O presente estudo foi dividido em duas fases; a primeira visou avaliar o desempenho de diversos meios de cultura, para fungos, no ar de ambientes de produção de alimentos, através da resposta de contagem e identificação dos gêneros que podem conter espécies indesejáveis; também foi avaliada a condição ambiental juntamente com a contagem total de bactérias. O ambiente de duas áreas foi utilizado para a pesquisa, uma indústria de doces, produção de doce de leite e doce de amendoim, na Cidade de Ribeirão Preto (SP) e, outra, uma indústria de embutidos, nos setores de empacotamento e produção, na Região de Piracicaba (SP). Os meios de cultura utilizados foram: "ichloran Rose Bengal Chloramphenicol Ágar" RBC), "Sabouraud Dextrose a 4% Ágar", "Malt Ágar" (MA), "Malt Extract Agar - Yeast and Molds" (MEAYM), "Plate Count Ágar-Cloranfenicol" (PCA-Cloranfenicol), "Dichloran 18% Glycerol Ágar" (DG 18), Batata Dextrose Ágar (BDA) e "Oxytetracycline Glucose YeastAgar" (OGY); para a contagem de bactérias foi utilizado o meio "Plate Count Agar" (PCA). Cada um dos pontos foi amostrado em triplicata utilizando um amostrador de impactação linear. A segunda fase do projeto avaliou os meios de cultura "Dichloran Rose Bengal Chloramphenicol Ágar" (DRBC), "Sabouraud Dextrose a 4% Ágar" selecionados da primeira fase. Novas coletas foram realizadas amostrando cinco repetições em cada um dos pontos, que permaneceram os mesmos da primeira fase. Em paralelo foram utilizadas culturas puras de Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Aspergillus parasiticus, Fusarium moniliforme, Fusarium verticulloides, Histoplasma capsulatum e Stachybotrys chartarum, inoculando os dois meios selecionados e avaliando o desenvolvimento desses fungos ao longo do período de incubação de sete dias, a 28ºC, para servir de parâmetro de comparação com as coletas de ar realizadas no mesmo período, a fim de se verificar se algum desses fungos indesejáveis estaria presente nas amostras de ar. De acordo com os resultados obtidos, os meios DRBC e Sabouraud Dextrose a 4% Ágar, foram, estatisticamente, melhores que os demais meios testados, apresentando um maior número de unidades formadoras de colônias/m3. O meio de Extrato de Malte diferenciou estatisticamente dos demais e teve o menor desempenho para a quantificação desses microrganismos no ar. A recomendação do melhor meio para identificação de fungos no ar de indústrias alimentícias não foi conclusiva, com exceção do PCA-Cloranfenicol que apresentou baixa diversidade de gêneros, sendo considerado reprovado. No geral foi observado um número elevado de unidades formadoras de colônias de fungos e bactérias/m 3 durante as amostragens. A avaliação quali-quantitativa dos ambientes estudados sugere que esses não se encontram em condições adequadas, sendo necessária a elaboração de um padrão referencial para o monitoramento da indústria alimentícia em nosso país. O amostrador utilizado nas coletas promoveu rapidez nas coletas e proporcionou a expressão dos resultados em medidas confiáveis, por ser um equipamento que permite calibração em seu sistema de aspiração de ar. / The present study consisted of two phases. The first one aimed at evaluating the performance of different culture media for fungi found in the air of food production environments, through the results of counting and identifying genders that may contain undesirable species. The environmental condition was also evaluated along with a total bacteria counting. The present work took place in two different places, an industry which produces sweets made from milk or peanuts, in Ribeirao Preto city (SP) and, in the packing and production sections of a meat encased products industry located in Piracicaba region (SP). The culture media used were: "Dichloran Rose Bengal Chloramphenicol Agar (DRBC)", "Sabouraud Dextrose 4% Agar (MA)", "Malt Extract Agar - Yeast and Molds (MEAYM)", "Plate Count Agar - Chloramphenicol (PCA-Chloramphenicol)", "Dichloran 18% Glycerol Agar (DG 18)", "Potato Dextrose Agar (BDA)" and "Oxytetracycline Glucose Yeast Agar (OGY)". The medium used for the bacteria counting was "Plate Count Agar (PCA)". Three replicates of each sampled spot were obtained by using a linear impacting sampler. The second phase of this project evaluated the following culture media, selected during the first phase of this study: "Dichloran Rose Bengal Chloramphenicol Agar (DRBC)" and "Sabouraud Dextrose 4% Agar". New sample collections (five replicates) were carried out for each of the spots selected. The sampled spots were the same for both phases. In a parallel manner, pure cultures of Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Aspergillus parasiticus, Fusarium moniliforme, Fusarium verticulloides, Histoplasma capsulatum and Stachybotrys chartarum were employed to inoculate the two selected media. The development of these fungi was evaluated throughout a 7-day-incubation period, at 28ºC, to function as a comparative reference for the air samples obtained in the same period in order to verify if any of these undesirable fungi was present in the air samples. According to the results obtained, DRBC and Sabouraud Dextrose 4% Agar media were statistically superior than the others, presenting a higher number of colony forming units/m3. The Malt Extract medium was statistically different from the others and showed the worse performance as to the quantification of microorganisms present in the air. There was no conclusive recommendation as to the best medium for the identification of fungi found in the air of food industries, except for PCA-Chloramphenicol, which showed low diversity of genders and was discarded. In general, a high number of fungi and bacteria colony forming units/m3 was observed during the sampling procedures. The qualitative-quantitative evaluation of the environments studied suggests that they do not present adequate conditions, evidencing the need for the establishment of a referential standard in order to monitor food industries in our country. The sampler used in this work allowed a quick sample collection and a reliable expression of results, as this equipment enables the calibration of its air intake system.

No Brasil, a multimistura vem sendo utilizada há mais de 25 anos como uma opção para combater a desnutrição infantil da população carente. Entretanto, seu uso ainda é motivo de controvérsias principalmente quanto à presença de fatores antinutricionais, à qualidade microbiológica e seu valor nutricional. Considerando o uso rotineiro da multimistura na região, esse trabalho teve como objetivo avaliar amostras de multimisturas coletadas na Região Metropolitana de Belo Horizonte/MG para determinação: dos fatores antinutricionais, da qualidade microbiológica, da composição centesimal e mineral, e ainda do efeito induzido pela radiação nestes fatores. Para as análises, as amostras passaram pelo processo de irradiação gama nas doses de: 2, 4, 6, 8 e 10 kGy e posteriormente foram avaliados os fatores antinutricionais (ácidos fítico e oxálico), a qualidade microbiológica (bolores e leveduras, Salmonella, Staphylococcus coagulase positiva, Bacillus cereus, coliformes a 45 C) a composição centesimal (umidade, cinzas, proteínas, lipídeos e carboidratos) e a eficiência do método de Ressonância Paramagnética Eletrônica (RPE) na detecção de amostras irradiadas. A composição mineral das amostras foi realizada através da irradiação por Ativação Neutrônica. As metodologias utilizadas foram pesquisadas na literatura. Os resultados obtidos sugerem que os teores dos ácidos fítico e oxálico podem não ser adequados às crianças com déficit nutricional grave e que seria necessário controle na ingesta dos mesmos devido ao poder complexante com os minerais. Em geral as amostras apresentaram qualidade microbiológica aceitável para consumo, exceto em uma das amostras, porém identificou-se a presença de produtores de micotoxinas. Os dados da composição centesimal e mineral, nas porções usualmente recomendadas, mostraram que os macronutrientes e os minerais, apresentaram-se em aquém do recomendado para a faixa etária. Não houve alteração significativa nos teores dos ácidos fítico e oxálico e na composição centesimal após a irradiação gama. A ressonância paramagnética eletrônica foi capaz de detectar amostras irradiadas. / In Brazil, the multimixture have being used since the eighties as an alternative against severe infantile malnutrition of the poorest population. However, its use is still reason of controversies mainly due to: the presence of anti nutritional factors, the microbiological quality and the nutritional value. Considering the routine use of multimixture in the region, this work aimed to evaluat samples of multimixture were collected in the metropolitan area of the City of Belo Horizonte/MG for determining the anti nutritional factors (phytic and oxalic acids), the microbiological quality, the centesimal and mineral composition, and still the induced effect in these factors of the gamma radiation. For the analyses, the samples passed by the process of gamma irradiation at doses of: 2, 4, 6, 8 and 10 kGy and then were evaluated antinutritional factors (phytic acid and oxalic), the microbiological quality (yeasts and molds, Salmonella, Coagulase positive Staphylococcus, Bacillus cereus, coliform to 45 C) to full percentage (moisture, ash, proteins, carbohydrates and lipids) and the efficiency of the method of Paramagnética Electronics Resonance (EPR) in the detection of irradiated samples. The mineral composition of the samples was carried out by the irradiation by Activation Neutrônica. The methods used were searched in literature. The obtained results suggest that the concentration of the phytic and oxalic acids can not be appropriated for the children with severe nutritional deficit and that it would be necessary additional control in their daily ingestion due to the absorption of essential minerals. In general the samples had presented acceptable microbiological quality for consumption, except by one of it. The data of the centesimal and mineral composition, in the usually recommended portions, showed lower concentration than recommended for children. Any significant alteration in phytic and oxalic acids as well as in the centesimal composition were detected after gamma irradiation. The electronic paramagnetic resonance can be detected irradiated samples.

Os processos de tratamento térmico por meio do aquecimento ôhmico revelam-se bastante promissores. A tecnologia de processamento de alimentos através do aquecimento ôhmico tem mostrado a obtenção de um produto final com características sensoriais e nutricionais superiores, quando comparada aos métodos convencionais (trocadores de calor ou banho de água). A principal vantagem atribuída ao aquecimento ôhmico é a habilidade de aquecer materiais rapidamente e de modo uniforme possibilitando desta forma a redução do abuso térmico aos produtos. A construção de um equipamento de aquecimento ôhmico foi realizada e seu funcionamento avaliado. Alguns pontos críticos para o funcionamento do equipamento foram encontrados e avaliados. Dentre os principais pontos críticos avaliados estão: o sistema de medição de temperatura e a distribuição dos campos elétricos. A avaliação destes pontos críticos possibilitou a realização de novo projeto de equipamento com o objetivo de otimizar a aplicação do aquecimento ôhmico. Realizou-se estudo comparativo da velocidade de inativação da fluorescência da proteína verde fluorescente (GFPuv) e da inativação da atividade da bacteriosina nisina, quando submetidas a aquecimento convencional (banho d\'água) e ôhmico, com o objetivo de avaliar a influencia da presença de campos elétricos. Leituras em λex = 394 nm, λem = 509 nm para excitação e emissão respectivamente para a GFPuv e avaliação por halo de inibição para a atividade da nisina foram realizadas periodicamente após tratamento térmico por metodologia convencional e ôhmica a temperaturas de 60º, 70º e 80ºC para GFPuv e de 70ºe 80ºC para a nisina. Os resultados indicam que para ambos, GFP e nisina, a presença de campos elétricos não influencia de modo significativo o comportamento quando comparada a tecnologia de aquecimento ôhmico e convencional. / Ohmic heating is an emerging technology that possesses many actual and future applications. One of the most promising applications for this technology is food processing. Ohmic heating has demonstrated to achieve better sensorial and nutritional values when compared to conventional heating (heat exchangers/water bath). The principal advantage of ohmic heating is the ability to heat materials rapidly and uniformly making possible to reduce thermal abuse to products. An ohmic heating equipment was constructed and evaluated. Critical functioning points were observed on the manufactured equipment and were evaluated. Among the observed critical points include the temperature measurement system and the distribution of the electric fields on the extension of the equipment\'s container. As a result of the evaluation of those critical points a new equipment project was created aiming to optimize the ohmic heating unit. The influence of the electric field over the fluorescence decay of the green fluorescent protein (GFPuv) and over nisin activity decay was evaluated. Fluorescence readings were performed at λex = 394 nm, λem = 509 nm for excitation and emission respectively for GFPuv and activity readings were performed by inhibition halo for nisin after several thermal treatment periods on ohmic and conventional heating. Samples were heated by conventional and ohmic heating at 60º, 70º and 80ºC for GFPuv and at 70º, 80º and 90ºC for nisin. The observed results indicate that the incidence of electric fields did not presented significative influence on the fluorescence decay of GFPuv or on the activity of nisin when ohmic heating was compared with conventional heating.

O objetivo do presente trabalho foi avaliar os sistemas de gestão da segurança de alimentos de indústrias de vegetais minimamente processados (VMP) do Rio Grande do Sul, avaliar a inativação de Salmonella Enteritidis (SE86) em alfaces submetidas aos diferentes métodos de lavagem e desinfecção observados nas indústrias investigadas e, por fim, elaborar uma proposta de regulamento técnico de Boas Práticas de Fabricação (BPF) para o setor. Cinco indústrias foram visitadas a fim de investigar os fatores contextuais e os sistemas de segurança de alimentos implementados. Em seguida, os métodos de lavagem e desinfecção observados em cada indústria foram simulados em laboratório e alfaces artificialmente inoculadas com S. Enteritidis SE86 foram submetidas a cada um deles. Com base nessas avaliações e outros documentos técnicos, elaborou-se uma proposta de legislação para indústrias de VMP. Os resultados demonstraram que as indústrias estavam operando em um contexto de alto risco, sem os controles necessários para a redução dos mesmos. Foi demonstrada a necessidade de melhorias em relação aos controles de fornecedores, instalações, design higiênico de equipamentos, programas de manutenção e calibração de equipamentos, programas de higienização, registros, capacitação de funcionários, bem como, na realização de análises microbiológicas do produto final. Nenhuma empresa demonstrou implementação completa das BPF, Procedimentos Operacionais Padronizados (POP) ou implementação de sistema Análise de Perigos e Pontos Críticos de Controle (APPCC). Os resultados laboratoriais indicaram que as indústrias estavam realizando procedimentos de lavagem e desinfecção capazes de reduzir significativamente contagens de S. Enteritidis SE86, porém, em nível industrial, a concentração de sanificante, o pH, a concentração de matéria orgânica e temperatura de água não estavam sendo controlados, o que sugere alto risco. Em vista dos resultados, recomendações foram realizadas na proposta de legislação de BPF e POP, as quais foram adicionadas a RDC 275/2002 (ANVISA) aplicável às indústrias de alimentos brasileiras. Foi sugerido a inclusão de dois POP, o primeiro referente a seleção dos fornecedores de matéria-prima (frutas e vegetais frescos) e o segundo com relação ao processo de lavagem e desinfecção. Além disso, no corpo da proposta, foi sugerido a adição de monitoramento e verificação das temperaturas das câmaras frias, capacitação adequada e contínua de pessoal sobre higiene e manipulação de alimentos e riscos associados a produção e consumo de frutas e vegetais frescos. Também sugeriu-se a obrigatoriedade de Responsável Técnico comprovadamente capacitado para orientar e controlar a implementação e continuidade dos sistemas de gestão da segurança de alimentos. As recomendações foram divididas entre aquelas de curto, médio e longo prazo, sendo as de curto prazo a implementação de controles do processo, principalmente nas etapas de lavagem e desinfecção e análises microbiológicas de produto final. As de médio prazo foram a seleção de fornecedores com Boas Práticas Agrículas (BPA) implementadas, bem como a implantação completa de BPF nas indústrias de VMP. Finalmente, a medida a ser implementada a longo prazo foi a implementação de APPCC. A Proposta de Regulamento específico para VMP pode ser discutida com o setor regulado, para em seguida ser encaminhada para consulta pública e possível publicação pela Vigilância Sanitária Estadual. Essas ações são propostas, a fim de melhorar a segurança dos VMP e desenvolver o setor. / The aim of this study was to evaluate Safety Management Systems of minimally processed vegetable industries (VMP) of Rio Grande do Sul, evaluate the inactivation of Salmonella Enteritidis (SE86) in lettuces exposed to different washing methods and disinfection observed in the investigated industries and, finally, prepare a draft technical regulation for Good Manufacturing Practices (GMP) for the sector. Five industries were visited to investigate the contextual factors and the implemented food safety systems. Then, the cleaning and disinfecting methods observed in each industry were performedin laboratory, by inoculating S. enteritidis SE86 on lettuces and subjecting to them. Based on these assessments and other technical documents, it was drawn up a proposed for legislation to VMP industries. The results showed that the industries were operating in a high risk environment, without the necessary control to reduce the risk. It has demonstrated the need for improvements in relation to suppliers of controls, facilities, hygienic equipment design, maintenance programs and calibration equipment, hygiene programs, records, employee training, as well as in carrying out microbiological analyzes of the final product. No company demonstrated full implementation of GMP, Standard Operating Procedures (SOP) or the implementation of Hazard Analysis System and Critical Control Points (HACCP). The laboratory results indicated that the washing and disinfection procedures performed in industries can significantly reduce S. Enteritidis SE86 counts, however, at the industrial level, the concentration of sanitizing, pH, concentration of organic matter and water temperature were not It is controlled, suggesting a high risk. In view of the results, recommendations were made in the proposed GMP and SOP legislation, which were added to DRC 275/2002 (ANVISA) applicable to Brazilian food industries. The inclusion of two SOP has been suggested, the first relating to the selection of suppliers of raw materials (fruits and vegetables) and the second with respect to the washing and disinfection process. In addition, the body of the proposal, it was suggested the addition of monitoring and checking temperatures of cold rooms, adequate and continuous training of personnel on hygiene and food handling and risks associated with production and consumption of fresh fruits and vegetables. It also suggested to proven capable mandatory technical manager to guide and monitor the implementation and continuity of Food Safety Management Systems. The recommendations were divided into short, medium and long term. Short term was the implementation of process controls, especially in the washing and disinfection steps and microbiological analyzes of the final product. Medium-term was the selection of suppliers with Good Agricultural Practices (GAP) implemented, as well as the full implementation of GMP in the VMP industries. Finally, the measure to be implemented in the long term was the implementation of HACCP. The Proposal for a Regulation specific to VMP can be discussed with the regulated sector, to then be sent for public consultation and possible publication by the State Sanitary Surveillance. These actions are proposed in order to improve the safety of VMP and develop the sector.

Os processos de tratamento térmico por meio do aquecimento ôhmico revelam-se bastante promissores. A tecnologia de processamento de alimentos através do aquecimento ôhmico tem mostrado a obtenção de um produto final com características sensoriais e nutricionais superiores, quando comparada aos métodos convencionais (trocadores de calor ou banho de água). A principal vantagem atribuída ao aquecimento ôhmico é a habilidade de aquecer materiais rapidamente e de modo uniforme possibilitando desta forma a redução do abuso térmico aos produtos. A construção de um equipamento de aquecimento ôhmico foi realizada e seu funcionamento avaliado. Alguns pontos críticos para o funcionamento do equipamento foram encontrados e avaliados. Dentre os principais pontos críticos avaliados estão: o sistema de medição de temperatura e a distribuição dos campos elétricos. A avaliação destes pontos críticos possibilitou a realização de novo projeto de equipamento com o objetivo de otimizar a aplicação do aquecimento ôhmico. Realizou-se estudo comparativo da velocidade de inativação da fluorescência da proteína verde fluorescente (GFPuv) e da inativação da atividade da bacteriosina nisina, quando submetidas a aquecimento convencional (banho d\'água) e ôhmico, com o objetivo de avaliar a influencia da presença de campos elétricos. Leituras em λex = 394 nm, λem = 509 nm para excitação e emissão respectivamente para a GFPuv e avaliação por halo de inibição para a atividade da nisina foram realizadas periodicamente após tratamento térmico por metodologia convencional e ôhmica a temperaturas de 60º, 70º e 80ºC para GFPuv e de 70ºe 80ºC para a nisina. Os resultados indicam que para ambos, GFP e nisina, a presença de campos elétricos não influencia de modo significativo o comportamento quando comparada a tecnologia de aquecimento ôhmico e convencional. / Ohmic heating is an emerging technology that possesses many actual and future applications. One of the most promising applications for this technology is food processing. Ohmic heating has demonstrated to achieve better sensorial and nutritional values when compared to conventional heating (heat exchangers/water bath). The principal advantage of ohmic heating is the ability to heat materials rapidly and uniformly making possible to reduce thermal abuse to products. An ohmic heating equipment was constructed and evaluated. Critical functioning points were observed on the manufactured equipment and were evaluated. Among the observed critical points include the temperature measurement system and the distribution of the electric fields on the extension of the equipment\'s container. As a result of the evaluation of those critical points a new equipment project was created aiming to optimize the ohmic heating unit. The influence of the electric field over the fluorescence decay of the green fluorescent protein (GFPuv) and over nisin activity decay was evaluated. Fluorescence readings were performed at λex = 394 nm, λem = 509 nm for excitation and emission respectively for GFPuv and activity readings were performed by inhibition halo for nisin after several thermal treatment periods on ohmic and conventional heating. Samples were heated by conventional and ohmic heating at 60º, 70º and 80ºC for GFPuv and at 70º, 80º and 90ºC for nisin. The observed results indicate that the incidence of electric fields did not presented significative influence on the fluorescence decay of GFPuv or on the activity of nisin when ohmic heating was compared with conventional heating.

<p>Mathematical modeling of heat transfer is a common method utilized in designing thermal processes for food, modeling degradation kinetics of microorganisms and nutrients, designing food processing equipment as well as for process optimization and for ensuring scale-up feasibility of a product. It is essential to have all the necessary components for modeling including the geometry, boundary conditions, initial temperature, and the temperature-dependent thermal properties. Getting temperature-dependent thermal properties of food product is difficult due to the lack of effective and efficient devices or techniques. To show the influence of temperature-dependent thermal properties, retort processing of potato soup was simulated using both temperature-dependent (dynamic) and fixed thermal properties. Three methods, TPCell, Choi-Okos predictive model and KD2 Pro, were used to determine the thermal conductivity at 25°C and 120°C for comparison. The proximate composition of the sample was determined for prediction of thermal properties with the Choi-Okos model. The accuracy of simulation was evaluated based on the temperature at the cold spot and corresponding sterilization value. Results suggested that using temperature-dependent thermal properties in heat transfer modeling increased the accuracy of the simulation. Simulation performed with temperature-dependent properties obtained from TPCell matched very closely with experimental heat penetration data. Additionally, the sensitivity of temperature-dependent thermal properties obtained from TPCell in detecting variation in product formulation was evaluated. Four variations of potato soup were prepared to compare their respective lethality value. Thermal conductivity, specific heat capacity and density of the potato soups were measured, and simulation was performed using the measured thermal properties and a scheduled process as boundary conditions. Thermal properties of food product changed with the formulation which affected the processing time to achieve minimum lethality value. A significant difference in thermal conductivities was seen for these potato soups causing the scheduled process to be only suitable for thermal processing of some formulations while others would be undercooked that could lead to food safety risk. Since the thermal conductivity measurements were sensitive in detecting the difference in the formulation, it can be used as a tool to select a formulation that can best suit the processing conditions of the heat penetration tests. The technique described can be used for any thermal processes in the food industry including pasteurization, retort, and aseptic processing. This application will be beneficial for the industry to pre-screen the iterations and only select formulation that suits the scheduled process for successful heat penetration trials and reduce trial costs.</p>

Carragenanas, agaranas e alginatos são hidrocolóides largamente utilizados em todo tipo de produtos alimentícios como aditivos espessantes. Eles não são absorvidos pelo organismo e, portanto não introduzem calorias extras na dieta. A irradiação se apresenta com grande potencial como um método alternativo na preservação de alimentos pois não induz aumento da temperatura, e é, portanto, de grande eficácia na descontaminação de ingredientes alimentícios sensíveis ao calor. Neste trabalho, soluções dos hidrocolóides agararana, carragenana e aiginato de sódio, foram irradiadas com diferentes doses (0-10 kGy) de radiação gama de Co-60 na presença de antioxidantes também utilizados na indústria alimentícia: ácido ascórbico, extrato vegetal de rosela (Híbiscus sabdariffa L.) e isofiavona de soja. As soluções dos polissacarídeos comestíveis agarana, carragenana e alginato de sódio mostraram ser bons sistemas para avaliar o efeito da radiação ionizante por apresentarem radiossensibilidade característica medida pelas mudanças na viscosidade. Os resultados obtidos mostram que esses antioxidantes apresentam, no geral, ação radioprotetora o que pode ser de grande valia nas aplicações futuras da irradiação de alimentos em escala comercial. / Carrageenan, agaran e alginates are hydrocolloids largely employed in every kind of food products as stabilizing agent and viscosity builder. The human body does not absorb them, so they do not introduce extra calories in the diet. Irradiation is presented as an important alternative method in food preservation because do not induce temperature increase being of good efficiency in cold food ingredients decontamination. In this work aqueous solutions of carrageenan, agar e sodium alginate were gamma irradiated (0-10 kGy) in presence of ascorbic acid, roselle {Hibiscus sabdariffa L.) extract and soy isoflavone. Edible polysaccharide solutions showed to be suitable systems for the evaluation of ionizing radiation effects as they presented a singular radiosensitivity through viscosity changes. The results obtained showed that in general the antioxidants employed had a radioprotective action that can be of importance in the future commercial applications of food irradiation.

Drying with the help of sun and wind is one of the oldest methods of food preservation known to man, but artificial drying, or dehydration, has been developed and used extensively only during the last two decades. The problem in dehydration is that the water content must be decreased sufficiently to maintain the stability of the product by retarding the rates of deteriorative biochemical, microbiological, and enzymatic reactions during subsequent storage. At the same time irreversible changes should not be brought about.

A processing procedure for the manufacture of directly acidified cottage cheese curd from 16% total solids ultrafiltered retentate was developed. The effects of preacidification of skim milk before ultrafiltration and heat treatment of retentate were investigated to improve the functional and sensory qualities of retentate curd. Retentate directly acidified with phosphoric acid and glucono-delta-lactone to pH 4.7 formed a dense, rubbery curd that could not be handled well in a vat. A heat treatment of 71.1°C for 30 min applied to the retentate resulted in a curd with acceptable handling properties. However, this heat treatment caused the curd to shift in pH, become translucent in appearance, and have a pasty texture. Preacidification of the skim milk to pH 5.8 12 h prior to ultrafiltration, and a less severe heat treatment of 71.1°C for 6 min made a stable curd with good sensory quality. A 3 x 4 x 3 randomized split block design experiment was done to test the effects of preacidification and heat treatment on the properties of retentate curd. Skim milk was pasteurized at 62.8°C for 30 min and split into three lots which were unacidified, phosphoric acid added to pH 6.2, and phosphoric acid added to pH 5.85. The three lots of skim milk were ultrafiltered at 54.4°C to 16% total solids. Each lot was divided into four treatments which were unheated, heated to 71.1°C for 7 s, 76.7°C for 7 s, and 82.2°C for 7 s. Each vat was replicated three times. Cottage cheese pH, total solids, and six sensory attributes were measured. Finished cottage cheeses were evaluated by an expert panel of five judges. Total solids, protein content, and fines content of the whey were also measured. Preacidification treatment at pH 6.2 enhanced curd structure, which increased solids recovery, reduced fines, and improved curd appearance, firmness, and texture. Heat treatments caused softening of the curd and increased moisture content in the curd. Excessive heat treatment caused shattering, fines, and mealiness. The best curd from the experiment was produced from pH 6.2 retentate heat treated at 71.1°C for 7 s. Whey proteins decreased in wheys from retentates heat treated at 76.7°C for 7 sand 82.2°C for 7 s. The effects of heat treatment were more pronounced with increasing acidification.

Changes in cheese physical properties during aging are related to proteolysis by coagulant type, culture enzymes, and non-starter lactic acid bacteria (NSLAB). Storage temperature also affects aging rate. Cultures are important for flavor development , but less is understood about their role in melting and textural properties. Our objective was to make Cheddar cheese using different cultures, to age it at 6 and 13°C, and measure physical and proteolytic properties over 12 mo to determine whether changes in texture and melting correlated with the extent of proteolysis that occurred during aging. Cheese was manufactured using Lactococcus lactis starter culture either alone or combined with one or both of Lac Lc. Lactis or Lactobacillus helveticus adjunct cultures . Three replicates of cheese were made using 1500 lb of milk. Cheese composition was 35.5 ± 1.0% moisture, 52.5 ± 2.5% FDB, 1.65 ± 0.05% salt, and pH 5.2 ± 0.1. All cheeses were initially stored at 6°C, then half moved to l3°C after 21 d. Texture profile analysis was performed using 25% and 60% compression and melting measured using a Meltmeter at 65°C. The data were analyzed based on culture and temperature over 12-mo storage time. The overall hardness decreased, while the cohesiveness decreased for all treatments. Extent of melting was significantly correlated with hardness (r = 0.62), cohesiveness (r = 0.40), and inversely with adhesiveness (r = 0.24). Correlations with adhesiveness and cohesiveness were not linear. Proteins were extracted from cheese at 1 wk, 1, 2, 4, 6, 9, and 12 mo of aging using 500 mM sodium citrate solution containing 1% sodium chloride. Purified extracts were then applied to a high-performance liquid chromatography CS reverse phase column and large hydrophobic peptides and protein peaks monitored at 214 nm. Melting was inversely correlated with the amount of intact ɑs1-caserienm remaining in the cheese (r = -0.54) and directly correlated with what was thought to be ɑs1-casein (f 24 - 199) (r = 0.56).