In the past few years, there has been increasing public
concern for food safety. This is because of the extensive
use of pesticides in agriculture. While pesticide use usually
increases agricultural productivity, accumulated pesticide
residues in treated plants present possible health risks to
consumers [1]. Toxicity and human health risk associated
with pesticide contamination in foods have made it necessary
to limit pesticide residues in our foods [2]. Detection
and quantification of pesticide residues in food samples are
essential to verify whether these pesticides are within
limits, the so-called ‘‘maximum residue limits (MRL)’’.
This regulation was established by the European Commission
and other regulatory authorities. Many developed
countries have adopted this regulation to oversee and
manage their food safety affair. However, in developing
countries such as Thailand, good agricultural practices are
not fully complied with.
Watermelon (Citrullus vulgaris Schrad.) is one of the
most common types of melons. Watermelon is a sweet,juicy, and very nutritious fruit that is rich in most of the
important antioxidants in nature. Besides vitamins A and
C, watermelon contains lycopene, an efficient free radical
scavenger. These help to protect against chronic diseases
such as cancers, cardiovascular diseases, and osteoarthritic
inflammation [3, 4]. Watermelon is eaten as fresh fruit and
is mainly used to make products such as juices, nectars, and
fruit cocktails. Even the by-products, such as peel and seed,
can be made into pickles, preserves, and other foods [5].
Thai people commonly use watermelon peel as a vegetable
ingredient in their curry dishes (watermelon rind sour
curry). Many kinds of pesticides have been applied to
protect watermelon from pests and fungi [3, 6]. In Thailand,
there is a common belief among people that watermelons
are cultivated with excessive use of pesticide
carbofuran and thus not safe to eat [7–11].
Durian (Duriozibethinus, family of Malvaceae) fruit is
delicious, soft, succulent, and very popular for its unique
characteristics. Durian is widely respected as the ‘‘King of
Fruits’’; it is a highly prized fruit in Southeast Asian
countries. Its production and export are dominated by
Thailand, followed by Malaysia and Indonesia [12, 13].
The tree is tropical and native to Brunei, Indonesia,
Malaysia, and Thailand. The tree grows up to 50 m in
height depending on the species. Durian is a seasonal fruit;
its season lasts typically from June until August, which
coincides with that of the other tropical-specific fruits such
as mangosteen, jackfruit, and mango. The flesh or pulp can
be eaten at various stages of ripeness, and it is used as a
flavor base in a wide variety of culinary and sweet preparations
in Southeast Asian cuisines. Its edible flesh emits a
distinctive odor which can be described as strong and
penetrating even when the husk is intact. This unusual
stinky and intense odor of the fruit may have prompted
many people to express diverse and peculiar opinions.
Though it contains a relatively high amount of fats among
fruits, it is free from saturated fats and cholesterol. Durian
is abundant in dietary fiber; the fiber content helps to
protect the colon mucous membrane by decreasing exposure
time as well as by binding to cancer-causing chemicals
in the colon [13]. The durian fruit is a good source of
antioxidants and vitamin C and enriches with healthbenefiting
vitamin B groups. Fresh durian fruit is also a
very rich source of potassium, an important electrolyte that
helps control heart rate and blood pressure. Additionally, it
contains high levels of essential amino acid, tryptophan
(also known as ‘‘nature’s sleeping pill’’) which in the body
metabolizes into serotonin and melatonin. These neurochemicals
have important functions like sleep induction
and are used in the treatment of epilepsy.
Information on pesticide residues in watermelon and
durian fruits does not exist in the country and is scarce
worldwide. We could not retrieve any residue data for durian in the literature, and there is very limited data on
watermelons. Therefore, this study aimed to determine
possible pesticide contamination in these fruit samples by
analyzing 28 pesticides and 2 metabolites using GC–MS/
MS methods. Also, we aimed to clarify if it was safe to eat
the two popular tropical fruits, watermelons and durians,
sold in Thailand.