Fresh-cut Carrots Research Articles

Monitoring of phytochemicals in fresh and fresh-cut vegetables: A comparison

Bearing in mind that fresh-cut market is currently the fastest growing subsector in the food industry, a comparison of the levels of phytochemicals in fresh and fresh-cut vegetables has been carried out. Thus, several families of phytochemicals, such as phenolic acids, isoflavones, flavones, flavonols and glucosinolates were determined in fresh and fresh-cut samples including tomato, carrot, grape, eggplant and broccoli. Both type of products have potential and similar beneficial properties, regarding its content as phytochemicals, except tomato, which should be consumed as fresh. Other factors such as commercial presentation (sliced, grated, diced) and storage conditions (temperature and light) were evaluated observing that in eggplant, the content of phenolic acids is statistically different depending on the presentation. On the other hand, the content of phytochemicals was higher when fresh-cut carrots were stored at 4°C regardless of the presence or absence of light. Multivariate analysis, based on cluster analysis was used as a first approach to distinguish between fresh and fresh-cut samples, obtaining good results except for eggplant and carrot.

Microbiological Quality of Fresh-Cut Carrots and Process Waters

Fresh vegetables may be contaminated by pathogens in different ways after harvest. Pathogenic microorganisms associated with fresh vegetables can cause severe outbreaks of foodborne disease. We discuss here the results of microbiological analysis of carrot samples, as well as of washing, processing, and wastewater samples. Washed, unpeeled carrots generally contained the highest aerobic plate counts (mean, 5.5 log CFU/g). Escherichia coli was not detected in any carrot or water sample examined. The amounts of coliform bacteria and enterobacteria were higher in carrot samples taken from the first steps in the processing line than in samples taken in later phases of the process. Yersinia pseudotuberculosis was not detected in any of the samples by the cultivation method; however, nonpathogenic Yersinia enterocolitica was detected from most carrot samples and almost all washing water and wastewater samples but only from 2 of 10 process water samples. Using a more-sensitive real-time PCR method, pathogenic Y. enterocolitica was found from several carrot samples, and when these positive samples were cultivated, no pathogenic Y. enterocolitica strains were detected.

Determination of the effects of refrigerated storage and packaging method on the instrumental textural attributes of fresh-cut carrot slices

In this research fresh-cut carrot slices were packaged by three different techniques (passive modified atmosphere packaging, modified atmosphere packaging and vacuum packaging), stored at 4±1 °C for 9 days and instrumental textural attributes (hardness and toughness) of carrot samples were determined at three-day intervals. As a result of the study, it was found that hardness values of the samples which were passive modified atmosphere packaged and vacuum packaged significantly increased during storage (P<0.05).

High pressure carbon dioxide pasteurization of fresh-cut carrot

High pressure carbon dioxide treatment (HPCD) was applied for the pasteurization of fresh-cut carrot. The inactivation kinetics of the natural microbial flora were determined as a function of the treatment conditions (8 or 12MPa, 22, 35, 40, 45°C, 5–45min) to investigate the more feasible process conditions to assure a microbial stability to the product. Further, the effect of HPCD treatment on the qualitative aspects of the product in terms of enzymatic activity (polyphenol oxidase (PPO), peroxidase (POD), pectin methylesterase (PME) and polygalacturonase (PG)), bioactive composition (phenol, flavonoid, carotenoid, ascorbic acid content and antioxidant capacity), texture, pH and tritatable acidity (TA) were measured. A storage study at refrigerated conditions (4°C) for 4 weeks was also performed to monitor the microbial and qualitative stability of the product. The results showed that 12MPa, 40°C, 15min were effective to inactivate the natural microbial flora and assure the microbial and enzymatic stability of the product for 4 weeks. Bioactive compounds content, antioxidant capacity, and enzyme stability were all preserved with the exception of the texture which exhibited a significant reduction up to 90% compared to the control, and the ascorbic acid content which was reduced down to 40%.

EFFECT OF DIMETHYL DICARBONATE AS DISINFECTANT ON THE QUALITY OF FRESH-CUT CARROT (DAUCUS CAROTAL.)

ABSTRACT The effect of dimethyl dicarbonate (DMDC) (200 mg/L) sterilization was tested. The reduction of microorganisms and the variation of nutritional and physiological quality in fresh-cut carrot treated by DMDC were evaluated. The results showed that the total aerobic plate count and count of total yeasts and molds in the fresh-cut carrot treated by DMDC were significantly reduced (P < 0.05) by 3.01 and 3.43 log cfu/g, respectively, in comparison with control (the fresh-cut carrot washed by sterile water). DMDC could also inhibit the activity of polyphenol oxidase and peroxidase and be beneficial to the maintenance of vitamin C level, quality of fresh-cut carrot during storage at 10C. DMDC made no marked impact on the β-carotene content of fresh-cut carrot. Therefore, DMDC was an effective disinfectant in fresh-cut carrot. PRACTICAL APPLICATIONS Fresh-cut fruits and vegetables usually have short shelf life because of the microbial contamination and quality deterioration. Various sanitizers such as sodium hypochlorite, ozone, peroxyacetic acid, etc., are now applied to extend the storage life of fresh-cut vegetables. Although sodium hypochlorite has been widely used, it may produce unhealthy byproducts. Ozone and other disinfectants could damage some antioxidant substances due to their strong capacity of oxidation. Therefore, a novel nonoxidizing disinfectant dimethyl dicarbonate (DMDC) without hazard to human health is needed urgently. In this study, DMDC was used to reduce effectively the population of microbial and maintain the nutrients and quality of fresh-cut carrot. Therefore, this new disinfectant will have a good prospect in fresh-cut industry in the future.

Effect of UV-B light and different cutting styles on antioxidant enhancement of commercial fresh-cut carrot products

Wounding stresses resulting from fresh-cut processing are known to enhance the antioxidant capacity (AC) of carrots by increasing the synthesis of phenolic compounds. Ultraviolet-B (UV-B) light exposure further promotes the formation of phenolic compounds. Changes in total soluble phenolics (TSP), 5-O-caffeoylquinic acid (5-CQA), total carotenoids, AC, and phenylalanine ammonia-lyase (PAL) activity of five commercial fresh-cut carrot products (baby carrots, carrot stixx, shredded carrots, crinkle cut coins, and oblong chips) were evaluated after exposure to UV-B dosage at 141.4 mJ/cm(2). Significant increases in TSP, AC and 5-CQA levels were observed for each sample following UV-B exposure. Increases in PAL activity were also observed in all carrot products, except crinkle cut coins. Total carotenoids of the carrot products were unchanged by UV-B exposure. Increases in AC levels corresponded directly with increases in the area/weight ratio (exposure area) of the fresh-cut carrot products.

Fresh-cut carrot (cv. Nantes) quality as affected by abiotic stress (heat shock and UV-C irradiation) pre-treatments

Abiotic stresses such as heat shock and UV-C irradiation can be used to induce synthesis of bioactive compounds and to prevent decay in fresh-cut fruits and vegetables. This study aimed to evaluate the effects of heat shock and UV-C radiation stress treatments, applied in whole carrots, on the overall quality of fresh-cut carrot cv. Nantes during storage (5 °C). Heat shock (HS, 100 °C/45 s) and UV-C (0.78 ± 0.36 kJ/m2) treated samples had higher phenolic content and exhibited reduced POD activities during storage when compared to control (Ctr) samples (200 mg/L free chlorine/1 min). All samples showed reduced carotenoid content considering raw material. Nonetheless, UV samples registered a three-fold increase in carotenoid content in subsequent storage. Fresh-cut carrot colour showed a continuous increase in whiteness index (WI) values during storage regardless of treatment without impairing visual quality. Respiratory metabolism was affected by both abiotic stress treatments since reduced O2/CO2 rates were found, more significant in HS samples. The decontamination effect was more expressive in HS samples, where a 2.5 Log10 cfu/g reduction in initial microbial load and reduced microbial growth were achieved.

Ultraviolet‐B light treatment increases antioxidant capacity of carrot products

The effect of ultraviolet-B (UV-B) light as a postharvest treatment to enhance the antioxidant content of carrots and fresh-cut carrot products was evaluated. Four levels of UV-B dose ranging from 1.3 to 12 kJ m⁻² were applied to whole, baby and various styles of cut carrots, and the changes in antioxidant capacity, total soluble phenolics and phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) activity were measured after a 3 day incubation period at 15 °C and 45% relative humidity. Both cutting style and dose level were factors in determining carrot responses to UV-B treatment. Antioxidant capacity increased significantly (1.4-6.6-fold). Total soluble phenolic results correlated directly with those of antioxidant capacity (R² = 0.953), indicating that the enhancements achieved were due to an increase in phenolic content. High-performance liquid chromatography analysis revealed that 5-O-caffeoylquinic acid (5-CQA) was the primary phenolic responsible for this increase. Higher PAL activity was also observed in UV-B-treated samples, indicating that the increase in 5-CQA was a biological response to UV-B exposure. UV-B treatment has the potential to increase the nutritional value of carrots and offers an exciting opportunity to increase consumer accessibility to dietary choices that are rich in antioxidants.

Calcium-alginate coating loaded with silver-montmorillonite nanoparticles to prolong the shelf-life of fresh-cut carrots

In this work, the effects of both active coating loaded with silver-montmorillonite (Ag-MMT) nanoparticles and film barrier properties on shelf life of fresh-cut carrots are presented. In particular, sensory and microbiological quality has been monitored during the storage period. While for microbiological quality the main spoilage microorganisms (mesophilic and psychrotrophic bacteria, Enterobacteriaceae spp., Pseudomonas spp., yeasts and moulds) were monitored, colour, odour, firmness and product overall quality were judged for the sensory evaluation. Results highlighted that statistically significant differences in microbial populations were found between coated and active coated samples. For the products with active coating microbial cell loads remained always below the selected microbial threshold. Moreover, samples packaged with the active coating appeared to be better preserved from a sensory point of view. As regards packaging mass transport properties, the film made up of oriented polypropylene with a thickness of 20μm was found to be the most suitable for fresh-cut carrots. Thus, experimental results demonstrated that a significant shelf life prolongation up to more than two months can be achieved by using the developed active coating before packaging the fresh-cut carrots in a proper system.

Growth potential of Escherichia coli O157:H7 on fresh-cut fruits (melon and pineapple) and vegetables (carrot and escarole) stored under different conditions

Minimally processed fruits and vegetables are ready-to-eat and do not require further treatment at home. These foods are usually stored in a modified atmosphere and should be maintained at refrigerated conditions until consumption. These fruits and vegetables can become contaminated by foodborne pathogens such as Escherichia coli O157:H7, Salmonella and Listeria monocytogenes, and it has been demonstrated that current industrial sanitising washing treatments do not guarantee the total elimination of the pathogen when present. Thus, it is very important to elucidate whether pathogens are able to grow or survive during storage at different conditions. This study was conducted to determine the effect of the type of produce (escarole, carrot, pineapple or melon), package gas composition (air or modified atmosphere) and temperature (5 or 25 °C) on the population dynamics of a strain of E. coli O157:H7. For vegetables, the growth in two films, which created different O2 and CO2 concentrations, and air were compared. At 25 °C, growth of E. coli O157:H7 was higher in fresh-cut carrots than in endive, reaching populations between 7.0–8.4 log cfu g−1 and 5.2–6.3 log cfu g−1 after 3 days of storage, respectively. In fruits, E. coli O157:H7 grew well in fresh-cut melon regardless of the atmospheric conditions in the package, reaching populations of 8.5 and 8.9 log cfu g−1 after 1 day of storage in modified atmosphere packaging (MAP) or under air conditions, respectively. No growth was observed in the fresh-cut pineapple. At 5 °C, E. coli O157:H7 did not grow but survived throughout the studied period in all tested commodities. This work emphasises the importance of strict temperature control from processing to consumption, including transportation, distribution, storage and handling in supermarkets and by consumers.

Packaging strategies to prolong the shelf life of fresh carrots (Daucus carota L.)

In this work, different strategies aimed to prolong the shelf life of fresh carrots are presented. Dipping into a hydro-alcoholic solution, and its combination before and after coating with sodium alginate, were investigated. Untreated samples were also used as the controls. After treatments, carrots were packaged into a micro-perforated polypropylene film (thickness 30 μm) under passive MAP and stored at 4 °C. The sole coated samples were also packaged under active MAP (10% O2, 10% CO2). Headspace gas concentrations, pH, mass loss, sensory quality and viable cell loads of main spoilage microorganisms were monitored. Results suggested that the coating treatment under both passive and active MAP enhanced product quality by preventing dehydration and microbial proliferation and delaying the respiratory activity. In fact, while mesophilic bacteria increased rapidly in the uncoated samples, for coated samples cell loads remained constant (3 Log cfu/g) until 7 days of storage and then increased up to 5.6 Log cfu/g. From the sensory point of view, coated samples were appreciated for about two weeks, whereas all the other fresh carrots were refused after only 2 days. Fresh-cut vegetables market has grown rapidly in recent years as a result of changes in consumer attitudes. There is a real need to find methods for preservation of minimally processed food products that can gain widespread acceptance by the industry. This paper suggests effective packaging solutions to delay the quality decay kinetic of fresh-cut carrots.

Effects of Tapioca Starch/Decolorized Hsian-Tsao Leaf Gum-Based Active Coatings on the Quality of Minimally Processed Carrots

Edible coatings made from tapioca starch/decolorized hsian-tsao leaf gum (dHG) containing cinnamon essential oil or grape seed extract (GSE) were developed and applied to minimally processed carrots. Coatings based on 0.3% dHG and 1.7% tapioca starch were prepared and incorporated with 0.1–0.3% cinnamon oil or 0.3–0.6% GSE as antimicrobial agents. Fresh-cut carrots were immersed into coating solutions, placed in expanded polystyrene trays, and sealed in polypropylene bag. Changes in the initial respiration rate, the headspace atmosphere, color, microbial growth, and sensory evaluation were then measured. During refrigeration, the initial respiration rates for carrots with various coating treatments slightly increased as compared to the control group carrots, and the coatings with cinnamon oil showed the highest rates. Headspace analysis revealed that coated samples also had higher CO2 and lower O2 concentrations, which were consistent with the initial respiration rate results. Though samples coated with the antimicrobial solutions (cinnamon oil or GSE) did not show advantages in reducing microbial growth as compared to the control group carrots, they presented better acceptance during the sensory evaluations. The use of edible coatings successfully maintained the surface appearance and retarded the formation of “white blush” on the surface of carrots during refrigeration. While the visual appearance quality of minimally processed carrots was significantly improved by the coating treatments, the microbial growth was the same or even worse in some cases. Based on the pronounced improvements of the carrots’ appearance and the comparable microbial control, the plain starch/dHG coating without cinnamon oil or GSE was recommended for extending the shelf life of minimally processed carrots.

Influence of temperature and edible coating on the physical and chemical parameters and sensory acceptance of fresh-cut organic carrots Influencia de la temperatura y cobertura comestible en los parámetros físicos y químicos y aceptación sensorial de las zanahorias cortadas frescas

The effects of storage temperature and edible coating on the microbiological, physical, and chemical properties and sensory acceptance of fresh-cut organic carrots (Daucus Carota L. cv. Brasília) were investigated. The samples were diced, sanitized in sodium hypochlorite, and the excess water was drained in a centrifuge. The dry samples were then immersed in a 2% gelatin solution, packed in multilayer polypropylene bags and sealed. The coated and non-coated samples were stored at 1 °C, 5 °C, and 10 °C for 15 days. The results showed that the weight loss was below 0.43% for all samples. The weight loss increased with temperature, and a significant effect was observed. The carrots' texture decreased with higher storage temperatures and longer storage periods for all samples, being the same behavior observed for color. Sensory analyses showed best responses for samples stored at 1 °C, for both treatments with and without coating. Fue analizado el efecto de la variación de la temperatura y el tiempo de almacenamiento sobre las propiedades microbiológicas, físicas, químicas y sensoriales, de zanahorias orgánicas, mínimamente procesadas (Daucus Carota L. cv. Brasília) con cobertura comestible. Las muestras fueron cortadas, sanitizadas en una solución hipoclorhídrica y el exceso de agua retirado por centrifugación. Las muestras drenadas fueron inmersas en una solución de gelatina al 2% y después empaquetadas en bolsas de polipropileno de múltiples capas. Muestras con y sin recubrimiento fueron almacenadas en temperaturas de 1 °C, 5 °C, y 10 °C durante quince días. Los resultados demostraron que en todas las muestras, la pérdida de peso fue inferior a 0.43%. Esta pérdida de peso tuvo un aumento significativo y proporcional con la temperatura. La textura de las zanahorias, en términos de dureza, se redujo con el aumento de la temperatura y el tiempo de almacenado, para todas las muestras. El mismo comportamiento fue observado en lo que se refiere al color. Los resultados del análisis sensorial mostraron una mejor aceptación para las muestras almacenadas a1 °C, sean ellas con o sin recubrimiento.

Efficacy of various plant hydrosols as natural food sanitizers in reducing Escherichia coli O157:H7 and Salmonella Typhimurium on fresh cut carrots and apples

In the present study, inhibitory effects of the hydrosols of thyme, black cumin, sage, rosemary and bay leaf were investigated against Salmonella Typhimurium and Escherichia coli O157:H7 inoculated to apple and carrots (at the ratio of 5.81 and 5.81 log cfu/g for S. Typhimurium, and 5.90 and 5.70 log cfu/g for E. coli O157:H7 on to apple and carrot, respectively). After the inoculation of S. Typhimurium or E. coli O157:H7, shredded apple and carrot samples were washed with the hydrosols and sterile tap water (as control) for 0, 20, 40 and 60 min. While the sterile tap water was ineffective in reducing (P>0.05) S. Typhimurium and E. coli O157:H7, 20 min hydrosol treatment caused a significant (P<0.05) reduction compared to the control group. On the other hand, thyme and rosemary hydrosol treatments for 20 min produced a reduction of 1.42 and 1.33 log cfu/g respectively in the E. coli O157:H7 population on apples. Additional reductions were not always observed with increasing treatment time. Moreover, thyme hydrosol showed the highest antibacterial effect on both S. Typhimurium and E. coli O157:H7 counts. Inhibitory effect of thyme hydrosol on S. Typhimurium was higher than that for E. coli O157:H7. Bay leaf hydrosol treatments for 60 min reduced significantly (P<0.05) E. coli O157:H7 population on apple and carrot samples. In conclusion, it was shown that plant hydrosols, especially thyme hydrosol, could be used as a convenient sanitizing agent during the washing of fresh-cut fruits and vegetables.

High pressure carbon dioxide treatment for fresh-cut carrot slices

Abstract The effects of high pressure carbon dioxide (HPCD) treatment on natural microorganisms, indigenous enzyme activity, damage to cell membranes and hardness in fresh-cut carrot slices were investigated. 1.86 log 10 cycle reduction for aerobic bacteria (AB) and 1.25 for yeasts and molds (Y&M) were achieved at 5 MPa and 20 °C for 20 min. The residual activity ( RA ) of peroxidase (POD), polyphenol oxidase (PPO), and pectinmethylesterase (PME) exhibited initially increase and secondly decrease with treatment time and their minimum activity was 75.8%, 90.9% and 52.8% at 5 MPa and 20 C for 15 min, respectively. Membrane damage was evaluated by relative electrolyte leakage (REL) and malondialdehyde (MDA) content. HPCD caused a significant increase of REL in carrot slices and the REL of carrot slices treated at 5 MPa and 20 °C for 15 min was 5.7 times as much as that of the untreated, however, HPCD showed no effect on MDA content. The hardness was well retained after HPCD treatment and the largest loss was 7.9% at 5 MPa and 20 °C for 15 min. Industrial relevance Fresh-cut carrot slices are one of the most widely used products in prepared salads, and it required strict treatment conditions to protect its quality, especially to prevent microbial spoilage and enzymatic discoloration. HPCD is one promising novel non-thermal technique without compromising the flavor, taste and nutrition aspect of food. This study analyzed the effectiveness of HPCD as a method of preserving fresh-cut carrot slices, including inactivating natural microorganisms and enzymes which are crucial to quality control. Available data provided in this study will benefit the fresh-cut fruits and vegetables industry.

Combination treatment of alkaline electrolyzed water and citric acid with mild heat to ensure microbial safety, shelf-life and sensory quality of shredded carrots

The objective of this study was to determine the synergistic effect of alkaline electrolyzed water and citric acid with mild heat against background and pathogenic microorganisms on carrots. Shredded carrots were inoculated with approximately 6–7 log CFU/g of Escherichia coli O157:H7 (932, and 933) and Listeria monocytogenes (ATCC 19116, and 19111) and then dip treated with alkaline electrolyzed water (AlEW), acidic electrolyzed water (AcEW), 100 ppm sodium hypochlorite (NaOCl), deionized water (DaIW), or 1% citric acid (CA) alone or with combinations of AlEW and 1% CA (AlEW + CA). The populations of spoilage bacteria on the carrots were investigated after various exposure times (1, 3, and 5 min) and treatment at different dipping temperatures (1, 20, 40, and 50 °C) and then optimal condition (3 min at 50 °C) was applied against foodborne pathogens on the carrots. When compared to the untreated control, treatment AcEW most effectively reduced the numbers of total bacteria, yeast and fungi, followed by AlEW and 100 ppm NaOCl. Exposure to all treatments for 3 min significantly reduced the numbers of total bacteria, yeast and fungi on the carrots. As the dipping temperature increased from 1 °C to 50 °C, the reductions of total bacteria, yeast and fungi increased significantly from 0.22 to 2.67 log CFU/g during the wash treatment ( p ≤ 0.05). The combined 1% citric acid and AlEW treatment at 50 °C showed a reduction of the total bacterial count and the yeast and fungi of around 3.7 log CFU/g, as well as effective reduction of L. monocytogenes (3.97 log CFU/g), and E. Coli O157:H7 (4 log CFU/g). Combinations of alkaline electrolyzed water and citric acid better maintained the sensory and microbial quality of the fresh-cut carrots and enhanced the overall shelf-life of the produce.

EFFECTS OF HIGH PRESSURE TREATMENT ON MICROBIOLOGICAL AND ORGANOLEPTIC QUALITY OF FRESH-CUT VEGETABLES

Effects of high pressure (HP) treatment on inactivation of various microorganisms in vitro and microbiological and organoleptic quality of fresh-cut vegetables in vivo were determined. For in vitro study, bacteria and bacterial and fungi isolates from indigenous microflora of vegetables were processed at HP ranging from 300 to 700 MPa for 10 min. For in vivo study, fresh-cut and whole vegetables were subjected to 400 MPa for 10 min. and microbial and organoleptic quality determined. With the in vitro study, populations of Pseudomonas fulva, P. mucidolen, Enterobacter kobei, and Lactococcus lactis decreased to below the level of detection with 400 MPa treatment, whereas population of Bacillus cereus decreased by only 1.5 logs at 700 MPa. Populations of indigenous bacteria and fungi isolated from some vegetables decreased to below the detection level at 400 MPa. With the in vivo study, the 400 MPa treatment resulted in reductions of 1.6 to >2.6 logs of bacteria and 3.5 to 5.3 logs of fungi in fresh-cut carrots, cucumber, and lettuce. Fresh-cut carrots and cucumber showed softened appearance and fresh-cut lettuce became brown after pressure treatment. Cut slices of treated whole carrots and cucumber had reduced microbial activity and loss of organoleptic quality. These results indicate that the HP at 400 MPa for 10 min. was effective in decreasing microbial activity in vitro and in vivo, except for spore-former such as Bacillus cereus, but caused deterioration of surface of fresh-cut vegetables, which was less appealing than whole vegetables pressurized and then cut.

Effects of mildly heated, slightly acidic electrolyzed water on the disinfection and physicochemical properties of sliced carrot

The efficacy of mildly heated, slightly acidic electrolyzed water (mildly heated SlAEW) at 45 °C for disinfection and maintenance of sliced carrot quality was studied. Mildly heated SlAEW (23 mg/L available chlorine, pH at 5.5) was used to treat the carrots, followed by rinsing with tap water (TW) for 2 min at 4 °C, and its effectiveness as a disinfectant was evaluated. The physicochemical properties of the carrots were determined and a comparison was made between treatments with SlAEW at room temperature (18 °C), TW at 18 °C and mildly heated TW at 45 °C. Results show that total aerobic bacteria, mold and yeast populations were significantly lower after mildly heated SlAEW treatment. Mildly heated SlAEW treatment reduced the total aerobic bacteria by 2.2 log 10 CFU/g and molds and yeasts by >1.9 log 10 CFU/g compared with TW treatment. Color indices of hue and chroma of sample surfaces were not affected by mildly heated SlAEW treatment and there were insignificant differences in hardness or the ascorbic acid and β-carotene contents of sliced carrots. The use of mildly heated SlAEW is suggested as an effective disinfection method for fresh cut carrots with low available chlorine.

Antioxidant phytochemicals in fresh-cut carrot disks as affected by peeling method

In order to investigate the effects of process severity, the influence of peeling methods of different severities on the retention of antioxidant phytochemicals in carrot disks was examined. Carrots were abrasion peeled using either fine or coarse carborundum plates or peeled manually using a hand-held peeler. They were subsequently cut into disks, packaged and stored for 8 d at 4 °C. Vitamin C (ascorbic acid and dehydroascorbic acid), total phenols, total antioxidants, total carotenoids, colour and pH were measured on production day and throughout the storage period. Antioxidants differed in their response to severity of processing. Initially, machine peeling resulted in a greater accumulation of phenolic compounds and increased total antioxidant activity compared to hand peeled carrot disks. However, at the end of storage no significant ( P > 0.05) effects of peeling method were observed on the levels of total phenolics and total antioxidants. Total carotenoids were also significantly affected by peeling method with hand peeled carrot disks having significantly ( P ≤ 0.05) higher levels of total carotenoids than coarse peeled carrot disks throughout the storage period. Ascorbic acid was the antioxidant most affected by severity of peeling method. As severity increased there was greater loss of ascorbic acid.

Effectiveness of ozone in combination with controlled atmosphere on quality characteristics including lignification of carrot sticks

Fresh-cut carrots were ozonized in water (1:2 w/v; @ 200 mg O 3/h) for 10 min and stored under controlled atmosphere (CA) conditions (2% O 2, 5% CO 2 and 93% N 2) at 6 ± 1 °C and 85% RH for up to 30 d. Ozonation was found to reduce lignification and maintaining the keeping quality of fresh-cut carrots during CA storage. The maximum decrease in respiration and ethylene emission rates were obtained by the combination of CA with ozone followed by CA alone and ozonation compared with the control samples kept under low temperature (6 ± 1 °C). Significant ( p < 0.05) reduction in ascorbic acid, carotenoids and oxidative enzymes such as polyphenol oxidase (PPO) and peroxidase (POD) were observed due to ozonation and CA storage. The control of lignification by ozone in synergy with CA was characterized by decrease in L∗ values. The results highlighted the positive role of ozonation in combination with CA storage in controlling lignification and microbial spoilage of carrot sticks.