Cantaloupe Cubes Research Articles

Efficacy of organic acid electrostatic spray for decontaminating Salmonella on cantaloupe cubes and cherry tomatoes

The effect of organic acid electrostatic spraying on Salmonella Typhimurium inoculated fresh produces and their texture and color changes was evaluated. Inoculated cantaloupe cubes and cherry tomatoes were electrostatically sprayed with varying concentrations of malic and lactic acids and monitored over 11-day storage at 4°C. Malic acid (4%) could significantly reduce Salmonella growth on cantaloupe cubes up to 2.6-log CFU/g by electrostatic spraying and only 0.9-log CFU/g by conventional spraying (p < 0.05). However, there was no significant difference (p > 0.05) using both methods in the log numbers of Salmonella survived on cherry tomatoes over 11-day storage. The electrostatic spraying treatments did not cause much effect on the color and texture of the produce samples. These findings suggest that the safety of fresh and fresh-cut produce may be enhanced using malic acid or combined with lactic acid applied by an electrostatic spraying system. Practical applications The current study illustrates the importance of natural antimicrobial organic acids that can minimize pathogenic Salmonella contaminations on fruits and vegetables. Electrostatic spray method reduces loss of treatment solutions while enhancing their antimicrobial activity without affecting their texture and color. This can lead to commercialization of the technology which can protect consumers from food-borne illnesses due to contaminations.

Survival and Growth of Listeria monocytogenes on Fresh-Cut “Athena” and “Rocky Ford” Cantaloupes During Storage at 4°C and 10°C

Cantaloupes, marketed as "Rocky Ford," were implicated in the U.S. multistate outbreak of listeriosis in 2011, which caused multiple fatalities. Listeria monocytogenes can survive on whole cantaloupes and can be transferred to the flesh of melons. The growth of L. monocytogenes on fresh-cut "Athena" and "Rocky Ford" cantaloupe cultivars during refrigerated storage was evaluated. Fresh-cut cubes (16.4 cm3) from field-grown cantaloupes were each inoculated with 5 log10 CFU/mL of a multi-strain mixture of L. monocytogenes and stored at 4°C or 10°C. Inoculated fresh-cut cubes were also: (1) continuously stored at 4°C for 3 days; (2) temperature-abused (TA: 25°C for 4 h) on day 0; or (3) stored at 4°C for 24 h, exposed to TA on day 1, and subsequently stored at 4°C until day 3. L. monocytogenes populations on fresh-cut melons continuously stored at 4°C or 10°C were enumerated on selected days for up to 15 days and after each TA event. Brix values for each cantaloupe variety were determined. L. monocytogenes populations on fresh-cut cantaloupe cubes stored at 4°C increased by 1.0 and 3.0 log10 CFU/cube by day 7 and 15, respectively, whereas those stored at 10°C increased by 3.0 log10 CFU/cube by day 7. Populations of L. monocytogenes on fresh-cut cantaloupes stored at 10°C were significantly (p < 0.05) greater than those stored at 4°C during the study. L. monocytogenes showed similar growth on fresh-cut "Athena" and "Rocky Ford" cubes, even though "Athena" cubes had significantly higher Brix values than the "Rocky Ford" fruit. L. monocytogenes populations on fresh-cut cantaloupes exposed to TA on day 1 and then refrigerated were significantly greater (0.74 log10 CFU) than those stored continuously at 4°C for 3 days. Storage at 10°C or exposure to TA events promoted growth of L. monocytogenes on fresh-cut cantaloupe during refrigerated storage.

Functional Nanomaterials: Energy and Sensing

Sponsored by the Nanomaterials Committee, this special topic has a unique combination of short review papers and research papers on some recent advances for using functional nanomaterials for energy conversion/storage and optical/electric/magnetic signal sensing. The invited paper from Zhu’s group is an extension of their talk ‘‘One-Dimensional Nanostructures for Wearable Devices’’ presented at the TMS 2015 Annual Meeting & Exhibition (TMS2015). The paper reviews nanomaterial-enabled dry electrodes for electrophysiological sensing, particularly on electrocardiography (ECG). It starts with an overview of two different commercial electrodes (i.e., pre-gelled wet electrode and dry electrode), their electrode–skin interface models and the source of noise. The overview shows that dry electrodes have certain advantages over the wet ones, such as the elimination of signal degradation caused by dehydration of the gel. The overview also points out that (1) flexible dry electrodes are needed to form intimate contact with skin surface so that the movement of electrodes and motion artifacts can be suppressed and reduced, and (2) the nanomaterials-based electrode could be the solution. The paper then presents a comprehensive review on recent developments of dry ECG electrodes made of various nanomaterials, including metallic nanowires, metallic nanoparticles, carbon nanotubes and graphene. Their fabrication processes and performances are discussed. The paper concludes that nanomaterials-enabled dry ECG electrodes are attractive candidates for long-term ECG sensing, and calls for more studies in this field. The invited paper from Zhao’s team is a recap of their talk ‘‘Detecting Bacteria by Surface Enhanced Raman Spectroscopy’’ at TMS2015. This paper reports how surface-enhanced Raman spectroscopy (SERS) contributes to food safety by detecting the low levels of pathogenic microorganisms that may exist in foods. In particular, vegetables and fruits are vulnerable to contamination by pathogenic microorganisms since they are natural vehicles of pathogens from cultivation to delivery. Therefore, to detect a small amount of harmful microorganisms is a very important, but challenging task for food safety. Compared with traditional Raman spectroscopy, SERS exploits novel metal nanostructures to enhance the sensitivity. In this study, the authors demonstrate that the limit of detection (LOD) of Salmonella Poona from cantaloupe cubes can be as low as 100 CFU/ml in less than 4 h by performing SERS measurements on vancomycin-coated silver nanorod (VAN AgNR) substrates. It is claimed that such a small LOD has not previously been reported for label-free, intrinsic SERS detection using real food samples. This result suggests that the SERS detection technique based on AgNR is a powerful platform for a rapid, simple, and inexpensive means of pathogenic bacteria detection, which will be very useful in securing the safety of fresh foods.

Rapid Detection of Pathogenic Bacteria from Fresh Produce by Filtration and Surface-Enhanced Raman Spectroscopy

The detection of Salmonella Poona from cantaloupe cubes and E. coli O157:H7 from lettuce has been explored by using a filtration method and surface-enhanced Raman spectroscopy (SERS) based on vancomycin-functionalized silver nanorod array substrates. It is found that with a two-step filtration process, the limit of detection (LOD) of Salmonella Poona from cantaloupe cubes can be as low as 100 CFU/mL in less than 4 h, whereas the chlorophyll in the lettuce causes severe SERS spectral interference. To improve the LOD of lettuce, a three-step filtration method with a hydrophobic filter is proposed. The hydrophobic filter can effectively eliminate the interferences from chlorophyll and achieve a LOD of 1000 CFU/mL detection of E. coli O157:H7 from lettuce samples within 5 h. With the low LODs and rapid detection time, the SERS biosensing platform has demonstrated its potential as a rapid, simple, and inexpensive means for pathogenic bacteria detection from fresh produce.

Growth of Salmonella enterica and Listeria monocytogenes on Fresh-Cut Cantaloupe under Different Temperature Abuse Scenarios

Effective cold chain management is a critical component of food safety practice. In this study, we examined the impact of commonly encountered temperature abuse scenarios on the proliferation of Salmonella enterica and Listeria monocytogenes on fresh-cut cantaloupe. Inoculated fresh-cut cantaloupe cubes were subjected to various temperature abuse conditions, and the growth of S. enterica and L. monocytogenes was determined. During 1 week of storage, Salmonella cell counts on fresh-cut cantaloupe increased by –0.26, 1.39, and 2.23 log units at 4°C (control), 8°C, and 12°C (chronic temperature abuse), respectively, whereas that of L. monocytogenes increased by 0.75, 2.86, and 4.17 log units. Under intermittent temperature abuse conditions, where storage temperature fluctuated twice daily to room temperature for 30 min, Salmonella cell count increased by 2.18 log units, whereas that of L. monocytogenes increased by 1.86 log units. In contrast, terminal acute temperature abuses for 2 to 4 h resulted in upwards to 0.6 log unit for Salmonella, whereas the effect on L. monocytogenes was less significant compared with L. monocytogenes on cut cantaloupe stored at 4°C. Significant deterioration of produce visual quality and tissue integrity, as reflected by electrolyte leakage, was also observed under various temperature abuse conditions.

Electrostatic Spray of Food‐Grade Organic Acids and Plant Extract to ReduceEscherichia coliO157:H7 on Fresh‐Cut Cantaloupe Cubes

AbstractThe objective of the study was to determine the effects of organic acids and plant extract alone and in combination when applied by electrostatic spraying onEscherichia coliO157:H7‐inoculated cantaloupe cubes. Inoculated cubes were sprayed with malic (M) and lactic (L) acids and grape seed extract at different concentrations (alone and various combinations) then stored at 4C. Under optimized concentrations,ML2% was able to reduceE. coliO157:H7 by 1.9 logs after 12 days of storage and was significantly different from the controls (P &lt; 0.05). Increasing the concentration ofM(4%) alone and in combination withL(2%) caused an increase in log reduction (4.6 logs). These treatments can be used as alternatives to commercial sanitizers in order to improve the safety of fresh‐cut cantaloupe cubes. Multiple hurdle technology of electrostatic sprayer combined with natural antimicrobials can be effective in improving the safety of food.Practical ApplicationElectrostatic sprayer is a technology that can be used to enhance the effectiveness of antimicrobials. Organic acids and plant extracts can be used as antimicrobials to efficiently reduce contaminated cantaloupe cubes when combined with electrostatic sprayer. This multiple hurdle technology can be used in different food industry settings.

Effect of chemical sanitizers on Salmonella enterica serovar Poona on the surface of cantaloupe and pathogen contamination of internal tissues as a function of cutting procedure.

Survival of Salmonella enterica subsp. enterica serovar Poona on surface and stem scar portions of inoculated cantaloupe following sanitizer application, transfer of pathogen from the rind to the flesh during cutting, and growth of Salmonella Poona on cantaloupe cubes over 15 days of refrigerated storage were investigated. Cantaloupes inoculated with a rifampin-resistant strain of Salmonella Poona (10(7) CFU/ml) for 3 min and dried for 12 h were washed with chlorine (200 mg free chlorine per liter, 3 min), lactic acid (2%, 2 min), or ozone (30 mg/liter, 5 min). Fresh-cut cantaloupe cubes were prepared by (i) cutting the cantaloupe and then removing the rind or by (ii) peeling the rind and then cutting the flesh into pieces. The numbers of Salmonella bacteria recovered were higher in the stem scar portion (6.3 ± 0.3 log CFU/cm(2)) than the surface (4.8 ± 0.2 log CFU/cm(2)). Surface treatment with tap water or chlorine did not reduce Salmonella numbers, while treatment with lactic acid or ozone reduced Salmonella by 2.5 or 2.3 log CFU/cm(2), respectively. The use of lactic acid to sanitize the cantaloupes resulted in less Salmonella transfer to flesh during cutting; Salmonella numbers decreased to below detectable levels over 9 days of refrigerated (4°C) storage. Cutting cantaloupes after peeling the rind was more effective at reducing transfer of Salmonella to the internal tissue than cutting of cantaloupes prior to rind removal. These data suggest that treatment of cantaloupe rinds with lactic acid or ozone may be effective at reducing Salmonella numbers, while lactic acid application resulted in reduction of Salmonella transfer to cantaloupe flesh.

Effect of Malic and Lactic Acid Incorporated Soy Protein Coatings on the Sensory Attributes of Whole Apple and Fresh-Cut Cantaloupe

ABSTRACT: Whole apples and fresh-cut cantaloupe cubes were coated with soy protein + glycerol (SP) films and 2 other films that were demonstrated to have antimicrobial activity in model system, SP + malic acid (MSP), and SP + lactic acid (LSP). Treated apples and cantaloupe cubes were stored at 5°C, and the sensory properties were evaluated with a trained descriptive analysis panelists. Texture and color were also measured with instruments. The sourness of SP-coated apples was lower than non-coated, MSP-coated, and LSP-coated apples after 28 d of storage. The sweetness of the LSP-coated cantaloupe cubes was higher than the non-coated and the MSP-coated samples at 7 d. The sensory evaluation of the MSP and LSP coatings on the apples and the cantaloupe cubes showed no significant difference in the other attributes of taste and appearance. Although instrumental measurements showed that hardness of the coated apples was higher than that of the non-coated ones, the panelists did not detect the differences. Instrumental measurements also showed that the hardness of the SP-coated cantaloupe cubes was lower than the non-coated, LSP-coated, and MSP-coated cantaloupe cubes, and the panelists did not detect the differences. The color of the apples evaluated by panelists was correlated with instrumental color measurements. Organic acid incorporated films (MSP and LSP) did not adversely impact the sensory properties of the tested products. Malic and lactic acids incorporated soy protein film that can be used to coat the whole apple and the fresh-cut cantaloupes without affecting the sensory properties.

Quality Changes and Nutrient Retention in Fresh-Cut versus Whole Fruits during Storage

The influences of processing and storage on the quality indices and nutritional content of fresh-cut fruits were evaluated in comparison to whole fruits stored for the same duration but prepared on the day of sampling. Fresh-cut pineapples, mangoes, cantaloupes, watermelons, strawberries, and kiwifruits and whole fruits were stored for up to 9 days in air at 5 degrees C. The postcutting life based on visual appearance was shorter than 6 days for fresh-cut kiwifruit and shorter than 9 days for fresh-cut pineapple, cantaloupe, and strawberry. On the other hand, fresh-cut watermelon and mango pieces were still marketable after 9 days at 5 degrees C. Losses in vitamin C after 6 days at 5 degrees C were < or = 5% in mango, strawberry, and watermelon pieces, 10% in pineapple pieces, 12% in kiwifruit slices, and 25% in cantaloupe cubes. No losses in carotenoids were found in kiwifruit slices and watermelon cubes, whereas losses in pineapples were the highest at 25% followed by 10-15% in cantaloupe, mango, and strawberry pieces after 6 days at 5 degrees C. No significant losses in total phenolics were found in any of the fresh-cut fruit products tested after 6 days at 5 degrees C. Light exposure promoted browning in pineapple pieces and decreased vitamin C content in kiwifruit slices. Total carotenoids contents decreased in cantaloupe cubes and kiwifruit slices, but increased in mango and watermelon cubes in response to light exposure during storage at 5 degrees C for up to 9 days. There was no effect of exposure to light on the content of phenolics. In general, fresh-cut fruits visually spoil before any significant nutrient loss occurs.

Combination of Hot-Water Surface Pasteurization of Whole Fruit and Low-Dose Gamma Irradiation of Fresh-Cut Cantaloupe

Improvements in methods for disinfecting fresh-cut cantaloupe could reduce spoilage losses and reduce the risk of food-borne illness from human pathogen contamination. The objective of this study was to investigate the feasibility of using hot-water treatment in combination with low-dose irradiation to reduce native microbial populations while maintaining the quality of fresh-cut cantaloupe. Whole cantaloupes were washed in tap water at 20 or 76°C for 3 min. Fresh-cut cantaloupe cubes, prepared from the washed fruit, were then packaged in clamshell containers, and half the samples were exposed to 0.5 kGy of gamma radiation. Native microflora populations and sensory qualities were evaluated during the subsequent 7 days of storage at 4°C. The hot-water surface pasteurization reduced the microflora population by 3.3 log on the surface of whole fruits, resulting in a lower microbial load on the fresh-cut cubes compared with cubes cut from fruit treated with cold water. Irradiation of cubes prepared from untreated fruit to an absorbed dose of 0.5 kGy achieved a low microbial load similar to that of cubes prepared from hot-water-treated fruit. The combination of the two treatments was able to further reduce the microflora population. During storage, the headspace atmosphere of the packages was not significantly influenced by any of the treatments. Color, titratable acidity, pH, ascorbic acid, firmness, and drip loss were not consistently affected by treatment with irradiation, hot water, or the combination of the two. Cubes prepared from hot-water-treated whole fruit had slightly lower soluble solids content. The combination of hot-water pasteurization of whole cantaloupe and low-dose irradiation of packaged fresh-cut melon can reduce the population of native microflora while maintaining the quality of this product.

Influence of 1-Methylcyclopropene (1-MCP) on the Shelf Life and Deterioration of Fresh-cut Cantaloupe

A study was conducted to determine the influence of the ethylene action inhibitor, 1-methylcyclopropene (1-MCP) on the shelf life and deterioration of fresh-cut cantaloupe (Cucumis melo var. reticulatus) during storage at 5 °C. Intact cantaloupe fruit, cv. Durango (3/4 to full-slip stage) were treated with 1-MCP (1 μL·L-1) for 24 h at 20 °C. Following cooling to 5 °C, the fruit were processed into ≈2.5-cm cubes and subsequently dipped in 1.34 mm sodium hypochlorite solution for 20 s. Fresh-cut cubes were stored in 1.7-L vented plastic containers for 12 d at 5 °C (85% RH). Intact fruit treated and stored under identical conditions were also examined. While 1-MCP-treated cantaloupe cubes were about 35% firmer than control cubes after the 24-h at 20 °C 1-MCP treatment, little softening occurred in either treatment during the subsequent 12-d at 5 °C storage period. In contrast, control and 1-MCP-treated intact fruit softened nearly 40% and 15%, respectively. 1-MCP did not significantly influence flesh color and soluble solid contents of either intact cantaloupe or fresh-cut cubes during storage at 5 °C. Increased decay incidence was observed in 1-MCP-treated fresh-cut cantaloupe cubes.

438 Optimization of a SPME Method for Flavor Characterization in Fresh-cut Cantaloupe

Fresh-cut melons in many consumer-ready packages are notorious for “wetting” and accumulation of standing juices. These conditions likely create undesirable flavor and aroma changes. We initiated a study to investigate flavor changes in stored fresh-cut cantaloupe. One objective was to optimize solid phase microextraction (SPME) to evaluate organoleptic compounds. Static head-space SPME analyses were performed on fresh-cut cantaloupe cubes (≈2.5 mm, 5 mm, or 2.5 cm), expressed juice, and homogenized slurries. SPME fiber (100 μm PDMS vs. 75 μm Carboxen/PDMS) exposure time (5, 7.5, 10, 12.5, 15, 17.5, 20 min) was evaluated at 40 °C with various head-space: product ratios, plus or minus NaCl to produce typical chromatograms. Fibers were desorbed in an HP5890 GC with a DB-624 or DB-5 column for 45-min runs and an HP6890 GC (DB-5) equipped with a 5973 MS detector for 35-min runs. Albeit qualitative, the best chromatograms were obtained with 7-ml slurries, stirred with NaCl, exposed to a 10 0μm PDMS SPME fiber for 12.5 min. The 100 μm PDMS fiber produced better chromatograms considering the fact that many important flavor volatiles are low-molecular-weight polar esters and alcohols. These conditions were subsequently used to analyze numerous fresh-cut cantaloupe samples stored various times (0 to 9 days). Over 100 peaks were identified, many of which changed through storage and some are suspected as probable agents responsible for undesirable flavor changes. Our analyses are progressing in an attempt to authenticate compounds associated with flavor-related changes in numerous fresh-cut cantaloupe varieties from various growing regions.