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Food ingredients decontamination by steam and irradiation

Steam and irradiation as complementary methods for decontamination and preservation of food ingredients. Optimization of the process and evaluation of physicochemical and microbiological characteristics.

The use of condiments and spices in the food industry is an area where the quality of the raw material is a constant concern. Since these products are of agricultural origin, they are consistently associated with a high microbial load originated in particular from soil and handling. This microbial load can then result in a rapid spoilage of the foods they are supposed to enhance. Furthermore, the presence of pathogenic bacteria like Clostridium perfringens, Staphylococcus aureus, Salmonella spp. and Bacillus cereus, and high levels of mycotoxins (aflatoxins and ochratoxin A) has also been extensively reported, which makes these products potential hazards for consumers’ health. Decontamination of condiments and spices with steam or with chemical fumigants such as ethylene oxide (EtO) are already in use. The heat treatment is particularly sensitive in the processing of herbs and spices as some volatile components can be lost, compromising the main characteristics of this type of product and under which lies their greatest commercial value. Sterilization by chemical fumigation constitutes a recognised hazard for operators’ health and to the environment; some of the chemicals used are included by the international cancer research organization in the list of carcinogens. There is also a possibility of the presence of residual amounts of those chemicals sprayed on plants. The disinfestation with fumigants is quite effective but nevertheless limited to a surface effect due to its low penetration ability, unlike other methods such as heat or irradiation. One technology that has shown an increasing application is irradiation, a physical non-thermal process, which in addition to significantly reducing microbial load, is a simple, modern, and clean method authorized in several countries, including in Europe (Directive 1999/2/EC). However, this method must be validated for each matrix since the results vary significantly with the type of food, radiation dose, food geometry (which affects dose uniformity), in order to understand how the major nutrients are preserved and simultaneously guarantee the microbial decontamination. Data for 2005 indicate that around 190 000 ton/year of irradiated plants were sold. However, despite the obvious benefits of this decontamination treatment, there is still a non-acceptance by some consumers due to fear and confusion about radiation and the lack of understanding of the process. The use of irradiation in food processing has been further validated by international organizations such as FAO - United Nations Food and Agriculture Organization, WHO- World Health Organization, and its use is currently regulated by Codex Alimentarius (CODEX STAN 106-1983, Rev. 1 -2003 ) and the EU Directive 1999/2/EC; in particular, the application of this type of processing applied to plants and spices does not need special permission from each member of the EU, as regulated in Directive 1999/3/EC, transposed into national law by Decree-Law No 337/ 2001 of 26th December. The present project aims to evaluate the feasibility of using steam and ionizing radiations, gamma and e-beam, for food treatment as alternatives to fumigation in dried herbs and spices. The optimization of the microbial and mycotoxin decontamination process will be carried out, in agreement with the evaluation of physico-chemical and microbiological characteristics throughout storage. The impact of the treatments on microbial inactivation will be studied by applying challenging tests. For that matter, samples will be artificially contaminated with known concentrations of moulds and bacteria (e.g. E. coli; Salmonella sp., Aspergillus spp.), submitted to different treatments and final microbial loads compared to those initially introduced. In this way, experiments will be carried out before and after the treatments using conventional culture methods to assess the efficiency of microbial inactivation in this specific matrix. Following these controlled experiments, inactivation efficiency will be confirmed in a limited number of naturally contaminated samples. The microbiological parameters to be evaluated will be: Total counts of the bacterial and fungal populations; detection of potential pathogenic microorganisms (Escherichia coli; Staphylococcus aureus; Salmonella sp.). Mycotoxicological tests will also be applied. For this, samples will be artificially contaminated with known amounts of aflatoxins and ochratoxin A and decontamination efficiency determined after each treatment. Mycotoxins will be quantified by high performance liquid chromatography coupled to fluorescence detection (HPLC-FLD). Various methods will be considered for studying the impact of the treatment (by steam or by irradiation) in the organoleptic changes of volatile compounds: gas chromatography coupled to flame ionization detection (GC/FID), GC coupled to mass spectrometry (GC/MS), HPLC-FLD, and sensory evaluation.
Acronym: 
SteamRadSter
Project ID: 
9 147
Start date: 
02-05-2014
Project Duration: 
24months
Project costs: 
1 000 000.00€
Technological Area: 
Food Processing
Market Area: 
Cultivation of cereals / crops / vegetables

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