Postharvest Biology and Technology of Fruits, Vegetables, and Flowers

408 POSTHARVEST BIOLOGY & TECHNOLOGY OF FRUITS, VEGETABLES, & FLOWERS
1993). S-(+)-carvone, a monoterpene extracted from caraway oil, is the first commercially
marketed (Talent TM ) plant-based product for sprout suppression in Europe. Continuous
treatment inhibits tuber sprouting (Oosterhaven et al., 1995a, b). Jasmonates and its derivative
compounds showed potential postharvest applications in fruits and vegetables (Buta
and Moline, 1998; Droby et al., 1999). The response to jasmonates in sprout suppression
activity of potato tubers is ambiguous (Lulai et al., 1995; Oberg and Klienkopf, 2000).
Coleman et al. (2001) examined ethnobotanical and natural products literature on aromatic
herbs in the northern Andean regions of South America, for food preservation, insect
repellant, and sprout inhibition properties. Based on the literature, they compared the active
ingredients in those plant species, S-(+)-carvone, with menthone and neomenthol for sprout
inhibition in potatoes. Menthone and neomenthone are 5–10 times more effective than S-
(+)-carvone in sprout suppression when applied in combination at a 0.5 ppm concentration
level in laboratory-scale experiments for 4 weeks at 10 ◦ C. Method of application is by direct
vapor, but the authors suggested using a porous polysterene matrix due to ease of handling
and application. Tubers maintained all acceptable processing quality characteristics with
these treatments.
Eugenol is an extract from clove (Syzygium aromaticum L.) marketed as Biox-A TM .
This is another plant-derived compound that is commercially marketed for sprout inhibition
(Kleinkopf and Frazier, 2002). It has an organic label from many states in the United
States. It is applied as thermal aerosol, and multiple applications are required. The recommended
dosage for a 60-day storage period is 90 ppm followed by 30 ppm after 3-week
gap (Kleinkopf et al., 2003). Sprout suppression is by physical and chemical damage to the
developing sprouts and buds.
Frazier et al. (1998, 2000) tested mint oils (spearmint and peppermint) for sprout inhibition
in potato storage. Mint oils need to be applied continuously for effective sprout
suppression. Cold aerosol and forced evaporation are more effective treatments when compared
to thermal fogging (Kleinkopf and Frazier, 2002).
For successful commercial application of these naturally occurring volatile compounds
as alternative sprout inhibitors, there is a need to test these compounds for their consumer
acceptability because they possess distinct aroma and flavor characteristics. Boylston et al.
(2001) tested the sensory quality of potatoes treated with different sprout inhibitors such as
salicylaldehyde, 1,8-cineole, and 1,4-dimethylnaphthalene and compared these with CIPCtreated
tubers. The evaluation was carried out using a sensory panel during a 16-week storage
period. This study revealed that tubers treated with 1,8-cineole and salicylaldehyde can be
differentiated from untreated or CIPC-treated tubers. No difference in sensory perception
was detected with 1,4-dimethylnaphthalene-treated tubers.
19.5.10 Ethylene
In the literature, conflicting results were published on the role of exogenous ethylene in
potato tuber dormancy. Depending on the concentration and duration, ethylene can either
extend or shorten dormancy. Short-term treatment of exogenous ethylene treatments reduced
dormancy length, and continuous treatment resulted in suppression of subsequent sprout
growth (Timm, 1986). The first long-term application of ethylene for sprout inhibition was
reported by Metlitskii et al. (1982). Prange et al. (1998) first published a 3-year study
on commercial application of ethylene using the Russet Burbank cultivar. By continuous