India is successfully managing carcinogenic toxins In Groundnut to meet stringent International standards.
India is the second largest groundnut producing country in the world, next to China. The production systems and situations are quite diverse, and the crop is grown almost round the year. The crop-weather situations, therefore, varies from high temperature (40-45C), scanty rainfall (450-500 mm) areas to low temperature (20-25C), high rainfall (1500-2000 mm) areas that supports very high to negligible Aflatoxin in produce.
Anantapur district in Andhra Pradesh is the world's largest groundnut growing District with estimated per capita consumption of nuts as high as 70 g/day. But at the same time, there is a high risk of Aflatoxin contamination both in pre and post-harvest stages. Aflatoxin content in fresh harvest in Anantapur produces. often goes beyond 50 ppb and moves up rapidly along with the length of storage (>100 ppb).
This seriously impacts human and animal health since Aflatoxin is carcinogenic as well as immunosuppressive in nature. In India, although the safe level of Aflatoxin has been kept at 30 ppb, the European standard is as stringent as 2 ppb (B1); whereas it varies between 5-15 ppb in most of the developed countries.
Cultural Practices to Curb Aflatoxin Contamination:
To address this very crucial issue, five villages in Anantapur district were identified based on the severity of the problem and other socio-economic aspects related to groundnut cultivation. The critical factors responsible for Aflatoxin contamination at farm and storage levels were identified and their impact studied through farmers' participatory mode. Afterward, validation of those components having bearing on Aflatoxin was made through On-Farm Demonstration for over three years. By integrating couple of key management factors at the pre and post-harvest levels it was possible to demonstrate negligible Aflatoxin contamination (0-5 ppb) in that high-risk areas even after 3-6 months of ordinary storage at household level. In 75% cases, the Aflatoxin contamination levels were <15 ppb in five villages adopted under the special project funded by UNDP, New Delhi.
Biological Control Measures:
Aflatoxin contamination in groundnut, caused by A. flavus group of fungi, is a major problem associated with rainfed agriculture in Semi-arid tropics of India. Biological control is one of the key components in integrated aflatoxin management to reduce pre-harvest kernel infection in the field.
The concept of biological control by competitive exclusion of A. flavus is a promising component of the integrated management of Aflatoxin contamination in groundnut. Bio-control of Aflatoxin contamination involves the use of competitive and antagonistic native microorganisms that can reduce the populations of aflatoxigenic strains present in the soil, and subsequently reduce infection to the developing pods and kernels of groundnut. The entry of A. flavus to the developing groundnut pods is directly from the soil surrounding it.
Several potential strains of fungal and bacterial cultures antagonistic to A. flavus have been isolated from rhizosphere of groundnut. Fluorescent pseudomonades are prominent inhabitants in the rhizosphere of many crop plants and these have been identified as promising bio-control agents against A. flavus contamination in groundnut. Varying levels of successes were achieved in containing Aflatoxin by using non-toxigenic strains. On some occasions, Aflatoxin levels in groundnuts were reduced by 95% compared with controls.
The advantages of using bio-control agents include minimal disturbance of the ecosystem, positive consumer perception/acceptance, no trans-gene implicating food safety regulations, and the potential of readily transferable low-cost technology to other countries. Integration of these bio-control agents with host-plant resistance and agronomic management would greatly help in reducing Aflatoxin contamination in groundnut, a major problem affecting the export and earning of foreign exchange in the developing countries, more particularly in India and Africa.
Having engaged in groundnut research and development for about 30 years in India and abroad, I feel Indian Groundnut (Peanuts) particularly originating from Gujarat having typical nutty flavor and meeting international standards are exported to EU Countries and other premier destinations for production of Peanut Butter and other confectionary uses. In India now we have confectionary varieties, characterized by low oil and high protein and oleic-linoleic ratio, suitable for such uses.
For further reading, consult the Bulletin on "Aflatoxin Management in Groundnut" authored by Dr. M. S. Basu, Principal Investigator & Formerly Director, National Research Centre for Groundnut (ICAR) and published by UNDP, New Delhi and Dept. of Agriculture & Cooperation (DAC), Ministry of Agriculture, Govt. of India.