The present invention relates to a method for the detoxification of food products and food raw materials contaminated with aflatoxins.

Aflatoxins are micotoxins produced by several species of Ascomycetes, genus Aspergillus, particularly Aspergillus flavus and Aspergillus parasiticus, and certain moulds.

Aflatoxins are extremely noxious for human health, as they are characterized by a considerable liver carcinogenity resulting from the fact that these substances are metabolized by the liver, by which they are turned into a reactive intermediate, aflatoxin Ml, and an epoxy.

Those members of the genus Aspergillus that are suitable to produce aflatoxins are widely found in nature. These micro-organisms can colonize and contaminate cultures, particularly of cereals, both during harvest and storage. Those cultures that are particularly subjected to infection by Aspergillus and accordingly to contamination by aflatoxins are cereals (such as maize, sorghum, millet, rice, wheat), oilseeds (such as peanut, soy, sunflower, cotton), spices and tree nuts (almond, pistachio, nut, coconut, Brazil nut). Aflatoxins can also develop in the milk of animals fed with contaminated feed.

The environmental conditions suitable to facilitate the development of Aspergillus are particularly connected to a high amount of humidity (at least 7%) and environmental stress conditions, such as for example drought periods and high temperatures.

The main problem of contamination of food products by aflatoxins results from these substances being very difficult to eliminate, and in that they resist to the treatments that are normally used for sterilizing food products. It should be also noted that the maximum rates of aflatoxins in food products as contemplated by law are very low, in the order of parts per billion (ppb). Paulsen MR et al., Journal of Food Science, vol. 14, No. 3, p 667-671, describe detoxification of peanuts contaminated with aflatoxins by dipping the latter within a 5% hydrogen peroxide solution. The Table 2 of this publication, however, indicates that the removal of the cuticle from shelled peanuts is essential to achieve a significant abatement of the afla- toxin contents, even after dipping in the hydrogen peroxide solution.

British patent GB 1,1 17,573 describes the treatment of food materials with an aqueous hydrogen peroxide suspension at a temperature of at least 70°C.

As far as the inventors are aware, no method is known for treating food products and food raw materials, particularly cereals and tree nuts, which is suitable to eliminate or reduce the aflatoxin rate below the limits contemplated by law, which at the same time does not suffer from the drawback of changing the organoleptic, nutritional and visual characteristics of the food product or food material, particularly the natural color thereof.

An object of the present invention is thus to provide a method for treating food products and food raw materials, which has such characteristics as flexibility of application, low price, high level of effectiveness in eliminating contamination by aflatoxins and/or other specific contaminants, without however causing any change in the visual, organoleptic and nutritional characteristics of the food products being treated or food raw material being treated.

Another object of the present invention is to provide a method for treating food products and food raw materials which does not involve the use of substances or conditions that are dangerous for operators and which further provides the operators with a high level of safety in handling the food products or raw materials being treated.

These and other objects are achieved by means of the present invention, which provides a method for the detoxification of food products and food raw materials contaminated with aflatoxins, particularly cereals and tree nuts, comprising the step of atomizing or nebulizing hydrogen peroxide on food products and/or food raw materials to be detoxified. The preferred treatment conditions are as follows: at least 2 minute time of contact between hydrogen peroxide and food product or food raw material to be detoxified, most preferably ranging between 2 and 20 minutes; concentration of the hydrogen peroxide ranging from 1 and 30%, preferably between 6 and 30%, most preferably between 4 and 20%; ambient temperature and pressure.

In a preferred embodiment of the method according to the invention, the step of atomiza- tion or nebulization of the hydrogen peroxide is followed by drying the food products and/or food raw materials which have been treated, up to a reduction in the residual humidity content below about 7%.

The experimental data obtained in the laboratory by applying the above-mentioned treatment conditions, have highlighted a great ability of destructing aflatoxins. Starting from a sample (pistachios) with 350 ppb contamination and exposing the latter to the above treatment conditions for about 2 minutes, including a drying step, levels of aflatoxin <2 ppb have been measured on the tested samples. Table 1 shows the results obtained from the tests, in terms of abatement of aflatoxins, based on the time of treatment.

Table 1

In two pistachio samples which after being treated with hydrogen peroxide for 30 and 45 seconds, respectively, resulted to be almost completely wet due to the accidental formation of condensate, no reduction in the initial content of aflatoxins has been observed (> 50 ppb).

Hydrogen peroxide can be delivered using any atomization or nebulization device that is preferably provided with a predefined control and dosing system.

The method of the invention advantageously results in the destruction (denaturation) of the aflatoxins that are present both on the surface of food products and deeply therein, without leaving any chemical residue and without changing neither the aspect nor the nutritional characteristics of the treated food product or food material, while ensuring the disinfection thereof.

The method of the invention can be applied to automatic packaging machines or it can be used in "stand-alone" conditions as an operating step to be carried out prior to other manufacturing treatments, such as for example roasting or other.

The method of the invention can be directly used both by the manufacturer at a time immediately after the harvest (before storage) or prior to overseas shipping, and by the importer when contaminations are detected in the oncoming cargo.

The application of this method which can, as demonstrated by the experiments, eliminate or however reduce the contamination by aflatoxins to acceptable levels, advantageously allows reducing the risk involved for the operators in charge of the manufacturing process, reducing the risk of contaminating other food products, reducing the damages to end-users' health and reducing the waste of material and the costs deriving from the forced disposal of contaminated product lots.