Caraway essential oil as potential inhibitor of potato sprouting

Potato tubers may suffer from premature sprouting during storage. Commonly used low temperature storage systems or chemical sprout inhibitors could be replaced by naturally occurring compounds. The study carried out in the se ason 1996/1997, 1997/1998 and 1998/1999 was focused not only on confirmatio n of sprout suppressing effect of monoterpen S-carvone, which is the major constituent of caraway essential oil, but on development of S-carvone based formulae suitable for practical use as well. The influence of caraway esse ntial oil on potato tubers cv. Karin was tested in small-scale experiments. The results were compared with experiments pursuit under the same conditio ns: untreated control, treatment with commonly used chemical inhibitor CIPC and treatment with commercial natural sprout inhibitor Talent. The vapour of caraway essential oil in dosage of 0.1 ml/kg tubers applied regularly in four and six weeks period successfully inhibited bud growth at 10 degreesC . Weight losses caused by sprouting were 0.4 and 0.3%, whereas in the contr ol sample 7.5% in season 1996/1997. Due to the fact, that a low, but stable S-carvone head-space concentration must be present around the tubers and t herefore active compound has to be applied regularly, several different S-c arvone based formulations had been also studied to elongate this period. Th e simplest methods such as direct spraying of essential oil or evaporation from disintegrated caraway seeds are without any practical use. Spraying of potato tubers with essential oil or with Talent in the season 1997/1998 de veloped tuber surface necroses and rotting, although the losses caused by s prouting were minimal. Essential oil on sorbent bentonite dusted as a powde r once per storage period was the most potent application in gradual active compound release from matrix to the storage atmosphere (0 and 2.7% losses by sprouting in 1997/1998 and 1998/1999, respectively). The direct dependen ce of sprouting on residual carvone and its biodegradation products concent ration in tubers was observed. S-carvone was converted into dihydrocarvone and dihydrocarvone especially in simply accessible tissues of sprouts, peel s and half tubers. Sensory analyses confirmed that S-carvone treatment of s tored tubers does not influence taste, odour and colour of cooked potatoes.