Bacterial pathogens on the surfaces of raw produce may be difficult to remove for identification and enumeration. The first part of this project examined whether ultrasonic treatment (40 kHz) of a rinse solution would enhance recovery of Salmonella spp. from various produce surfaces. Strawberries, apples, and cantaloupe were surface inoculated with a five-strain cocktail of nalidixic acid resistant Salmonella spp. Samples were subjected to one of six different treatments using different combinations of agitation methods (manual shaking or ultrasound), diluent temperatures (25°C and 40°C), and agitation times (60 and 120 seconds). After treatment, diluent was spiral plated onto tryptic soy agar supplemented with 50 ppm of nalidixic acid and plates were incubated at 37°C for 48 hours. Results from this study indicate that ultrasonic treatment of a rinse solution did not enhance or diminish recovery of Salmonella spp. from produce surfaces, as compared to manual agitation. The effects of diluent temperature and exposure time appeared to have a significant effect on recovery, depending on the type of produce. The second part of this project used a computer imaging system to determine the surface area of various types of produce. The imaging system acquired and stored multiple images of the produce samples. From these images, surface fitting and approximation of a 3-D wire frame model were used to calculate surface area. From these measurements, it was determined that there were statistical relationships between surface area and weight. Surface area measurements were used to develop equations to predict surface area from weight measurements. / Master of Science

Water used in fresh produce washing is a potential vehicle of foodborne pathogen contamination. This work focused on assessing the sanitizing efficacy of ethanol mist to reduce Salmonella populations on the surfaces of tomatoes and cantaloupes. Ethanol (70%) mist was applied to whole tomatoes and cantaloupe rind plugs using a Biomist sanitation system, which uses CO2 as a carrier gas to spray vapors through a fine droplet spray nozzle. Fresh red tomatoes (Solanum lycopersicum) and cantaloupe (Cucumis melo) plugs were inoculated with Salmonella enterica Newport to a concentration of log 7 CFU/tomato and log 7 CFU/cm2 respectively. Application time (5, 10, and 15 sec), dry vs. wet surface, and stem scar contamination were evaluated on tomatoes, while only application time was evaluated on cantaloupe. Application of ethanol mist for 10 seconds was the most effective treatment time, reducing Salmonella by 3.3 log CFU/tomato. Application of ethanol mist was more effective on dry opposed to wet tomato surfaces by approximately 0.7 log CFU/tomato. Ethanol mist application to inoculated tomato stem scars reduced Salmonella 1.2 log CFU/tomato. Additionally, Salmonella decreased by 1.3 log CFU/cm2 on cantaloupe rind plugs at 10 seconds, again the most effective treatment time. Ethanol mist resulted in sufficient reductions of Salmonella populations on dry tomato surfaces, but was limited in effectiveness if the surface was wet, or if Salmonella adhered to the stem scar. Furthermore, this technique was overall not an efficient method to sanitize cantaloupe surfaces. / Master of Science in Life Sciences / Water is often used in washing and moving fresh produce during harvesting. However, this water is often found to be a source of contamination that can cause the fruits or vegetables to become unsafe to eat. In order to resolve this problem, a mist-type sanitizing system is being explored to wash fresh produce in packinghouses. In this experiment, a mist of ethanol (70%) was applied to whole tomato and cantaloupe plugs using a Biomist sanitation system, which turns liquids into a mist. Whole fresh tomatoes and cantaloupe plugs were infected with Salmonella enterica bacteria. Tomatoes and cantaloupe plugs were treated with ethanol mist for various times of 5, 10, or 15 seconds. Additionally, tomatoes were treated with ethanol to compare a wet surfaced tomato, as well as the tomatoes stem scar (where the vine of the tomato is attached during growing). Ethanol mist application was most effective at 10 seconds, but there was very little difference in bacterial elimination when all the times were compared to the untreated tomatoes. In addition, the mists effectiveness decreased if the surface of the tomato was wet compared to dry, and was even less effective if the bacteria were located where the vine attaches. Also, the ethanol mist has very little effect if bacterial contamination is present on a cantaloupes surface. If a harvested tomato remains dry post harvest, ethanol mist may make for a good washing system. However, it is probably not the best for rough surfaced produce like cantaloupes.

The impact of foliar salt deposition, similar to that which is predicted to occur in the vicinity of the Palo Verde Nuclear Generating Station, was investigated on cantaloupe and cotton. Simulated salt drift was applied throughout the growing season. There was an increase in the amount of lead found in the fruit harvested from the highest treatment level as compared to the untreated plants. No other observable salt-induced responses were observed in the cantaloupe. A trend toward reduced yields was observed in the cotton plots receiving the salt treatments.

A study was made of the response of six kinds of melons to different nitrogen fertilizer rates when grown with drip irrigation. Results indicated a general response of petiole nitrate and yields to increasing N rates, depending on the kind of melon. The study will be continued in 1990 and include water and N rates with three kinds of melons.

Increase in consumption of fresh produce over the past decade has resulted in a rise in incidents of foodborne outbreaks due to pathogens. Chemical sanitizers have been extensively used in the industry for decontamination of fresh produce. However, they are ineffective in certain commodities and under certain processing conditions, necessitating the evaluation of alternative technologies. Electron beam irradiated sliced cantaloupe were tested for 21 days of storage for total aerobic bacterial counts, texture, color and sensory parameters as a function of irradiation doses 0, 0.7 and 1.4 kGy and the wash treatments, water and 200 mg/L chlorine applied to the melons before cutting. Melons washed only with water prior to cutting had total aerobic bacterial counts of 4.0, 2.0 and 0.8 log cfu/g on day 0 at irradiation doses of 0, 0.7 and 1.4 kGy respectively. On day 0, melons washed with chlorine prior to cutting had total aerobic bacterial counts of 2.7, and 0.7 log cfu/g at irradiation doses of 0 and 0.7 kGy and below detection limit at 1.4 kGy. Texture measured as compression force was lower only for cantaloupe irradiated at 1.4 kGy. Irradiation did not affect objective color and descriptive attribute flavor and texture sensory attributes of cantaloupe. Irradiation reduced Salmonella Poona by 1.1 log cfu/g at 0.7 kGy and 3.6 log cfu/g at 1.5 kGy. The D-value of S. Poona on irradiated sliced cantaloupe was found to be 0.211 kGy. Among the spoilage organisms, lactic acid bacteria and mold were reduced effectively by irradiation but there was no significant effect on reduction of yeasts. Our results show that electron beam irradiation in combination with chemical sanitizers is effective in decontamination of fresh-cut produce. Electron microscopy images provided valuable information on attachment sites of S. Poona on cantaloupe rind. The ineffectiveness of chemical sanitizers due to possible inaccessibility to pathogens in these attachment sites provides the basis for application of irradiation in decontamination of fresh produce.

The consumption of fresh-cut fruits has been increasing in recent years due to their health benefits. Fresh-cut cantaloupe (Cucumis melo L.) represents a great snack alternative due to its low caloric content, freshness, and basic component of a healthy diet. One of the latest alternatives to reduce the decay of quality brought by minimal processing of fruits is the development of edible coatings. Acting as a barrier to moisture and gases, the coatings are expected to extend the shelf-life of fresh-cut products, thus the main objective of this research was to determine the effectiveness of an antimicrobial edible coating on the shelf-life of fresh cut cantaloupe (stored at 4 degrees C for 15 days) while maintaining its quality attributes. The effect of different coating compositions and their concentrations on a product's chemical properties and quality attributes was studied. A set of solutions containing chitosan, beta-cyclodextrin, trans-cinnamaldehyde, pectin and calcium chloride were used as coating systems for the fruit using the layer-by-layer method. Quality was measured in terms of texture, color, weight loss, moisture, acidity, and pH. In addition, a consumer sensory test was carried out to support the findings from the objective quality data. Microbiological tests were carried out to determine the effectiveness of trans-cinnamaldehyde as antimicrobial agent within the coating. Uncoated fresh-cut cantaloupe samples stored at 4 degrees C served as controls. In terms of microbiological and physicochemical quality attributes, the antimicrobial coating improved the shelf-life of fresh-cut cantaloupe (up to 12 days), compared to the controls (only 6 days). The coating composed of 2% antimicrobial, 2% chitosan and 1% pectin was the most effective in terms of consumer's acceptance (P<0.05) and shelf-life extension. The results indicated that different ratios between solutions present a variation for each specific quality attribute. The thicker the coating, the firmer the fruit and different thicknesses resulted in different amounts of antimicrobial compound in the coating, thus critically affecting the shelf-life of the product. This study demonstrates the feasibility of a new generation of edible coating for fresh-cut cantaloupe, the coating consists of using a system specially designed to allow the incorporation of natural antimicrobial agents by means of the application of microencapsulation and the layer-by-layer assembly.

Since 2006 there have been four Salmonella enterica and one Listeria monocytogenes foodborne outbreaks linked to whole cantaloupe fruit. No post-harvest intervention to reduce potential contamination on cantaloupe currently exists. The complex surface topography of netted cantaloupes aids bacterial attachment. This research evaluates the use of allyl isothiocyanate (AITC; a natural antimicrobial) to reduce populations of S. enterica Michigan and L. monocytogenes on the surface of cantaloupe. Fifty μl of S. Michigan or L. monocytogenes was inoculated onto whole ‗Athena‘ or ‗Hales Best Jumbo‘ (‗HBJ‘) cantaloupe fruit in 22 mm diameter circles and allowed to dry for 90 min. resulting in 6.60 log CFU/g. Cantaloupe received either AITC liquid or vapor, sterile deionized water, 200 ppm sodium hypochlorite per circle, or no treatment. All cantaloupes were stored in separate sealed glass desiccators for 1 or 24 h at 25°C or 35°C. To enumerate the bacteria following treatment, 22 mm sections of the rind were removed, homogenized and plated onto appropriate agar. Headspace analysis using Gas Chromatography-Mass Spectrometry (GC-MS) quantified the concentration of each AITC vapor treatment. The texture quality of the pericarp tissue of whole cantaloupes was evaluated after 24 h treatments, followed by two weeks of storage at 4°C. The concentration of vapor ranged from 3.4 to 19.6 μl AITC/L inside the desiccators. The liquid treatment reduced (P < 0.05) S. Michigan populations on ‗Athena‘ (3 log CFU/g) and L. monocytogenes on ‗HBJ‘ (2.6 log CFU/g). The longer exposure time to the AITC vapor (24 h versus 1 h) resulted in a greater reduction of both S. Michigan and L. monocytogenes on ‗Athena‘ and treatments at 35°C reduced microbial populations up to 4.5 times greater (P < 0.05). The highest vapor concentration reduced (P < 0.05) both pathogens at least 3.0 log CFU/g on ‗Athena‘ at 25°C. Generally, bacterial pathogens from the surface of ‗Athena‘ cantaloupe were reduced more than pathogens inoculated on the surface of ‗HBJ.‘ The application of AITC liquid or vapor is a natural alternative post-harvest treatment to 200 ppm free chlorine to reduce the level of bacterial contamination on cantaloupe surfaces for certified organic production. / Ph. D.

Since the surfaces of cantaloupes are highly rough or irregular, Salmonella enteric and other bacteria can easily attach to these surfaces and are difficult to remove. Cetylpyridinium chloride (CPC) is the active ingredient of some antiseptic oral mouth rinses and has a broad antimicrobial spectrum with a rapid bactericidal effect on Gram-positive pathogens. Delmopinol hydrochloride (delmopinol) is a cationic surfactant that is effective for treating and preventing gingivitis and periodontitis. The application of delmopinol or CPC to cantaloupe surfaces may be an alternative post harvest technique to reduce the frequency and level of Salmonella contamination. Cantaloupe (Athena and Hale's Best Jumbo (HBJ) cultivars) rind plugs were inoculated with a broth culture of Salmonella Michigan. After 15 min, plugs were sprayed with 10 ml of a 1% delmopinol solution, or a CPC solution (0.5 or 1.0%) or distilled water (Control), and held at 37 oC for 1 hr or 24 hr. For additional samples, the chemical treatments were applied 15 min before pathogen inoculation. Melon plugs were submerged in Butterfield's Phosphate Buffer, shaken, sonicated and solutions were enumerated on Tryptic Soy Agar. The texture quality and color of additional melon samples were evaluated after delmopinol or CPC spray treatments and storage at 4 oC. A 1.0% application of CPC reduced Salmonella levels up to 2.34 log CFU/ml (Athena) and 4.95 log CFU/ml (HBJ) in comparison to the control (p<0.01). A 1.0% delmopinol treatment reduced Salmonella levels as much as 3.1 log CFU/ml in comparison to the control (p<0.01) on both cultivars. In general, the log recovery of Salmonella on cantaloupes treated with delmopinol or CPC solutions, after 1 hr storage, was significantly lower (p<0.05) than the recovery from control cantaloupes, but Salmonella recovery was not significantly different after 24 hr. No significant differences were observed in the texture and color of melons treated with delmopinol or CPC after 14 days. A surface spray application of delmopinol hydrochloride or cetylpyridinium chloride could be an alternative antimicrobial post-harvest treatment that could make cantaloupes surfaces more susceptible to sanitizers or enhance physical removal of bacteria. / Ph. D.

A fruticultura brasileira é uma das culturas de maior expansão no mercado internacional, porém os atributos de qualidade e de tecnologias pós-colheita não vêm acompanhando esta situação. Associado ao mercado internacional de frutas, o consumo no Brasil visa excepcionalmente, o valor nutricional, em vista da necessidade de nutrientes para a grande maioria da população. Tecnologias como a radiação ionizante aplicadas na pós-colheita, podem conservar as características físico-químicas, nutricionais e sensoriais originais permitindo aos mercados consumidores receberem frutos com ótimas qualidades. Este trabalho avaliou durante três etapas, a aplicação da radiação ionizante, originária do Cobalto 60, em melão Cantaloupe visando a conservação pós-colheita durante 7 dias de armazenamento a temperatura variando de 20-22ºC.Foram estabelecidos os limites de doses de radiação através de 7 intervalos de doses (0, 150, 300, 450, 600, 750 e 900Gy) baseados nas doses quarentenárias múltiplas de 150 Gy, para o estabelecimento de doses mínima, máxima e ideal. Posteriormente, foram acompanhadas as características físico-químicas e nutricionais da tecnologia aplicada nos melões Cantaloupe e, por fim, as características sensoriais, através do teste de aceitabilidade.Os resultados indicaram que doses acima de 450 Gy afetaram os parâmetros físicos de firmeza, rendimento de polpa e cor (L e a*). Todavia, analisando-se os parâmetros físico-químicos e nutricionais, as doses 450 e 900 Gy mantiveram os resultados estáveis de pH, acidez titulável, sólidos solúveis, cor (a* e b*), clorofila e carotenóides, compostos fenólicos, além da taxa respiratória e do nível de etileno. O período de armazenamento foi o fator mais importante que afetou a qualidade dos frutos, independente das doses utilizadas. Pelo teste de aceitabilidade, os frutos mais apreciados pelos degustadores foram os melões irradiados com doses de 450 e 900 Gy. Portanto, concluiu-se que, a radiação ionizante é uma tecnologia viável para a conservação pós-colheita de melão Cantaloupe, porém, deve ser utilizada em combinação com outras tecnologias, especialmente para o controle de fungos / Although brazilian fructiculture has been growing in the international market, the fruit quality and the postharvest technology have not been improved properly. In Brazil, fruit nutritional factors are very important because of their potential to provide suitable nutrients for a significant part of the Country population. Some postharvest technologies, such as ionizing radiation, can keep the physical, chemical, nutritional and sensorial characteristics of the natural fruit, improving the quality of the fruits in the market. This work evaluated the effects of Cobalt 60 irradiation in Cantaloupe melon, aiming the postharvest conservation during 7 days of storage, at a temperature ranging from 20 to 22C. The doses of irradiation were set to 0, 150, 300, 450, 600, 750 and 900Gy, based on the multiple of 150Gy quarantine dose, aiming to establish the lowest, the highest and the ideal doses. Afterwards, physical, chemical and nutritional characteristics of irradiated fruit were checked and, finally, the sensorial characteristics through acceptability test. Results indicated that the doses higher than 450Gy affected firmness, pulp yield and color (L e a*) parameters. Nevertheless, analyzing physical, chemical and nutritional parameters, doses of 450 and 900Gy kept pH, tetrable acidity, soluble solids, color (a* and b*), chlorophyll and carotenoids, phenolic compounds, respiratory rate and ethylene level. The storage period was the most important factor that affected the quality of the fruit, despite of the radiation doses. Based on the acceptability test, the best evaluated fruits were from the treatments of 450 and 900Gy. This work allowed toconclude that fruit radiation is an appropriate technology for Cantaloupe melon post harvest conservation, but it is necessary to be used in combination with other technologies, especially to fungi control

A fruticultura brasileira é uma das culturas de maior expansão no mercado internacional, porém os atributos de qualidade e de tecnologias pós-colheita não vêm acompanhando esta situação. Associado ao mercado internacional de frutas, o consumo no Brasil visa excepcionalmente, o valor nutricional, em vista da necessidade de nutrientes para a grande maioria da população. Tecnologias como a radiação ionizante aplicadas na pós-colheita, podem conservar as características físico-químicas, nutricionais e sensoriais originais permitindo aos mercados consumidores receberem frutos com ótimas qualidades. Este trabalho avaliou durante três etapas, a aplicação da radiação ionizante, originária do Cobalto 60, em melão Cantaloupe visando a conservação pós-colheita durante 7 dias de armazenamento a temperatura variando de 20-22ºC.Foram estabelecidos os limites de doses de radiação através de 7 intervalos de doses (0, 150, 300, 450, 600, 750 e 900Gy) baseados nas doses quarentenárias múltiplas de 150 Gy, para o estabelecimento de doses mínima, máxima e ideal. Posteriormente, foram acompanhadas as características físico-químicas e nutricionais da tecnologia aplicada nos melões Cantaloupe e, por fim, as características sensoriais, através do teste de aceitabilidade.Os resultados indicaram que doses acima de 450 Gy afetaram os parâmetros físicos de firmeza, rendimento de polpa e cor (L e a*). Todavia, analisando-se os parâmetros físico-químicos e nutricionais, as doses 450 e 900 Gy mantiveram os resultados estáveis de pH, acidez titulável, sólidos solúveis, cor (a* e b*), clorofila e carotenóides, compostos fenólicos, além da taxa respiratória e do nível de etileno. O período de armazenamento foi o fator mais importante que afetou a qualidade dos frutos, independente das doses utilizadas. Pelo teste de aceitabilidade, os frutos mais apreciados pelos degustadores foram os melões irradiados com doses de 450 e 900 Gy. Portanto, concluiu-se que, a radiação ionizante é uma tecnologia viável para a conservação pós-colheita de melão Cantaloupe, porém, deve ser utilizada em combinação com outras tecnologias, especialmente para o controle de fungos / Although brazilian fructiculture has been growing in the international market, the fruit quality and the postharvest technology have not been improved properly. In Brazil, fruit nutritional factors are very important because of their potential to provide suitable nutrients for a significant part of the Country population. Some postharvest technologies, such as ionizing radiation, can keep the physical, chemical, nutritional and sensorial characteristics of the natural fruit, improving the quality of the fruits in the market. This work evaluated the effects of Cobalt 60 irradiation in Cantaloupe melon, aiming the postharvest conservation during 7 days of storage, at a temperature ranging from 20 to 22C. The doses of irradiation were set to 0, 150, 300, 450, 600, 750 and 900Gy, based on the multiple of 150Gy quarantine dose, aiming to establish the lowest, the highest and the ideal doses. Afterwards, physical, chemical and nutritional characteristics of irradiated fruit were checked and, finally, the sensorial characteristics through acceptability test. Results indicated that the doses higher than 450Gy affected firmness, pulp yield and color (L e a*) parameters. Nevertheless, analyzing physical, chemical and nutritional parameters, doses of 450 and 900Gy kept pH, tetrable acidity, soluble solids, color (a* and b*), chlorophyll and carotenoids, phenolic compounds, respiratory rate and ethylene level. The storage period was the most important factor that affected the quality of the fruit, despite of the radiation doses. Based on the acceptability test, the best evaluated fruits were from the treatments of 450 and 900Gy. This work allowed toconclude that fruit radiation is an appropriate technology for Cantaloupe melon post harvest conservation, but it is necessary to be used in combination with other technologies, especially to fungi control