Fresh-cut Cantaloupe Research Articles

Improved barrier, mechanical and antioxidant properties of pH-responsive film by incorporating dialdehyde starch and anthocyanins into rice protein/sodium alginate

This study aimed to develop rice protein/sodium alginate (RP/SA) pH-responsive films with enhanced properties by incorporating dialdehyde starch (DAS) and Lycium ruthenicum anthocyanins (LRA) and the film was applied to monitor the fruit freshness. The effect of the DAS and LRA content on the morphology, mechanical, water barrier, oxygen barrier, ultraviolet-blocking and thermal stability properties of RP/SA-based films was investigated. The best water vapor permeability of the film was 3.33 g·mm/(m2·d·kPa) with 10 % DAS. With increasing the DAS content from 0 % to 20 %, the tensile strength of the film was increased by 66.3 % compared with that of the film without DAS, while the thermal stability, oxygen barrier and ultraviolet light barrier properties were significantly enhanced. These results may be due to the formation of a compact structure observed by scanning electron microscopy, and stronger hydrogen bonding interactions and lower binding energy in the RP/SA/DAS/LRA system obtained by Fourier transform infrared spectroscopy, X-ray diffraction and molecular dynamics simulation. The RP/SA/DAS10/LRA5 film had 51.6 times higher antioxidant property than the film without LRA and exhibited significant color variations with changes in fresh-cut cantaloupe quality. The developed RP/SA-based films with improved properties are potential intelligent food packaging materials.

Structural characterization of modified soy protein isolate composite coatings and its application on fresh-cut cantaloupe (Cucumis melo cv. Xiaomi)

Fresh-cut cantaloupe is very perishable due to the mechanical damage and susceptibility to microorganism infections, which limit their shelf life. Cantaloupe is a popular fruit with high moisture content and nutritional value. This study aimed to enhance fresh-cut cantaloupe quality and extend the shelf life by employing soy protein isolates (SPI) coating solutions containing calcium lactate (CaL) and λ-aminobutyric acid (GABA). Cold plasma (CP) was used to augment the antioxidant and antimicrobial activities of the coatings. The coatings were meticulously characterized, and their impact on fresh-cut cantaloupe was assessed through physicochemical and microbiological parameters. The incorporation of CaL and GABA and the CP treatment heightened the antioxidant activity of the SPI coating, resulting in a substantial increase in DPPH and ABTS free radical scavenging activities by 58% and 30%, respectively. Application of the composite coating included a noteworthy 24% reduction in water loss on fresh-cut cantaloupe, maintaining color stability and total soluble solids content. Moreover, the treatment of composite coating effectively controlled microbial growth, ensuring fresh-cut cantaloupe remained in an edible state at the conclusion of the storage period. The coating treatment has extended the shelf life of fresh-cut cantaloupe from 6 d to 10 d at 0 °C. In conclusion, the CP-treated bioactive coating containing CaL and GABA prolonged the shelf life, enhanced nutritional value, and preserved the microbial quality attributes of fresh-cut cantaloupe.

Exogenous CaCl2 delays flesh softening by inhibiting the degradation of cell wall in fresh-cut cantaloupe

Flesh softening is closely related to the quality of postharvest produces. Although the use of calcium chloride (CaCl2) has been shown to inhibit fruit softening, the underlying molecular mechanisms have remained unclear. In our present investigation, CaCl2 treatment resulted in an enhancement of cytosolic free Ca2+ and polysaccharide contents, firmness, and the integrity of the cell wall structure, particularly evident in the denser middle lamella of fresh-cut cantaloupe. CaCl2 treatment also inhibited the cell wall degrading enzyme activities and gene expressions. Moreover, CmCAMTA2 could identify and bind to the CG-box structure of CmCellulase, Cmα-Gal3, and Cmβ-Glu12, thereby suppressing their transcription. In conclusion, current findings illustrated that CaCl2 treatment triggered CmCAMTA2-mediated transcriptional suppression on cell wall degrading genes, inhibited the polysaccharide component degradation, and maintained better structure integrity of the cell wall, thereby delaying the flesh softening of fresh-cut cantaloupe.

Utilizing Xanthan Gum Coatings as Probiotic Bacteria Carriers to Enhance Postharvest Quality and Antioxidants in Fresh-Cut Cantaloupe and Honeydew (Cucumis melo L.) Melons.

Due to spoilage microflora and browning, minimally processed fresh-cut fruits have a short shelf life, and over the years, studies have shown the potential of using edible coatings to extend the shelf life and improve the safety of fresh-cut fruits. Recently, there has been a rise in research on the incorporation of probiotics in edible coatings due to the bespoke health and biopreservation benefits they impart. Therefore, in this study, lactobacillus strains (Lactiplantibacillus plantarum 75 and Bifidobacterium longum) were incorporated into a xanthan edible coating to enhance color retention, sensory properties, antioxidant retention (ascorbic acid, carotenoids, total phenols), and antioxidant activity (FRAP antioxidant power, ABTS scavenger activity) of fresh-cut cantaloupes and honeydew cucumis melo L. melons during cold storage at 5 C and 85% RH for five days. The edible coating was prepared by mixing 0.5% xanthan gum, 1% glycerol, and 2% citric acid solution with L. plantarum 75 (LAB 75) and Bifidobacterium longum bacteria separately, and the final lab count for each strain was made to be 8.0 log CFU/mL. Stable probiotic coatings with ζ-potential of between -39.7 and -51.4 mV and a PdI of 1 were developed, and the incorporation of the probiotic bacteria into the coating was justified using FTIR analysis. The probiotic coatings showed a typical pseudoplastic behavior, in which the viscosity curves fall as the shear rate increases. Thermal stability analysis showed a continuous and multi-step weight reduction in this work, illustrating how the edible coating components interact. The survival of both Lactobacillus strains was recorded on day 5. Both freshly cut melons coated with xanthan and loaded with Lactobacillus strains retained a sufficient quantity of probiotics at the end of storage, while L. plantarum 75 (7 log CFU/g for cantaloupe and 8 log CFU/g for honeydew) retained the highest viability compared to B. longum (6 log CFU/g for cantaloupe and 7 log CFU/g for honeydew). In comparison to the coated and uncoated control samples, the inclusion of L. plantarum 75 in xanthan coatings significantly retained the color properties, pigments (total chlorophyll and carotenoids), ascorbic acid, total phenols, and antioxidant activity (FRAP, DPPH, and ABTS). The overall acceptability of fresh cuts of cantaloupe and honeydew melons coated with xanthan gum loaded with L. plantarum 75 was higher than that of other treatments. Thus, xanthan gum loaded with L. plantarum 75 coating is most suitable for reducing postharvest losses in fresh cuts of honeydew melons and cantaloupe, which will help preserve antioxidant and bioactive properties. The xanthan gum loaded with L. plantarum 75 coatings exhibited the highest preservation impact; therefore, it can be recommended for the fresh-cut industry.

CmCML11 interacts with CmCAMTA5 to enhance γ-aminobutyric acid (GABA) accumulation by regulating GABA shunt in fresh-cut cantaloupe

The effect of calcium chloride (CaCl2) treatment on γ-aminobutyric acid (GABA) accumulation in fresh-cut cantaloupe and the involved mechanisms were investigated. The result showed that 1% (w/v) CaCl2 treatment increased GABA content and activities of glutamate decarboxylase (GAD) and succinate semialdehyde dehydrogenase (SSADH), while decreased glutamate (Glu) content and GABA transaminase (GABA-T) activities in fresh-cut cantaloupe. CmCML11 and CmCAMTA5 expressions of CaCl2-treated fruit increased by 187.4% and 165.6% than control fruit in the initial 6 h. Besides, expressions of GABA shunt genes, including CmGAD1, CmGAD2, CmGABA-T and CmSSADH were also up-regulated by CaCl2 treatment during early storage. Moreover, acting as a transcriptional activator, CmCAMTA5 could bind to the CG-box in promoters of CmGAD1, CmGABA-T and CmSSADH and activate their transcription. Furthermore, the interaction between CmCML11 and CmCAMTA5 could enhance the transcriptional activation on GABA shunt genes which were regulated by CmCAMTA5. Collectively, our findings revealed that CaCl2 treatment promoted GABA accumulation in fresh-cut cantaloupe via the combined effect of CmCML11 and CmCAMTA5 in the regulation of expressions of CmGAD1, CmGABA-T, and CmSSADH in GABA shunt.

CaCl2 promoted phenolics accumulation via the CmCAMTA4-mediated transcriptional activation of phenylpropane pathway and energy metabolism in fresh-cut cantaloupe

Phenolics are secondary metabolites in plants. Calcium chloride (CaCl2) application could promote phenolics accumulation whereas the molecular mechanism remains uncertain. In this study, CaCl2 treatment reinforced the increase of individual phenolic acid content, PAL, C4H and 4CL activities and activated related expressions of CmPAL1, CmPAL2, CmPAL3, CmC4H1, CmC4H2, CmC4H3, Cm4CL1 and Cm4CL2 in fresh-cut cantaloupe. The total phenolics, total flavonoids content and antioxidant capacity in CaCl2-treated fresh-cut cantaloupe were 39.53%, 33.33% and 23.08% higher than those in control fruit after 24 h of storage, respectively. In the meantime, CaCl2 application elevated of H+-ATPase, Ca2+-ATPase, SDH, CCO activities and elicited the transcription of CmH+-ATPase4, CmCa2+-ATPase2, CmSDH5 and CmCCO6 genes in fresh-cut cantaloupe. Moreover, CmCAMTA4, an up-regulated calmodulin-binding transcription activator (CAMTA) induced by CaCl2 was identified in fresh-cut cantaloupe. Further study suggested that CmCAMTA4 could bind the CG-box in the promoter region of CmPAL3, Cm4CL1 and CmCCO6 to activate their transcription. In summary, these findings indicated that CaCl2 treatment could activate the transcription of CmPAL3, Cm4CL1 and CmCCO6 mediated by CmCAMTA4, which stimulated the phenylpropane pathway and maintained higher energy status, thus facilitating the biosynthesis of phenolics in fresh-cut cantaloupe during storage.

High virulence Proteus mirabilis strains cause acceleration of decay of fresh-cut fruits

The role of Proteus mirabilis on food safety has not been investigated before. Three P. mirabilis strains (swupm1, swupm2 and swupm3) isolated from fresh-cut fruits were shown to vary in swarming motility, with strains swupm1 and swupm2, but not swupm3 exhibiting the characteristic bull's-eye phenotype. Strains swupm1 and swupm2 grew faster and produced stronger biofilm than swupm3. These strains were all multidrug resistant and exhibited high virulence in Galleria mellonella (100% mortality at around 100 CFU inoculum) with swupm1 being the most virulent one. P. mirabilis was shown to be able to survive in fresh-cut cantaloupe at 4 °C and facilitate the growth of other bacteria. At 25 °C, P. mirabilis could significantly accelerate the decay of fresh-cut fruits. Headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS) analysis showed that P. mirabilis strain swupm1 could cause dramatic changes in the volatile components of fresh-cut cantaloupe, such as ethyl acetate, ethanol and formic acid. This study indicates that P. mirabilis can accelerate the decay of fresh-cut fruits and that the virulence level of these strains seems to be closely associated with the adverse effect of such strains on food quality.

Impact of food-relevant conditions and food matrix on the efficacy of prenylated isoflavonoids glabridin and 6,8-diprenylgenistein as potential natural preservatives against Listeria monocytogenes

Prenylated isoflavonoids can be extracted from plants of the Leguminosae/Fabaceae family and have shown remarkable antimicrobial activity against Gram-positive food-borne pathogens, such as Listeria monocytogenes. Promising candidates from this class of compounds are glabridin and 6,8-diprenylgenistein. This research aimed to investigate the potential of glabridin and 6,8-diprenylgenistein as food preservatives against L. monocytogenes. Their antimicrobial activity was tested in vitro at various conditions relevant for food application, such as different temperatures (from 10 °C to 37 °C), pH (5 and 7.2), and in the presence or absence of oxygen. The minimum inhibitory concentrations of glabridin and 6,8-diprenylgenistein in vitro were between 0.8 and 12.5 μg/mL in all tested conditions. Growth inhibitory activities were similar at 10 °C compared to higher temperatures, although bactericidal activities decreased when the temperature decreased. Notably, lower pH (pH 5) increased the growth inhibitory and bactericidal activity of the compounds, especially for 6,8-diprenylgenistein. Furthermore, similar antimicrobial efficacies were shown anaerobically compared to aerobically at the tested conditions. Glabridin showed a more stable inhibitory and bactericidal activity when the temperature decreased compared to 6,8-diprenylgenistein. Therefore, we further determined the antimicrobial efficacy of glabridin against L. monocytogenes growth on fresh-cut cantaloupe at 10 °C. In these conditions, concentrations of glabridin of 50, 100 and 250 μg/g significantly reduced the growth of L. monocytogenes compared to the control, resulting on average in >1 Log CFU/g difference after 4 days compared to the control. Our results further underscored the importance of considering the food matrix when assessing the activity of novel antimicrobials. Overall, this study highlights the potential of prenylated isoflavonoids as naturally derived food preservatives.

Effects of temperature abuse on the growth and survival of Listeria monocytogenes on a wide variety of whole and fresh-cut fruits and vegetables during storage

Twenty types of fruits and vegetables representing a broad range of fresh produce categories were assessed for the growth potential and growth kinetics of Listeria monocytogenes under conditions reflecting commercial practices for storage and distribution and conditions reflecting sustained temperature abuse. Whole and fresh-cut produce was obtained from various commercial sources and inoculated with L. monocytogenes strains to evaluate the survival and growth for up to 25 days, depending on the projected commercial storage or retail shelf life for each commodity. The L.monocytogenes populations showed a sustained decline on all tested whole fruits, including avocado, blueberry, grape, mango, peach, green pepper, and tomato. Under “normal” storage conditions (defined as those reflective of common commercial practices), significant L. monocytogenes growth was only observed on fresh-cut cantaloupe (∼0.8 log) and fresh-cut mango (∼0.6 log). Exposure to temperature abuse conditions did not change the overall trends of L. monocytogenes survival on the whole fruits but did result in significant growth on several fresh-cut products, including celery, cauliflower, mango, onion, romaine lettuce, and cantaloupe. After inoculation on certain products (e.g., fresh-cut carrot and whole peach), L. monocytogenes seemed to lose cultivability rapidly but did retain viability as determined by the maintenance of cell membrane integrity.

Dynamics of Listeria monocytogenes and the microbiome on fresh-cut cantaloupe and romaine lettuce during storage at refrigerated and abusive temperatures

Listeria monocytogenes (Lm) outbreaks and recalls associated with fresh produce in recent years have heightened concerns and demands from industry and consumers to more effectively mitigate the contamination risk of this foodborne pathogen on fresh produce. In this study, the growth of Lm and indigenous bacteria on fresh-cut cantaloupe and romaine lettuce held at refrigerated (4 °C) and abusive (10–24 °C) temperatures was determined by both culture dependent and independent methods. Composition and dynamics of bacterial communities on Lm inoculated and non-inoculated samples were analyzed by 16S rRNA high-throughput sequencing. Fresh-cut cantaloupe provided favorable growth conditions for Lm proliferation (1.7 and >6 log increase at refrigerated and abusive temperatures, respectively) to overtake indigenous bacteria. The Lm population also increased on fresh-cut lettuce, but the growth rate was lower than that of the total mesophilic bacteria, resulting in 0.4 and >2 log increase at refrigerated and abusive temperatures. Microbial diversity of fresh-cut cantaloupe was significantly lower than that of fresh-cut romaine lettuce. The Shannon index of microbial communities on cantaloupe declined after storage, but it was not significantly changed on lettuce samples. Shifts in the bacterial microbiome on cantaloupe were mainly affected by Lm inoculation, while both inoculation and storage temperature played significant roles on lettuce bacterial communities. Multiple indigenous bacteria, including Leuconostoc and Weissella spp., were negatively correlated to Lm abundance on romaine lettuce, and were determined by bioassay as potential anti-listerial species. Data derived from this study contribute to better understanding of the relationship between Lm and indigenous microbiota on fresh-cut produce during storage.

Fabrication of γ-cyclodextrin-Based metal-organic frameworks as a carrier of cinnamaldehyde and its application in fresh-cut cantaloupes

Cinnamaldehyde (CA) is a promising antimicrobial agent for the preservation of fruits and vegetables due to its excellent antibacterial activity. The application is however, limited by its unstable and volatile properties. A biocompatible carbon dots hybrid γ-cyclodextrin-based metal organic framework (CD/MOF) was developed by the seed-mediated method to improve the encapsulation and sustained continuous release of CA. CD/MOF-0.5 exhibited a CA loading efficiency of 28.42% and a sustained release duration time of more than 15 days at 8 oC. The release kinetics results showed that the release behavior of CD/MOF-0.5 fitted well with the Korsmeyer–Peppas release kinetics model, indicating that its sustained release is mainly controlled by diffusion. Both the Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses revealed that CD/MOF-0.5 and CA molecules were linked by hydrogen bonds. Due to the high sustained release performance, CA-loaded CD/MOF-0.5 considerably inhibited the growth of Escherichia coli, hence preventing the spoilage of fresh-cut cantaloupes. CD/MOF-0.5/CA treatment also maintained the qualities of the fresh-cut cantaloupes, prolonging their edibility to five days. This work provides a promising strategy for the prevention of spoilage in food industry.

Change of soluble sugars, free and glycosidically bound volatile compounds in postharvest cantaloupe fruit response to cutting procedure and storage

In order to investigate the effects of cutting procedure and storage on the changes of sugars and volatiles in postharvest cantaloupe and explore the interactions among sugars, free and bound volatile compounds, two comparative groups were designed in this study (whole fruit stored at 4 °C at 0 d vs fresh-cut cantaloupe stored at 4 °C at 0 d; fresh-cut cantaloupe stored under 4 °C for 0, 1, 3, 5, 7 d). Changes of sugars, free and bound volatiles, β-glucosidase in whole and fresh-cut cantaloupe were determined. Results showed that most aldehydes, alcohols, esters and ketones in free form exhibited significant enhancements at the early storage period, while most bound volatiles decreased along with the storage. Cutting promoted the decrease of benzaldehyde, nonanal, decanal, 1-octen-3-ol, β-ionone and 3-octanone in bound form, but promoted the emissions of these components in free form correspondingly, which was consistent with the β-glucosidase activity in cantaloupe after cutting process. Bedsides, the in vitro test results indicated that sugars play key roles in the synthesis of bound volatiles in cantaloupe.

Influence of cold plasma on quality attributes and aroma compounds in fresh-cut cantaloupe during low temperature storage

In this study, cold plasma (CP) was applied in fresh-cut cantaloupe to investigate the changes of quality attributes and flavors. Results showed that CP maintained the qualities by suppressing the decrease of color, ascorbic acid, soluble solid contents and firmness in fresh-cut cantaloupe stored at 4 °C for 10 days. Besides, CP significantly inhibited the decrease of aldehyde at the early storage but promoted the conversion of aldehydes into downstream volatiles afterwards. Total alcohols increased firstly but decreased afterwards and CP inhibited the decrease of alcohols at 4 d and 6 d mainly due to (Z)-3-none-1-ol accumulation. For the floral- and fruity-note aromas, most of esters, ketones and lactones increased at first and then decreased afterwards, and CP inhibited decrease of these three aromas. Furthermore, CP induced the activities of lipoxygenase, hydroperoxide lyase and alcohol O-acyltransferase, indicating that CP promoted the conversion of aldehydes and alcohols into esters by enhancing the activities of these three key enzymes.

Synthesis and properties of core-shell thymol-loaded zein/shellac nanoparticles by coaxial electrospray as edible coatings

In this study, a coaxial electrospray process was used to produce nanoparticles, in which thymol was encapsulated in a core–shell of zein and shellac. We then investigated fluid velocity and solution concentrations on the electrospray. Scanning electron microscopy revealed that the thymol/zein/shellac particles prepared at a flow rate ratio of 0.6:0.3 mL/h were rounder with smaller diameters. The highest encapsulation efficiency of thymol was 81.34%, the average particle size was 606.53 nm, and the retention rate of thymol was 68.74% after 30 days. Moreover, we investigated the thermal stability, antimicrobial activity, and simulated gastrointestinal release curves of the nanoparticles. Finally, the nanoparticles were used as a coating for fresh-cut cantaloupe. Compared with the blank nanoparticle control group, the coating significantly extended the shelf life of cantaloupe to 16 days. Our results indicate that these nanoparticles have great potential for application in food preservation.

Effect of cellulose nanofiber-based coating with chitosan and trans-cinnamaldehyde on the microbiological safety and quality of cantaloupe rind and fresh-cut pulp. Part 2: Quality attributes

The quality characteristics of fruits and vegetables can be protected with coatings. The presented study aimed to evaluate the effect of cellulose nanofiber (CNF) based coatings with chitosan (CHI) and trans-cinnamaldehyde (TC) on the quality attributes, including weight loss, total soluble solid (TSS) content, firmness, and color of whole and fresh-cut cantaloupe during storage at 22 °C and 4 °C, respectively. Results showed that CNF-based coating was effective in protecting whole cantaloupes from firmness reduction and color change in redness/greenness (a*) and yellowness/blueness (b*) during room-temperature storage for up to 11 days. Coating containing only CNF was not able to prevent the quality changes of fresh-cut cantaloupe during the cold storage, but CNF + CHI/CNF + CHI + TC significantly decreased the weight loss, decelerated the firmness increase and maintained the lightness (L*) of fresh-cut cantaloupe for up to 7 days. The incorporation of chitosan (1%, w/w) improved the protection effect of CNF-based coatings against quality changes during storage for both whole and fresh-cut cantaloupes, but TC (1%, w/w) did not show significant enhancement on the protection effects of coatings for most quality attributes. This study indicates that the CNF-based coatings have the potential to maintain quality attributes of whole and fresh-cut fruits during storage and distribution.

Effect of Nano Silicon Dioxide Coating Films on the Quality Characteristics of Fresh-Cut Cantaloupe.

The prime objective of the research was to explore the coating effects of chitosan and nano-silicon dioxide with nisin as an antimicrobial agent on physicochemical properties, microbiological stability, and sensorial quality changes during the storage at 4 °C. The combination of nano-material and chitosan in addition to nisin was effective for reducing the postharvest attributes of fresh-cut cantaloupes in addition to the highest score in sensory evaluation. Chitosan coating treatment enhanced the microbiological quality 2.50 log CFU/g and 1.87 log CFU/g for aerobic counts and mold/yeasts populations, respectively. In a word, the combination of chitosan/nano-silica/nisin treatment was the best condition for fresh-cut cantaloupe shelf life extension by maintaining color, vitamin C 22.29 mg/100g, peroxidase activity 8.06 U/min.g, and other microbiological tests up to storage time of 8 days.

Enriched makiang (Cleistocalyx nervosum var. paniala) seed extract and citric acid to control pathogenic bacteria and color of fresh cut cantaloupe

Consumers demand for good appearance and safe fresh-cut fruits without synthetic preservatives. Phenolic compounds from makiang seeds were extracted and applied as a natural preservative. Makiang seed extract (MKSE) was treated with 5 various amount of Diaion® HP-2MG, a macro porous resin, to enrich the phenolic compound content. The application of 0.375 g Diaion® to 1 mL of 12.5 mg mL−1 MKSE was suitable for adsorbing the phenolic compounds. The eluent of 70% ethanol was able to release phenolic compounds with the highest recovery rate (61.22%). After drying, the phenolic enriched MKSE (PMKSE) contained 97.24% phenolic compounds and 4.99% flavonoids. The antagonistic effect of the MKSE was increased with the enrichment of phenolic content. The fresh cut cantaloupe (FCC) soaked with 1MBC PMKSE reduced the number of bacterial count on FCC, but affected the FCC color. The equal volume of 3.13 mg mL−1 PMKSE and 6.25% citric acid (MC) could reduce the number of spiked E. coli on FCC to 1.66 log CFU g−1 and retard the growth of pathogenic bacteria without significantly change in color. The MC had a potential to be applied for maintaining the bacterial quality and color of fresh-cut produce and minimal processed foods.

Effect of two mulberry (Morus alba L.) leaf polyphenols on improving the quality of fresh-cut cantaloupe during storage

Mulberry leaf polyphenols (MLP) with good biological activities have not been applied to the preservation of fresh-cut (FC) fruits and vegetables. In present study, MLPs (Jialing20 and Naxi) were firstly used as natural preservatives in FC cantaloupe to improve its quality. FC cantaloupes were treated with 5 mg mL−1 MLPs (Naxi and Jialing20) and stored at 25 °C for four days. MLP-treated samples exhibited significantly better retention in color, firmness, soluble solids content, titratable acidity, total phenolic content and weight compared with samples treated by sterile distilled water (p < 0.05). The ranking of antioxidant activity was: Naxi MLP-treated FC cantaloupes > Jialing20 MLP-treated FC cantaloupes > untreated FC cantaloupes, indicated by higher DPPH radical-scavenging activity and reducing power. MLP treatment inhibited bacterial growth, contributing to improving the safety of FC cantaloupes. The antibacterial activity of Jialing20 MLP was significantly higher than that of Naxi MLP, but the total phenolic content of Naxi MLP was significantly higher than that of Jialing20 MLP (p < 0.05). Five major monomers (gallic acid, chlorogenic acid, caffeic acid, rutin and isoquercitrin) were detected in Naxi and Jialing20 MLP by HPLC. Moreover, p-coumaric acid was detected only in Jialing20. The monomers of different contents in MLP could account for different antibacterial activities between Naxi and Jialing20 MLP. These results indicated that Naxi MLP could be valorized as a promising natural antioxidant and Jialing20 MLP as a natural antimicrobial agent inhibited foodborne bacterial pathogens growth. Hence, MLP improved the quality of stored FC cantaloupe and can be applied to preserve minimally processed fruit.

Application of Nano-coating and Chitosan Combination Films on Cantaloupe Preservation.

Fresh-cut cantaloupe faces several quality challenges as an increase of decay rate, browning, respiration and other changes which can reduce the shelf life. Nano-coating combination films as chitosan-nano-silicon dioxide and chitosan-nano-titanium dioxide can extend the shelf life of cantaloupe pieces. Cantaloupes were classified into four sets, Control (C), Chitosan (CTSN), Chitosan-Nano-Silicon Dioxides (CTSN/NSD) and Chitosan-Nano-titanium Dioxide (CTSN/NTD). Coated cantaloupe pieces had the best browning activity of polyphenol oxidase (PPO) (0.26 U/min/g) and the lowest water activity (Aw) (0.89) by chitosan-nano-silicon dioxide films. Chitosan-nano-titanium dioxide films could maintain weight loss (0.93%) and color pigments for L* value. It worked effectively against lipid peroxidation (MDA) (0.15 nmol g-1), Peroxidase Activity (POD) (3.92 U/min/g) and microbial contaminations (6.44 log CFU g-1). Both nano-coating films improved some chemical parameters as Titratable Acidity (TA), Soluble Solid Content (SSC) and pH. Nano-coatings films techniques were recommended for cantaloupes preservation methods.

An in situ-Synthesized Gene Chip for the Detection of Food-Borne Pathogens on Fresh-Cut Cantaloupe and Lettuce.

Fresh foods are vulnerable to foodborne pathogens which cause foodborne illness and endanger people’s life and safety. The rapid detection of foodborne pathogens is crucial for food safety surveillance. An in situ-synthesized gene chip for the detection of foodborne pathogens on fresh-cut fruits and vegetables was developed. The target genes were identified and screened by comparing the specific sequences of Salmonella Typhimurium, Vibrio parahemolyticus, Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli O157:H7 from the National Center for Biotechnology Information database. Tiling array probes were designed to target selected genes in an optimized hybridization system. A total of 141 specific probes were selected from 3,227 hybridization probes, comprising 26 L. monocytogenes, 24 S. aureus, 25 E. coli O157:H7, 20 Salmonella Typhimurium, and 46 V. parahemolyticus probes that are unique to this study. The optimized assay had strong amplification signals and high accuracy. The detection limit for the five target pathogens on fresh-cut cantaloupe and lettuce was approximately 3 log cfu/g without culturing and with a detection time of 24 h. The detection technology established in this study can rapidly detect and monitor the foodborne pathogens on fresh-cut fruits and vegetables throughout the logistical distribution chain, i.e., processing, cleaning, fresh-cutting, packaging, storage, transport, and sale, and represents a valuable technology that support the safety of fresh agricultural products.