Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-03-28T19:08:17Z No. of bitstreams: 1 2017 - Yuri Duarte Porto.pdf: 1910618 bytes, checksum: 969c177c9241195f2d92cb156f231abb (MD5) / Made available in DSpace on 2018-03-28T19:08:17Z (GMT). No. of bitstreams: 1 2017 - Yuri Duarte Porto.pdf: 1910618 bytes, checksum: 969c177c9241195f2d92cb156f231abb (MD5) Previous issue date: 2017-04-06 / CAPES / Corn is one of the most cultivated cereals in Brazil and it is susceptible to contamination by mycotoxins that are toxic secondary metabolites produced by fungi. An adoption of quality management systems during a corn production chain is essential to ensure food safety concerning mycotoxin contamination. However, there is a possibility that these recognized carcinogenic metabolites may already be found in the matrix. Hence the search for alternative solutions capable of reducing contamination to safe levels by the application of emerging technologies has been intense. The methods of decontamination of foods must to obey some premises as: inactivate, destroy or remove the toxins; do not produce others toxic waste; maintain the nutritional value and acceptability of the product. Ozone, which meets almost all of these characteristics, is recognized by the Food and Drug Administration as a GRAS (Generally Recognized as Safe) product for use as a sanitizer in food processing. Since then its use has been investigated in several types of food, including cereals contaminated by mycotoxins. Corn canjiquinha is a cultural food easily accessible by Brazilian consumers at low prices, as well as posing a potential risk of exposure due to contamination with aflatoxins. In this study, aliquots of canjiquinha samples were inoculated with concentrations of 106 CFU/g conidia of Aspergillus spp. and Fusarium spp. previously isolated from this food. Other aliquots were contaminated with aflatoxins B1, B2, G1 and G2 at a concentration of 50 ?g/kg for each. The application of gaseous ozone was tested in different combinations of exposure time, ozone concentration and canjiquinha mass, being these independent variables investigated. After treatment by ozonation, to evaluate the effects on aflatoxin concentrations, the samples were analyzed by high-performance liquid chromatography with fluorescence detection (HPLC-FD system) with pre-column derivatization (C18) by trifluoroacetic acid (TFA). The analytical method used in this study was optimized and parameters such as accuracy, precision, linearity, selectivity, limits of detection and limits of quantification of the analytical method were previously evaluated. Additionally, aflatoxin quantification tests were carried out on commercial samples of corn kernels. The method was adequate and presented recovery values within the range of 80-110% with a coefficient of variation of less than 15%, with detection and quantification limits equal to 0.8 and 3.6 ?g/kg, respectively, for each of the aflatoxins. Isolation of fungi was carried out according to the criteria of the Brazilian Ministry of Agriculture. Thus, the efficacy of gaseous ozonation on aflatoxin levels B1, B2, G1 and G2 and on microbial contamination of canjiquinha grains showed reductions of up to 57% in aflatoxin levels. The total fungal count had a reduction of about 3.0 log cycles UFC/g and the total counts of mesophiles were reduced to undetectable levels. These results demonstrated that ozonation is an effective alternative to reduce microbial contamination and the concentration of aflatoxins in corn kernels and, consequently, can improves the safety of this product. / O milho ? um dos cereais mais cultivados no Brasil e est? exposto ? contamina??o por micotoxinas que s?o metab?litos t?xicos secund?rios produzidos por fungos. A ado??o de sistemas de gest?o da qualidade durante a cadeia de produ??o de milho ? essencial para garantir a seguran?a do alimento quanto ? contamina??o por micotoxinas. Contudo, h? possibilidade desses metab?licos reconhecidamente carcinog?nicos j? encontrarem-se na matriz. Da? a busca por solu??es alternativas capazes de reduzir a contamina??o para n?veis seguros pela aplica??o de tecnologias emergentes tem sido intensa. Os m?todos de descontamina??o de alimento devem obedecer algumas premissas como: inativar, destruir, ou remover as toxinas; n?o produzir res?duos t?xicos; manter o valor nutricional e a aceitabilidade do produto. O oz?nio atende quase todas estas caracter?sticas, ? reconhecido pelo United States Food and Drug Administration (FDA) como uma subst?ncia GRAS (Geralmente Reconhecido como Seguro) para uso como sanitizante no processamento de alimentos. Desde ent?o sua utiliza??o tem sido pesquisada em diversos tipos de alimentos, incluindo cereais contaminados por micotoxinas. A canjiquinha de milho ? um alimento cultural de f?cil aquisi??o pelo consumidor brasileiro pelo baixo pre?o, al?m de representar um potencial risco de exposi??o por contamina??o com aflatoxinas. Neste estudo, al?quotas de amostras de canjiquinha foram inoculadas concentra??es de 106 UFC/g de con?dios de Aspergillus spp. e Fusarium spp. previamente isolados do alimento. Outras al?quotas foram contaminadas com aflatoxinas B1, B2, G1 e G2 na concentra??o de 50 ?g/kg para cada. A aplica??o de oz?nio gasoso foi testada em diferentes combina??es de tempo de exposi??o, concentra??o do oz?nio e massa de canjiquinha, sendo essas as vari?veis independentes pesquisadas. Ap?s tratamento por ozoniza??o, para avalia??o dos efeitos sobre as concentra??es de aflatoxinas, as amostras foram analisadas por cromatografia l?quida de alta efici?ncia com detec??o por fluoresc?ncia (sistema CLAE-DF) com derivatiza??o pr?-coluna (C18) por ?cido trifluoroac?tico (TFA). O m?todo anal?tico utilizado neste estudo foi otimizado e par?metros como a exatid?o, precis?o, linearidade da faixa de trabalho, seletividade, limites de detec??o e limites de quantifica??o do m?todo anal?tico foram previamente avaliados. Adicionalmente efetuaram-se ensaios para quantifica??o das aflatoxinas em amostras comerciais de canjiquinha de milho. O m?todo mostrou-se adequado e apresentando valores de recupera??o dentro da faixa de 80-110% com coeficiente de varia??o menor que 15%, sendo os limites de detec??o e quantifica??o iguais a 0,8 e 3,6 ?g/Kg, respectivamente, para cada uma das aflatoxinas. O isolamento de fungos foi realizado de acordo com as normas do Minist?rio da Agricultura. Assim a avalia??o da efic?cia da ozoniza??o gasoso sobre os n?veis de aflatoxinas B1, B2, G1 e G2 e sobre a contamina??o microbiana dos gr?os de canjiquinha apresentou redu??es de at? 57% nos n?veis de aflatoxinas. A contagem de fungos totais teve uma redu??o de cerca de 3,0 ciclos log UFC/g e a contagem total de mes?filos foram reduzidas a n?veis n?o detect?veis. Estes resultados demonstraram que a ozoniza??o ? uma alternativa eficaz para reduzir a contamina??o microbiana e a concentra??o de aflatoxinas em canjiquinha de milho e, consequentemente, melhora a seguran?a desse produto.