Note: Descriptions are shown in the official language in which they were submitted.
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METHOD FOR TREATING PINEAPPLE TO
PREVENT P I NEAPPLE FRU I T DI SEASES
This invention pertains to a method for trea~ing
ripening pineapple fruit in the field to inhibit infection by
disease-causing microrganisms.
BACKGROUND O~ THE INVENTION
Ripening pineapple fruit is susceptible to infection
by a variety of disease-causing microorganisms. Such diseases
tend to develop and damage the fruit during fruit maturation
starting from 20 days before the fruits are harvested until
they reach the consumer as fresh fruit or are processed in the
¦cannery as canned pineapple. Thus, the internal quality of
- l fresh fruit is reduced and fruit solid recovery in the cannery
may ~e significantly decreased due to attack by such
microorganisms as Acetomonas sp., and Erwinia herbicola, which
are believed to cause pineapple pink disease. Other
deteriorating pineapple diseases resulting from microbial
action include marbling, which is believed to be caused by
species of Acetobacter, and fruitlet-core rot (black spot),
which is is believed to be caused by a complex of
microorganisms such as Penicillium sp., and Fusarium sp.,
bacteria, and yeasts.
It is known in the art that the deterioration of
fruit by microbial action, e.g. fungus or bacterial growth, can
be inhibited by subjecting the fruit after harvesting to an
atmosphere having a low oxygen and high carbon dioxide content.
See, A.A. Kader, M.A. El-Govrani, and N.F. Sommer, Effect of
CO~ Elevated CO2 and/or Reduced Q2 Levels on Postharvest
Behavior and Quality of Peaches, Vol. 14(3) Hort Science
(1979), p. 471.
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Accordingly, efforts have been made to create a
micro-environment which is unfavorable for the growth of fruit
microorganisms, for example, by applying a coating of wax to
the surface of the harvested fruit. However, the use of wax is
often objectionable from a consumer standpoint, because the
color, texture, or flavor of the fruit is often undesirably
effected by the wax coating. Additionally, it is difficult to
apply such wax coatin~s evenly over the surface of the fruit
~ithout using so much wax that the normal "breathing~' of the
fruit is interfered with to an undesirable extent.
SUMMARY AND OBJECTS O~ THE INVENq~ION
Accordingly, it is an ob~ect of the present invention
to provide a method for treating pineapple fruit which is
effective for inhibiting the growth of pineapple disease-
causing microorganisms.
A fu~ther object of the invention is to provide a
method for controlling microbial spoilage of pineapple fruit by
coating the ripening fruit in the field with aqueous solutions
of certain non-phytotoxic and nonionic surfactants, in the
absence of added wax.
These objects and other subsidiary objects which will
be apparent to those skilled in the art are achieved by the
practice of the present invention.
' The present invention provides a method for treating
pineapple plants to control pineapple fruit diseases caused by
microbial action, which comprises the step of treating the
ripening fruit in the field prior to harvesting with effective
amounts of an aqueous solution of a nonionic, non-phytotoxic
surfactant, to inhibit infection of the fruit by pineapple
fruit disease-causing microor~anisms, wherein the surfactant is
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61051-2413
selected from the group consisting of ethoxylated natural fats and
oils, ethoxylated alkylphenols, glycerol esters, preferably
ethoxylated glycerol esters of fatty acids~ polyoxyethylene fatty
acid esters, and mixtures thereof. Microbial spoilage of the
fruit is arrested, thus improving the internal quality of
pineapple fruit intended for sale in the fresh fruit market.
Additionally, disease blemishes in the fruit are reduced, so that
increased fruit solid recovery in the cannery is made possible.
DETAILED DESCRIPTION OF T~E INVENTION
While the invention is susceptible to various
modifications and alternative forms, there will be described
herein the preferred embodiments.
The present invention provides a method for inhibiting
the infection of ripeniny pineapple fruit by rot and disease
causing microorganisms. Accompli6hment of this desirable goal is
achieved by coating the surface o~ the pineapple fruit in the
field with effective amounts of an aqueous solution of certain
surfactants.
As understood by those skilled in the art, tha term
"surfactant" is used to describe a variety o~ amphipathic
molecules composed of separated groups having opposing
solubiliziny tendencies. For example, a surfactant may contain an
oil-soluble hydrocarbon chain separated by a sùitable degree from
a water-soluble ionic group. C. Arno and J. Lynn, Jr.,
Surfactants and Dete _1Y~ , vol. 22 EncvcloPedia of Chemlcal
Technoloqy 3rd ed. tKirk-Othmer ~983), pp. 332 - 3~6.
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61051 -2413
Surfactants are generally classified according to the
charge of the larger group in the molecule. In anionic
surfactants, this moeity carries a negative charge, while in
cationic surfactants the charge is positive. Nonionic
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surfactants carry no charge, and the solubilizing contribution
is usually supplied by a chain of ethylene oxide groups. In
amphoteric surfactants, on the other hand, solubilization is
provided by the presence of both positively and negatively
charged groups.
Although there are a wide variety of surfactants,
tests have indicated that only certain ones of these, or
mixtures thereof, are suitable for use in the present
invention. The surfactants, which are non-phytotoxic in the
usual concentrations in which they are applied, are preferably
nonionic surfactants selected from the group consisting of
ethoxylated glycerol esters of fatty acids, polyoxyethylene
fatty acid esters, ethoxylated natural fats and oils,
ethoxylated alkylphenols, and mixtures thereof.
While not wishing to be limited to a particular
theory or mode of action, it is believed that the surfactant
when applied provides a seal over substantially all of the
fruit's surface, thereby creating an internal fruit micro-
environment of low oxygen and high carbon dioxide content which
is unfavorable for the growth and reproduction of pineapple
disease microorganisms and the development of fruit-disease
symptoms. It is believed that the applied surfactant also
causes the natural waxes present on the surface of the fruit to
be~ome evenly distributed over the fruit surface. Thusl the
sealing effects provided by the natural waxes present on the
fruit surface are enhanced.
Additionally, it has been found that the seal on the
surface of the fruit formed ~y the surfactant coating also
prevents the escape of fruit esters from the ripening fruit.
Consequently, the freshness of the fruit is maintained from the
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time the fruit is ha~vested until it reaches the consumer.
The following two surfactant have been found
particularly effective at inhibiting infection of pineapple
fruit by disease-causing microorganisms:
1. TANDEM~ 55~, a blend of mono and diglycerides,
and polyoxyethylene sorbitan monostearates, which is
commercially available from Kraft Inc , U.S. and
which is presently patented as a liquid dough
strengthener and crumb softener for yeast-raised
baked goods (U.S. Patent No. 3,785,993~; and
2. AGRISOL SP 100~, an emulsifier blend of
monoglyceride and polyoxyethylene fatty acid esters
which is commercially available from KAO Corporation,
Japan.
Other surfactants, such as LUTENSOL A-8~ ~an
ethoxylation product of fatty alcohols based on coconut oil,
which is commercially available from BASF, AG, West Germany~;~
TRITON X-45~ (an octyl phenoxy polyethoxy ethanol commercially
available from Rohm & Haas, U.S.); and LOVING KL~ (a food
detergent containing sucrose mono and dioleates, potassium
pyrophosphate and phosphoric acid, which is commercially
available from KAO Corporation, Japan); as well as several
vegetable and mineral oils, were found to be useful but less
effective in controlling microbial spoilage than the preferred
5urfactants listed above.
For the prevention of pineapple fruit diseases
according to the invention, an aqueous solution having a
surfactant concentration of about 5% by weight is preferably
utilized. The solution is applied to the ripening fruit in the
field, r or to harvesting, by such methods as spraying with
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knapsack or boom sprayers, or pouring, so as to ensure coating
of substantially all of the fruit~s surface. Although the
amount of surfactant required per ton of fruit will vary
depending on the size of the fruit, etc., the aqueous solution
is preferably ap~lied at a rate of about 400 gallons per acre.
Additionally, the surfactant-containing solution is preferably
applied about twenty days before the pineapple fruit is
harvested.
The invention does not alter the conventional
techniques employed in the harvestin~, storage, shipment, and
marketing of pineapple fruit treated according to the
inyention. Thus, the temperature and humidity conditions
normally used for preserving the freshness of the harvested
fruit are suitable for use in connection with the invention.
By treating fruit with an aqueous, surfactant-
containing solution in accordance with the invention,
deterioration of the pineapple fruit by disease causing
microorganisms is arrested, and the internal quality of fresh
pineapple fruits is improved and the marketable life of the
subsequently harvested fruit is extended. Also, disease
blemishes in pineapple fruits for the cannery is reduced, thus
increasin~ recovery of pineapple fruit solids. Additionally,
the es~ape of fruit essences from the ripening fruit is
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