Postharvest Biology and Technology of Fruits, Vegetables, and Flowers

140 POSTHARVEST BIOLOGY & TECHNOLOGY OF FRUITS, VEGETABLES, & FLOWERS
CH 3
Fig. 7.1
Structure of 1-MCP.
7.2 Registration and application of 1-MCP
Commercial applications of 1-MCP were first made available for ornamental crops. This
product with the trade name EthylBloc was approved by the United States Environmental
Protection Agency (EPA) in 1999, and was marketed by Floralife, Inc. (Waterboro, SC).
Further testing and registration of 1-MCP for edible crops were undertaken by AgroFresh
Inc., a subsidiary of Rohm and Haas (Springhouse, PA). Several investigations have shown
that 1-MCP is nontoxic to humans, has negligible residue, and is active at concentrations
of parts per billion (ppb).
The safety, toxicity, and environmental profiles of 1-MCP to humans, animals, and in
the environment were reported by the EPA (2002). The LC 50 for inhalation in rats was
greater than 2.5 mg/L (or 1,126 ppm active ingredient in air). Acute toxicity of 1-MCP or
clinical signs of systemic toxicology have not been observed in toxicology studies (EPA,
2002).
With the approval by the EPA in 2002, 1-MCP is marketed under the trade name of
SmartFresh. The use of SmartFresh has been approved by over 20 countries. The approval is
for specific crops and includes apple, apricot, avocado, carrot, kiwifruit, mango, melon, nectarine,
papaya, peach, pear, pepper, persimmon, pineapple, plantain, plum, squash, tomato,
and tulip bulbs. Table 7.1 gives a summary of the fruits and vegetables that respond to 1-MCP.
At 20 ◦ C, 1-MCP is released as a gas from a formulated cyclodextrin powder when it
is mixed with water in nearly 20–30 min. A complete release may take longer duration at
lower temperatures. Under such conditions, 1-MCP is absorbed by the harvested material
over time. Peaches absorbed 80–90% of the 1 μL/L applied either at 20 ◦ Cor0 ◦ C when held
in a closed container for 20 h (Liguori et al., 2004). As well, an increase in CO 2 levels due to
respiration does not inhibit the effectiveness of binding of 1-MCP (Blankenship and Dole,
2003) in closed systems. In addition, ethylene is also produced by harvested materials. Since
1-MCP shows a higher affinity toward the ethylene receptor, nearly 100-fold higher levels of
ethylene are required to effectively compete for the binding site. The highest concentration
of 1-MCP that is approved for use is 1 μL/L. After binding to the receptors, 1-MCP does not
get released, and any reversal of 1-MCP treatment is potentially because of the synthesis
of new ethylene receptors in the tissue (E.C. Sisler, personal communication). Repeated
weekly applications of 1-MCP (Mir et al., 2001; Mir and Beaudry, 2001; Jayanty et al.,
2004) helped prevent apple softening at 20 ◦ C more than at 0 ◦ C, and this was attributed to
an increased turnover of the receptor at high storage temperature.
It has also been noticed that 1-MCP can be absorbed or adsorbed nonspecifically to
sites other than ethylene receptors. In storage rooms, various plastics did not absorb the