Fresh-cut Processing Research Articles

Studies on browning inhibition technology and mechanisms of fresh-cut potato

Potato is rich in nutrition and easily gets surface browning in short term after fresh-cut processing, significantly reducing its commercial value. In this article, fresh-cut potatoes were treated with L-cysteine (L-cys), citric acid (CA), ascorbic acid (AA), and ultrasonication. The response surface analysis was used to determine the best browning-inhibiting treatment. The optimum condition to inhibit browning was the solution containing 0.06% L-cys, 0.19% CA, and 0.09% AA plus with 130 W ultrasonication. Under this condition, the browning degree (BD) of fresh-cut potato after 15 days storage was 3.32 ± 0.06, which was closed to the predicted value. Moreover, the BD, polyphenol oxidase, and peroxidase activities of treated potatoes were significantly lower than those of untreated potatoes. In summary, the browning process of fresh-cut potatoes was inhibited, and the sensory quality was improved with the optimal antibrowning treatment. Practical applications The optimal browning-inhibiting formula was determined by the response surface method. The application of antibrowning agents and ultrasonication efficiently inhibited the activities of polyphenol oxidase and peroxidase, increasing shelf life and consumers' acceptability during the process of raw potato products. The optimized antibrowning treatment is safe, economic and applicable, which can be used to slow down the browning of fresh-cut potato theoretically and technically.

Effect of genotype, raw-material storage time and cut type on native potato suitability for fresh-cut elaboration

The suitability for fresh-cut processing of three native colored-fleshed potatoes (i.e., Bruja, Michuñe roja and Michuñe azul) and one commercial non-colored-fleshed potato (i.e., Asterix) was investigated. The impact of the storage time of the raw material and the type of cut (i.e., cube and chip) was also examined. Fresh-cut potato from raw material stored 2 months at 12°C and 90% relative humidity (RH) displayed 1 to 2.5 times higher respiration activity than potatoes stored 4 months under the same conditions. Lower CO2 emission was only observed when potatoes stored 4 months were used. Fresh-cut potato shelf life decreased (less than 23 d at 5°C) due to microbial growth. Approximately 7 log cfu g−1 for mesophilic and psycrophilic bacteria and Enterobactericeae when potatoes stored 4 months were used. Microbial growth was higher in chips than cube. The native colored-fleshed potatoes were rich in polyphenols, and total antioxidant capacity is 1 to 2 times higher than that of commercial potato. Total polyphenol content was not affected by the storage time of the raw material and remained stable under storage at 5°C. However, fresh-cut potato processed from raw material stored 2 months had 1.5 to 3 times more total antioxidant capacity than that processed from raw material stored 4 months. For both parameters, Bruja exhibited values approximately 60% higher. Although all the analyzed varieties were suitable for fresh-cut elaboration, Bruja and Michuñe roja displayed higher metabolic activity and susceptibility to microbial deterioration and browning. To guarantee fresh-cut potato quality, raw material should be maintained no longer than 4 months in storage. From this moment some quality parameters alterations, that limited the fresh-cut shelf life, begin to be observed.

Innovations in fresh-cut fruit process lines

Innovations in fresh-cut fruit process lines

Breeding lettuce for improved fresh-cut processing

Breeding lettuce for improved fresh-cut processing

Effect of cutting styles on quality and antioxidant activity in fresh-cut pitaya fruit

The effect of different cutting styles on the quality and antioxidant activity of pitaya fruit during 4 d of storage at 15°C was investigated. Pitaya fruit was cut into slice, half-slice and quarter-slice, all in 1cm of thickness, with corresponding wounding intensity (A/W) of 2.0, 2.9 and 3.7cm2g−1, respectively. Resultsshowed that cutting styles had little influence on fruit quality parameters such as vitamin C, soluble solids, titratable acidity and flesh color. While total phenolic content, antioxidant activity, and phenylalanine ammonia-lyase activity increased significantly with cutting wounding intensity at the first 2 d of storage. In addition, fresh-cut processing induced the reactive oxygen species (ROS) generation and enhanced the activity of antioxidant enzymes including catalase, superoxide dismutase and glutathione reductase at the initial storage time. These results demonstrated that cutting styles didn’t have much adverse effect on the organoleptic quality, but significantly induced the biosynthesis of phenolics and improved the antioxidant activity of fresh-cut pitaya fruit. Moreover, ROS may act as signaling molecules in the accumulation of phenolics in fresh-cut pitaya fruit.

Phenolic profiles and postharvest quality changes of fresh-cut radicchio (Cichorium intybus L.): nutrient value in fresh vs. stored leaves

The quality traits of two “Radicchio di Chioggia” hybrids (Corelli and Botticelli), processed as fresh-cut and stored in unsealed bags or in passive modified atmosphere for 25days at 5°C, were measured in two consecutive experiments. Moreover, a detailed structural characterization of polyphenols extracted from fresh and stored radicchio samples was performed by HPLC and electrospray ionization multistage ion trap mass spectrometry (ESI-ITMSn). Twenty-one compounds were identified and quantified in Corelli extract, and 19 were detected in Botticelli extract. Quercetin-7-O-glucoside-3-O-(6″-malonyl)-glucoside and isorahmnetin-7-O-glucuronide were found only in Corelli. Interestingly, the presence of dihydroflavonol glycosides in “Radicchio di Chioggia” is here reported for the first time. In the second experiment (performed on Botticelli), fresh-cut processing promoted a 2-fold increase in bioactive compounds, quantified in a significant amount (305mg/100g fresh weight) and in leaves that had been considered unmarketable. Thus this hybrid, suitable for fresh-cut processing, has been shown to be an interesting and inexpensive source of antioxidant phenolics even in leaves considered as unmarketable. Although less suitable for fresh-cut processing, Corelli fresh-cut radicchio can be considered a valuable hybrid for fresh consumption and a source of polyphenols because of the high content of these compounds in both the fresh and stored leaves.

Pre-drying treatment of plant related tissues using plasma processed air: Impact on enzyme activity and quality attributes of cut apple and potato

Abstract During post-harvest processing of fresh cut and dried fruits and vegetables, polyphenol oxidase (PPO) and peroxidase (POD) need to be inactivated or inhibited in order to avoid undesirable browning reactions and loss of sensorial or nutritional quality. To meet this goal, the application of plasma processed air (PPA) offers a promising “gentle” alternative to traditional methods, such as pasteurization or the addition of anti-browning compounds. Using ambient air as process gas instead of an expensive noble gas, such as argon, exhibits a substantial improvement for the development of large-scale plasmas at ambient pressure and allows the indirect treatment of larger goods within a remote exposure reactor. In this study the ability of PPA to inactivate PPO and POD in complex food matrices and its impact on quality parameters, such as color, texture and cell integrity directly after freshly cutting and during storage of warm air dried and freeze dried produce was evaluated. The study evidently shows that PPA processing is capable of reducing the activity of PPO and POD in the freshly cut tissue from both apple and potato. Following exposure to PPA for 10 min the PPO activity was reduced by about 62% and 77% in fresh cut apple and potato tissue, respectively. POD, as the more temperature-stable enzyme, was even less stable upon PPA treatment for 10 min and was reduced by about 65% and 89% in fresh cut apple and potato tissue, respectively. Blackening of the potato tissue could be completely prevented by plasma treatment while a browning different from the habitual nature of enzymatic browning occurred upon exposure of the apple tissue to PPA. In both cases, the pH value on the tissue surface dropped to 1.5 while cell integrity and dry matter content were not significantly affected. Industrial relevance The quality and shelf life of freshly cut and dried fruits and vegetables greatly depend on the activity of naturally occurring enzymes which catalyze browning reactions at cut surfaces. This study shows that the application of PPA, as a promising nonthermal “pasteurization” technology, enables the inactivation of PPO and POD in complex food matrices. It further describes the impact of the PPA treatment on quality parameters of the freshly cut tissue from apple and potato and goes beyond on evaluating color, texture and enzyme activity in warm air dried and freeze dried tissue over a storage time of three weeks. The results contribute to the understanding and product-specificity of PPA-induced effects on quality and shelf life of fresh cut and dried fruit and vegetable produce and could be a basis for a possible industrial implementation.

Heat treatment and active packaging to improve the storage of fresh-cut melons (Cucumis meloL.)

Introduction. Melon (Cucumis melo L.) is highly appreciated by consumers due to its sensory attributes and nutritional content. Producing minimally processed fruit has potential, because consumers look for freshness and convenience. However, fresh-cut processing increases the contact enzymes and their respective substrates because the cell tissue rupture, and this causes browning, softening and decay. This study investigated the effect of a combination of heat treatment with active modified atmosphere packaging on the quality of fresh-cut melons. Materials and methods. Whole ‘Charentais’ melon fruits were dipped in hot water (at 50 °C for 30 min), cooled, minimally processed and packaged in traditional polymeric film (oriented polypropylene, OPP) or biodegradable film (polylactic acid, PLA) with an initial flush of a gas mixture composed of 2−3% O2 and 7−8% CO2 . The quality of the fresh-cut melons was monitored for 11 days after treatment. Results and discussion. Gas changes demonstrated that (i) PLA permeability was higher than OPP permeability, and (ii) the heat treatment could temporarily reduce the respiration rate of fresh-cut melons. Heat treatment as a stress could also increase the beta-carotene content. Conclusion. The combination of heat treatment and active MAP with OPP film significantly improved both the decay development and the visual quality of fresh-cut melons for up to 11 days.

Combined effects of deficit irrigation and fresh-cut processing on quality and bioactive compounds of nectarines

Falagan N., Artes F., Gomez P.A., Artes-Hernandez F., Perez-Pastor A., de la Rosa J.M., Aguayo E. (2015): Combined effects of deficit irrigation and fresh-cut processing on quality and bioactive compounds of nectarines. Hort. Sci. (Prague): 42: 125–131. Water scarcity makes necessary the use of tools for increasing water productivity such as regulated deficit irrigation strategies (RDI). The effect of RDI on fresh-cut white flesh extra-early nectarine was studied. Initially, the soluble solids content of nectarines from RDI was higher than in control and over-irrigated fruits (9.72 ± 0.20 vs. 8.57 ± 0.05°Brix, respectively) but after shelf-life storage no differences were found. During storage, RDI fruits had a more stable antioxidant capacity and soluble phenolic content. This treatment showed 10% more vitamin C than the other irrigation treatments, due to an increase in dehydroascorbic acid content. No pathogenic bacteria growth was found and all microbial counts were below the European legal limits. For all the irrigation treatments, the final sensorial scores were above the limit of marketability. Overall, RDI enabled savings of about 1,260 m3 of water/ha and year, without negatively affecting the quality of the fruit, allowing for their use as a fresh-cut product with a shelf-life of 8 days at 5°C.

Identification of sampling points suitable for the detection of microbial contamination in fresh-cut processing lines

Traditionally, microbiological testing for food safety assurance in fresh-cut industries relied on end product to evaluate compliance with microbial standards. Replacement of end-product testing by a preventive system is being recommended by competent authorities for the production of safe food. In the fresh-cut processing industry, there is still a need for the identification of suitable sampling points which facilitate the detection of a contaminated lot. The goal of this study was to gain insight on the microbial contamination throughout the processing operations involved in fresh-cut leafy green production to identify sampling points and their relation with the microbial contamination of end products. Three Spanish fresh-cut processing companies of baby spinach were visited three times. During the processing schedule, samples from product (raw material and end product), water (pre-wash water, wash water, rinse water and centrifuge water) and surfaces (workers' plastic gloves and equipment surfaces) were taken at three time intervals: at the beginning, in the middle and at the end of the working day. Presence of pathogenic microorganisms such as Listeria monocytogenes, Salmonella spp. and pathogenic Escherichia coli as well as the levels of generic E. coli and coliforms were analysed in all the samples. Enterococcus spp. and Enterobacteriaceae were assessed in water and surface samples, respectively. L. monocytogenes and pathogenic E. coli were not found in any of the samples tested. Salmonella spp. were isolated from two centrifuge effluent water samples. Generic E. coli was only found in centrifuge effluent water samples. To evaluate if the centrifuge water was the most suitable sampling point to detect microbial contamination of the end product, additional lab scale tests were carried out. Baby spinach inoculated with generic E. coli confirmed the potential of centrifuge water as a control point for the detection of microbial contamination. Routine monitoring of this centrifuge water for pathogens and E. coli as the hygiene indicator appears to be a promising tool for the evaluation of product safety.

QUALITY CHANGES OF FRESH-CUT 'MAHACHANOK' MANGO AT DIFFERENT STORAGE TEMPERATURES

‘Mahachanok’ mango is very popular in domestic and export markets of Thailand. After fresh-cut processing, produce quality deteriorates quickly due to tissue darkening, development of glassy appearance, surface desiccation and loss of firmness. Very little is known about the marketable period of the fresh-cut produce. In this study, fruit were peeled, flesh removed from the seed, and then stored at 4, 7, 10 and 25°C. Results showed that 4 and 7°C storage prolonged shelf life for six days while at 10 and 25°C, shelf life was only four days and one day, respectively. Color as hue values was best maintained at 7°C whereas it declined most rapidly at 25°C. Total sugar content and firmness did not significantly differ with treatment. Titratable acidity decreased with storage at a lower rate at 7°C than at 25, 10 and 4°C.

Influence of cultivar and ripeness stage at the time of fresh-cut processing on instrumental and sensory qualities of fresh-cut mangos

Mango cultivar and ripeness stage at the time of cutting are important factors that consequently affect the quality of the fresh-cut mango product. In this study, physico-chemical and sensory qualities were measured instrumentally, with sensory descriptive analysis, and by consumer acceptance tests. All tests were performed on fresh-cut ‘Kent’ and ‘Tommy Atkins’ mangos from different initial ripeness stages (45N, 35N, and 25N). Instrumental quality parameters (color, firmness, soluble solids, titratable acidity) and sensory descriptive analysis were assessed periodically during 9 days of storage at 5°C. During storage, the sensory profile of fresh-cut ‘Kent’ mango was predominant in fruity aroma, overall aroma intensity and orange flesh color, whereas fresh-cut ‘Tommy Atkins’ had less aroma and orange flesh color, but had greater edge sharpness, edge fibrousness, moist and glossy appearance and fibrous texture. Fresh-cut mango consumers found the ‘Kent’ cultivar more desirable than ‘Tommy Atkins’. The initial ripeness stage of 35N for ‘Kent’ mango and 25N for ‘Tommy Atkins’ mango were optimal ripeness stages for fresh-cut mango in terms of handling, visual quality, and quality maintenance during storage, and were also well received by consumers. The a*/b* value and instrumental firmness of ‘Kent’ mango were correlated well with edge sharpness, sensory hue, and tartness. In addition, the L* value and instrumental firmness of fresh-cut ‘Tommy Atkins’ mango were demonstrated to be useful predictors for the texture attributes, including melting, slipperiness, chewiness and firmness. Interestingly, SSC and SSC/TA were not good predictors of sensory sweetness.

PRE- AND POSTHARVEST STRATEGIES TO ENHANCE BIOACTIVE CONSTITUENTS OF FRUITS AND VEGETABLES

In addition to vitamins, minerals, and dietary fibre, fruits and vegetables provide a whole range of non-nutrient constituents that have been suggested to be responsible for the health benefits associated with their consumption. Different strategies for increasing the health-promoting properties of fruits and vegetables have been explored. Successful examples of breeding and selection challenge for new cultivars have been described. An important strategy for growers to maximize specific phytochemicals is that the plants should be grown in open environments rather than in greenhouses. Solar radiation affects the production of phytochemicals involved in plant defence responses. Greenhouse grown plants have lower levels of phytonutrients due to the combined effects of higher temperatures and lower light intensities. To date, agricultural practice recommendations have been established primarily for productivity goals, but not as a way to increase the phytonutrients. However, agricultural practices including type and rate of fertilization, irrigation and time of harvest can also be managed to enhance the content of bioactive compounds. It is difficult to draw definitive conclusions from data that prove more benefits to the organic vs. conventional agricultural practices. High doses of organic fertilizers can promote plant growth and decrease the content of bioactive compounds. Management of water frequency is critical for the yield and postharvest quality. Different beneficial phytochemicals tend to reach optimal levels around harvest maturity stage. Some flexibility exists for growers to harvest within a window of opportunity, but it seems evident that immature and over mature vegetables will contain lower concentrations of some important phytochemicals. Baby and multi leaves are excellent raw materials with high content of bioactive compounds. The effect of fresh-cut processing can increase the content of bioactive compounds which can be preserved under optimum storage conditions.

Different peach cultivars and their suitability for minimal processing

Consumption of minimally processed fruits has been increased lately mainly due to their fresh-like quality characteristics. One of the major alterations that limit the shelf-life of these products is browning caused by polyphenol oxidase (PPO) activity on phenolic compounds. Six yellow-flesh peach cultivars, Spring Lady, Royal Glory, Ruby Rich, Summer Rich, Ryan Sun, and O’Henry, were selected. Peaches were hygienised and then samples were processed in a clean room. Slices were washed in cold tap water, dried, packaged in modified atmosphere, and stored at 4°C during 9 days; physicochemical and other quality parameters were studied. Principal Component Analysis (PCA) and correlation study were carried out in order to evaluate the relation between variables and cultivars. In conclusion, Spring Lady, Royal Glory, and Ruby Rich cultivars were the cultivars that offered the most suitable fruits for fresh-cut processing, mainly due to their low BP and PPO activity.  

Biochemical and color changes of fresh-cut melon (Cucumis melo L. cv. Galia) treated with UV-C

The importance of minimally processed commodities in the retail groceries of most developed countries has been rising continuously during the last decades. Cantaloupe melon is used more than any other fruit in fresh-cut processing. Ultraviolet (UV) light has been extensively used to simulate biological stres in plants and for determining resistance mechanisms of plant tissues. In this study the effect of ultraviolet irradiation on some properties of fresh-cut cantalope melon was determined during storage. Freshly cut cantalope melons cubes treated with ultraviolet irradiation at the doses of 1, 2 or 3 min before storage, and then placed in a cold room at 5±1°C temperature and 85-90% RH. Hue angle values of control group is low compared to UV-C treated samples, whereas L values of is high. EL of UV treated samples higher than those of control group. Total soluble solids of fresh-cut melon samples in UC3 treatment increased during storage. The results indicate that UV-C treatments on fresh-cut cantaloupe melon cubes increased total soluble solids independently from water loss.

Tracking an Escherichia coli O157:H7–Contaminated Batch of Leafy Greens through a Pilot-Scale Fresh-Cut Processing Line

Cross-contamination of fresh-cut leafy greens with residual Escherichia coli O157:H7-contaminated product during commercial processing was likely a contributing factor in several recent multistate outbreaks. Consequently, radicchio was used as a visual marker to track the spread of the contaminated product to iceberg lettuce in a pilot-scale processing line that included a commercial shredder, step conveyor, flume tank, shaker table, and centrifugal dryer. Uninoculated iceberg lettuce (45 kg) was processed, followed by 9.1 kg of radicchio (dip inoculated to contain a four-strain, green fluorescent protein-labeled nontoxigenic E. coli O157:H7 cocktail at 10(6) CFU/g) and 907 kg (2,000 lb) of uninoculated iceberg lettuce. After collecting the lettuce and radicchio in about 40 bags (∼22.7 kg per bag) along with water and equipment surface samples, all visible shreds of radicchio were retrieved from the bags of shredded product, the equipment, and the floor. E. coli O157:H7 populations were quantified in the lettuce, water, and equipment samples by direct plating with or without prior membrane filtration on Trypticase soy agar containing 0.6% yeast extract and 100 ppm of ampicillin. Based on triplicate experiments, the weight of radicchio in the shredded lettuce averaged 614.9 g (93.6%), 6.9 g (1.3%), 5.0 g (0.8%), and 2.8 g (0.5%) for bags 1 to 10, 11 to 20, 21 to 30, and 31 to 40, respectively, with mean E. coli O157:H7 populations of 1.7, 1.2, 1.1, and 1.1 log CFU/g in radicchio-free lettuce. After processing, more radicchio remained on the conveyor (9.8 g; P < 0.05), compared with the shredder (8.3 g), flume tank (3.5 g), and shaker table (0.1 g), with similar E. coli O157:H7 populations (P > 0.05) recovered from all equipment surfaces after processing. These findings clearly demonstrate both the potential for the continuous spread of contaminated lettuce to multiple batches of product during processing and the need for improved equipment designs that minimize the buildup of residual product during processing.

Multistate foodborne disease outbreaks associated with raw tomatoes, United States, 1990-2010: a recurring public health problem.

We examined multistate outbreaks attributed to raw tomatoes in the United States from 1990 to 2010. We summarized the demographic and epidemiological characteristics of 15 outbreaks resulting in 1959 illnesses, 384 hospitalizations, and three deaths. Most (80%) outbreaks were reported during 2000-2010; 73% occurred May-September. Outbreaks commonly affected adult (median age 34 years) women (median 58% of outbreak cases). All outbreaks were caused by Salmonella [serotypes Newport (n = 6 outbreaks), Braenderup (n = 2), Baildon, Enteritidis, Javiana, Montevideo, Thompson, Typhimurium (n = 1 each); multiple serotypes (n = 1)]. Red, round (69% of outbreaks), Roma (23%), and grape (8%) tomatoes were implicated. Most (93%) outbreaks were associated with tomatoes served predominantly in restaurants. However, traceback investigations suggested that contamination occurred on farms, at packinghouses, or at fresh-cut processing facilities. Government agencies, academia, trade associations, and the fresh tomato industry should consider further efforts to identify interventions to reduce contamination of tomatoes during production and processing.

Effect of Slightly Acidic Electrolyzed Water (SAEW) Treatment on the Microbial Reduction and Storage Quality of Fresh-Cut Cilantro

The disinfection efficacy of acidic electrolyzed water (AEW) on the fresh-cut vegetables has been recognized. However, the application of AEW in the fresh-keeping of fresh-cut vegetables was limited due to its low pH (<2.7) and higher available chlorine concentration (80–200 mg/L). In the present study, the microbial reduction and storage qualities of fresh-cut cilantro treated by slightly acidic electrolyzed water (SAEW) were evaluated. The results demonstrated that AEW, mild heat AEW, SAEW and mild heat SAEW treatments could reduce the populations on fresh-cut cilantro at 0 day. However, there were no significant differences among all the treatments during the late storage periods. SAEW and mild heat SAEW treatments could keep the firmness of fresh-cut cilantro and maintain the level of electrolyte leakage in comparison with other treatments. SAEW treatment showed the advantage in keeping the overall quality of fresh-cut cilantro compared with other treatments. SAEW may be a better choice in the storage of fresh-cut cilantro than AEW. Practical Applications In the fresh-cut vegetables and fruits industry, the fresh-cut processing of cilantro is usually accompanied by the disruption of surface cells and the injury stress of underlying tissues, fresh-cut production is more susceptible than whole cilantro to spoilage microbial and pathogen contaminations. The objective of this present study was to evaluate the effect of SAEW on the storage quality of fresh-cut cilantro. The information would be hopeful to be referenced for the development of fresh-cut production.

Effectiveness of Calcium Chloride and Calcium Lactate on Maintenance of Textural and Sensory Qualities of Fresh‐Cut Mangos

The effects of calcium chloride (CaCl2 ) and calcium lactate on maintaining textural and sensory quality of fresh-cut "Kent" and "Tommy Atkins" mangos and determination of treatments preferred by consumers were investigated. Mango cubes (1.5 × 1.5 × 1.5 cm) were subjected to different CaCl2 and calcium lactate concentrations (0 M, 0.068 M, 0.136 M, 0.204 M) and dip times (0, 1, 2.5, 5 min). Instrumental quality parameters (firmness, color, soluble solids, titratable acidity) were analyzed periodically during 9 d of storage at 5 °C. Tommy Atkins mango cubes became more orange, but also had more browning than Kent mango cubes during storage at 5 °C. Firmness retention during storage was greater with mangos cubes treated with CaCl2 than with calcium lactate, therefore we focused our instrumental analysis only on CaCl2 -treated cubes. The firmness of Tommy Atkins mango cubes was higher than Kent. Soluble solids content (SSC), titratable acidity (TA), and SSC/TA were higher in fresh-cut Kent mango cubes. Mangos treated with CaCl2 showed retarded softening during storage, and the retardation was greater at higher calcium concentrations. A consumer test was conducted to cluster consumers based on mango preference in order to correlate consumer liking and calcium treatments, as well as to uncover consumer intentions for in-store fresh-cut mango purchases. Treatment at 10 °C with 0.136 M CaCl2 for 2.5 min for Tommy Atkins mangos and 1 min for Kent mangos was effective in retaining firmness during storage at 5 °C and was also not disliked by consumers. A cluster analysis divided consumers into 2 preference groups, with Kent mangos significantly preferred over Tommy Atkins. Fresh-cut mangos often develop tissue softening and discoloration during storage. Short dips (1 to 3 min) in either CaCl2 or calcium lactate effectively improve fresh-cut mango firmness and color retention after cutting. Mango samples treated with CaCl2 had higher liking scores compared to those treated with calcium lactate. "Kent" mango variety is more suitable than "Tommy Atkins" for fresh-cut processing in terms of less tissue browning and higher consumer liking.

Dual-species biofilm formation by Escherichia coli O157:H7 and environmental bacteria isolated from fresh-cut processing facilities

Biofilm formation is a mechanism adapted by many microorganisms that enhances the survival in stressful environments. In food processing facilities, foodborne bacterial pathogens, which many are poor biofilm formers, could potentially take advantage of this protective mechanism by interacting with other strong biofilm producers. The objective of this study was to determine the influence of bacteria native to fresh produce processing environments on the incorporation of Escherichia coli O157:H7 in biofilms. Bacteria strains representing 13 Gram-negative species isolated from two fresh produce processing facilities in a previous study were tested for forming dual-species biofilms with E. coli O157:H7. Strong biofilm producing strains of Burkholderia caryophylli and Ralstonia insidiosa exhibited 180% and 63% increase in biofilm biomass, and significant thickening of the biofilms (B. caryophylli not tested), when co-cultured with E. coli O157:H7. E. coli O157:H7 populations increased by approximately 1 log in dual-species biofilms formed with B. caryophylli or R. insidiosa. While only a subset of environmental isolates with strong biofilm formation abilities increased the presence of E. coli O157:H7 in biofilms, all tested E. coli O157:H7 exhibited higher incorporation in dual-species biofilms with R. insidiosa. These observations support the notion that E. coli O157:H7 and specific strong biofilm producing bacteria interact synergistically in biofilm formation, and suggest a route for increased survival potential of E. coli O157:H7 in fresh produce processing environments.