Inhibition of Aspergillus flavus and Aflatoxin in Maize by Acorus calamus (Bojo)

Abstract

This study was carried out to reveal the effect of Bojo powder on Aflatoxin production and growth of Aspergillus flavus 'ITCC 5192' in maize grain stored at four different moisture levels of 13, 17, 21 and 24%. For the inhibition study, Bojo powder was used in the concentration of 0.0, 0.5, 0.75, 1.0, 1.25 and 1.5% (w/w) in maize samples. After inoculation of Aspergillus flavus .ITCC 5192. and incubation for 15 days, Aflatoxins were extracted and quantified by using Thin Layer Chromatography (TLC). Maize sample with moisture content 17% and Bojo powder concentration at 1.0% prevented the growth of Aspergillus flavus and production of Aflatoxin. Aflatoxins as high as 1416ppb were detected in control sample (i.e. no Bojo added) and stored at 17 and 21% respectively. Formation of Aflatoxins and growth of Aspergillus flavus 'ITCC 5192' was not completely inhibited in maize grains at high moisture levels (i.e. 21 and 24%). J. Food Sci. Technol. Nepal, Vol. 6 (59-64), 2010 DOI: http://dx.doi.org/10.3126/jfstn.v6i0.8261

Postharvest Handling and Prevalence of Aflatoxin Contamination in Nepalese Maize Produce

“…At 16% moisture, afl atoxin levels reach 116μg/kg, while at 22% moisture, 2166 μg/kg afl atoxin were obtained (Morena-Martinez et al, 2000). Thapaliya et al (2010) found that maize at 13% moisture content showed no afl atoxin formation and proved that such low moisture content does not support for A. fl avus growth and toxin formation. Nepal government has set a standard for food grains for moisture content which should not be greater than 16% and should contain less than 10% insect damaged grains (Nepal Gazzette, 2001).…”

“…Before storage in bins, grains are dried. According to Thapaliya et al (2010), at 13% moisture, there is no growth of Aspergillus. In developed countries, maize is used as a feed rather than food, so it is of lesser concern thought their legislations are more stringent (Table 6) regarding afl atoxin than the developing countries.…”

“…In Nepal there is problem with drying after harvest (Paudyal et al, 2001) and storage (Thapaliya et al, 2010) which is sought to be the critical point afl atoxin reduction. Higher afl atoxin levels were prevalent with maize mono cropping, no use of fertilizer, damage of maize in fi eld, delayed harvesting, fi eld drying, heaping harvested maize and cobs shelled latter, no preparation of the storage structure, no insect control and storage of maize in poorly aerated structures; whereas rotation of crop, mixed-cropping, use of diammonium phosphate fertilizer, farmer awareness of incomplete husk cover, harvesting at crop maturity and with husk, sun drying on platform without husk, immediate removal of damaged cobs, use of clean & aerated storage structures, use of insecticide or smoke caused lower afl atoxin levels (Hell et al 2008;Hell and Mutegi, 2011).…”

“…Farmers have neither the knowledge nor the equipment to measure maize moisture content and therefore they simply dry the maize for 4-5 days before storing. Lack of knowledge regarding to harvesting technology, factors of contamination and lack of proper storage techniques and structures have further worsen this situation (Thapaliya et al, 2010). Afl atoxin producing fungi infests food grains or other food items usually during storage (Koirala et al, 2005)..…”

Mycotoxins in Foods: Occurrence, Challenges and Management in Context of Nepal

“…For instance, harvesting time of the summer maize is late monsoon when the cobs have quite high moisture content (23-28%). Rural farmers do not have proper knowledge of moisture measurement and hence simply dry maize in sun for 4 to 5 days before storage which favors the growth of fungus in stored maize (Thapaliya et al, 2010).…”