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Efficacy of different washing solutions and contact times on the microbial quality and safety of fresh-cut paprika B. Kumar Das, Ji Gang Kim and Ji Weon Choi Food Science and Technology International 2011 17: 471 originally published online 27 September 2011 DOI: 10.1177/1082013211398842 The online version of this article can be found at: http://fst.sagepub.com/content/17/5/471

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Article

Efficacy of different washing solutions and contact times on the microbial quality and safety of fresh-cut paprika B. Kumar Das, Ji Gang Kim and Ji Weon Choi

Abstract The role of different washing solutions and contact times was investigated to determine their use as potential sanitizers for maintaining the microbial quality and food safety of fresh-cut paprika. Samples were cut into small pieces, washed for both 90 and 180 s by different washing solutions: tap water, chlorinated water (100 mg/L and pH 6.5–7), electrolyzed water (pH 7.2) and ozonized water (4 mg/L). Then, samples were packaged in 50 mm polypropylene bags and stored at 5 C for 12 days, followed by an evaluation of the antimicrobial efficacy of the treatments. Various quality and safety parameters, such as gas composition, color, off-odor, electrical conductivity and microbial numbers, were evaluated during storage. Results revealed insignificant differences in gas composition, and no off-odor was observed in any of the samples during the storage period. However, longer contact time resulted in slightly lower hue angle value than a short one for all washing solutions. Moreover, samples washed with ozone washings showed lower electrolyte leakage than other washing solutions. Samples washed for longer contact time except those washed in ozonized water showed increased microbial numbers during storage. Hence, it has been concluded that longer contact time with ozone has positive effects, whereas the other washing solutions adversely affect the microbial quality and safety aspects of fresh-cut paprika.

Keywords Chlorinated water, contact time, electrolyzed water, fresh-cut paprika, microbial quality, ozonized water Date received: 21 July 2010; revised: 26 October 2010

INTRODUCTION In recent years, the fresh-cut vegetable market has grown rapidly due to an increased consciousness of the importance of consuming fresh, healthy and convenient food. However, increasing public health concern related to the microbial safety of fruit and vegetables has resulted in an increasing number of studies that analyze the efficiency of different methods for maintaining food safety in fresh-cut products (Beuchat et al., 2004; Go´mez-Lo´pez et al., 2007; Inatsu et al., 2005; Lukasik et al., 2003; Selma et al., 2008; Ukuku et al., 2005). These studies have concluded that the simple practice of washing raw fruits and vegetables removes a portion of pathogenic and spoilage microorganisms, thereby decreasing Food Science and Technology International 17(5) 471–479 ! The Author(s) 2011 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1082013211398842 fst.sagepub.com

their initial levels and microbiological activity. Because bacterial cells attach to the surface of fruit and vegetables in a relatively short time period and they tend to locate in protected binding sites, they may escape contact with washing or sanitizing agents, thereby making the removal of all cells by vigorous washing or treatment with chlorine and electrolyzed water (EW) difficult (Allende et al., 2008; Mandrell et al., 2006; Wang et al., 2004). Thus, the success of washing fruits and vegetables depends on different factors, such as the target microorganisms, characteristics of produce surfaces, type of attachment of cells to produce surfaces, formation of resistant biofilms and internalization of National Institute of Horticultural and Herbal Science, RDA, Suwon 440706, Republic of Korea. Corresponding author: B. Kumar Das, National Institute of Horticultural and Herbal Science, RDA, Suwon 440706, Republic of Korea Email: [email protected]; [email protected]


Food Science and Technology International 17(5) microorganisms, type of washing, exposure time, dose, pH, temperature, etc. (Kim et al., 2003). Hence, maintenance of a reduction in microbial numbers and activity during storage is equally as important as the initial microbial reduction after washing (Ragaert et al., 2007). The active metabolism of the plant tissues, the damage during washing, cutting, handling and shredding and the exposure of their cut surfaces to external factors can adversely affect the relative stability of the produce over the shelf life likely due to microbial growth and deterioration in its food quality (Rico et al., 2007). Research has generally agreed that an ideal sanitizing agent should have the following two important properties: a sufficient level of antimicrobial activity and a negligible effect on the sensory quality of the product. Notably, the concentration/level of sanitizers or other intervention methods may be limited by an unacceptable sensory impact on the produce. Therefore, the sensory quality of the product should also be evaluated when selecting the optimal sanitizing technique (Martı´ nezSanchez et al., 2006). Currently, chlorine is the sanitizing agent most used by the fresh-cut industry mainly due to its antimicrobial activity and low cost. However, increasing public health concerns about the possible formation of chlorinated organic compounds, which may be carcinogenic and the emergence of new more tolerant pathogens have raised doubts about the continued use of chlorine by the fresh-cut industry (Kim et al., 2007; Sapers, 2001; Singh et al., 2002a). Therefore, research on the efficacy of new commercial sanitizers and other alternative technologies are becoming increasingly necessary. EW is a relatively new concept that is based on a new, previously unknown law of anomalous changes of reaction and catalytic abilities of aqueous solutions subjected to electrochemical, unipolar (i.e., either anodic or cathodic) treatment. Due to the alteration of its chemical composition, acidity and also alkalinity within a wide range, it is used for technological processes for the purposes of improving production quality, reducing the labor-consuming practices, etc. It has a strong bactericidal effect against pathogens and spoilage microorganisms and is more effective than chlorine due to its high oxidation reduction potential (Bari et al., 2003; Kiura et al., 2002). The use of EW at neutral pH appears to produce good results for fresh-cut vegetables (Izumi, 1999; Rico et al., 2008). However, the prevalence of chlorine and its cost-effectiveness remain a challenge for fresh-cut research and processing industries. Numerous studies have focused on the effect of ozone treatments on the safety and quality of iceberg lettuce (Beltran et al., 2005; Hassenberg et al., 2007; Koseki and Seichiro, 2006; Singh et al., 2002b; Yuk et al., 2006). However, we did not find a single study related to

ozone treatments on fresh-cut paprika. Nevertheless, the interest in ozone as an alternative to chlorine washing and EW washing with different contact times for cleaning and disinfection operations is based on its high biocidal efficacy, wide antimicrobial spectrum, absence of byproducts that are detrimental to health and ability to generate it on demand without needing to store it for later use (Kim et al., 2003). Second, it is environmental friendly and in compliance with statutory obligations (Pascual et al., 2007). The inactivation of microorganisms by ozone is a complex process involving an attack on various cell membrane and cell wall constituents (e.g., unsaturated fats) and constituents within the cell contents (e.g., enzymes and nucleic acids). Molecular ozone and the free radicals produced by its breakdown, all play a part in this inactivation mechanism. Microorganisms are killed by cell envelope disruption or disintegration, which leads to the leakage of cell contents. Again, the effectiveness of ozone against microorganisms depends on the applied concentration of ozone. Regarding the spectrum of action, each microorganism has an inherent sensitivity to ozone (Khadre et al., 2001; Kim et al., 1999, 2003; Olmez and Akbas, 2009). Bacteria are more sensitive than yeasts and fungi. Gram-positive bacteria are more sensitive to ozone than Gram-negative organisms, and spores are more resistant than vegetative cells (Pascual et al., 2007; Rice et al., 2002). The need to investigate the efficacy of new commercial sanitizing methods and other alternative technologies is growing in order to reduce the use of chlorine for processing within fresh-cut industries. This study was designed to determine the effectiveness of tap water (TW), chlorinated water (CL), EW and ozonized water at different contact times on improving and maintaining the microbial food quality of fresh-cut paprika. Additionally, their influence on the quality of fresh-cut paprika during storage was evaluated.

MATERIALS AND METHODS Material Fresh paprika of red color variety (Capsicum annuum L.) was obtained from a local super market in Suwon, Korea. Paprika with defects in surface color, damage, scratches, etc., were discarded; the rest were washed with TW for 90 s and left to dry in the processing room at temperature (14 1 C) for 10 min. Then, the paprika was cut into small pieces (i.e., 3 cm in width by 5 cm in length) using a sharp knife. These fresh-cut paprika samples (i.e., 1.8 kg per sample in a net bag) were washed carefully with gentle agitation in separate buckets each containing 20 L of solution from one of the following treatments: TW, CL (100 mg/L, pH 6.5–7), EW

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Das et al. (pH 7.2), and a continuous flow of ozonized water (O3, 4 mg/L). These treatments ensued for a contact time of 90 and 180 s (i.e., TW-90 s, TW-180 s, CL-90 s, CL-180 s, EW-90 s, EW-180 s, O3-90 s, and O3-180 s) individually. The washed samples were centrifuged for 1 min with a dryer (WS 6501 T, Hanil, Republic of Korea) to remove excess water. Then, dewatered samples of 100 g each were packaged in 50 mm polypropylene bags (20 25 cm2) and sealed and stored at 5 C for 12 days. Sampling for quality evaluation occurred on days 0, 3, 6, 9 and 12. The experiment was conducted twice with similar results. The results from the second experiment are reported here. Methods Preparation of washing solutions. A chlorine solution (100 mg/L) was prepared with food grade bleach, and the pH was adjusted to 6.5–7.0 with 1N HCl. The available chlorine was determined with a portable chlorine colorimeter (Model-1200, Lamotte, Washington, USA). The solution was used within 30 min of preparation. EW was generated using an EW System (HBS-500, Han Bio, Republic of Korea). The pH was adjusted to 7.2 with a residual chlorine concentration of 100 mg/L, and the EW was used within 1 h of preparation. An aqueous ozone solution (4 mg/L) was prepared by continuously circulating the water through an ozone water sterilizing system (OS-800, Advanced Scientific Technology, Republic of Korea) and a stainless steel water tank. The ozone generator was equipped with a vortexer to facilitate dissolving of gaseous ozone in water. The concentration of dissolved ozone was determined by a DO3 meter (DDK-TOA Corporation, Japan). When an ozone concentration of 4 mg/L was achieved, the solution was used immediately. Gas composition and off-odor. Changes in oxygen (O2) and carbon dioxide (CO2) concentrations within the packages were periodically measured using a gas analyzer (Checkmate 9900, PBI Dansensor, Denmark) for up to 12 days of storage. The gas measurement was performed with a hypodermic needle inserted through an adhesive septum that was previously affixed to the bag. Samples were taken at a flow rate of 1.5 mL/min for 1 min, and the monitoring included a sensitivity of 0.001 for O2 and 0.1 for CO2. The accuracy of the reading was 1% of the reading in the calibrated range and 2% of the full range for CO2. Three bags per treatment were evaluated for each day of the experiment. Immediately after opening the bags in a sensory room, equipped with individual cabinets, the samples were evaluated for off-odors by a three-member trained

panel. Training was given to the panel members on how to recognize and scale the quality attributes of fresh-cut paprika. Prior to each evaluation, the panel members were given reference samples to calibrate the scales. The samples were coded with three-digit numbers to mask the treatment identity in an effort to minimize the test subjectivity and ensure test accuracy. Off-odor was scored on a 0–4 scale, where 0 ¼ no off-odor, 1 ¼ slight, 2 ¼ moderate, 3 ¼ strong and 4 ¼ extremely strong; a score of 3 or above was considered unacceptable (Kim et al., 2007). Electrolyte leakage analysis. The electrolyte leakage of fresh-cut paprika was measured immediately after treatment and during storage to determine possible tissue deterioration. Samples of 20 g of paprika were submerged in 200 mL of deionized water for 30 min at room temperature. The conductivity (s/cm) of the solution was determined with a conductivity meter (Orion 4 star portable pH/conductivity meter, Thermo Electron Corporation, USA) and was used to characterize the electrolyte leakage of plant tissues. Color measurement The surface color was measured for fresh-cut paprika pieces as change of lightness (L*) in the HunterLab color system, where an L* value of 100 is white and 0 black. Color measurements were taken with a Minolta Chroma Meter (model CR-400, Minolta Co., Japan), which was calibrated with a standard white tile (Y 93.5, x 0.3155, y 0.3320). The color values of a* and b* were converted into hue angle (i.e., hue ¼ tanÿ1(b*/a*). Due to the inherent color variations among fresh-cut pieces within the same bag, three readings were taken per bag to ensure that the resulting data truly represented the color of the samples. Microbial analysis. Samples of 20 g each were homogenized in 180 mL of 1% sterile buffered peptone water using filter stomacher bags (Stomachem 400, Seward, England) for 60 s at 230 rpm. One milliliter of the appropriate sample dilution was pour-plated on an aerobic plate (3M Pertifilm, 3M Microbiology, St. Paul, USA) and incubated at 25 C for 48 h. Simultaneously, 1 mL of the appropriate sample dilution was pour-plated on a coliform plate (3M Pertifilm, 3M Microbiology, St. Paul, USA) and incubated at 25 C for 24 h. Only colonies showing typical coliform morphology were counted. Aerobic and coliform counts were also performed for a control sample, i.e., prior to washing with washing solutions. Furthermore, in this study, we have emphasized broadly on the aerobic and coliform colony counts only.


Food Science and Technology International 17(5)

Results Gas composition and off-odor. The O2 partial pressure decreased rapidly and reached a steady state on day 3. In contrast, the CO2 partial pressure generally increased until day 3 and then decreased slightly or maintained equilibrium levels after 3 days of storage (Figure 1). The results of the gas composition did not differ significantly among washing solutions and contact times in this experiment. Simultaneously, no off-odor was detected throughout the storage period for any of the treatments (data not shown). Electrolyte leakage. Ozone washing for 180 s of contact time (O3-180 s) showed the best result for lowering and maintaining leakage (i.e., 52.07–31.56 ms/cm) in comparison to the other washing treatments during the storage period (Figure 2). However, ozone washing for 90 s of

Color. No significant differences in color characteristics were observed in L*, a* and b* values among the different wash treatments during the storage period. However, paprika washed with longer contact times (i.e., 180 s) showed slightly lower hue angle values than the one washed with short contact times (i.e., 90 s) for all washing solution treatments (Table 1). Microbial analysis. The aerobic plate count increased with a longer contact time for all washing solutions except ozone washing (i.e., log cfu 2.14 (O3-90 s)–1.96 (O3-180 s) on day 0 and log cfu 7.26 (O3-90 s)–6.66 (O3180 s) on day12 (Figure 3). However, lesser numbers of

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contact time (O3-90 s) also initially lowered leakage (i.e., 54.10–36.37 ms/cm) as effectively as 180 s of contact time with TW (i.e., TW-180 s, 43.50–26.86 ms/cm). The highest electrolyte leakage was observed with CL and EW washings at both 90 and 180 s.

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RESULTS AND DISCUSSIONS

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Figure 1. O2 (top) and CO2 (below) composition in fresh-cut paprika during storage period. In figure, samples washed for 90 s (a) and 180 s (b) in TW, CL, EW and ozonated water (O3). Data are the mean of three replications with SE. () TW-90 s, (p) CL-90 s, () EW-90 s, (#) O3-90 s, () TW-180 s, (p) CL-180 s, () EW-180 s, (#) O3-180 s.


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31.3 0.27 29.7 0.18 32.9 0.43 32.6 0.33 32.1 0.29 31.4 0.23 32.0 0.28 31.2 0.35

32.5 0.37 30.5 0.24 32.2 0.35 31.9 0.45 30.8 0.39 29.6 0.30 30.6 0.31 29.9 0.31

33.0 0.31 30.4 0.21 32.7 0.34 32.1 0.40 31.1 0.40 32.9 0.36 31.7 0.36 31.6 0.39

31.0 0.32 29.9 0.33 32.4 0.39 30.5 0.36 30.7 0.40 29.8 0.35 32.8 0.31 30.6 0.25

31.8 0.30 31.0 0.20 34.4 0.39 31.9 0.38 32.4 0.30 31.0 0.30 30.8 0.35 30.1 0.28

Notes: Samples were washed in TW, CL, EW and ozonated water (O3) for 90 and 180 s. Data are the mean of nine replications with SE.

coliforms were initially observed in samples with short contact washing times (90 s), i.e., up to 3 days of storage, but samples exposed to a longer contact time (i.e., 180 s) eventually showed lower coliform numbers on the 12th day of storage for all washing solutions (Figure 4). Except the samples washed with ozone, the longer washing time adversely affected microbial reduction among the remaining washing solutions used in this experiment. Moreover, control sample showed higher aerobic and coliform count than samples washed in washing solutions (data not shown). The experiment was repeated twice, and similar results were observed as mentioned earlier. Discussion At the end of the storage period, all the samples from each treatment reached similar O2 (5–10) and CO2 levels (3–5), i.e., without differences among the treatments

(Figure 1). Low O2 modified atmosphere (MA) packaging is widely used to slow down plant metabolism and respiration. Respiration rate (RR) and gas exchange through the package material are the processes involved in creating an MA inside a package that will extend the shelf life of fresh produce. Thus, RR of the produce and the selection of perfect packaging films are crucial for an MA packaging system. The main characteristics to consider are gas permeability, water vapor transmission rate, mechanical properties, transparency, type of package and sealing reliability (Kim et al., 2005). For freshcut paprika, recommended O2 and CO2 concentrations are 3% and 5–10%, respectively (Kader, 2002). In this experiment, O2 levels (5.0–9.6 kPa) for all treatments from day 3 to the end of storage were higher than the recommended concentrations. Nevertheless, the CO2 concentration in the fresh-cut bags did not reach the phytotoxicity limit of 10 kPa, which is responsible for the off-odors. In this study, O2 and CO2 concentrations


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in fresh-cut paprika bags subjected to different washing treatments showed similar levels and a similar tendency during the storage (Figure 1). This indicates that the RR of fresh-cut paprika was not influenced by the washing solution. Our results agree with other authors who observed no differences in the gas composition of packaged fresh-cut vegetables regardless of the washing solutions (TW, sodium hypochlorite, ozone and peroxyacetic acid; Beltra´n et al., 2005). However, no off-odor was detected in packaged fresh-cut paprika during storage for all the samples irrespective of washing solutions and contact times. Since off-odor is always associated with the onset of an aerobic respiration under lower O2 and high CO2 levels, the lack of off-odor indicates

that no aerobic respiration had occurred (Figure 1). Additionally, studies have reported that conditions of O2 levels below 2–4 kPa and CO2 levels over 10–15 kPa induced anaerobic metabolism with the generation of off-flavors mainly due to the production of ethanol, aldehyde, ethyl acetate, volatile compounds and ethylene-associated compounds. These compounds are basically responsible for the production of off-odor during the storage period due to either the living cells or microbes present in the packaging bags. The lack of off-odor detected in our study might be due to the high oxygen transmission rate of the packaging film used in our study. Similarly, the insignificant gas exchange indicates that the packaging film that was utilized was good 476


Das et al. in terms of the oxygen transmission rate (Kim et al., 2004). Furthermore, the RR of fresh-cut paprika was low based on the gas analysis data. RR is often a good indication of the storage life of a crop; i.e., as the RR increases, the shelf life shortens and vice versa (Figure 1). During the processing or handling of fresh-cut produce, common symptoms of injury due to a malfunction of the membrane systems include water-soaked appearance, loss of turgor, leakage of electrolytes and discoloration of tissues. The nutrients that are leaked by the cell may also play a key role in the growth and development of pathogens. Electrolyte leakage is generally considered an indirect measure of plant cell membrane damage (Bajji et al., 2002). Many commercially prepared fresh-cut vegetables have already been cut into small pieces and no further preparation is necessary. Therefore, measurement of electrolyte leakage is ideal for commercially available fresh-cut vegetables. Our research has indicated that electrolyte leakage decreased with longer contact time for all washing solutions as compared to consumer washing with shorter contact times. Moreover, in our experiment, we specifically observed that a longer contact time with ozone washing maintained the electrolyte leakage, which is contradictory to the results observed in case of fresh-cut cilantro (Wang et al., 2004). This difference may be due to the continuous flow of ozone that we employed during washing and the effect of the highly oxidizing nature to prevent further damage after washing and during storage. In this study, the longer contact time resulted in lower electrolyte leakage than the shorter contact time for all potential sanitizing solutions on day 0. This may be because the longer washing time more effectively washed the leaked cell sap off as compared to the short contact time, thereby decreasing conductivity (Arvind et al., 2004). Fresh-cut produce is attractive and eye-catching to a large degree due to the richness of the pigment that it contains, which is vital for quality maintenance. Chlorophyll degradation that results in a loss of green color is a major quality defect for most leafy green vegetables. The color analysis showed insignificant changes in the L*, b* and a* values among washing solutions. However, for all washing solutions, paprika washed with a longer contact time (i.e., 180 s) showed slightly lower hue angle values than the samples washed with a short contact time (i.e., 90 s; Table 1). This indicates that the color of the paprika pieces was not affected by the different sanitizing solutions used in this study as indicated earlier by some researchers (Beltran et al., 2005; Hildebrand et al., 2008; Kim et al., 2007; Wang et al., 2004). With exception to ozone (O3-180 s) washing, longer washing contact time resulted in increasing aerobic plate count numbers linked to lower electrolyte leakage,

which may be directly influenced by microbial growth. The surface wash off of the paprika might become reattached to the samples during the washing time. No findings reported the efficacy of ozone against food-borne pathogens in fresh-cut paprika; however, in lettuce, the efficacy depends on the concentration and contact time of the ozone, which is determined by the effectiveness of the ozone delivery method, the type of material, the target microorganisms and the physiological state of the bacterial cells at the time of treatment (Omlez and Akbas, 2009; Yuk et al., 2006). Moreover, control sample showed higher aerobic and coliform count than samples washed in washing solutions (data not shown). Again, the coliform plate count decreased following a short contact washing time (i.e., 90 s) up to day 3, but the longer contact time (i.e., 180 s) eventually resulted in decreasing coliform plate counts. Perhaps, the short washing contact time proved to be beneficial for short-term storage, but for longer storage periods, the effect of different washing solutions with longer contact times is necessary in terms of controlling coliform growth. Furthermore, just after washing, the washing solutions may control a further proliferation of coliform numbers, but in long-term storage, longer contact time proved to be effective for all washing solutions (Allende et al., 2008; Mandrell et al., 2006; Wang et al., 2004). Again, toward the end of the storage period, the increased numbers of aerobic bacteria might interact with the coliforms, hence lowering the coliform numbers. Also, the coliform groups might simply be suppressed by the higher number of aerobic groups; i.e., the aerobic groups merely outcompete the coliform groups (Kim et al., 2003).

CONCLUSIONS Different washing solutions have been applied to freshcut produce in an effort to reduce the aerobic and coliform groups for a long time. Based on our observations, a longer contact time is not a good practice for washing with chlorine or EW; however, ozone washing proved to be the most effective among all the washing solutions that we tested. Ozone (4 mg/L) washing with a rather long contact time (i.e., 180 s) is good for maintaining the safety and microbial quality of fresh-cut paprika. Based on our findings, we recommend that fresh-cut industries and minimally processed vegetable industries should adopt this method of sanitization for fresh-cut paprika. However, economical aspects like investments costs and difficulties for its implementation must be analyzed before a final recommendation. REFERENCES Allende A, Marı´ a VS, Lo´pez-Ga´lvez F, Raquel V and Marı´ a IG. (2008). Role of commercial sanitizers and washing systems on epiphytic microorganisms and sensory quality of


Food Science and Technology International 17(5) fresh-cut escarole and lettuce. Postharvest Biology and Technology 49(1): 155–163. Arvind AB, Robert AS and Judith AA. (2004). Evaluation of wash treatments for survival of foodborne pathogens and maintenance of quality characteristics of fresh-cut apple slices. Food Microbiology 21(3): 319–326. Bajji M, Kinet J and Lutts S. (2002). The use of the electrolyte leakage method for assessing cell membrane stability as a water stress tolerance test in durum wheat. Plant Growth Regulators 36(1): 61–70. Bari ML, Sabina Y, Isobe S, Uemura T and Isshiki K. (2003). Effectiveness of electrolyzed acidic water in killing Escherichia coli O157:H7, Salmonella enteridis, and Listeria monocytogenes on the surfaces of tomatoes. Journal of Food Protection 66(4): 542–548. Beltran D, Selma MV, Marın A and Gil MI. (2005). Ozonated water extends the shelf life of fresh-cut lettuce. Journal of Agricultural and Food Chemistry 53(14): 5654–5663. Beltran D, Selma MV, Tudela JA and Gil MI. (2005). Effect of different sanitizers on microbial and sensory quality of fresh-cut potato strips stored under modified atmosphere or vacuum packaging. Postharvest Biology and Technology 37(1): 37–46. Beuchat LR, Adler BB and Lang MM. (2004). Efficacy of chlorine and a peroxyacetic acid sanitizer in killing Listeria monocytogenes on iceberg and romaine lettuce using simulated commercial processing conditions. Journal of Food Protection 67(6): 1238–1242. Gomez-Lopez VM, Devlieghere F, Ragaert P and Debevere J. (2007). Shelf-life extension of minimally processed carrots by gaseous chlorine dioxide. International Journal of Food Microbiology 116(2): 221–227. Hassenberg K, Christine I, Eleanor M, Martin G, Matthias P and Jeremy B. (2007). Use of ozone in a lettuce-washing process: an industrial trial. Journal of the Science of Food and Agriculture 87(5): 914–919. Hildebrand PD, Charles FF, Jun S, Lihua F and McRae KB. (2008). Effect of a continuous low ozone exposure (50 nL Lÿ1) on decay and quality of stored carrots. Postharvest Biology and Technology 49(3): 397–402. Inatsu Y, Bari ML, Kawasaki S, Isshiki K and Kawamoto S. (2005). Efficacy of acidified sodium chlorite treatments in reducing Escherichia coli O157:H7 on Chinese cabbage. Journal of Food Protection 68(2): 251–255. Izumi H. (1999). Electrolysed water as a disinfectant for freshcut vegetables. Journal of Food Science 64(2): 536–539. Kader AA (ed.) (2002) Postharvest Technology of Horticultural Crops, 3rd edn. Oakland, USA: Division of Agriculture and Natural Resources UC Publication 3311, University of California. Khadre MA, Yousef AE and Kim JG. (2001). Microbiological aspects of ozone applications in food: a review. Journal of Food Science 66(9): 1242–1252. Kim JG, Luo Y and Kenneth CG. (2004). Effect of package film on the quality of fresh-cut salad savoy. Postharvest Biology and Technology 32(1): 99–107. Kim JG, Luo Y, Robert AS and Kenneth CG. (2005). Delayed modified atmosphere packaging of fresh-cut Romaine lettuce: effects on quality maintenance and shelf-life. Journal

of the American Society for Horticultural Sciences 130(1): 116–123. Kim JG, Luo Y and Yang T. (2007). Effect of the sequential treatment of 1- methylcyclopropene and acidified sodium chlorite on microbial growth and quality of fresh-cut cilantro. Postharvest Biology and Technology 46(2): 144–149. Kim JG, Yousef AE and Chism GW. (1999). Applications of ozone for enhancing the microbiological safety and quality of foods: a review. Journal of Food Protection 62(9): 1071–1087. Kim JG, Yousef AE and Khadre MA. (2003). Ozone and its current and future application in the food industry. Advances in Food and Nutrition Research 45: 167–218. Kiura H, Sano K, Morimatsu S, Nakano T, Morita C, Yamaguchi M, et al. (2002). Bactericidal activity of electrolyzed acid water from solution containing sodium chloride at low concentration, in comparison with that at high concentration. Journal of Microbiological Methods 49(3): 285–293. Koseki S and Seichiro I. (2006). Effect of ozonated water treatment on microbial control and on browning of iceberg lettuce (Lactuca sativa L.). Journal of Food Protection 69(1): 154–160. Lukasik J, Bradley ML, Scott TM, Dea M, Koo A, Hsu WY, et al. (2003). Reduction of poliovirus 1, bacteriophages, Salmonella Montevideo, and Escherichia coli O157:H7 on strawberries by physical and disinfectant washes. Journal of Food Protection 66(2): 188–193. Mandrell RE, Gorski L and Brandl MT. (2006). Attachment of microorganisms to fresh produce. In: Sapers GM, Gorny JR and Yousef AE (eds) Microbiology of Fruits and Vegetables. Boca Raton, FL: CRC Press, 33–73. Martinez-Sanchez A, Allende A, Bennett RN, Ferreres F and Gil MI. (2006). Microbial, nutritional and sensory quality of rocket leaves as affected by different sanitizers. Postharvest Biology and Technology 42(1): 86–97. Olmez H and Akbas MY. (2009). Optimization of ozone treatment of fresh-cut green leaf lettuce. Journal of Food Engineering 90(4): 487–494. Pascual A, Llorca I and Canut A. (2007). Use of ozone in food industries for reducing the environmental impact of cleaning and disinfection activities. Trends in Food Science and Technology 18(supplement 1): S29–S35. Ragaert P, Devlieghere F and Debevere J. (2007). Role of microbiological and physiological spoilage mechanisms during storage of minimally processed vegetables. Postharvest Biology and Technology 44(3): 185–194. Rice RG, Graham DM and Lowe MT. (2002). Recent ozone applications in food processing and sanitation. Food Safety Magazine 8(5): 10–17. Rico D, Martin-Diana AB, Barat JM and Barry-Ryan C. (2007). Extending and measuring the quality of fresh-cut fruit and vegetables: a review. Trends in Food Science and Technology 18(7): 373–386. Rico D, Martin-Diana AB, Barry-Ryan C, Jesus MF, Gary TMH and Barat JM. (2008). Use of neutral electrolysed water (EW) for quality maintenance and shelf-life extension of minimally processed lettuce. Innovative Food Science and Emerging Technologies 9(1): 37–48.


Das et al. Sapers GM. (2001). Efficacy of washing and sanitizing methods for disinfection of fresh fruit and vegetable products. Food Technology and Biotechnology 39(4): 305–311. Selma MV, Ibanez AM, Allende A, Cantwell M and Suslow T. (2008). Effect of gaseous ozone and hot water on microbial and sensory quality of cantaloupe and potential transference of E. coli O157:H7 during cutting. Food Microbiology 25(1): 162–168. Singh N, Singh RK, Bhunia AK and Stroshine RL. (2002a). Efficacy of chlorine dioxide, ozone, and thyme essential oil or a sequential washing in killing Escherichia coli 0157:h7 on lettuce and baby carrots. LWT Food Science and Technology 35(8): 720–729. Singh N, Singh RK, Bhunia AK and Stroshine RL. (2002b). Effect of inoculation and washing methods on the efficacy

of different sanitizers against Escherichia coli O147:H7 on lettuce. Food Microbiology 19(2–3): 183–193. Ukuku DO, Bari ML, Kawamoto S and Isshiki K. (2005). Use of hydrogen peroxide in combination with nisin, sodium lactate and citric acid for reducing transfer of bacterial pathogens from whole melon surfaces to fresh-cut pieces. International Journal of Food Microbiology 104(2): 225–233. Wang H, Feng H and Luo Y. (2004). Microbial reduction and storage quality of fresh-cut cilantro washed with acidic electrolyzed water and aqueous ozone. Food Research International 37(10): 949–956. Yuk HG, Yoo MY, Yoon JW, Moon KD, Marshall DL and Oh DH. (2006). Effect of combined ozone and organic acid treatment for control of E. coli 0157:H7 and L. monocytogenes on lettuce. Journal of Food Science 71(3): 83–87.



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