Diced Tomatoes Research Articles

Impact of sanitizer application on Salmonella mitigation and microbiome shift on diced tomato during washing and storage

This study examined the shift in Salmonella and indigenous microbiota on diced tomato after washing with three different sanitizers and during post-wash cold storage. Roma tomatoes were inoculated with a Salmonella cocktail (initial level ∼ 5.6 CFU g−1), diced and washed along with uninoculated diced tomato in simulated flume wash water with sanitizers, including 10 mg L−1 free chlorine (FC10), 90 mg L−1 peracetic acid (PA90), PA90 in combination with a proprietary acidified surfactant blend (PS90), and unsanitized control (CK). Salmonella, total mesophilic aerobic bacteria (MAB), and yeast and mold (YM) populations on both inoculated and uninoculated samples were measured before and after washing, and during storage at 4 °C. 16S rRNA amplicon sequencing was also performed to determine the shift in bacterial microbiome. Washing with all tested sanitizers, especially PS90 (> 4 log Salmonella reduction), reduced Salmonella and MAB populations on inoculated diced tomatoes. Additionally, application of sanitizers mitigated Salmonella cross-contamination onto uninoculated samples. PS90 treatment inhibited the proliferation of most dominant bacteria on diced tomatoes during storage, including Erwiniaceae, Curtobacterium, Pantoea, Erwinia and Enterobacterales, which may benefit product quality and safety.

Industrial Processing Affects Product Yield and Quality of Diced Tomato

The tomato industry has been searching for new genotypes with improved fruit production, both in the field and industrially processed, together with high-quality performance under sustainable management conditions. This research was carried out in Southern Italy with the aim of assessing the effects of industrial processing on the yield and quality of four tomato hybrids grown according to organic farming methods and addressed at dicing. MAX 14111 and HMX 4228 showed the highest values of field and processing yield as well as reduced sugars and fructose. MAX 14111 had the highest values of total solids and soluble solids, titratable acidity, fiber, energetic value, polyphenols, and also rutin, though not significantly different from Impact. HMX 4228 performed best in terms of sugar ratio, color and naringenin. Concerning the diced products, the sensorial qualities of the four hybrids differed significantly. Total polyphenols, naringenin and rutin in the tomato fruits were higher in the processed than in the raw product. The appreciable fruit yield and quality resulting from both field and processing phase represent a promising perspective for identifying improved tomato genotypes addressed at dicing.

Use of a Novel Sanitizer To Inactivate Salmonella Typhimurium and Spoilage Microorganisms during Flume Washing of Diced Tomatoes

As demand for fresh-cut produce increases, minimizing the risk of salmonellosis becomes critical for the produce industry. Sanitizers are routinely used during commercial flume washing of fresh-cut produce to minimize cross-contamination from the wash water. This study assessed the efficacy of a novel sanitizer blend consisting of peracetic acid (PAA; OxypHresh 15) with a sulfuric acid-surfactant (SS) antimicrobial (PAA-SS; ProduceShield Plus) against Salmonella during simulated commercial washing of diced tomatoes. Triplicate 9.1-kg batches of Roma tomatoes were dip inoculated in a two-strain avirulent Salmonella cocktail (Salmonella Typhimurium LT2 and MHM112) to achieve 5 to 6 log CFU per tomato and air dried for 2 h. After mechanical dicing, the tomatoes were washed in a pilot-scale processing line for 60 s with or without an added organic load in 90 ppm of PAA-SS (pH 1.8), SS at pH 1.8, 90 ppm of PAA, 5 or 10 ppm of free chlorine or sanitizer-free water as the control. Overall, PAA-SS (1.75 ± 0.75 log CFU/g) was significantly (P ≤ 0.05) more effective than water (0.69 ± 0.42 log CFU/g), chlorine (0.35 ± 0.36 log CFU/g), or SS (0.36 ± 0.19 log CFU/g) in reducing Salmonella. After washing for 20 s, PAA-SS was the only sanitizer to show a significant (P ≤ 0.05) reduction (1.93 ±0.59 log CFU/g) in Salmonella. All wash water samples were negative for Salmonella, except for 5 and 10 ppm of chlorine and the water control. Using PAA-SS with an organic load, yeast and mold populations were below the limit of detection (1.40 log CFU/g) and significantly (P ≤ 0.05) lower on diced tomatoes after 14 days of refrigerated storage compared with the other treatments (8.37 ± 0.08 log CFU/g), with SS at pH 1.8 (3.91 ± 0.93 log CFU/g) most effective against yeast and mold in the absence of an organic load. On the basis of these findings, the safety and shelf life of commercially washed diced tomatoes can be improved with PAA-SS.

Life cycle assessment of California processing tomato: an evaluation of the effects of evolving practices and technologies over a 10-year (2005\u20132015) timeframe

PurposeCalifornia is the largest US producer of processing tomatoes, generating 96% of all domestic production and nearly 30% of global supply. Processing tomatoes are mostly processed into diced and paste products. Consumers and actors along their supply chains are increasingly interested in understanding their environmental burdens and identifying opportunities for improvements. This study applies life cycle assessment (LCA) to California diced and paste products over a 10-year timeframe to characterize current impacts and historical trends.MethodsThe LCA considers a scope from cradle-to-processing facility gate and accords with relevant Product Category Rules as published by the International EPD® System. Extensive primary data were collected for tomato cultivation for the years 2005 and 2015, and from processing facilities for 2005, 2010, and 2015 to understand the effects of evolving practices and technologies. We estimate crop and regional specific nitrous oxide and nitrate leaching emissions using a biogeochemical model, and the USES-LCA model is used to determine potential impacts from pesticide application. A suite of impact assessment categories is included based on the CML method (only global warming potential and freshwater consumption values are in the abstract).Results and discussionThe 2015 results of the study indicate that diced tomatoes are responsible for 0.16 kg CO2e and 71 L of freshwater per kg, and paste is responsible for 0.83 kg CO2e and 328 L of freshwater per kg. The main opportunities for improvement include natural gas use in the greenhouse phase, energy for irrigation pumping and fertilizer type in the cultivation phase, and natural gas and electricity use in the facility processing phase. These hotspots are consistent with studies of processing tomato in other parts of the world. Evaluating trends over time showed that technological improvements in the industry had reduced life cycle impacts; for example, global warming potential decreased by 12% for paste and 26% for diced products between 2005 and 2015.ConclusionsTrends over time show increasing efficiency at the cultivation and processing facility stages that have led to reductions in all impact categories evaluated. However, additional opportunities exist beyond efficiency improvements. Fertilizer and pesticide choice are potential opportunities for further reducing impacts. Also, the introduction of renewables in each phase of the supply chain (solar-powered irrigation pumps and onsite solar energy generation for facilities) could reduce the overall supply chain GWP100 impacts by 9–10%.

Quantitative transfer and sanitizer inactivation of Salmonella during simulated commercial dicing and conveying of tomatoes

Diced tomatoes have been linked to outbreaks of salmonellosis in the United States. Compared to slicing, commercial production of diced tomatoes is more complex and includes mechanical dicing as well as washing, dewatering, conveying, and packing. Consequently, this study aimed to 1) quantify Salmonella transfer during pilot-scale dicing of tomatoes, 2) assess the efficacy of three sanitizer treatments against Salmonella during flume tank washing, and 3) assess the efficacy of four sanitizers against Salmonella during conveyance of diced tomatoes. One 0.9 kg batch of Salmonella Typhimurium LT2-inoculated Roma tomatoes (∼5 log CFU/g) was mechanically diced, followed by ten batches of uninoculated tomatoes. All uninoculated tomatoes yielded Salmonella with populations decreasing from 3.3 to 1.1 log CFU/g during dicing. Flume tank washing in sanitizer-free water or water containing 80 ppm of peroxyacetic acid, mixed peracid, or total chlorine decreased Salmonella populations in diced tomatoes 1.3 ± 0.2, 2.3 ± 0.4, 2.35 ± 0.4, and 2.4 ± 0.1 log CFU/g, respectively. After processing, Salmonella populations in flume water containing a sanitizer were always below the limit of detection (−1.0 log CFU/ml) and were significantly lower (P ≤ 0.05) than for the sanitizer-free control (1.5 ± 0.3 log CFU/ml). When the same three sanitizer treatments as well as electrolyzed water (80 ppm chlorine) were applied to smooth and interlocking belts on a dual track conveyor, Salmonella reductions were greater using mixed peracid (6.49 and 6.76 log) and peroxyacetic acid (5.95 and 6.10 log) as compared to chlorine (3.72 and 5.70 log) and electrolyzed water (3.50 and 4.53 log), respectively. All four sanitizer treatments were more effective than water alone in reducing Salmonella on conveyor belt surfaces. These findings should help provide some practical guidelines for the industry and aide in the development of improved risk assessments.

Yield, quality, antioxidant, and sensorial properties of diced tomato as affected by genotype and industrial processing in Southern Italy

Research was carried out on processing tomato in Southern Italy in order to compare four round-prismatic type hybrids oriented to diced produce (4420, Miceno, Nemabrix, Impact as a control). The hybrid Nemabrix attained the highest marketable yield (180.9 t ha–1), due to both the highest number of fruit per plant and their mean weight (103.7 and 70 g, respectively), and it was not significantly different from the other genotypes in terms of processing efficiency both as a total and along dicing chain (67.8% and 65.6%, respectively). Lycopene attained the highest concentration in Nemabrix (155 mg kg–1), and β–carotene was most concentrated in 4420 and Miceno (2.8 mg kg–1). Significant differences arose between the genotypes with regard to the sensorial variables aspect, colour, taste, firmness, and fresh taste.

Predicting the Growth of Listeria monocytogenes and Salmonella Typhimurium in Diced Celery, Onions, and Tomatoes during Simulated Commercial Transport, Retail Storage, and Display

Temperature is arguably the most important factor affecting microbial proliferation in fresh-cut produce. In this study, growth of Listeria monocytogenes in diced onions and celery and Salmonella Typhimurium in diced tomatoes was determined in modified atmosphere packages and snap-fit containers using three fluctuating temperature scenarios for transport, retail storage, and display. As expected, L. monocytogenes growth in diced onions and celery varied depending on the extent of temperature abuse, with exposure to high and intermediate temperature-abuse scenarios generally being growth supportive. A Baranyi primary model with a square-root secondary model for maximum growth rate, and a linear model for maximum population density, were used to estimate Listeria growth under fluctuating temperature. Accuracy and acceptability of the model prediction were evaluated in terms of root mean square error (RMSE) and acceptable prediction zone (APZ), respectively. Overall, growth predictions for L. monocytogenes were more accurate for celery (RMSE, 0.28 to 0.47) than onions (RMSE, 0.42 to 1.53) under the fluctuating temperature scenarios tested. However, both predictions yielded APZ values that ranged from 82 to 100% for celery and 36 to 78% for onions. In contrast, Salmonella Typhimurium populations increased more than 1 log CFU/g in diced tomatoes under the three fluctuating temperature scenarios studied. Overall, these diced products packaged under a high-oxygen atmosphere showed decreased pathogen growth compared with product stored in a passive modified atmosphere. Findings from this study will be particularly useful in assessing the risk associated with consumption of diced celery, tomatoes, and onions and in designing effective packaging strategies to minimize pathogen growth in fresh-cut produce.

Assessment of premium quality factors (nutritional, functional and taste) for five Italian tomato cultivars and relative diced tomatoes products

Assessment of premium quality factors (nutritional, functional and taste) for five Italian tomato cultivars and relative diced tomatoes products

Improving diced tomato firmness by pulsed vacuum calcification

Vacuum impregnation is a non-thermal technique used in food technology to replace the air occluded in the products with specific substances, thus modifying food quality. Here, this technique was employed to allow calcium ions to penetrate more efficiently in the tissue structure of diced tomatoes with consequent increase of the product firmness. Calcification was obtained in two ways, that is, either by keeping diced tomatoes at the reduced pressure of 100 mbar or by subjecting the product to cycles of pulsed vacuum from 1013 mbar to 30 mbar. Both procedures were conducted in the presence of calcium chloride solutions at various concentrations and temperatures. The results showed that the highest firmness was obtained by pulsed vacuum calcification at 30 mbar and 45 °C by using 4 cycles of pulsed vacuum. In these conditions, after two-months storage at room temperature, the treated diced tomatoes packaged in tinplate cans showed firmness increase of about 90% with respect to product not treated by vacuum infiltration. These results indicate the pulsed vacuum calcification as a promising process that can be effectively introduced in some phases of the industrial tomato transformation to improve the product texture.

SRO_ANN: An integrated MatLab toolbox for multiple surface response optimization using radial basis functions

SRO_ANN, a MatLab® toolbox for implementing multiple surface response optimization by artificial neural networks (SRO_ANN) is presented. Radial basis functions, a type of artificial neural networks, are applied through an easily managed graphical user interface. A detailed description of the interface is provided, including a simulated and two literature examples which allow one to show the potentiality of the software. The discussed experimental examples correspond to: (1) the maximization of the research octane number (RON) of fuels, influenced by three factors (reaction temperature, operating pressure and low liquid hourly space velocity), and (2) the optimization of the calcification process for diced tomatoes, evaluated through three different responses (calcium content, firmness and pH), which are affected by three factors (calcium concentration, solution temperature and treatment time). The results show that the application of a nonparametric tool can enhance the performance of optimization modeling tasks.

Adequate Hand Washing and Glove Use Are Necessary To Reduce Cross-Contamination from Hands with High Bacterial Loads

Hand washing and glove use are the main methods for reducing bacterial cross-contamination from hands to ready-to-eat food in a food service setting. However, bacterial transfer from hands to gloves is poorly understood, as is the effect of different durations of soap rubbing on bacterial reduction. To assess bacterial transfer from hands to gloves and to compare bacterial transfer rates to food after different soap washing times and glove use, participants' hands were artificially contaminated with Enterobacter aerogenes B199A at ∼9 log CFU. Different soap rubbing times (0, 3, and 20 s), glove use, and tomato dicing activities followed. The bacterial counts in diced tomatoes and on participants' hands and gloves were then analyzed. Different soap rubbing times did not significantly change the amount of bacteria recovered from participants' hands. Dicing tomatoes with bare hands after 20 s of soap rubbing transferred significantly less bacteria (P < 0.01) to tomatoes than did dicing with bare hands after 0 s of soap rubbing. Wearing gloves while dicing greatly reduced the incidence of contaminated tomato samples compared with dicing with bare hands. Increasing soap washing time decreased the incidence of bacteria recovered from outside glove surfaces (P < 0.05). These results highlight that both glove use and adequate hand washing are necessary to reduce bacterial cross-contamination in food service environments.

MicroSEQ® Salmonella spp. Detection Kit Using the Pathatrix® 10-Pooling Salmonella spp. Kit Linked Protocol Method Modification.

The results of the method modification were compared to standard cultural reference methods for diced tomatoes, chocolate, and deli ham. All three matrixes were analyzed in a paired study design. An additional set of chocolate test portions was analyzed using an alternative enrichment medium in an unpaired study design. For all matrixes tested, there were no statistically significant differences in the number of positive test portions detected by the modified candidate method compared to the appropriate reference method. The MicroSEQ Salmonella spp. protocol linked with the Pathatrix individual or 10-Pooling procedure demonstrated reliability as a rapid, simplified, method for the preparation of samples and subsequent detection of Salmonella in diced tomatoes, chocolate, and deli ham.

Comparing environmental impacts of regional and national-scale food supply chains: A case study of processed tomatoes

This study uses life cycle assessment methodology to quantify the energy use, greenhouse gas (GHG) emissions, and water use of processed tomato products grown, processed, and consumed within the Great Lakes region of the United States, and tomato products produced in California and then shipped to the Great Lakes region for consumption. The purpose is to assess the potential for regional food systems to reduce selected environmental impacts, particularly the energy and GHG footprints, of consumer-ready, processed food products, when compared to national-scale food systems in which consumer products are shipped long distances. The study also examines the role of different types of food processing in influencing life cycle energy use, water use, and emissions.Our results indicate that California-produced conventional and organic tomato paste and canned diced tomatoes are almost equivalent in energy use and GHG emissions to regionally produced and consumed products, but use of developed water resources is significantly higher for California-grown products. California tomato production benefits from higher per hectare yields and soil amendments with lower carbon dioxide emissions. These efficiencies substantially offset the added energy use and GHG emissions associated with long-distance shipment of products to the Great Lakes region, as long as shipments are made by rail rather than by truck. Paste, the more processed and concentrated product evaluated, amplifies any environmental advantages or disadvantages accrued in the field production stage, due to its raw tomato to finished product ratio of 6:1, suggesting that comparative regional advantage can play a role in lowering life cycle environmental impacts of highly condensed foods shipped long distances.

Antioxidant Availability of Commonly Consumed Vegetables in the U.S. Food Supply

The genesis and progression of a number of chronic diseases are believed to involve oxidative-based cellular insult and injury (1). As a measure of antioxidant capacity, the Oxygen Radical Absorption Capacity (ORAC) assay quantifies the degree of inhibition of peroxy-radical-induced oxidation (2). We determined the per capita antioxidant availability from commonly consumed vegetables in the U.S. food supply by: 1) using the USDA Economic Research Service loss-adjusted food availability database (2009) to identify non-starchy vegetables comprising the greatest quantitative contribution to total vegetable intake (3) and 2) the USDA database for ORAC (release 2, 2010)(4). The predominant source of the vegetable (raw, canned, or frozen) was used exclusively unless a second source contributed 20% or more of the total availability of that vegetable. ORAC values of tomato paste and canned diced tomatoes were determined independently, as they make a significant contribution to total vegetable intake, but are not currently in the USDA database. Canned tomato products (sauce, paste, and tomatoes) accounted for 39% of the total per capita ORAC availability, onions 14%, green bell pepper 9%, iceberg lettuce 8%, raw tomatoes 7%, broccoli (raw and frozen) 7%, carrots 5%, celery 4%, cabbage 4%, and green beans (raw, canned, and frozen) 3%. Tomato paste had the greatest and canned green beans the lowest ORAC concentration (1580 and 290 μmol trolox equivalents/100 grams, respectively). These data show canned tomato products are the single most important contributor to dietary antioxidant intake amongst commonly consumed vegetables due to their high per capita availability and ORAC concentration.

High hydrostatic pressure processing reduces Salmonella enterica serovars in diced and whole tomatoes

Fresh and fresh-cut tomatoes have been associated with numerous outbreaks of salmonellosis in recent years. One effective post harvest treatment to reduce Salmonella enterica in tomatoes may be high pressure processing (HPP). The objectives of the study were to determine the potential for HPP to reduce S. enterica serovars Newport, Javiana, Braenderup and Anatum in tryptic soy broth (TSB) and to determine the effect of HPP to reduce the most pressure resistant of the four serovars from fresh diced and whole tomatoes. To evaluate pressure resistance, TSB containing 8 log CFU/ml of one of the four serovars was packaged in sterile stomacher bags and subjected to one of three different pressures (350, 450 or 550MPa) for 120s. The most pressure resistant S. enterica serovar evaluated was Braenderup. Subjecting the broth culture to 350, 450 and 550MPa resulted in a 4.53, 5.74 and 7.09 log reduction in S. Braenderup, respectively. Diced tomatoes (150g) and whole red round tomatoes (approximately 150g) were inoculated with 0.1ml of 9.1 log CFU/ml S. Braenderup, and subjected to the same pressure treatments (350, 450 or 550MPa). Significant reductions of S. Braenderup concentrations in diced tomatoes (P<0.05) were seen after processing at 350 (0.46CFU/g), 450 (1.44 log CFU/g), and 550MPa (3.67 log CFU/g). In whole tomatoes, significant reductions (P<0.05) were also seen at 350 (1.41 log CFU/g), 450 (2.25 log CFU/g) and 550MPa (3.35 log CFU/g). HPP may be an effective post harvest strategy to reduce low levels of S. enterica contamination in whole and diced tomatoes.

Changes in phenolic profile and antioxidant activity during production of diced tomatoes

Tomatoes and tomato-based products are rich in antioxidants such as carotenoids, vitamin C and polyphenols. The industrial processing of diced tomatoes involves heat treatments in which these antioxidant compounds may be potentially affected. In this study, we evaluate the effect of each separate step in the dice-making process. Three technological processes were investigated: Hot, Cold and Cold treated with calcium salt (CaCl2). Four stages were monitored in each process: (1) fresh tomatoes; (2) peeled tomatoes; (3) diced tomatoes; and (4) final product after sauce addition. The main tool for minimising or counteracting the eventual processing damage was the strategy of ‘reconstitution’, achieved by adding a sauce rich in seeds and peels with high levels of antioxidants and phenolics to the diced tomatoes. Different analyses were carried out in order to evaluate the effect of each processing step. First, total polyphenols (TP) were evaluated using Folin–Ciocalteau (F–C) assay and antioxidant activity using ABTS+ and DPPH assays. Flavonols, flavanones, hydroxycinnamic and phenolic acids were then quantified using liquid chromatography/electrospray ionisation tandem mass spectrometry (HPLC–ESI–MS/MS). The combination of principal component analysis (PCA) and analysis of variance (ANOVA) revealed that each processing step induces alterations in the antioxidant and phenolic profile, and in particular sauce addition and calcium treatment significantly affected the levels of antioxidants and phenolics during the dice-making process.

Changes in pectin methylesterification and accumulation of methanol during production of diced tomatoes

The degree of methylesterification (DM) of the pectins in tomatoes affects the firmness of diced products and the consistency of juices. We examined the changes in DM that occur during commercial production of diced tomatoes packed in tomato juice. Ripe processing tomatoes contained low amounts of free methanol (<20 μg g fresh weight −1) and had a high degree of pectin methylesterification (60%). During production of diced tomatoes, the level of free methanol increased while the degree of pectin methylesterification decreased. Diced tomatoes canned in tomato juice contained about 200 μg methanol g fresh weight −1, and had a DM of about 35% in the dice and less than 25% in the juice. Similar results were obtained for aseptically processed bulk packed tomatoes. Low-temperature blanching of canned diced tomatoes caused additional pectin de-esterification in the diced tomatoes and improved firmness. Heating of the diced tomatoes prior to mixing with topping juice, first to temperatures that maximally activate PME then to temperatures that inactivate PME and other enzymes, is proposed as a way to both improve dice firmness and preserve the consistency of the topping juice.

Aroma volatiles of tomatoes and tomato products evaluated by solid‐phase microextraction

AbstractSolid‐phase microextraction (SPME) was examined to investigate volatiles in tomatoes and tomato products. Aroma volatiles and differences in volatile composition of different varieties of fresh tomatoes and several commercial tomato products, such as tomato juice, tomato puree, tomato paste and canned diced tomatoes, were analysed by a manual headspace SPME technique coupled with gas chromatography (GC–FID and GC–MS). Fresh and processed tomato aroma was composed of terpenes and lactones, esters, carbonyls and alcohols, sulphur compounds, free acids and oxygencontaining heterocyclic compounds. In most samples of processed tomatoes, lower relative concentrations of volatiles than in fresh tomato samples were determined, but in some cases (especially in samples of tomato juice) higher concentrations were observed. The most important difference between fresh tomato and processed tomato aroma was the almost complete loss of cis‐3‐hexenal and the presence of furfural in tomato products. On the basis of the aromatic profiles obtained by GC analysis, relationships between fresh and processed tomato samples were obtained, using multivariate PCA statistical analysis. Copyright © 2007 John Wiley &amp; Sons, Ltd.

1% Calcium Chloride Treatment in Combination with Gamma Irradiation Improves Microbial And Physicochemical Properties of Diced Tomatoes

The purpose of this study was to determine the effect of a combination of a 1% calcium chloride dip with low dose irradiation on microbial populations, and biochemical and physical properties, of fresh diced tomatoes during a two-week storage period. Vine tomatoes at the light-red stage (trial 1) and Celebrity tomatoes at the table ripe stage (trial 2) were diced, dipped in 1% CaCl(2), and irradiated at 1 kGy from a Co(60) source. Tomatoes were also contaminated with cocktail of nalidixic-acid resistant Salmonella strains (S. Poona, S. Hartford, S. Gaminara, S. Michigan, and S. Montevideo) and subjected to gamma irradiation. Calcium treatment alone stimulated ethylene production in the diced tomatoes, whereas irradiation treatment alone suppressed ethylene production. The combination of calcium and irradiation treatments resulted in no change in ethylene production compared to the nontreated control, but respiration rate was suppressed by both irradiation and calcium treatment. The calcium dip was found to limit irradiation-induced loss of firmness. Irradiation, by itself and in combination with calcium treatment, resulted in a >3 log CFU/g decrease in total aerobic counts and psychrotrophs. Additionally, irradiation at 1.5 kGy eliminated > 3 log CFU/g of Salmonella organisms from tomatoes contaminated with Salmonella. Counts continued to decrease to an undetectable level over the 11 day storage period. The results indicate that the combination of calcium treatment and irradiation can reduce the risk of disease due to pathogenic organisms such as Salmonella and can eliminate the problem of softening induced by irradiation.

Irradiation D Values ofSalmonellaspp. in Diced Tomatoes Dipped in 1% Calcium Chloride

Outbreaks of salmonellosis have been associated with eating raw domestic tomatoes. In this study, we examined the efficiency of combined irradiation and a 1% calcium chloride dip to reduce the population of Salmonella enterica strains on diced tomatoes. Tomatoes were contaminated with nalidixic acid-resistant strains of S. Hartford, S. Montevideo, or a mixture of 5 strains (S. Hartford, S. Montevideo, S. Poona, S. Michigan, S. Gaminara). We irradiated tomatoes at various doses up to 0.9 kGy from an electron beam source to conduct a D-value study (decimal reduction time required to eliminate 90% of the organism). Surviving Salmonella populations were detected by standard and recovery plating methods. D-value results ranged from 0.26 to 0.39 kGy, indicating that a 5 log(10) CFU/g reduction in Salmonella spp. in diced tomatoes would require a dose of 1.3-1.95 kGy.