hexan‐1‐ol, (Z)hex‐3‐ynyl acetate, (E)hex‐2‐enal and cinnamyl acetate as prominent peaks. Incorporation of 14C glucose, 14C phenylalanine and 14C acetate from the growth medium into the volatile fraction of the callus cultures was 0.07, 0.09 and 0.14% respectively during a 4‐day incubation.