Fresh-cut Carrots Research Articles

Shelf-life extension and quality retention in fresh-cut carrots coated with pectin

Abstract Fresh-cut carrot slices were treated with 2% calcium chloride, 2% calcium propionate, 0.01% chlorine, 0.5% hydrogen peroxide, chitosan (0.5 and 1%), 5% sesame oil emulsion, 0.5% ascorbic acid and a mixture of 0.5% ascorbic acid and 0.03% EDTA, low methoxyl pectin (0.75 and 1.5%), methyl cellulose, and polyvinyl alcohol (2 and 4%). Samples coated with polyvinyl alcohol or pectin could be stored at 8 °C for 12 days, compared to other treatments, where the samples could be stored only for 5–7 days. However, pectin, because of its GRAS status and efficacy was selected for coating the fresh-cut carrots for shelf-life and biochemical characterization studies. An increase of about eight to twelve times in the concentration of phenolic acids was seen in control samples stored for eight and 12 days. About three- to seven-fold increase in the total flavonoid concentration was seen in control samples, compared to pectin-treated samples during their storage for eight and twelve days. Among the flavonoids, accumulation of apigenin, hesperetin, myricetin and narenginin was higher, compared to other flavonoids in control samples. Fresh and pectin-coated samples were closely placed in the biplot for phenolic acids and flavonoids, indicating comparable concentrations of phenolic acids and flavonoids in fresh as well as pectin-coated carrots. An increase of about three and seven times in the concentration of phenolic acids and flavonoids, respectively was observed in control samples, compared to pectin-treated samples on the twelfth day of storage. This could be directly co-related with white blush formation and bitterness in control samples, resulting in low acceptability for such samples. Industrial relevance Low shelf-life of fresh-cut carrots during storage is largely attributed to white blush and deterioration in sensory attributes. This study revealed that coating of fresh-cut carrot slices with low methoxyl pectin helped in extending their shelf-life up to 12 days during refrigerated storage. Compared to control, carrot slices coated with 0.75% pectin showed nearly three-fold lower accumulation of phenolic acids, responsible for white blush formation and seven-fold lower flavonoid content, responsible for astringency and bitterness in fresh-cut carrot slices during storage for12 days. Therefore, pectin coating of fresh-cut carrots for enhancing their shelf-life holds promise for commercial applications.

UVA, UVB and UVC Light Enhances the Biosynthesis of Phenolic Antioxidants in Fresh-Cut Carrot through a Synergistic Effect with Wounding.

Previously, we found that phenolic content and antioxidant capacity (AOX) in carrots increased with wounding intensity. It was also reported that UV radiation may trigger the phenylpropanoid metabolism in plant tissues. Here, we determined the combined effect of wounding intensity and UV radiation on phenolic compounds, AOX, and the phenylalanine ammonia-lyase (PAL) activity of carrots. Accordingly, phenolic content, AOX, and PAL activity increased in cut carrots with the duration of UVC radiation, whereas whole carrots showed no increase. Carrot pies showed a higher increase compared to slices and shreds. Phenolics, AOX, and PAL activity also increased in cut carrots exposed to UVA or UVB. The major phenolics were chlorogenic acid and its isomers, ferulic acid, and isocoumarin. The type of UV radiation affected phenolic profiles. Chlorogenic acid was induced by all UV radiations but mostly by UVB and UVC, ferulic acid was induced by all UV lights to comparable levels, while isocoumarin and 4,5-diCQA was induced mainly by UVB and UVC compared to UVA. In general, total phenolics correlated linearly with AOX for all treatments. A reactive oxygen species (ROS) mediated hypothetical mechanism explaining the synergistic effect of wounding and different UV radiation stresses on phenolics accumulation in plants is herein proposed.

Carvacrol-loaded chitosan nanoparticles maintain quality of fresh-cut carrots

Abstract The effects of carvacrol-loaded chitosan-tripolyphosphate nanoparticles (Np-EO) on the physicochemical, sensory and microbial quality of fresh-cut (FC) carrot slices stored up to 13 days at 5 °C were studied. Np-EO was compared to samples treated by NaOCl (100 mg L − 1 ), Np (chitosan-tripolyphosphate nanoparticles without carvacrol) or individual chitosan (0.5%) and carvacrol (0.5%) solutions. Np-EO achieved the best sensory scores also avoiding carvacrol-related off-flavours found with the carvacrol solution. Furthermore, whitening of FC carrot slices was highly reduced in Np-EO samples. Np-EO reduced microbial levels in FC carrot slices by 0.6–3.0 log units on processing day compared to untreated (control) samples. Np-EO allowed to reduce the microbial growth in FC carrot slices during the first 9 days of storage similarly to carvacrol solution. Furthermore, Np-EO highly controlled microbial loads at the end of storage showing 2.3 (lactic acid bacteria), 6.1 (yeasts and moulds) and 5.1–5.4 (mesophiles, psychrophiles and Enterobacteriaceae ) lower log CFU g − 1 units compared to control samples. Conclusively, Np-EO highly maintained microbial (2–6 lower log CFU g − 1 units compared to control), sensory (up to 2.5 better scores than control) and physicochemical quality of FC carrot slices than control for 13 days at 5 °C. Industrial relevance Natural essential oils industrially extracted from plants are potential alternative substances with high antimicrobial properties when tested in vitro . However, their microbicidal efficacy is greatly reduced due to their low solubility in washing solutions of fresh-cut products. Accordingly, chitosan-tripolyphosphate nanoencapsulation of essential oils such as carvacrol is a great opportunity to increase the antimicrobial properties of carvacrol to be used in fresh-cut fruit and vegetables alternatively to conventional NaOCl sanitation.

Influence of 6-Benzylaminopurine, Chitosan and Carboxy Methyl Cellulose on Quality and Shelf Life of Fresh Cut Carrot (Daucus carota L.) Shreds under Refrigerated Storage

Influence of 6-Benzylaminopurine, Chitosan and Carboxy Methyl Cellulose on Quality and Shelf Life of Fresh Cut Carrot (Daucus carota L.) Shreds under Refrigerated Storage

Effects of UV-B and UV-C combination on phenolic compounds biosynthesis in fresh-cut carrots

The single and combined effects of UV-B (1.5kJm−2) and UV-C (4.0kJm−2) radiation treatments were studied on the phenylalanine ammonia-lyase (PAL) activity, phenolic content and antioxidant capacity (TAC) of shredded fresh-cut carrots during 72h at 15°C. Non-irradiated samples were used as control (CTRL). PAL activity of UV-B and CTRL samples was increased by approximately 760% after 72h while increases of 120–140% in the remaining radiation treatments were found. Chlorogenic acid represented 70% of the sum of phenolic compounds of initial samples. UV-B treatment showed the highest phenolic accumulation with 498% after 72h, regarding its initial value, while single and combined UV-C treatments achieved an accumulation of 440%, which was similar to CTRL samples. Such phenolics data were highly correlated (R2=0.82) to total antioxidant capacity throughout storage. Conclusively, UV-B treatment achieved the highest phenolic compounds accumulation and related antioxidant capacity in shredded carrot during 3days at 15°C. Furthermore, the use of UV-C treatment with sanitizing purposes combined with UV-B radiation did not negatively affect the accumulation of bioactive compounds, achieving similar enhancements to CTRL samples.

Quantifying Bacterial Cross-Contamination Rates between Fresh-Cut Produce and Hands

This study quantifies the cross-contamination rates between fresh-cut produce and hands using a nalidixic acid-resistant nonpathogenic Enterobacter aerogenes and cocktails of rifampin-resistant Salmonella or Escherichia coli O157:H7 strains. Volunteers performed the E. aerogenes experiments (n = 20), and one of the authors performed the Salmonella and E. coli O157:H7 experiments multiple times (n =15 and n =10, respectively). Each participant handled 25 g of fresh-cut carrots, celery, or cantaloupe in two different scenarios. In the first scenario, gloved hands were inoculated with 6 log CFU per hand of the bacteria, and in the second scenario, five 25-g pieces of fresh produce were inoculated to a concentration of 6 log CFU/25 g. The glove juice method was used to quantify the bacterial concentration on the gloved hands. About 30% of E. aerogenes on gloved hands was transferred to the carrots and celery, and 18% of E. aerogenes on gloved hands was transferred to the cantaloupe. When carrots or cantaloupe was inoculated with E. aerogenes , 1% was transferred to gloved hands; from inoculated celery, about 0.3% of E. aerogenes was transferred to gloved hands. There was not a significant difference between E. aerogenes and Salmonella cross-contamination rates (P > 0.05). When gloved hands were contaminated with E. coli O157:H7, about 30% was transferred to carrots, about 10% to celery, and about 3% to cantaloupe. When carrots and celery were inoculated with E. coli O157:H7, about 1% was transferred to gloved hands, but from inoculated cantaloupe only about 0.3% was transferred. Direction of transfer (to versus from produce), difference in type of produce, and differences among the bacterial species all had significant effects on the transfer rate. Understanding transfer rates to and from fresh-cut produce will allow for better risk assessment and management of microbial food safety risk related to fresh-cut produce.

Combination of nisin and ε-polylysine with chitosan coating inhibits the white blush of fresh-cut carrots

Effects of the combination of nisin and ε-polylysine with chitosan coating on quality maintenance and white blush inhibition were investigated in fresh-cut carrots. Fresh-cut carrots were treated with 1% lactic acid solution (v/v), 1% chitosan solution (w/v), or 1% chitosan solution containing 64 μg/mL nisin and 250 μg/mL ε-polylysine (LA + CH + Nisin + ε-PL). The samples were packed in polyethylene plastic bags and stored at 4 °C for 9 days. Changes in sensory attributes, physicochemical indices, respiration rate, microbiological counts and white blush were measured. Results showed that LA + CH + Nisin + ε-PL significantly (P < 0.05) inhibited respiration rate, decline of ascorbic acid and growth of microorganism (yeast and mold, total viable counts, total coliforms counts, Staphylococcus aureus and Pseudomonas spp.), and increased total phenol content and phenylalanine ammonialyse (PAL) activity compared with the control after 9-day storage. It was also strongly effective in inhibiting the white blush of fresh-cut carrots. Furthermore, LA + CH + Nisin + ε-PL significantly (P < 0.05) reduced the lignin synthesis in fresh-cut carrots by inhibiting the cinnamate-4-hydroxylase (C4H) and 4-coumarate-CoA ligase (4CL) activity, as well as Dc4CL and DcC4H gene expression. Our results may provide some basis for the use of the combination of nisin and ε-polylysine with chitosan coating as an alternative preservation method for fresh-cut carrots.

Combined effect of starch/montmorillonite coating and passive MAP in antioxidant activity, total phenolics, organic acids and volatile of fresh-cut carrots

This work evaluates fresh-cut carrots (FCC) coated with montmorillonite (MMT) subjected to passive modified atmosphere packaging. Carrots were sanitized, cooled, peeled and sliced. Half of the FCC were coated with MMT nanoparticle film and the other half were not. All FCCs were packed in a polypropylene rigid tray, covered with a polypropylene rigid lid or sealed with polyethylene + propylene film, in four treatments (RL, rigid lid; RLC, rigid lid + coating; ST, sealed tray; STC, sealed tray + coating). FCCs were stored at 4 °C and were analyzed weekly for 4 weeks (total antioxidant activity by 2,2-diphenyl-1-picryl hydrazyl method and the β-carotene/linoleic acid, phenolic compounds, organic acids and volatile compounds). The use of coating film with starch nanoparticles and a modified atmosphere leads to the preservation of the total antioxidant activity, the volatile and organic acids of FCC.

Postharvest Quality of Fresh-Cut Carrots Packaged in Plastic Films Containing Silver Nanoparticles

Active food packaging containing antimicrobial additive goes beyond traditional functions of packaging, once it can extend food shelf life maintaining its quality, safety and reducing postharvest losses by controlling food spoilage. Among several antimicrobial additives employed in polymeric films for packaging, metallic nanoparticles outstand due to its facility for synthesis, low-cost of production, and intense antimicrobial properties. In this work, extruded plain films of low-density polyethylene (LDPE) containing silver nanoparticles (AgNPs) embedded in SiO2 and TiO2 carriers (namely MS and MT, respectively) were produced and used as active packaging for maintaining the physicochemical and microbiological quality of carrots (Daucus Carota L. cv. Brasilia). The neat (LDPE) and composite films containing MS and MT were characterized by scanning electron microscopy and permeability to oxygen and used for packaging fresh-cut sliced carrots stored at 10 °C for 10 days. After the storage time, the physicochemical properties of carrots were characterized, while the antimicrobial properties of films and AgNP migration were investigated. Our results revealed that both MT and MS packages showed antimicrobial activity even for films containing low concentration of AgNP. In addition, AgNP antimicrobial activity demonstrated to be carrier-dependent, once MT-LDPE showed improved performance compared to MS-LDPE. Regarding the physicochemical properties of packaged carrot, lower soluble solids and weight loss and higher levels of ascorbic acid were observed for carrots packaged with MT-LDPE films (compared to MS-LDPE), leading to a better postharvest quality conservation. Such differences observed in physicochemical properties of carrots are related to the distinct antimicrobial and film permeability properties for each composite film. In addition, under the conditions employed in this study, AgNP migration from the packages to fresh-cut carrot was not observed, which is highly desirable for food packaging safety, indicating the potential of such active packages for food preservation application.

Development and evaluation of biodegradable films and coatings obtained from fruit and vegetable residues applied to fresh-cut carrot (Daucus carota L.)

This work aimed to develop biodegradable coatings and films by using different extraction methods from fruit and vegetable residues. The effect of two coating strategies (immersion and spraying) and packaging methods on weight loss, color and microbial quality of minimally fresh-cut carrots (sliced and shredded) was investigated. Mechanical properties of the films were measured. The film obtained using a pH 7.0 buffer was applied to carrots as it had enhanced mechanical properties such as tensile strength and elongation at break (0.14MPa and 17%, respectively). Microbial growth on coated carrots was similar to that of the control. Samples packaged with film had 27% weight loss less than the control samples. Immersion and spray coated shredded carrots had 12 and 25% less mass loss than the control, respectively, while for sliced carrots the difference was not significant. The whiteness index of film-packaged samples and immersion coated shredded carrots did not change appreciably. Despite the observed drop in color saturation expressed by chroma values, the color index was positive for all samples, indicating that orange color did not change during storage. The cutting method had a greater impact on the total color change than the coating treatment. In general, coated sliced carrots had a more prominent color change coated shredded ones. The data demonstrate the potential of a multicomposite vegetable matrix for producing coatings and packaging materials. Additional efforts are necessary to evaluate and optimize this process.

Potential use of microwave treatment on fresh-cut carrots: physical, chemical and microbiological aspects.

The effect of microwave treatments (900 and 750 W for 45 and 60 s) on the microbial, physicochemical and sensory properties of fresh-cut carrot slices and the contents of several bioactive compounds was studied. Carrot samples were stored for 7 days at 5 °C. The microwaving of fresh-cut carrots reduced the initial respiration rate (8.6 CO2 mL kg(-1) h(-1)) by 55-74% compared with untreated samples, although the rates then increased during storage. The initial pH (6.7), titratable acidity (0.036%), soluble solid content (8.2 °Brix) and shelf-life of the samples did not differ greatly from those of the untreated samples. Microwaving prevented the incipient whitening and surface dryness during storage. In general, no significant changes in phenylalanine ammonia lyase activity (5.5 µmol t-cinnamic acid kg(-1) h(-1)), total phenolics (TP, 81.3 mg chlorogenic acid equivalent kg(-1) fresh weight (FW)) or total antioxidant capacity (TAC, 74.2 µmol Trolox equivalent kg(-1) FW) were observed on the processing day or over storage. However, the mildest treatment (750 W for 45 s) caused TP and TAC enhancements of 118 and 394% respectively after 7 days of shelf-life. Microwave treatments reduced the initial microbial loads of the samples by up to 1.8 log units, although their microbial growth was greater than that of the untreated samples throughout storage. Mild microwave treatments such as 750 W/45 s and 750 W/60 s are a good sustainable alternative to the use of NaOCl; however, combining them with other sanitizing techniques is needed to control microbial growth throughout the shelf-life of fresh-cut carrot slices.

Effect of carrot puree edible films on quality preservation of fresh-cut carrots

Abstract The effect of edible films based on carrot puree, chitosan, corn starch, gelatin, glycerol and cinnamaldehyde on fresh-cut carrots was studied during storage. Several parameters, such as firmness, colour, weight loss, total carotenoids, total phenols, polyphenol oxidase (PPO) activity and peroxidase (POD) activity in coated carrots were determined at regular intervals and then compared with the uncoated carrots throughout the storage period. Significant and expected changes were observed in all carrot samples that were compared. The coating treatment significantly (P &lt; 0.05) delayed the senescence, reduced the deterioration of exterior quality and retained total carotenoids well compared with control (P &lt; 0.05). In addition, significant inhibition of PPO activity (P &lt; 0.05) and POD activity (P &lt; 0.05) as well as reduced accumulation of polyphenols (P &lt; 0.05) were observed for all coated samples. All of these favourable responses induced by coating treatment on minimally processed fresh-cut carrots showed beneficial physiological effects, which would give some useful references to the fresh-cut fruit and vegetable processing industry and satisfy people’s requirements allowing for extending product shelf life without negatively affecting the sensory quality or acceptability.

Systematic Study of the Content of Phytochemicals in Fresh and Fresh-Cut Vegetables.

Vegetables and fruits have beneficial properties for human health, because of the presence of phytochemicals, but their concentration can fluctuate throughout the year. A systematic study of the phytochemical content in tomato, eggplant, carrot, broccoli and grape (fresh and fresh-cut) has been performed at different seasons, using liquid chromatography coupled to triple quadrupole mass spectrometry. It was observed that phenolic acids (the predominant group in carrot, eggplant and tomato) were found at higher concentrations in fresh carrot than in fresh-cut carrot. However, in the case of eggplant, they were detected at a higher content in fresh-cut than in fresh samples. Regarding tomato, the differences in the content of phenolic acids between fresh and fresh-cut were lower than in other matrices, except in winter sampling, where this family was detected at the highest concentration in fresh tomato. In grape, the flavonols content (predominant group) was higher in fresh grape than in fresh-cut during all samplings. The content of glucosinolates was lower in fresh-cut broccoli than in fresh samples in winter and spring sampling, although this trend changes in summer and autumn. In summary, phytochemical concentration did show significant differences during one-year monitoring, and the families of phytochemicals presented different behaviors depending on the matrix studied.

Produção de revestimento comestível à base de resíduo de frutas e hortaliças: aplicação em cenoura (Daucus carota L.) minimamente processada

Este estudio tuvo como objetivo desarrollar un recubrimiento biodegradable a base de harina de residuos de frutas y hortalizas. La estrategia de recubrimiento por inmersion fue elegida para evaluar la calidad de las zanahorias minimamente procesadas en terminos de perdida de peso, cambio de color, pH, acidez titulable y solidos solubles durante el almacenamiento refrigerado. Zanahorias recubiertas mostraron un mejor rendimiento, con una tendencia de disminucion del indice de blancura en comparacion con el control y una mejor apariencia general. A pesar de haberse observado una tendencia a disminuir la saturacion del color expresado por los valores de croma (en el rango de 59 a 46), el indice de color fue positivo para todas las muestras (13 a 15), indicando la preservacion del color naranja durante el almacenamiento de las mismas. Aunque el parametro de color haya sido influenciado por el tratamiento de recubrimiento en las zanahorias, pequenos cambios ocurrieron en relacion a la perdida de peso, pH, acidez total y solidos solubles totales durante el almacenamiento. Los resultados demostraron el potencial de la harina de residuos de frutas y hortalizas para la formulacion de recubrimientos comestibles. La aplicacion practica en zanahorias minimamente procesadas confirma la adecuacion de este residuo como un material de recubrimiento alternativo y constituye una ruta motivadora para evaluar y optimizar esta tecnica de conservacion.

High pressure carbon dioxide combined with high power ultrasound pasteurization of fresh cut carrot

Nowadays, combination of innovative technologies aiming to obtain additive or synergistic effects on microbial inactivation of food products compared to the single processes is considered a field of great interest. In this context, the feasibility of a combined high pressure carbon dioxide and high power ultrasound (HPCD+HPU) treatment was tested for the pasteurization of fresh cut carrot.Inactivation kinetics of the natural microbial flora (mesophilic microorganisms, lactic acid bacteria, total coliforms and yeasts and molds) were determined at 12MPa and 10W delivered every 2min of treatment as a function of temperature (22, 35 and 40°C) and time (from 5 up to 30min). Further Escherichia coli was spiked on fresh cut carrot and inactivation kinetics were obtained at 6, 8, 10MPa and 10W delivered every 2min of treatment as a function of temperature (22 and 35°C) and times (from 3 up to 30min). The results of the inactivation kinetics were compared with those obtained with thermal, HPU and HPCD treatments.Additionally color, pH, acidity, texture and sensory analyses of the samples were performed to assess the quality of HPCD+HPU treated carrots in comparison with the fresh product.It was demonstrated that the combined treatment was not able to induce a greater reduction of the natural microbial flora at milder process conditions compared to HPCD. At 40°C, 12MPa, 15min and 10W still a residual load of mesophilic microorganisms was detected. On the contrary, the inactivation kinetics of E. coli showed a faster reduction: 3min at 10MPa, 35°C and 10W were enough to obtain 8log reductions.Texture and sensory analyses revealed significant changes of HPCD+HPU treated samples with great reduction of firmness, friability and crispiness. The results showed the potentials and limits of the combined technology applied to fresh cut vegetables.

Effect of pre storage treatments on the shelf-life of fresh cut carrots

SUMMARY : Fresh carrots collected from the local market were used for the study. Freshly collected carrots were washed, surface sanitized using the standardized 30 ppm sodium hypo chlorite solution, outer skin scraped, washed and shreds were prepared and these shreds were air dried and kept in aluminiumtrays wrapped with cling film under refrigerated storage for taking observations. The physical, physiological and chemical quality parameters were analyzed and based on the microbial analysis it was found that 2 per cent calcium ascorbate as the best effective chemical treatment for shredded carrots.

Effects of processing and storage variables on penetration and survival of Escherichia coli O157:H7 in fresh-cut packaged carrots

The effects of severity of slicing and peeling, and of storage atmosphere and temperature on the survival of Escherichia coli O157:H7 at and below the cut surfaces of fresh-cut carrot discs were determined. Slicing with a blunt machine blade enhanced penetration of E. coli O157:H7 and its subsequent survival during storage at 8 °C. Significantly (P < 0.05) higher numbers of cells (0.5 log CFU g−1) penetrated deeper (475–500, 725–750 and 975–1000 μm) into carrot tissue sliced with a blunt machine blade compared to those sliced with a razor blade. Counts on Day 3 and Day 5 of storage remained higher in carrot tissue sliced with a blunt machine blade at all depths sampled. There were no significant effects of peeling method on penetration and survival. Storage of carrot slices in sub-optimal atmospheres (20%CO2/1%O2 resulted in increased survival of cells at the surface and within the tissue compared to storage in more optimal atmospheres (5% CO2/3% O2). Increasing storage temperature from 4 to 10 °C resulted in growth of E. coli O157:H7 at all sample depths. For all experiments, E. coli O157:H7 cells colonising the surface generally survived better than cells that penetrated into the tissue. The data are relevant to improving microbial safety in the fresh-cut sector by demonstrating that cutting with sharp blades (e.g. during harvesting and processing) reduces the depth of potential contamination by E. coli O157:H7. This may also have implications for more efficient anti-microbial dipping and reduced pathogen survival during storage.

Validation of a mathematical model for predicting high pressure carbon dioxide inactivation kinetics of Escherichia coli spiked on fresh cut carrot

Inactivation kinetics of Escherichia coli spiked on fresh cut carrot and exposed to high pressure carbon dioxide (HPCD) treatment at several conditions of pressure (6, 8, 10, and 12MPa) and two conditions of temperature (26 and 35°C) were obtained as a function of the treatment time (up to 30min).The Weibull model was applied to fit the inactivation kinetics and calculate δ and n model parameters for each pressure and temperature. The results demonstrated that the model was able to fit with good agreement the inactivation curves (high R2 and low RMSE values). In a second attempt, the model parameters were correlated with CO2 density resulting in a linear relationship. Validation of the proposed model was also performed at 6.6 and 10MPa, 26°C and at 8MPa, 35°C providing log reduction residual values (observed value–predicted value) lower than 0.50 and showing a good agreement between the experimental and the predicted inactivation data.The model proved to be a powerful tool to fit and predict, in the proposed operative range, the inactivation kinetics of E. coli spiked on fresh cut carrot treated by HPCD. The results demonstrated the potential of a relative simple correlative model for the interpretation of the inactivation data and for HPCD process design and optimization.

Identification of respiration rate and water activity change in fresh-cut carrots using biospeckle laser and frequency approach

For consumers, fresh-cut fruits and vegetables are a convenient product and a healthy source of fresh food that has nutritional and sensory characteristics similar to those of intact products. In this paper, a non-destructive method for analyzing fresh-cut fruit and vegetables is described. The biospeckle laser technique is based on the optical phenomenon of interference generated by a coherent light interacting with biological materials or dynamical systems. Although many publications on this technique's biological applications have reported that biospeckle activity corresponds to the activity of biological samples, there is some difficulty in determining the correlation between a particular phenomenon and the activity observed. In this study, we evaluated the use of biospeckle data for measuring the physiological properties of fresh-cut carrots stored at two temperatures (0 and 10°C). In conjunction with the biospeckle activity, the moisture content, respiration rate, water activity, and mass loss changes were monitored using traditional analytical methods to evaluate the possible correlation of the biospeckle data with any of these phenomena with or without the use of frequency signatures. The results showed that the manifestation of water in the monitored activity was isolated only by removing these high frequencies, thus allowing the activity manifested in the material to be linked to a specific phenomenon, such as respiration. Therefore, we were able to monitor the respiration process in fresh-cut carrots and assign a spectral signature to their water content and respiration.

Bacterial inactivation on solid food matrices through supercritical CO2: A correlative study

In this paper the effectiveness of dense phase carbon dioxide (DPCD) treatment to inactivate different bacterial strains inoculated on the surface of solid food matrices is studied. The bacterial survival is investigated on three distinct matrices: Salmonella enterica spiked on fresh cut coconut (Cocos nucifera), Escherichia coli on fresh cut carrot (Daucus carota) and Listeria monocytogenes on dry cured ham surface. Bacterial inactivation experiments are carried out in order to develop and identify mathematical models whose relative performance is assessed in terms of goodness-of-fit and a posteriori statistics obtained after parameters estimation. Operational maps illustrating the time required to achieve an assigned inactivation degree are built in order to guide the choice of the best operating conditions to be used in the process.The results demonstrate the potential of relatively simple correlative models to represent the DPCD pasteurisation process at different experimental conditions, paving the way to more complex model formulation that can be used in DPCD process design and optimisation.