Physical and chemical quality, biodiversity, and thermodynamic prediction of adhesion of bacterial isolates from a water purification system: a case study

The objective of this study was to evaluate the quality of water purification system and identify the bacteria this system, predict bacterial adherence according to the hydrophobicity of these microorganisms and of the polypropylene distribution loop for purified water. The assessment of drinking water that supplies the purification system allowed good-quality physical, chemical, and microbiological specifications. The physicochemical specifications of the distributed purified water were approved, but the heterotrophic bacteria count was higher than allowed (>;2 log CFU mL-1).The sanitation of the storage tank with chlorine decreased the number of bacteria adhered to the surface (4.34 cycles log). By sequencing of the 16SrDNA genes, six species of bacteria were identified. The contact angle was determined and polypropylene surface and all bacteria were considered to be hydrophilic, and adhesion was thermodynamically unfavorable. This case study showed the importance of monitoring the water quality in the purified water systems and the importance of sanitization with chemical agents. The count of heterotrophic bacteria on the polypropylene surface was consistent with the predicted thermodynamics results because the number of adhered cells reached approximate values of 5 log CFU cm-2

Avaliação de revestimento contendo extrato de mostarda e da sanitização na conservação de batata-baroa

Batata-baroa (Arracacha xanthorriza Bancroft) é um produto de alta perecibilidade, devido à perda de massa fresca por transpiração e a deterioração causada por microrganismos. Este trabalho teve por objetivo avaliar o efeito de um revestimento com extrato de mostarda e da sanitização sobre o desenvolvimento de microrganismos em batata- baroa durante o armazenamento em temperatura ambiente. A bactéria fitopatogênica Erwinia carotovora, causadora da podridão-mole, foi inoculada sobre a superfície da batata-baroa, em alguns tratamentos, para acelerar a sua deterioração. Os tratamentos foram: sanitização; sanitização e inoculação; revestimento com extrato de mostarda; revestimento sem extrato de mostarda; revestimento, inoculação e com extrato de mostarda; revestimento, inoculação e sem extrato de mostarda; e sem tratamento. Foram avaliados o desenvolvimento de fungos filamentosos e leveduras e mesófilos aeróbicos; perda de peso; e número de lesões aos 0, 3 e 6 dias de armazenamento. As contagens de fungos filamentosos e leveduras e mesófilos aumentaram durante o armazenamento na ordem de 1,5 e 5,5 ciclos logarítmicos, respectivamente. A sanitização na concentração usada não foi suficiente para inibir o crescimento dos fungos filamentosos e leveduras. A baixa eficiência do extrato de mostarda pode estar relacionada com sua volatilidade. A perda de peso máxima para todos o tratamentos foi de 4,5%. No terceiro dia de armazenamento, o tratamento com sanitização e inoculação apresentou menor número de lesões, enquanto as batatas-baroas submetidas ao revestimento com extrato, inoculadas, e aquelas somente sanitizadas apresentaram elevado número de lesões em relação às demais. O revestimento proporcionou brilho e não interferiu na cor amarela do produto.Peruvian carrot (Arracacha xanthorriza Bancroft) is a highly perishable produce because of the fresh mass loss and deterioration by microorganisms. This work aimed to evaluate the effects of a coating containing mustard extract and the sanitation process on microorganism growth in Peruvian carrots during storage under ambient conditions ( 25 ± 2oC, 74 ± 2%UR). Erwinia carotovora was inoculated on Peruvian carrot surface, in some treatments, to accelerate the produce deterioration. Seven treatments were carried out: sanitation; sanitation and inoculation; coating with mustard extract; coating without mustard extract; inoculation and coating with mustard extract; inoculation and oating without mustard extract, and without treatment (control). Mold and yeast and aerobic mesophilic, mass loss and number of lesions at zero, three and six days of storage. Mold and yeast and mesophilic aerobic counting increased during storage period by 1.5 and 5.5 log-cycles, respectively. Sanitation with 200 ppm chlorine was not efficient to inhibit mold and yeast and mesophilic aerobic. The low efficiency of mustard extract may be related to its volatility. Maximum mass loss was 4.5% for all treatments. Smaller lesion number was found for the inoculated and sanitized treatment, while the Peruvian carrots inoculated and coated with mustard extract and those sanitized showed larger lesion number compared with the other treatments. The coating provided the produce with shining appearance and did not interfere with the yellow color

PHYSICAL CHEMICAL EVALUATION OF THE FREEZING AND DEFROSTING EFFECTS OF MADEIRA SAUCE

Present in most events, madeira sauce stands out for taste and elegance in cooking. Some companies, due to the large number of guests, need to prepare it with some advance. So that, the product can be prepared in this period, to improve the condition of the quality and organoleptic aspects, it is necessary its freezing after preparation. However, due to the freezing, potential problems can be observed, such as segregation of phases and difference to its original aspects. The purpose of this study was to evaluate the production system as well as the process of freezing and thawing of the madeira sauce, aiming to guarantee aspects of freshly prepared sauce. Therefore, physicochemical analysis in order to determine the properties of the fresh sauce were made, obtaining value as 787,92 kg.m-3, 3,85 kJ.kg-1.K-1, 0,53 W.m-1.K-1 e 1,3 x 10-5 m2.s-1 to specific weight, specific heat, thermal conductivity and thermal diffusivity, respectively, as well as the construction of its quick and slow freezing curves for indication of freezing time, these being 4 hours and 30 minutes and -1,8 ºC, respectively. Thus, it was compared to the values ​​obtained by mathematical models of Nagoaka, Pham and Plank. The quick freezing had more positive influence than the slow freezing, so, the appearance of madeira sauce after this type of freezing was closest to the freshly prepared sauce, then this was the most appropriate for the product

Bebida eletrolítica a base de permeado da ultrafiltração de leite: avaliação física, química e microbiológica durante o armazenamento

Este trabalho teve como objetivo a elaboração de uma bebida eletrolítica a base de permeado da ultrafiltração de leite e avaliação de suas características físicas, químicas e microbiológicas, durante o período de armazenamento por 30 dias, nas temperaturas de 7°C e 25°C. A bebida apresentou-se clara, com coloração amarelo-esverdeada, osmolalidade de 311,6mOsmol.L-1 e carboidratos totais de 6,48% m/v. Não foram observadas alterações significativas de pH, acidez titulável e sólidos solúveis durante o tempo e temperatura de armazenamento (P>0,05). A osmolalidade e o teor de açúcares totais foram afetados pelo tempo (P0.05). The osmolality and total sugars were affected by time (P<0.05), whereas the increase in reducing sugars was affected by storage temperature and time (P<0.05). Positive correlation (P<0.05) between total reducing sugars and osmolality was observed, but the drink was within the osmolality range for isotonic drinks (290mOsm L-1 and 330mOsm L-1). L*, a*, b*, and C* coordinates were affected only by the storage time (P<0.05). In the study of shelf life, the drink showed to be microbiologically stable. The permeate can be used as industrial residue in the preparation of electrolyte drinks in view of osmolality criteria, besides containing natural minerals

Qualidade de alho (Allium sativum) minimamente processado envolvido com revestimento comestível antimicrobiano

Alho minimamente processado apresenta uma curta vida de prateleira devido, principalmente, a crescimento de fungos. A retirada da casca que protege o produto das influências externas é um dos fatores que contribui para a deterioração do produto. Neste estudo, foram avaliados os efeitos de revestimentos comestíveis antimicrobianos a base de amido de mandioca, quitosana e glicerol no recobrimento de alho minimamente processado. O produto final foi submetido a avaliações de perda de peso, alterações na cor e contagem de psicrotróficos e bolores e leveduras. Os resultados mostraram não haver diferença significativa (p < 0,05) entre os tratamentos para perda de massa e saturação e tonalidade da cor. O uso do revestimento antimicrobiano com quitosana nos bulbos mostrou que, em até 15 dias de estocagem a 10 &deg;C, a contagem de fungos não ultrapassou 10(5) UFC.g -1. Dentro do conceito da tecnologia de barreiras de proteção, o uso dos revestimentos antimicrobianos é uma tecnologia de grande potencialidade para aumentar a segurança do alho minimamente processado e prolongar sua vida útil

Physical and chemical quality, biodiversity, and thermodynamic prediction of adhesion of bacterial isolates from a water purification system: a case study

ABSTRACT The objective of this study was to evaluate the quality of water purification system and identify the bacteria this system, predict bacterial adherence according to the hydrophobicity of these microorganisms and of the polypropylene distribution loop for purified water. The assessment of drinking water that supplies the purification system allowed good-quality physical, chemical, and microbiological specifications. The physicochemical specifications of the distributed purified water were approved, but the heterotrophic bacteria count was higher than allowed (>2 log CFU mL-1).The sanitation of the storage tank with chlorine decreased the number of bacteria adhered to the surface (4.34 cycles log). By sequencing of the 16SrDNA genes, six species of bacteria were identified. The contact angle was determined and polypropylene surface and all bacteria were considered to be hydrophilic, and adhesion was thermodynamically unfavorable. This case study showed the importance of monitoring the water quality in the purified water systems and the importance of sanitization with chemical agents. The count of heterotrophic bacteria on the polypropylene surface was consistent with the predicted thermodynamics results because the number of adhered cells reached approximate values of 5 log CFU cm-2

Behaviour of polydiacetylene vesicles under different conditions of temperature, pH and chemical components of milk

Blue polydiacetylene vesicles were studied with regard to their behaviour under variations in storage temperature, heating, potentiometric titration and in the presence of chemical components of milk, to evaluate their application as a sensor in the food industry. Vesicles were prepared using 10,12-pentacosadienoic acid (PCDA)/1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC). Their changes were monitored using UV–Vis absorption. Temperatures not exceeding 25 °C did not cause colour change in PCDA/DMPC vesicles for a period of up to 60 days of storage. Heating for 10 min at 60 and 90 °C, exposure to pH higher than 9.0 and the simulant solutions of the whey proteins, β-lactoglobulin and α-lactalbumin, promoted colour change from blue to red for the vesicles studied. The effects of routine factors on the characteristics and stability of polydiacetylene vesicles is important in defining the parameters related to their application as a sensor for the food industry