Thermotolerant Coliform Counts Research Articles

Impacts of anthropic action on water quality from spring water

Due to the sensitivity of water to external effects such as precipitation, land use and management, water quality must be monitored. This information is essential for decisions on its multiple and integrated use, as well as helping to mitigate environmental impacts. The aim of this study was to assess the water quality of perennial springs in the Palmital stream watershed, in Urutaí - GO. Water samples were collected from these sites for physical, chemical and microbiological characterization, and the water quality index (WQI) was determined during the dry and rainy seasons of 2023. According to the results, it was found that point D (an area close to farming and extensive cattle breeding) showed the highest values for total and thermotolerant coliform counts in both periods. In addition, the WQI values ranged from 59.61 to 72.70 during the dry season and from 67.93 to 74.79 during the rainy season, being classified as "Good".

BACTERIOLOGICAL EVALUATION OF KWATA ABATTOIR WASTE WATER AWKA, NIGERIA

Abattoir wastes can have a detrimental effect on the environment, public health, animal health, and economy of a country if they are not effectively managed and controlled. The bacteriological evaluation of waste water from Kwata abattoir was carried out to determine the bacterial load present and if the waste water generated is suitable for direct discharge into the environment. A total of two samples were aseptically collected, in which the physicochemical analysis of the waste water showed objectionable color and odor, pH of 7.3 and 6.5, and temperature of 30.2°C and 25.3°C for samples A and B, respectively, of which the pH and temperature were within acceptable limits by WHO. The membrane filter method was used to determine the total coliform and thermotolerant coliform counts present per 100 mL of the samples using MacConkey agar and Eosin Methylene Blue Agar, respectively. The total viable count was obtained for both samples: 5.1×105 CFU/mL for sample A and 1.4×106 CFU/mL for sample B. Phenotypic and biochemical tests were carried out for four isolates, which include Escherichia coli, Salmonella spp., Bacillus spp., and Bacillus cereus. Thus, it can be concluded from the above study that untreated abattoir waste water contains a high level of pollutants, which supports the growth of the microbial population, as evidenced in the microbial study. Therefore, waste water has to be treated before discharge into the environment to protect public health and promote the safety of the environment.

Microbiological evaluation of homemade mayonnaise and self-serve acai sold in Araguaína, Tocantins.

Foodborne diseases are common illnesses caused by the consumption of food contaminated with microorganisms, such as viruses, fungi, bacteria, and protozoa. Every year, 600 million people become ill and 420,000 people die as a result of consuming contaminated food. Therefore, food safety is an important issue. In this study, samples of homemade spiced mayonnaise and self-serve acai sold in the city of Araguaína, Tocantins, Brazil were analyzed for microbiological contaminants. Acai was collected from 10 stores, one sample from each store, and tested for mold, yeast, and coliforms, as well as coliform identification and total and thermotolerant coliform counts. Mayonnaise was collected from 20 snack bars, one sample from each. These samples were inoculated on MacConkey and Salmonella Shigella agar plates, and the plates were analyzed for growth. Salmonella spp. were detected in some Mayonnaise samples, and coliforms were detected in all acai samples; 60% of samples had thermotolerant coliforms, and only 40% were within the limits established by ANVISA. The collected samples of mayonnaise and acai were contaminated with molds and yeasts above the established limit of 103 CFU/g. Thus, the analyzed mayonnaise and acai samples were contaminated and unfit for consumption, demonstrating the importance of hygienic-sanitary measures in food handling.

Microbiological and parasitological quality of fruit pulps and juices used for detoxifying purposes

ABSTRACT The juice consumption with detoxifying properties has increased in the last few years, but inadequately produced food may transport pathogens. This study aimed to investigate the occurrence of parasitological and microbiological contamination in fruit juices and fruit pulp used for detoxifying purposes. Twenty samples were analyzed, 10 of fruit pulp and 10 juices from July to August 2018. Thermotolerant coliform, mold, and yeast were counted. Parasitological analysis was performed by spontaneous sedimentation method and sedimentation by centrifugation techniques. Results showed that 20% and 60% of the fruit pulp and juice samples exhibited thermotolerant coliform counts above 1 log CFU/mL, respectively. The results showed that 60% of the pulp samples presented mold and yeast counts above 3 log CFU/mL. The protozoa found in the samples were Endolimax nana, Entamoeba coli, and E. histolytica/E. dispar cysts. The presence of thermotolerant coliforms in juices is an indicator of the presence of enteropathogens, mainly Escherichia coli. The high mold and yeast populations and the presence of protozoa in the fruit pulp and juices indicate hygienic and sanitary failures in the food processing. It may be concluded that there is a need for supervision and training in Good Manufacturing Practices by health agencies, aiming at the food safe production. KEY WORDS: Coliforms; parasites; food hygiene; food safety.

PHYSICAL-CHEMICAL AND MICROBIAL QUALITY OF THE “CERVEJA CASEIRA” (HOMEBREWED BEER) OF GUARAPUAVA/STATE OF PARANÁ – BRAZIL

“Cerveja caseira” is a homebrewed beer sold in the Guarapuava municipality (State of Paraná, Southern Brazil). It was introduced by Slavic immigrants and adapted to Brazilian ingredients, being much appreciated in the region and disseminated by popular knowledge. The objective of this research is a physical-chemical and microbial analysis of cerveja caseira produced and sold in Guarapuava. Fifty-six samples divided in 14 lots were acquired in October and November 2020 in streets, houses, commerce, and markets of Guarapuava. The physical-chemical analyses included the determination of the following parameters: color, pH, original extract, apparent extract, alcohol, density, bitterness, SO2, and calories. The microbial quality was assessed via counts of total aerobic mesophiles, total and thermotolerant coliforms, positive-coagulase Staphylococcus, Pseudomonas spp, Bacillus spp, molds, and yeasts. The physical-chemical results indicate the lack of standards for the cerveja caseira production, with ample variations regarding color, original and apparent extract, alcohol percentage, and bitterness. Regarding microbial quality, all cerveja caseira lots contained pathogens, mainly mesophiles, yeasts, and Staphylococcus aureus, but no total and thermotolerant coliforms, important contamination indicators. According to Brazilian beer-related regulations, only lot 4 could be commercialized, despite its high percentage of alcohol (2.5% v/v), which characterizes it as an alcoholic beverage, not suitable for consumption by children and adolescents. Cerveja caseira recipes have been passed on from generation to generation, adapted to the climate and to the products available in Brazil, being part of the cultural heritage of the western region of Paraná that should be preserved.

Prevalence, Biofilm Formation, and Antimicrobial Resistance of Escherichia coli, Staphylococcus aureus, and Salmonella Isolates from Goat Meat Marketed in Petrolina, Brazil

The aim of this study was to evaluate the prevalence and antibacterial resistance and biofilm formation by bacterial strains isolated from raw goat meat sold in street fairs (SF) and commercial establishments (CE) in Petrolina, Pernambuco, Brazil. SF samples had mesophilic aerobic bacteria counts of 3.71 to 7.57 log CFU/g, S. aureus counts of 1.78 to 5.38 log CFU/g, total coliform counts of 2.3 × 101 to >1.1 × 103 most probable number (MPN)/g, thermotolerant coliform counts of <3.0 to >1.1 × 103 MPN/g, and Escherichia coli counts of <3.0 to >1.1 × 103 MPN/g. CE samples had mesophilic aerobic bacteria counts of 2.90 to 6.00 CFU/g, S. aureus counts of 2.00 to 4.49 log CFU/g, total coliform counts of 2.3 × 101 to >1.1 × 103 MPN/g, thermotolerant coliform counts of 3.0 to >1.1 × 103 MPN/g, and E. coli counts of <3.0 to >1.1 × 103 MPN/g. Salmonella was detected in 25% of SF and CE samples. All isolates of S. aureus and Salmonella and 95.6% of E. coli isolates were biofilm producers. Resistance to multiple drugs was found in isolates of Salmonella, E. coli, and S. aureus from SF and CE samples. Goat meat marketed in Petrolina is heavily contaminated with pathogenic bacteria resistant to multiple drugs and capable of biofilm formation.

The importance of water quality in classifying basic water services: The case of Ethiopia, SDG6.1, and safe drinking water.

IntroductionSustainable Development Goal (SDG) 6 aims to coordinate international efforts toward “clean water and sanitation.” However, water contaminated with pathogenic bacteria or thermotolerant coliforms (TTC) will not achieve the SDG target of clean water in the lives of people around the world. The aim of this study is to assess the water quality parameters of basic water services in Amhara and Afar regions of Ethiopia as well as the role and importance of local managerial committees in ensuring basic water functionality.MethodsThis mixed methods research, conducted in January-June 2019, sampled 22 districts from food-insecure areas in the Amhara and Afar regions of Ethiopia. From the 22 districts, which represent nearly one third of all districts in each region, 111 water services classified as “basic” were randomly selected. For each selected water service, research included: water quality sample testing, visual observation of water services, interviews and focus group discussions with the associated water managerial committee members. Descriptive statistics frequency, percent, mean, median, standard deviations, normal tables, cross-tables and graphs are used to present the data.ResultsAlthough the international water standard for thermotolerant coliform (TTC) levels is 0 CFU/100ml, in our sample of 111 water services, the maximum TTC counts were 71 CFU/100 ml and the mean was 4 CFU/100 ml. Thermotolerant coliform counts were above the permissible standard values for nearly 40% (n = 111) of the basic water services. TTC was detected in 44 (39.64%) (n = 111) basic water services. Of these, 38 (34.23%) were operationally functional while 6 (5.41%) were not functional. Approximately one third of the basic water services sampled, deemed “functional” by international standards, do not provide potable water due to thermotolerant coliform (TTC) levels.ConclusionOur findings from the Amhara and Afar regions of Ethiopia demonstrate that water quality parameters are not currently considered in classifying basic water services. This suggests that international efforts to address SDG 6 should incorporate water quality as a key parameter to better track international progress toward “clean water and sanitation” efforts. We discuss two potential pathways for stronger inclusion of water quality parameters in international definitions: (1) to mandate water quality within “functional” and “non-functional” definitions or (2) to add a ladder rung titled “safe basic water services” to the international drinking water ladder. Our findings from Ethiopia suggest that additional research should be undertaken in development contexts to assess whether or not “functional” basic water services provide safe drinking water to users.

Microbiological evaluation of the meat from young collared peccaries (Pecari tajacu Linnaeus, 1758)

The increased demand for meat from wild animals for human consumption, as an alternative protein source, brings with it the need for research that demonstrates the quality of such product. The technical information about the meat from collared peccaries still needs studies and aiming to collaborate with the already existing knowledge, this research had as its objective to provide subsidies for evaluation of the sanitary quality of the meat from collared peccaries. Twelve animals were used, six males and six females, aged four to five months, from the breeding stock of the Federal Rural University of the Semi-Arid and, after euthanasia by a slaughter technique used in goats, the meat samples were collected through sterile swabs at the locations of the hind leg, loin, belly and axilla of each animal, totaling 48 samples. The maximum mesophilic count found was 1.9 x 103 CFU/ml, the total coliform and thermotolerant coliform counts were below the one determined in the legislation for meat from domestic animals, however, through biochemical tests, the presence of E. coli from the biotype 1 and biotype 2 was found, in seven and six samples, respectively. Search results for Salmonella spp. were negative in all samples and, as for Staphylococcus spp., only one sample had the count above the level allowed by law. The contamination load related to the bacteria E. coli proved to be high, making 13 samples unfit for consumption. Regarding the other data, the meat from young collared peccaries showed a low contamination load.

Microbiological characteristics of meliponine honey marketed in the State of Paraná – Brazil

Meliponine is a honey with particular characteristics; it has a high percentage of humidity, which can favor the development of microorganisms, thereby causing changes in the quality of the product. The objective of this study was to evaluate the microbiological characteristics of meliponine honey produced by different species and marketed in the State of Paraná-Brazil. The sample unit was composed of honey of Tetragonisca angustula (n = 15), Scaptotrigona bipunctata (n = 05), Melipona quadrifasciata quadrifasciata (n = 05) and Melipona bicolor schencki (n = 01). The following microbiological parameters were evaluated: counts of total and thermotolerant coliforms, fungi count and detection of Salmonella spp. Principal component analysis (PCA) was used to evaluate the possible relationships among species, locality and type of microorganism. For microorganisms of the total coliform group, 15.38% of the analyzed samples had values >3 MPN/g. The presence of thermotolerant coliforms was observed in 7.69% of the samples, all of which were T. angustula samples. For fungi counts, 100.00% of the analyzed samples had values within the established range created by the Agricultural Defense Agency of Paraná. The presence of Salmonella spp. was not observed in any of the samples evaluated. The amount of water in the honey is related to the location of the apiary and edaphoclimatic factors. Adoption of good handling practices by beekeepers is indispensable for the safety of the final product.

Sanitary, Hygienic and Epidemiological Aspects of Recreational Water Use of the Population of the Upper Don River Basin

Introduction: The problem of safe recreational water use is closely related to conditions of surface water bodies (rivers, reservoirs, lakes, and ponds) experiencing a significant anthropogenic load and their water quality. The purpose of the study was to assess safety of recreational water use of the population based on the results of testing water quality in the bodies of water of the Upper Don River basin. Materials and methods: In 2015–2019, surface water samples were taken at 73 water quality checkpoints of 26 water bodies and tested for chemical, microbiological and parasitological indicators. Test results were then used to assess hazards related to recreational water use of the population. Results: It was found that in 26 of 73 surveyed recreation areas (35.6 %) water quality failed to meet recreational water quality criteria. Poor microbiological water quality indicators were established at 21 of 73 sites (26.7 %) with the proportion of water samples with high thermotolerant and total coliform counts varying from 1.5 to 75.0 %. Risks of epidemic hazard posed by recreational water use were assessed to be the highest in three recreation areas (4.1 %) and moderate – in 18 areas (24.7 %). Conclusions: The estimated reliability of differences in the long-term incidence rates of infectious diseases probably related to microbiological surface water quality indicators (by Student’s t-test) confirmed the hypothesized association between poor microbiological water quality parameters and high incidence rates of acute intestinal infections and bacillary (Flexner) dysentery (p < 0.05). The findings demonstrate the necessity of implementing measures to ensure health and epidemic safety of recreational water use of the population.

Influence of different sources of contamination on the microbiological quality of lettuce in the Teresópolis region, RJ, Brazil

ABSTRACT Irrigation water and cultivated soil have been identified as possible sources of contamination in several crops. In certain vegetables that are eaten raw, such as lettuce, this contamination can lead to public health problems. Aiming to evaluate the influence of these sources on the quality of lettuce grown in the Córrego Sujo Basin, Teresópolis, RJ, an important agricultural pole whose production services the metropolitan region of Rio de Janeiro, water from different sources (spring, weir and river) was collected in this region, as well as samples of soil and lettuce irrigated with these waters, to carry out conventional microbiological analyzes (counts of total heterotrophic bacteria and thermotolerant coliforms) and molecular analyzes (PCR-DGGE). The count of fecal coliforms in lettuce suggests that there is an influence of irrigation water and the cultivated soil on the contamination of these vegetables. The grouping of bacterial communities in the different samples obtained by the PCR-DGGE technique shows that irrigation water has a greater influence on the contamination of these vegetables in relation to the soil where they are grown. These results corroborate the need to monitor water bodies used for irrigation and demonstrate that the PCR-DGGE technique is of great value for the study of microbial communities and, when associated with specific primers, can help in the detection of pathogens in food.

Performance and egg quality of laying hens fed different dietary levels of cashew nut shell liquid

Organic acids have stood out as alternatives to antibiotic growth promoters, especially those extracted from plants, such as anacardic acid, which is present in cashew nut shell liquid (CNSL). This study evaluates the effects of CNSL as a source of anacardic acid in diets of laying hens on performance, egg quality, lipid stability of yolk and microbiological analysis of excreta. A total of 216 commercial Hisex White laying hens were housed in cages and distributed in a completely randomized design with six treatments and six replicates of six birds per treatment. Treatments consisted of a diet without antibiotic growth promoter (AGP); diet with AGP (Halquinol 60% at 0.1 g/kg and Enramycin 8% at 0.1 g/kg); and four diets without AGP and with the inclusion of 2.5, 5.0, 7.5 and 10.0 g/kg CNSL. No effects of dietary addition of AGP and CNSL were observed in bird performance and external quality of eggs. A quadratic effect was observed for lipid oxidation in egg yolk, the minimum value of which was found at 5.8 g/kg CNSL. There were no significant effects of treatments on total mesophilic, total coliform and thermotolerant coliform counts on excreta. In conclusion, adding up to 10.0 g/kg of CNSL as source of anacardic acid in laying hen diet did not influence performance or egg quality, but the addition from 7.5 g/kg of CNSL upwards reduced lipid oxidation and improved the yolk colour.Keywords: Anacardium occidentale, lipid oxidation, natural antioxidant, organic acid

Análise microbiológica de manipuladores e superfícies de manipulação de escolas públicas

As doenças transmitidas por alimentos contaminados são ocasionadas principalmente pela falta de higienização adequada das mãos dos manipuladores dos alimentos bem como das superfícies em que estes produtos são manipulados. Teve por objetivo realizar a análise microbiológica das mãos de manipuladores e superfícies de manipulação em escolas de um município do Maranhão. Foram realizadas análises microbiológicas das mãos de dez manipuladores de alimentos e cinco superfícies de manipulação. Foram feitas as determinações da contagem de coliformes totais e termotolerantes, por meio do método de Tubos Múltiplos em Número Mais Provável. Verificou-se que somente um manipulador não apresentou contaminação pelos micro-organismos estudados, e em relação as superfícies de manipulação todas apresentaram contaminação. Portanto verificou-se que nas escolas avaliadas todas apresentaram falhas no processo de higienização das mãos e das superfícies.

Microbiological, chemical, physical, and proteolytic activities of raw milk after thermal processing

ABSTRACT The aim was to evaluate the microbiological, chemical- physical, and shelf-life quality of milk samples after pasteurization (HTST) for 10 days or ultra-high temperature (UHT) treatment for 120 days. Raw milk counts of mesophilic aerobic microorganisms, Staphylococcus spp. and thermotolerant coliforms before HTST and UHT processing were 6.73 and 7.77; 2.84 and 4.30, and 4.68 and 4.37log10, respectively. Pseudomonas spp. were found in raw milk samples. No presence of any other microorganisms studied was detected and no microbial inhibitor was found. Processed samples met microbiological legal requirements. However, aerobic mesophilic counts for HTST pasteurized milk samples stored for 5 and 10 days increased to values comparable to those in raw milk. Composition chemical- physical of all samples were within legal limits. These results demonstrate that, although HTST and UHT processed milk comply with the microbiological standards required by Brazilian law, high microbial counts in raw milk are an issue, possibly due to failures in the early stages of the production chain. Increase in casein macropeptide (CMP), probably because of proteases psychrotrophic bacteria. It is concluded that the quality of raw milk directly influences the progressive increase of the CMP values.

Determination of thermotolerant coliforms present in coconut water produced and bottled in the Northeast of Brazil

Abstract Coconut water is considered to be a natural isotonic drink and its marketing is gradually increasing. The objective of the present study was to evaluate the microbiological quality of the coconut water produced and bottled in the Northeast of Brazil. Products form ten industries from different states in the Northeast of Brazil were analyzed. The most probable number (MPN) method was used to quantify the coliforms. Samples showing positive for coliforms were seeded on ChromAgar Orient plates and the bacteria identified from isolated colonies using the automated system Vitek 2 (BioMérieux), according to the manufacturer's instructions for the preparation of the inoculum, incubation, reading and interpretation. The samples showed thermotolerant coliform counts between 6.0×102 and 2.6×104 MPN/100 mL. The presence of Klebsiella pneumoniae, Morganella morganii and Providencia alcalifaciens was observed. The implementation of preventive methods and monitoring of the water quality by the industries is required.

Thermotolerant coliform counts and nutrient levels as indicators of water quality in sub-Mediterranean karst river

Thermotolerant coliform counts and nutrient levels as indicators of water quality in sub-Mediterranean karst river

Applying spatial regression to evaluate risk factors for microbiological contamination of urban groundwater sources in Juba, South Sudan

This study developed methodology for statistically assessing groundwater contamination mechanisms. It focused on microbial water pollution in low-income regions. Risk factors for faecal contamination of groundwater-fed drinking-water sources were evaluated in a case study in Juba, South Sudan. The study was based on counts of thermotolerant coliforms in water samples from 129 sources, collected by the humanitarian aid organisation Médecins Sans Frontières in 2010. The factors included hydrogeological settings, land use and socio-economic characteristics. The results showed that the residuals of a conventional probit regression model had a significant positive spatial autocorrelation (Moran’s I = 3.05, I-stat = 9.28); therefore, a spatial model was developed that had better goodness-of-fit to the observations. The most significant factor in this model (p-value 0.005) was the distance from a water source to the nearest Tukul area, an area with informal settlements that lack sanitation services. It is thus recommended that future remediation and monitoring efforts in the city be concentrated in such low-income regions. The spatial model differed from the conventional approach: in contrast with the latter case, lowland topography was not significant at the 5% level, as the p-value was 0.074 in the spatial model and 0.040 in the traditional model. This study showed that statistical risk-factor assessments of groundwater contamination need to consider spatial interactions when the water sources are located close to each other. Future studies might further investigate the cut-off distance that reflects spatial autocorrelation. Particularly, these results advise research on urban groundwater quality.

Reduced Nutrient Excretion and Environmental Microbial Load with the Addition of a Combination of Enzymes and Direct-Fed Microbials to the Diet of Broiler Chickens

This study evaluated the effects of the dietary inclusion of an enzyme blend and a direct-fed microbials in broiler diets on litter production and quality. In total, 900 Cobb 500(r) broiler chicks were distributed according to a completely randomized design into 4 treatments and 9 replicates of 25 birds each. Broilers were reared from 1 to 42 days of age. The treatments consisted of the following diets: NC: negative control; DFM: NC + 500 ppm of direct-fed microbials product (DFM), containing Bacillus subtilis and Bacillus licheniformis; ENZ: diet formulated with an enzyme blend (20 ppm phytase, 200 ppm protease and 200 ppm of xylanase); DFM+E: ENZ + DFM. Birds and litter were weighed at the start and end of the rearing period, for litter production and waste ratio (Rw) determination. Litter samples were analyzed for dry matter (DM) content, total and thermotolerant coliform counts, nutrient composition (nitrogen (N), phosphorous (P) and potassium (K)), and fiber fraction (neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin). The dietary inclusion of the evaluated additivesdid not influence litter production or Rw; however, ADF (%), NDF (kg and kg/kg DM litter), and total and thermotolerant coliform counts were reduced, and N content increased in the litter. The diets containing enzymes (ENZ and DFM+E) reduced litter P content. The addition of exogenous enzymes and their combination with a DFM based on Bacillus spp .Did not affect waste production, and reduced litter microbial load, and the contents of P and insoluble fiber in the litter.

MICROBIOLOGICAL ASSESSMENT OF LETTUCE SALADS AND ANTIMICROBIAL RESISTANCE OF STAPHYLOCOCCUS SPP.

self-service restaurants in which food is served ready to be consumed are liable to have some products contaminated by pathogenic microorganisms causing food-transmitted diseases. evaluates the microbiological quality of lettuce salads in restaurants in Pelotas RS Brazil by counts of thermo-tolerant coliforms, E. coli, Staphylococcus spp. and detection of Salmonella spp. Antimicrobial resistance of Staphylococcus spp. isolates are also assessed. thirty-six samples of lettuce salads were collected from nine restaurants and thermotolerant coliforms, Escherichia coli and Staphylococcus spp. were quantified, coupled to a research on Salmonella spp., following methodology by the Bacteriological Analytical Manual. Staphylococcus spp. isolates underwent antimicrobial resistance test by the disc-diffusion method. results showed that 61.1% of the salad samples contained more thermotolerant coliforms than allowed by Brazilian legislation and E. coli was confirmed in 5.6% of the samples. Positive and negative coagulase Staphylococcus occurred respectively in 5.6% and 77.8% of isolates, but no sample had Salmonella spp. Further, 56.7% of the thirty isolates of Staphylococcus spp. tested were resistant to penicillin; 46.7% to oxacillin; 26.7% to erythromycin and 23.3% were multi- resistant. inadequate quality of the salad was due to pathogenic microorganisms, while Staphylococcus spp. isolates had a high percentage of antimicrobial resistance.

Aplicação de silício, em hidroponia, na conservação pós-colheita de alface americana 'Lucy Brown' minimamente processada

Este trabalho teve por objetivo verificar o efeito da aplicação de silício em hidroponia na conservação pós-colheita de alface americana 'Lucy Brown' minimamente processada. As alfaces foram cultivadas hidroponicamente e a fonte de silício utilizada foi o silicato de potássio nas concentrações de 0; 28; 56; e 84mg L-1. Após a colheita, as folhas selecionadas foram lavadas em água corrente, semiprocessadas mediante o corte de 20mm de largura e sanitizadas por imersão em Sumaveg(r). Estas foram centrifugadas manualmente e acondicionadas em sacos de polipropileno, que, posteriormente, foram selados e armazenados a 3ºC e 85±3% de umidade relativa (UR). Durante 16 dias de armazenamento, foram avaliadas a cada quatro dias e em triplicata, a composição gasosa, a firmeza, o teor de clorofila e de acidez titulável, as atividades das enzimas polifenoloxidase e peroxidase e as análises microbiológicas. Até o 4odia de armazenamento, observaram-se reduções nos níveis de O2para todos os tratamentos, no entanto, para os níveis de CO2, houve aumentos percentuais de 5% no tratamento com 28mg L-1de silício. As maiores concentrações de silício mantiveram maior firmeza das folhas. Os teores de clorofila total se mantiveram estáveis durante o período de armazenamento. A atividade da enzima polifenoloxidase reduziu até o 8° dia. A atividade da peroxidase apresentou aumento durante o período avaliado, na concentração de 84mg L-1de silício. A contagem microbiana de coliformes termotolerantes e totais manteve-se baixa durante o armazenamento. A concentração de 84mg L-1de silício propiciou maior firmeza das folhas das alfaces minimamente processadas, deixando-as mais túrgidas e conservando sua vida útil por 16 dias