CARROT QUALITY
Receiving Information: Good quality carrots should be well-shaped with firm, smooth exteriors. Color should be vibrant orange to orange-red. For best quality, tops should be closely trimmed since they tend to decay rapidly. Avoid flabby, soft, or wilted carrots or product that shows any mildew, decay, growth cracks, or splits. Bitter flavor„carrots may acquire a bitter flavor if exposed to ethylene gas. Store away from ethylene producing fruits and ripening rooms. Wilting-carrots may wilt if stored in a n area with low humidity. Decay; sprouting-may begin to decay or sprout if stored at high temperatures. Cracks; flabby or discolored skin„these are indications of freeze damage. Yellow tips; soft spots„these are signs of age and will result in a poor flavored product. Storage/Handling: Temperature/humidity recommendation for short-term storage of 7 days or less: 32 _36 degrees F. 85-95% relative humidity. Store in coldest part of cooler away from doors and blowers.
Avoid cross contamination with other food products such as; fresh meat, poultry, seafood, dairy products, or any fully cooked product. Maintain an active rotation system that adheres to FIFO, or ñfirst inî, first out.î
Use and honor ñuse-byî dates.
Description:
Although there are many varieties of carrots, they are generally sold according to size. Carrots are characterized by a firm, smooth exterior, orange to orange-red color, and crunchy texture. Carrots are a root vegetable originating in the Middle East and central Asia. The ancestor of the carrot we know today was purple in color, verging on black. The yellow variety is most likely the result of a mutation. Both the purple and yellow varieties were used by the Greeks and Romans for the medicinal qualities.
CARROT, DAUCUS CAROTA / UMBELLIFERAE (APIACEAE)
Postharvest Atmosphere Management
The best conditions for long term conservation, up to several months, are temperatures at 0 to 1ºC and 95 to 98% relative humidity, in order to reduce weight loss and to maintain the original quality of the root. The soluble sugar content increases under these conditions, there is an increase of reducing sugars whereas the sucrose remains stable. The amount of carotenes is not affected by these conditions, since it remains constant through all the period. The same happens with the fiber content.
The product’s quality preservation is based on a fast decrease in temperature, that must drop to 5-8ºC. This also prevents damages by hits during the harvesting. The water pre-cooling is the most suitable method used for carrots.
The carrots allow a relatively long storage, although the exact duration and the type of conservation used depends on the type of produce. The carrots with foliage behave in similar way to the leaf vegetables and they can only be kept for few days.
The produce harvested before its maturity (tender carrots) has a higher tendency to perish than the ripe produce; due to its high water content, it also tends to lose turgidity. Ripe carrots, sometimes stored up to 6 months, are usually marketed, like carrots with foliage, in few days. The unripe carrots are kept up to 2 months.
The carrot may acquire a bitter taste when ethylene is in the environment, so it is not advisable to store or transport carrots with other products that give off ethylene, such as tomatoes, melons or apples.
Distribution
During transport and distribution the ethylene concentration must be avoided, since this species is very sensitive to it. The satisfactory conditions vary depending on the type of transport, whether it is by sea or road. The distribution of carrots must be carried out at 5-10ºC and average moisture.
The road transport must be at temperature above 20ºC, depending on the duration. The sea transport must be carried out at 0ºC, and 95-100% relative humidity.
Concerning distribution, temperatures between 5 and 10ºC and average humidity and ventilation are recommended. Direct light must be avoided.
Postharvest Problems
Carrots may show several problems of conservation, caused by unsuitable conditions in the storage rooms, low relative humidity, or by certain fungi that cause rottings in the roots.
Carrots may show different physiological alterations or diseases during their conservation:
Blightness and loss of weight: They are due to the loss of water, and they are prevented in humidity saturated atmospheres.
Sprouting and roots: during the storage, carrots tend to sprout and to give off roots. This process is favoured by high temperatures.
Erwinia is a bacterium that causes humid rotting. This organism infects the vegetable through damages and leaves. The affected area becomes soft and humid and it darkens. The rotting spreads very fast towards the heart of the vegetable.
Watery soft rot: It is caused by the Sclerotinia fungus. The first symptoms are soft and watery injuries, with a white and cottony down that may cover all the vegetable. There appear great, black and irregular matters.
Gray rot: It is caused by the fungus Botrytis, and it develops through the damages caused by harvesting or handling. Gray short hair covers the carrots.
Bitter rot: It is caused by the Geotrichum fungus, that attacks through any area of weak tissues. The infected area decolours and becomes watery. The carrots give off a vinegar smell, and a white down develops on the carrot.
Black rot: Caused by the Stemphylium fungus, it covers the affected areas with a black down.
Carrot quality: progress and challenges for breeding and production
Carrot is an essential vegetable produced and consumed worldwide. If yield and resistance to pests and diseases are major production concerns and breeding traits, product quality becomes more and more an issue, driven by society evolution and consumer demand. Product quality includes visual, nutritional, sensory attributes. Only a few of quality criteria are studied but most are influenced by agro-environmental conditions and controlled by a complex genetic determinism, making difficult to valorize quality in production or select for in breeding programs. The present article covers the various quality attributes, addresses the issue of plasticity/adaptability of carrot cultivars and the influence environmental and stresses on product quality, presents the genetic basis of quality and the tools to facilitate quality measurements, in order to help master product quality both at breeding and production levels.
Effects of ozone treatment on postharvest carrot quality
Abstract
Ozone (O3) is a powerful oxidant and is used in water treatment, pest disinfection and the removal of pesticides, mycotoxins and other contaminants from fruits and vegetables. However, the treatment conditions should be specifically determined for all types of products for the effective and safe use of ozone. The aim of this study was to evaluate the effect of ozone applied as gas (0–5 mg L−1) and dissolved in water (0–10 mg L−1) on the quality of carrots. The exposure of carrots to ozone as gas and dissolved in water did not alter the weight loss percentage, firmness and the color of the vegetable. The O3 treatments as gas also did not affect the pH of the carrots. However, in treatments with O3 dissolved in water, the ozone concentrations and its interaction with temperature temporarily affected the pH of carrots. Moreover, O3 as gas prevented the sharp increase in soluble solids during storage for five days (18 ± 2 °C, 80 ± 5% RH), thereby increasing the shelf-life of carrots.
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Keywords
Daucus carota L.StorageOzonationSoluble solidsShelf-life
1. Introduction
The fresh produce industry is constantly growing, due to increasing the consumer demand (Alothman, Kaur, Fazilah, Bhat, & Karim, 2010). The shelf-life of the fresh produce, however, is limited and determined by its initial quality at harvest and subsequent storage conditions (Nunes, Emond, Rauth, Dea, & Chau, 2009). Thus, techniques for reducing undesired microbial contamination, spoilage and decay and for maintaining the visual, textural and nutritional quality of the product are required at all steps of the production and distribution chain.
Sanitizing agents have widespread applications for assuring safety and quality in the food industry. However, certain agents, such as chlorine, can react to form trihalomethanes, which are of concern for both human dietary safety and as environmental pollutants (Charisiadis et al., 2014). Therefore, the food industry is searching for technologies that effectively inactivate pathogens and remove contaminants, limit the loss in product quality and ensure food freshness, are adaptable to food processes and economically feasible, and are environment-friendly (Pandiselvam, Sunoj, Manikantan, Kothakota, & Hebbar, 2016). For meeting these criteria, the use of ozone in the food industry has been studied in the disinfection of microorganisms and controlling pests and mycotoxins, pesticide decontamination and preservation of food quality (Ali et al., 2014, Freitas et al., 2016, Heleno et al., 2016, Sousa et al., 2016).
Ozone (O3) was discovered and named by Schoenbein in 1840, but its applications for food treatment were not developed until considerably later (Gabler et al., 2010, Rice, 1986). Ozone is the tri-atomic oxygen formed by the addition of a free radical of oxygen to the molecular oxygen (Tiwari, Muthukumarappan, O'Donnell, & Cullen, 2008). Ozone exists in the gaseous state at room temperature and is partially soluble in water. In both cases, ozone is unstable with a short half-life (Cullen, Tiwari, O'Donnell, & Muthukumarappan, 2009). Ozone decomposes to form oxygen; therefore, food products treated with ozone are free of chemical residue (Tiwari et al., 2008). Thus, according to the United States Department of Agriculture, food can be treated with ozone and can still be classified as “100% organic” or “organic”, depending on the O3 usage (USDA, 2011).
When O3 is used in post-harvest treatments, during storage or food processing, its high oxidation power may promote undesirable changes in the food quality. Fruits and vegetables are the most affected by the negative effects of ozone due their high moisture content, enzymes and phenolic compounds (Gabler et al., 2010, Sandhu et al., 2011). Consequently, an optimization of the conditions for treatment must be studied for each food. The aim of this study was to evaluate the effect of treatments with ozone as gas and dissolved in water in on carrots (Daucus carota L.). Thus, the immediate impact and the effect throughout storage of combinations of O3 concentration, temperature and treatment time on weight loss, color, soluble solids concentration, pH and firmness of fresh carrots was assessed.
2. Materials and methods
2.1. Carrots field
The carrot cultivation (Carandaí variety) was performed in the Universidade Federal de Viçosa (UFV), Viçosa - MG, Brazil in four beds (1 × 10 m) previously prepared and fertilized according to the soil analysis. The cultural practices were carried out until harvest following the recommendations of the Manual of Safety and Quality for Carrot Culture (EMBRAPA, 2004). After harvest (80 days after the planting), the roots were taken to the Postharvest Laboratory of the Agricultural Engineering Department of the UFV and washed with tap water. Next, the carrots were separated into samples with three roots each, which constituted the replicates.
2.2. Ozone treatments conditions
Two experiments were performed separately, one for the optimization of the treatment conditions of O3 as gas and the other one O3 dissolved in water. In both experiments, ozone was produced by an ozone generator O&L3.ORM (Ozone & Life, São José dos Campos, SP, Brasil). The ozone generator used an oxygen flow of 2 L min−1 from the Mark 5 Plus Concentrator Oxygen Concentrator (Nidek Medical Products, Birmingham, AL, EUA). The ozone concentrations in the experiment of O3 as gas were quantified at the inlet and outlet of the treatment chambers using the iodometric method by indirect titration; for the experiment of O3 dissolved in water, the ozone concentrations were quantified both at the inlet of the chamber with water and dissolved in water. Briefly, the O3 gas was bubbled in a solution of KI or the ozonated water was added to the solution KI and the O3 was quantified using the iodometric method by indirect titration (Eaton and Franson, 2005, Gottschalk et al., 2009). After the passage through the entire system, the residual ozone was directed to a catalyst filter (Ozone & Life, São José dos Campos, SP, Brasil) to degrade ozone to oxygen. Eighteen carrots (≌ 2000 g) were used in each treatment of both experiments.
Experiment 1–O3 as gas: The carrots were treated with ozone as gas in an acrylic chamber of 0.075 m3 (0.32 × 0.53 × 0.44 m) with perforated shelves that enabled the free flow of O3 gas inside the chamber (Fig. 1a). The chamber was fitted with an inlet at the top coupled to the ozone generator. The gas outlet connected to catalyst filter was inserted in the lower part of the chamber.
Fig. 1
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Fig. 1. Design of the experimental apparatus for the ozone (O3) treatments as gas (a) and dissolved in water (b). 1: oxygen concentrator, 2: ozone generator, 3: climatic chamber, 4a: acrylic chamber with perforated shelves, 4b: PVC chamber with deionized water, 5: ozone catalyst filter.
Experiment 2–O3 dissolved in water: The treatment of the carrots with ozone dissolved in water was carried out in a circular chamber of PVC, 50 × 80 cm (diameter x height) containing 10 L of deionized water (0.5 mS m−1). The ozone gas inlet occurred through an aperture in the medial portion of the chamber and was coupled to a perforated spiral that ran through the water column until it was concentrated in the inferring part of the chamber (Fig. 1b). A perforated metal plenum was placed over a 10 cm layer of glass beads (2 cm) above the spiral located at the bottom of the chamber to provide support for the carrots and a better distribution of the ozone gas in water. The outlet of the remaining gas was through an aperture at the top part of the chamber, and it was connected to a catalyst filter. After ozonation, the carrots were withdrawn from the water and allowed to dry at room temperature (23 °C) for 30 min.
In both experiments, for the temperature to remain constant throughout the treatment, the chambers were inserted into a climatic chamber that allowed the variation of ± 1 °C. The water used in each experiment was let at the desired temperature overnight (12 h) to guarantee the thermal equilibrium of the water with the climatic chamber condition. Moreover, right before starting each experiment, the water temperature was verified with a thermometer. The carrots were submitted to quality analysis before and after the ozonations.
2.3. Factorial planning
The ozone treatments were optimized to maintain the quality of the carrots employing a central composite design with five replicates at the central point (Table 1). Three variables were studied: ozone concentration, treatment time, and temperature. The variables were studied at two levels, and the analyses were performed in triplicate. The effects of each variable and the interactions between the variables in the carrots quality were calculated using the Statistica 13.5 software (Statsoft Inc., Tulsa, OK, USA). The data were presented in graphs generated using the SigmaPlot 12.5 software (Systat Software, Inc., San Jose, CA, USA).
Carrot is an essential vegetable produced and consumed worldwide. If yield and resistance to pests and diseases are major production concerns and breeding traits, product quality becomes more and more an issue, driven by society evolution and consumer demand. Product quality includes visual, nutritional, sensory attributes. Only a few of quality criteria are studied but most are influenced by agro-environmental conditions and controlled by a complex genetic determinism, making difficult to valorize quality in production or select for in breeding programs. The present article covers the various quality attributes, addresses the issue of plasticity/adaptability of carrot cultivars and the influence environmental and stresses on product quality, presents the genetic basis of quality and the tools to facilitate quality measurements, in order to help master product quality both at breeding and production levels.