Agriculture Reference
In-Depth Information
Similarly, in the case of baby formula, ingredients used in formulation are derived
from the milk, produced by cattle. Thus, a sensitive detection technique is needed
that could sense prion during the various processing steps of gelatin and that might
be used as a quality measure to screen baby formula samples (Anand et al.
2005
).
Ochratoxin A (OTA), a secondary fungal metabolite produced by various
Asper-
gillus
and
Penicillium
strains, is found to be one of the predominant contaminating
mycotoxins in a wide range of food commodities like dried fruits, cereals, spices,
cocoa, coffee beans, nut, wine, beer, etc. (Ahmed et al.
2007
; Bennett and Klich
2003
; Ghali et al.
2008
,
2009
; Imperato et al.
2011
; Van Der Merwe et al.
1965
).
This toxin is highly nephrotoxic, hepatotoxic, mutagenic and teratogenic to most
mammalian species (Duarte et al.
2010
; Hussein and Brasel
2001
). A reliable and
fast sensing platform has been developed for the detection of mycotoxin OTA based
on a target-induced structure-switching signalling aptamer. In the absence of a
target, a fluorescein-labelled OTA aptamer hybridizes to a complementary DNA
strand involving a quencher moiety, bringing the fluorophore and the quencher into
close proximity for highly efficient fluorescence quenching. Upon OTA addition, a
conformational change in the aptamer releases the quencher involving a DNA
strand, generating a strong concentration-dependent fluorescent signal. Using this
technique, the entire analysis and detection process of OTA could be completed
within 1 min. Under optimized assay conditions, a wide linear detection range from
1 to 100 ng/ml was achieved with a detection limit down to 0.8 ng/ml. Additionally,
the proposed assay system presented high selectivity for OTA against other myco-
toxins (zearalenone and aflatoxin B
1
) and limited interference from the structural
analogue ochratoxin B. The biosensor was also applied to a non-contaminated corn
material spiked with a dilution series of OTA, obtaining recoveries from 83 to
106 %. Utilization of the proposed biosensor for a quantitative determination of
mycotoxins in food samples might offer significant improvements in the quality
control of food safety through a rapid, simple and sensitive testing system for
agricultural product monitoring (Chen et al.
2012
).
Acetaldehyde has a common natural occurrence. It occurs in tobacco leaves and
oak and is a natural component of broccoli, apples, grapefruit, coffee, lemons,
mushrooms, onions, grapes, oranges, pears, pineapples, peaches, strawberries and
raspberries; consumers might be exposed to acetaldehyde in heated milk, cheese,
cooked chicken, cooked beef and rum. Wherever fermentation processes play a role
in the production of beverages and food, the concentration of acetaldehyde rises
considerably. Acetaldehyde is commonly found in alcoholic beverages as a result of
the enzymatic oxidation of ethanol; it is more toxic than ethanol and plays an
important role in the manifestation of alcohol intoxication. The concentration of
acetaldehyde is a very important parameter because of its capacity of reacting with
sulphur dioxide to form a very stable combination, therefore preventing it from
exercising its antiseptic and antioxidant function. In addition to these, it is one of
the earliest parameters to be noticeably affected when malfunction occurs during
wine production. Due to its strong electrophilic properties, acetaldehyde is believed
to induce biological changes as carcinogenesis and mutagenesis by reacting with
DNA (Guru and Shetty
1990
). Thus, an accurate and rapid assay for acetaldehyde
