A study conducted by the citybased Directorate of Rice Research revealed that most of the rice available to consumers is infested by a type of fungus known as Aspergillus. Rice that is over 36 months old is most affected by the fungus.
As part of the study, senior DRR scientists Dr C.S. Reddy and Dr K. Muralidharan collected 900 rice samples of 250 varieties from 20 states across the country. The samples were from areas exposed to rain or flood or of rice stored in bins and from wholesale and retail markets.
The team isolated an aflatoxinproducing mycoflora of the Aspergillus species from the samples.
“Aspergillus contamination was detected in most of the seed samples. A. flavus, A. niger, A.
ochraceus and A. parasiticus were collected from these samples. In general, Aspergillus contamination was higher in seed samples exposed to rain followed by long storage periods,” they pointed out. Around 60 to 84 per cent of the rice samples collected were found to contain Aflatoxin B1. Of the samples collected from different sources, 93 per cent of those exposed to rain tested positive for the cancer-causing toxin. Of the samples stored for more than three years, 77 to 79 per cent contained Aflatoxin B1 as did 75 per cent of the samples collected from consumer markets. Of these, 21 samples recorded 32.8 to 308 ig of Aflatoxin B1 per kilo of rice, which is above the permissible limit.
The DRR team attributed the growth of fungus in rice to the crop being exposed to frequent and heavy rainfall and floods, particularly just before harvest. Often harvested sheaves remain wet and the grain becomes prone to invasion by fungi.
“Invasion by field and storage fungi takes place.
Aflatoxin contamination of agricultural commodities including rice is a serious food safety issue besides being a significant economic concern,” the DRR study warned