A PROCESS FOR REMOVING ACRYLAMIDE FROM FOODS Field of the invention

The invention relates to a process for removing acrylamide from foods. State of the art Acrylamide is known to develop in foods containing carbohydrates and the amino acid asparagine, particularly foods containing starches, when subjected to heat treatment. Acrylamide is an odourless, colourless, low molecular weight substance and hence undetectable to the senses, which is very soluble in water, and with which a potential carcinogenic action is associated. Indeed, exposure to high levels of acrylamide for prolonged periods in laboratory animals is known to be carcinogenic.

On the basis of these results and despite the risk levels to humans being unknown, considerable alarm was raised concerning this substance mainly following the publication of data on foods, obtained by public food safety authorities such as the Swedish National Food Administration and the British Food Standards Agency, and communicated thereby in 2002. Products most at risk of containing high levels of acrylamide are all starch-based foods subjected to high temperature cooking treatments such as frying, oven baking and toasting, hence a wide range of foods such as French fries, bread, toasted cereal-based products, biscuits and coffee.

Briefly, acrylamide forms by the reaction between the amino acid asparagine and the carbonyl group of a reducing sugar following heat treatments conducted at temperatures higher than 120°C (Stadler R.H. et al., 2002 Nature, 419, 449-450), although other reaction mechanisms are not excluded. Notwithstanding the numerous research studies aimed at understanding the mechanisms and the effect of the numerous variables involved in the formation of this substance, drawing up effective guidelines for minimizing its development in food products has not been possible. Indeed, in most cases, these interventions lead to the obtaining of poorly acceptable finished products from the sensory viewpoint.

The reasons for this are essentially ascribable to: i) an incomplete understanding of the effect of processing and product variables on acrylamide formation

(particularly a _w and the physical state); ii) the close relationship between acrylamide formation and the development of desired sensory properties in heat treated products.

Despite this, in view of the social significance of acrylamide's potential carcinogenic effect and the economic significance of the food and agriculture industrial sector, several technical strategies aimed at reducing acrylamide formation in cooked foods have been proposed. These relate to:

- the selection of raw materials which are "poor" in acrylamide precursors (Biedermann M. et al., 2002 Mitteilungen aus Lebensmitteluntersuchung und Hygiene 93, 668-687; Amrein T.M. et al., 2003 J. Agric. Food Chem. 51 , 5556- 5560):

- pre-treatments based on reducing the concentration of sugars and asparagine and lowering the pH (Tareke E. et al., 2002 J. Agric. Food Chem. 50, 4998-5006; Jung M.Y. et al., 2003 J. Food ScL 68, 1287-1290; Zyzak D.V. et al., 2003 J. Agric. Food Chem. 51 , 4782-4787; Pedreschi F. et al., 2004 Lebensmittel- Wissensschaft und -Technologie 37, 679-685);

- modification of the original formulation of the food product by using compounds able to compete with asparagine or reduce the pH of the formulation (Vattem D. A., Shetty K., 2003 Innovative Food Sci. and Emerging Technologies 4, 331 -338; Grob K. et al., 2003 Eur. Food Res. Technol. 217, 185-194; Fiselier K. et al., 2004 Eur. Food Res. Techn. 219, 1 1 1 -1 15; Amrein T.M. et al., 2004 J. Agric. Food Chem. 52, 4282-4288; Brathen E. et al., 2005 J. Agric. Food Chem. 53, 3259- 3264);

- modification of the processing conditions, mainly by reducing the temperature and/or cooking times (Grob K. et al 2003 ret cit; Granada C. et al., 2004 J. Food

Sci. 69, E405-E41 1 ).

Since the aforecited methods are preventative in nature, they involve considerable formulation and/or processing changes in the preparation of foods, and such changes may not be acceptable from the consumer appreciation viewpoint. With the aim of removing acrylamide after preparation of the foods, and not only of preventing its formation, patent application US 2003/0219518 describes a process that comprises vacuum conditions and high temperatures up to 125°C,

preferably from ambient temperature to 125°C, more preferably from 87°C to 125°C. A further embodiment of the process also comprises, in addition to the aforementioned vacuum and temperature, treatment with light radiation, visible light, ultraviolet, x-ray and gamma radiation, to induce acrylamide polymerization. Another embodiment also comprises, in addition to the aforementioned vacuum and temperature, treatment with ozone to induce oxidative degradation of the acrylamide. In each case the treatment time does not appear to significantly affect removal, this being reasonable when considering the extreme conditions adopted and the fact that the defined temperatures are much higher than the sublimation temperature. Moreover, the teaching derived from the examples is to use in each case a high vacuum of 0.01 torr and a temperature of 85°C for at least one hour when these treatments are not combined with light radiation treatment. The main drawback of the described process is that it involves very extreme conditions which are difficult to apply industrially or are applicable with high operating costs. Added to these limitations is the fact that these extreme conditions affect the quality of the final product. In this respect, adopting high temperatures is known to be responsible for inducing and/or accelerating degradation processes in food. The specific conditions of the process described in the cited patent application, and in particular the treatment conducted at 0.01 torr and 85°C, can cause undesirable changes in the compositional, nutritional and sensory characteristics of the food.

It is therefore evident that the need exists for a process for removing acrylamide from starch-based foods subjected to high temperature heat treatments such that acrylamide formation is induced. One purpose of the present invention is therefore to provide an efficient process for removing acrylamide from finished foods comprising treatment conditions which are mild and such as not to cause sensory changes in the food itself. A further purpose of the present invention is the provision of an efficient method for removing acrylamide from finished foods which is easily industrialized and which has moderate operating costs. Summary of the invention Consequently, to fulfil the said purposes, the present invention provides a process

for removing acrylamide from foods under mild conditions which do not cause sensory changes therein.

The process of the invention removes acrylamide from foods in a physical manner by making use of the passage from solid phase to vapour phase of the substance. The present invention therefore provides a process for removing acrylamide from foods characterized in that said removal is obtainable by subjecting foods to a treatment under suitable pressure and temperature conditions whereby the pressure is between 0.02 and 0.5 torr and the temperature is between 35°C and 75°C. For the purposes of the present invention, treatment of the foods at the defined pressures and temperatures is conducted for a period of at least 30 minutes. Detailed description of the invention

The objectives and advantages of the process for acrylamide removal from finished foods, according to the present invention, will be better understood from the following detailed description in which the general process and examples of the process applied to finished foods will be described by way of non-limiting illustration.

The process of acrylamide removal described herein finds useful application in the food and agriculture industry and in particular in the industrial preparation of carbohydrate-containing ready-to-eat foods and those subjected to heat treatment, particularly starch-based foods such as potatoes and potato-based products, cereals and cereal-based products, rice and rice-based products and in particular, for example, chips, French fries, pasta, bread, snacks, biscuits and coffee. The conditions under which acrylamide passes from the solid to vapour phase are known, and comprise specific temperature and pressure combinations, for example at a pressure of 5 torr the corresponding temperature is 103°C and at 0.01 torr the corresponding temperature is 26°C. Despite this fact the conditions to be applied for removing solid acrylamide are not immediately obvious, when incorporated within the solid mass of the treated food, likewise the processing conditions suitable for acrylamide removal without inducing processes that alter the physico-chemical characteristics of the finished

food are also not obvious. Indeed it is very important for product appreciation that the acrylamide is not only removed but that degradation processes and/or changes to sensory characteristics, being undesirable to the consumer, are non triggered.

The process of the invention provides the conditions for efficiently removing acrylamide without impairing the sensory characteristics of the treated food.

To accomplish the purposes of the invention, the conditions to be applied for removing acrylamide are pressures within the range from 0.02 to 0.5 torr and temperatures within the range from 35°C to 75°C. Preferably, the pressure applied is between 0.05 and 0.2 torr and the temperature is between 45°C and

62°C. Even more preferably the pressure is 0.1 torr and the temperature is 55°C.

Foods can be subjected to the aforedescribed treatment for a time of at least 30 minutes, preferably for a time between 30 and 90 minutes and even more preferably for a time of 60 minutes.

By applying the process conditions defined by the invention, acrylamide removal is at least 50% and can attain values of around 80-95%.

In this respect, by applying a treatment conducted at a pressure of 0.1 torr and at a temperature of 55°C in a model system, the results relating to removal of acrylamide given in table 1 below, are obtained.

Table 1 : Concentration of acrylamide in a model system during treatment conducted at a pressure of 0.1 torr and at a temperature of 55°C for different treatment times.

Furthermore, the process of the invention presents the additional advantage of removing moisture to an industrially acceptable level. A decrease in moisture is simultaneously obtained in a percentage which depends on its initial content in the food. In foods with a low-medium moisture level, water removal under the

determined process conditions is less than 20%. Such drying is not only industrially acceptable, but is also usually implemented industrially by food drying steps. For example, most baked products and cereal- and potato-based snacks in which acrylamide forms actually require a drying step after cooking to achieve moisture levels of less than 3%. At these moisture levels, the product is stable from the microbiological viewpoint and acceptable from a sensory viewpoint. With the process of the invention two results are hence obtained, both important from the industrial viewpoint: on the one hand, acrylamide removal and on the other, a determined extent of drying suited to the preservation of the food, hence eliminating additional food drying steps. This advantage can hence be added to the aforesaid advantages deriving from the fact that with the process neither the formulation of the foodstuff nor the cooking process is modified. The acrylamide removal process of the invention typically consists of introducing the finished food into a chamber into which one of the vacuum and temperature conditions proposed for implementing the objectives of the invention is applied, this being preferably 0.1 torr and 55°C. Maintenance of the food under the aforesaid temperature and pressure conditions varies from 30 minutes to 90 minutes. At the end of the process the food is removed and packaged in accordance with usual methods. Example of acrylamide removal from potato chips

100 g batches of potato chips were introduced into a chamber to which a pressure of 0.1 torr and a temperature of 55°C were subsequently applied. The experiments were conducted while maintaining the samples in the chamber for time periods between 30 minutes and 6 hours. The acrylamide and water content were then measured.

Acrylamide was measured by gas chromatography-mass spectrometry combined with solid-phase microextraction (SPME/GC-MS), in accordance with the method modified by Lagalante and Felter (Lagalante, A.F., Felter, M. A., 2004 J.Agric.Food Chem. 52, 3744-3748). Briefly, this method consists of the following consecutive steps: extracting the acrylamide from the food matrix with acetonitrile in the presence of the internal standard (2,3,3[ ² H ₃ ] acrylamide) and subsequent silanization with bis(trimethylsilyl)trifluoroacetamide (BSTFA); adsorbing the

vapour phase of the silanized acrylamide onto polydimethylsiloxane fibre; thermal desorbing of the acrylamide in the gas-chromatographic injector; separating, identifying, and quantifying the acrylamide (GC-MS analysis). Moisture was measured according to the AOAC method (Official method 985.14, 1995) which consists of determining the variation in moisture after totally drying the sample at

105°C for 15 hours.

The results obtained are given in table 2 below:

Table 2: Acrylamide concentration and moisture content of potato chips during a treatment conducted at a pressure of 0.1 torr and a temperature of 55°C for different treatment times.