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Temperature variability during shipment of fresh produce
Abstract
Exporters of fresh produce to distant markets (such as from Australasia to Europe) generally have three options for transport of their goods to distant markets; by airfreight, stowed in refrigerated containers or placement into the refrigerated hold of a vessel. Airfreight is generally used for high-value, low volume, short shelflife products. As this study dealt with large volume, long shelf-life products, airfreight was not monitored. Integral refrigerated container systems have become the system of choice for many fresh produce exporters as they provide a convenient unit, with perceived control of product conditions. Larger volume exporters are able to take advantage of a lower cost option whereby product is placed in a refrigerated deck of a ship. In recent years a number of intensive temperature surveys have been undertaken to ascertain the variability within produce loads in order to guide export industries on heuristics to minimise undesirable out-turns. This paper presents measured data from typical container and refrigerated vessel shipments, monitored throughout voyages from Australasia to markets in Europe and Japan. Thermographic plots of the temperature distribution in stows are presented. A number of factors considered likely to have caused the variability are also proposed.
... A main insight that arises from these preliminary results is that in the steady-state phase, the location within the cargo (spatial variability) was more crucial than the travel duration (time variability), reaching a maximum range of 4 °C (mean range 3.30 ± 0.37). A spatial variability of up to 6 °C has also been verified in several transcontinental transport studies in the last decade [14,16], having in common the use of 40′ reefer containers (12 m long) which are the most common for intercontinental transport. ...
... Regarding the effect of journey time, in the start-up period the temperature range was 15.75 °C, while during the steady-state the mean temperature range for 16 loggers was reduced to 1.68 °C. Similar local temperature deviations, in the range of 2 °C and 12 °C, had been previously found inside trucks and containers [16]. ...
... A main insight that arises from these preliminary results is that in the steady-state phase, the location within the cargo (spatial variability) was more crucial than the travel duration (time variability), reaching a maximum range of 4 • C (mean range 3.30 ± 0.37). A spatial variability of up to 6 • C has also been verified in several transcontinental transport studies in the last decade [14,16], having in common the use of 40 reefer containers (12 m long) which are the most common for intercontinental transport. ...
To supply the off-season melon market, Europe imports from distant markets in other countries, mainly Brazil. Cold transportation takes at least 15–20 days, thus increasing the risk of quality losses. Moreover, product deliveries, especially in international markets, can result in supply chain inefficiencies that negatively affect carbon footprint and expected freshness. Implementing quality sensors and advanced cold chain management could help to reduce these problems. The objective of this work was to monitor a real transoceanic intermodal transport of melons (Brazil to Spain), through the implementation of multi-distributed environmental sensors (15 ibuttons loggers) to evaluate the remaining shelf-life (RSHL) of melons at destination. The sensors’ location within the cargo reached a maximum variability range of 4 °C. Using digital sensors to track temperature variations, it was verified that in different locations in the container, the melon RSHL at the end of the journey, was nine days and 19 h in colder spots, while in the hottest spot, the RSHL was reduced to five days and 22 h. This fact has substantial implications for improved tracking of temperature to maintain fruit quality for market, potentially reducing waste, and contributing to higher profit margins for international food supply chains.
... The volumetric expansion of the global blueberry industry has resulted in the need to transport the crop in refrigerated sea freight containers. Spatial temperature variation within a single refrigerated container has been reported to be as much as 4 • C during fresh fruit shipment (Tanner and Amos, 2003;Punt and Huysamer, 2005;Dodd and Worthington-Smith, 2006;Dodd, 2013). It is not known whether this type of temperature heterogeneity during shipping could constitute an important factor affecting final blueberry quality in the marketplace. ...
... Increased storage temperature decreases CO 2 and O 2 solubility in aqueous solutions (blueberry tissue) and will accelerate CO 2 production and O 2 consumption by increasing the respiration rate. Hence the type of temperature heterogeneity during the shipping period as reported by Tanner and Amos (2003) could alter CA effects or alternatively CA could influence the effects of temperature variations during shipping as observed by East et al. (2013) for apples. ...
... Evaluation after storage Cultivar Reference after completing the delay period, clamshells were closed and placed in the storage environment of desired atmosphere and temperature. Two storage temperatures were chosen: 0 • C as recommended for blueberries (Perkins-Veazie, 2004;Forney, 2009) and 4 • C, given that this temperature range was reported by Tanner and Amos (2003) to occur within 40 foot refrigerated containers during extended marine shipments. Atmosphere conditions were either air or one of two controlled atmospheres (10% CO 2 + 2.5% O 2 or 10% CO 2 + 20% O 2 ), which are both within the range recommended for blueberries Cappellini, 1979, 1985;Fan, 1993;Harb and Streif, 2006). ...
Southern hemisphere blueberry producers often export their products through extended supply chains to Northern hemisphere consumers. During extended storage, small variations in temperature or atmosphere concentrations may generate significant differences in final product quality. In addition, relatively short delays in establishing cool storage temperatures may contribute to quality loss. In these experiments a full factorial analysis was done of the effects of three cooling delays (0, 12 or 24 h at 10 • C), three atmosphere concentrations (air, 10% CO 2 + 2.5% O 2 and 10% CO 2 + 20% O 2) and two storage temperatures (0 • C and 4 • C) which were assessed for their impact on final quality, measured as weight loss, firmness and rot incidence. Two blueberry cultivars were studied: 'Brigitta', a highbush cultivar, and 'Maru', a rabbiteye. Delays in cooling had a small effect on final product weight, whereas variation in storage temperature and atmosphere during simulated transport influenced both firmness and rot incidence. Atmospheres with 10% CO 2 reduced decay incidence, particularly at low oxygen concentration (2.5% O 2), although the latter conditions tended to soften fruit. In order to achieve optimal postharvest storage for blueberries, minimising temperature variability in the supply chain is important, as is finding the potentially cultivar-specific optimal combination of high CO 2 and low O 2 concentration that results in simultaneously minimising rot incidence and induced softening.
... Some empirical researches have been focused on the study of thermal variations and airflow during long distance journey. Thus,Tanner and Amos (2003a)[11] carried out several experiments in order to determine the spatial temporal thermal variations during a trip from New Zealand to Belgium.Twenty pallets of fruit were monitored by means of thermocouples in order to gather temperature data. Pallets were placed into a refrigerated hold of a vessel and transported from New Zealand to Belgium. ...
... Some empirical researches have been focused on the study of thermal variations and airflow during long distance journey. Thus,Tanner and Amos (2003a)[11] carried out several experiments in order to determine the spatial temporal thermal variations during a trip from New Zealand to Belgium.Twenty pallets of fruit were monitored by means of thermocouples in order to gather temperature data. Pallets were placed into a refrigerated hold of a vessel and transported from New Zealand to Belgium. ...
... These results are congruent with that of Lindqvist(1998, 1999) [5][6] who used an experimental approach to measure pressure inside a full-scale laboratory model of a refer, concluding that the high pressure gradients were measured in the front of the vessel while the low pressure ones were observed in the rear.More on a theoretical basis, many studies are ongoing in order to improve analytical models of cooling systems, such as refrigeration rooms or containers.In this context, Computational Fluid Dynamics (CFD) tools for solving the Navier-Stokes equations are widely used as stated in several recent review papers (Scott & Richardson, 1997; Wang & Sun, 2003; Xia & Sun, 2002) [16-17]. There are also many recent works on the applications of CFD to cold storage of perishable products (Nahor, Hoang, Verboven, Baelmans, & Nicola'i, 2004; Verboven, Hoang, Baelmans, & Nicola'i, 2004; Xie, Qu, Shi, & Sun, 2006)[2],[9][10][11][12][13][14]. Some of these experiments have been developed for studying the pressure drops through batches of apples and chicory roots. ...
The shelters are like a housing structures used for the army for sheltering in terrain places. These shelters are mounted over the army vehicles which subjected to static, dynamic and thermal loads due to vehicle transportation in all kinds of terrains. The shelters are subjected to a different thermal loads due to seasonal externally weather conditions and inside there are heat dissipating elements. The objective is to maintain the temperature inside the shelter around 27 0C for which the CFD analysis is required to be performed to predict the temperature variation inside the shelters. This study uses the Fluent software to evaluate the indoor thermal environment of Shelter. The objective of the work is to perform Thermal and air flow analysis for prediction of the temperatures inside the shelter when the components (heat dissipating elements) are dissipating heat inside the shelter. Shelter contains four Panels and one air pre heater which dissipate heat. The shelter subjected to an extreme operating temperature -300 C, +550 C and there is need of Air conditioners (AC’s) for temperature control. In this study the location and number of AC's required and on off conditions are to be studied for the temperature predictions.
Continuity and Momentum equations have been solved by Control Volume Method. SIMPLE algorithm is used and Steady, k-ε turbulence model and Incompressible flow of a constant property of fluid under Boussinesq’s approximation have been considered. The temperature, velocity and pressure contour results are presented for both 3 AC’s and 2 AC’s on position. The shelter houses have number of panels which have to be maintained within permissible temperature limits. The flow will be sent with the air conditioner with appropriate operating conditions. Further thermal and airflow simulations for the prediction of the temperatures inside the containers in several scenarios, with full or partial air condition and without air conditions, under the extreme temperatures is performed and obtained results are reported and discussed.
... Over the past few years, work in New Zealand and Australia has been undertaken that has focused on the ability of transport systems to maintain uniform temperatures close to the specified setpoint. Trucking systems have been studied by Estrada-Flores et al. (2002), 40' reefer containers by Amos (2001), Tanner and Amos (2003b), and holds of reefer vessels by Tanner and Amos (2003b) and Amos and Tanner (2003). The present paper discusses some of these assessments and the relevance of these results with respect to product quality. ...
... Over the past few years, work in New Zealand and Australia has been undertaken that has focused on the ability of transport systems to maintain uniform temperatures close to the specified setpoint. Trucking systems have been studied by Estrada-Flores et al. (2002), 40' reefer containers by Amos (2001), Tanner and Amos (2003b), and holds of reefer vessels by Tanner and Amos (2003b) and Amos and Tanner (2003). The present paper discusses some of these assessments and the relevance of these results with respect to product quality. ...
... This example (Tanner and Amos, 2003b) outlines a comprehensive temperature survey of a 40 ft refrigerated container loaded with pallets of ZESPRI GREEN kiwifruit. The data presented are representative of a monitoring programme in which multiple containers and vessels were studied. ...
... Heterogeneity of the temperature inside a pallet and according to the position of the pallets inside a refrigerated container have been reported by a number of authors (Amador, Emond & Nunes 2009;Defraeye et al. 2016;Tanner & Amos 2003). Tanner and Amos (2003) compared shipments of kiwifruit in a refrigerated container and a specialised refrigerated vessel from New Zealand to Belgium. ...
... Heterogeneity of the temperature inside a pallet and according to the position of the pallets inside a refrigerated container have been reported by a number of authors (Amador, Emond & Nunes 2009;Defraeye et al. 2016;Tanner & Amos 2003). Tanner and Amos (2003) compared shipments of kiwifruit in a refrigerated container and a specialised refrigerated vessel from New Zealand to Belgium. They found significant variability in temperature along the length of the deck of the refrigerated vessel. ...
Background: Fruit is an important export commodity for South Africa and accounts for 35% of its agricultural exports. South Africa is the second largest citrus exporter in the world, behind Spain. Maintaining the postharvest cold chain is key to ensuring that fruit quality meets export standards.
Objectives: The main objectives of this research were to investigate the frequency, location, magnitude and duration of temperature deviations in the South African leg of the clementine and navel orange cold chain.
Method: Temperature trials were conducted on two consignments of clementines and two consignments of navels. Each consignment contained 36 iButtons®, of which 18 measured pulp temperature and 18 measured ambient temperature. Data were successfully retrieved from 130 of the 144 iButtons®.
Results: This research identified areas where the temperature went outside the prescribed range along the South African portion of the export cold chain of navel oranges and clementines from Citrusdal, South Africa to the Port of Newark, United States of America.
Conclusion: The temperature incidents identified could result in a breach of the cold sterilisation (steri) protocols and quality defects. Recommendations were made to address these deficiencies to improve the South African citrus industry’s global competitiveness.
Contribution: This research allowed the citrus industry to investigate and adjust current cold chain practices to improve the integrity of the entire export cold chain, potentially resulting in a higher quality product and increased revenue.
... Their findings showed that the temperature was lower ( by as much as 3° C-4°C) near the bottom of the pallets than near the top, a difference that is explained by the vertical airflow pattern inside refrigerated containers. In other investigations, Tanner and Amos ( 2003) monitored the temperature inside a refrigerated container and a specialized vessel during the shipment of kiwifruits from New Zealand to Belgium. Those authors reported a significant temporal and spatial heterogeneity of the temperature inside 9780367498191_C001.indd ...
... As such, when the sensor measured a temperature above the set point of 0.5°C, a decrease in the delivery air temperature down to −5°C was observed, increasing the likelihood of freezing injuries for the pallets near the air delivery. Tanner and Amos ( 2003) also reported that the temperature was more uniform for transportation inside the hold of the vessel, although the number of kiwifruits outside the recommended range of temperature remained significant. The heterogeneity of the temperature can be attributed to several factors related to the operation and design of the container or the vessel as well as the properties of the product and packaging. ...
... Refrigerated container relies on the flow of cooled air around stacked fruit to remove field heat during transportation to a distant export or domestic market (Smale, 2004). The control of air temperature and circulation inside a refrigerated container depends on the following factors: (i) container thermal insulation (Laguerre et al., 2008), (ii) flooring design of the container (Smale, 2004), (iii) pallet stacking patterns and (iv) packaging designs (vent-hole configurations) (Berry, 2015;Fadiji, 2015;Getahun et al., 2018;Tanner and Amos, 2003). ...
... In postharvest handling systems such as a refrigerated freight container, controlling the conditions of fruit depends on the factors including thermal insulation of the container (Laguerre et al., 2008), floor design and stacking pattern of the packaging boxes (Berry, 2015;Berry et al., 2016;Defraeye et al., 2014;Fadiji, 2015;Getahun, 2016;Getahun et al., 2018;Tanner and Amos, 2003). Also, the required refrigerated capacity of a container can be affected by environmental impacts, insulation quality of the container, rate of air exchange, leakage and the initial temperature of cargo (Keller, 2006). ...
The ineffective utilisation of refrigerated container's (RC) space is a pressing problem for the South African fruit industry. Current packaging systems do not optimally make use of the refrigeration unit for airflow distribution and cooling efficiency of fruit. This results in heterogeneous airflow circulation and ineffective cooling of fruit. The aim of this research was to develop a validated computational fluid dynamics (CFD) model. The model was then used to explore novel packaging system for improved RC space utilisation and cooling performance. Both cooling and space utilisation aspects of the container need to be improved simultaneously, as market trends are increasingly demanding higher-quality fresh produce at lower costs.
Firstly, a 3D CFD model of a fully packed RC was developed and validated experimentally. Pallets were considered as a porous media, and their directional loss properties were experimentally determined. A functional refrigeration unit was incorporated in the model to account for the dynamic cooling modes of the container. The resulting model predicted acceptable results with respect to airflow and temperature. Modelling prediction error was 17% for airflow distribution and 11% for the temperature prediction.
Subsequently, the developed CFD model was used to evaluate conceptual packaging systems for space utilisation and cooling efficiency. Numerical simulations were performed to characterise the airflow distribution and cooling performance of the packaging system in a fully loaded refrigerated container. A multi-parameter approach was used to evaluate the performance of five loading scenarios, namely: Standard A, Standard B, Standard C, Hex and Tes in a fully loaded refrigerated container. The average convective heat transfer coefficient (CHTC) relative standard deviation (RSD) of the Standard packaging system is 47% higher than the Hex design and 51% higher than the Tes design. Overall, Tes design shows significant improved performance for space utilisation and quality preservation of packaged fruit. The results thus highlighted the substantial improvements that are possible concerning shipping costs and quality preservation if alternative packaging system designs are considered in the future.
Lastly, the pallet stack ventilation requirements of the Standard packaging system in a refrigerated container was characterised. The influence of packaging system directional loss properties (i.e. the pallets ventilation) on airflow patterns within the pallet stacks was demonstrated. This has significant implications on the cooling uniformity and quality preservation of packaged fruit. The study further provides, for the first time, a benchmark for the design of ventilation in fresh produce packaging towards improved usage of refrigerated containers.
... An important practical consideration before any potential application of dual temperature storage as a postharvest management practice is the spatial variations in temperature within coolrooms (Gruyters et al., 2017) or temporal variations in temperature during shipping in containers and reefer vessels (Bollen et al., 2013;Tanner and Amos, 2003). Such variability could result in a gradient of up to 10 °C (Tanner and Amos, 2003). ...
... An important practical consideration before any potential application of dual temperature storage as a postharvest management practice is the spatial variations in temperature within coolrooms (Gruyters et al., 2017) or temporal variations in temperature during shipping in containers and reefer vessels (Bollen et al., 2013;Tanner and Amos, 2003). Such variability could result in a gradient of up to 10 °C (Tanner and Amos, 2003). Current management of temperatures in coolrooms and containers are not precise enough for direct application of such dual temperature storage. ...
Kiwifruit develop physiological disorders when stored at or below 0 °C. As symptoms are only evident after long term storage, this study aimed at investigating the possibility of reducing chilling injury by temperature switching during storage. ‘Hayward’ and ‘Zesy002’ kiwifruit of different maturities were subjected to dual temperature treatments by switching fruit from either 0 or 2 °C to 2 or 0 °C, respectively, at different times in storage. Initial storage of ‘Hayward’ at 0 °C and later switching to 2 °C resulted in a lower proportion of soft fruit and reduced chilling injury incidence. ‘Zesy002’ was more resistant than ‘Hayward’ to chilling injury. Tolerance to chilling injury was related to maturity at-harvest. After 150 d in storage, a sudden decline in firmness was observed in ‘Hayward’ kiwifruit stored continuously at 0 °C, but not in the dual temperature treatments. Proportion of soft fruit was correlated with chilling injury incidence.
... Globally the supply of reefer vessels is reducing, resulting in increased pressure to move more exports into containerised format (Dekker, 2014, Drewry, 2015. For the growing kiwifruit and apple industries this represents a significant challenge and additional risk to the supply chain given the known benefits to temperature control of using reefer vessels in comparison to containers (Smale, 2004;Tanner and Amos, 2002). Additional challenges of shifting to containerisation are the increased time length of supply chains due to non-direct shipping, and potential for gas contamination (ethylene or flavour tainting) given that containers of different products may be placed adjacent to each other. ...
... The Centre for Postharvest and Refrigeration Research at Massey University has a strong tradition of conducting research with New Zealand's fruit export industries, and strengthening the cool chain of these industries. Foci of this research are associated with design of packaging to assist cooling and temperature control of fresh produce, (Defraeye et al., 2015;East et al., 2013b;Olatunji et al., 2016;O'Sullivan et al., 2013O'Sullivan et al., , 2016O'Sullivan et al., , 2017, development of new methods to measure and cool chain systems (East et al., 2009;Huang et al., 2017;Olatunji et al., 2017;O'Sullivan et al., 2014;Redding et al., 2016), measurement of real world cool chain scenarios (Bollen et al., 2015;East et al., 2003a;O'Sullivan, 2016;Shim et al., 2016;Smale, 2004;Tanner and Amos, 2002) and their subsequent influence on produce quality (East et al., 2008(East et al., , 2013a(East et al., , 2013cPaniagua et al., 2012Paniagua et al., , 2014Zhao et al., 2015) culminating in the development of mathematical models to predict fruit quality based on supply chain temperature information East, 2011;Hertog et al., 2016). ...
Approximately 45 % of all exports from New Zealand are food products or by-products, and an estimated 60 % of these are exported in the refrigerated state. The leading food sectors in terms of volume and income are in order: the dairy industry, the red meat industry, the horticultural industry and the seafood industry. Due to its geographic isolation, New Zealand food exports form part of some of the longest cold chains in the world. Responsibility for temperature integrity in the cold chain is placed on the processors and exporters and is overseen by the Ministry for Primary Industry of the Government of New Zealand. Currently, the major research theme related to the cold-chain in New Zealand is focussed around optimising chilling and freezing processes for shelf-life extension. Improving energy efficiency in refrigeration processes is also a significant research theme.
... Both Amador and others (2009) and Defraeye and others (2016) reported that the temperature was lower (by as much as 3°C to 4°C) near the bottom of the pallets than near the top, a difference that is explained by the vertical airflow pattern inside refrigerated containers. Tanner and Amos (2003) monitored the temperature inside a refrigerated container and a specialized vessel during the shipment of kiwifruits from New Zealand to Belgium. Those authors reported a significant temporal and spatial heterogeneity of the temperature inside the container. ...
... For instance, when the sensor measured a temperature above the set point of 0.5°C, a decrease in the delivery air temperature down to −5°C was observed, increasing the likelihood of freezing injuries for the pallets near the air delivery. Tanner and Amos (2003) also reported that the temperature was more uniform for transportation inside the hold of the vessel, although the number of kiwifruits outside the recommended range of temperature remained significant. The heterogeneity of the temperature can be attributed to a number of factors related to the operation and design of the container or the vessel as well as the properties of the food product and packaging (Tanner and Smale 2005). ...
The cold chain is responsible for the preservation and transportation of perishable foods in the proper temperature range to slow biological decay processes and deliver safe and high-quality foods to consumers. Studies show that the efficiency of the cold chain is often less than ideal, as temperature abuses above or below the optimal product-specific temperature range occur frequently, a situation that significantly increases food waste and endangers food safety. In this work, field studies on time–temperature conditions at each critical stage of the cold chain are reviewed to assess the current state of commercial cold chains. Precooling, ground operations during transportation, storage during display at retail and in domestic refrigerators, and commercial handling practices are identified and discussed as the major weaknesses in the modern cold chain. The improvement in efficiency achieved through the measurement, analysis, and management of time–temperature conditions is reviewed, along with the accompanying technical and practical challenges delaying the implementation of such methods. A combination of prospective experimental and modeling research on precooling uniformity, responsive food inventory management systems, and cold chains in developing countries is proposed for the improvement of the cold chain at the global scale.
... Refrigerated shipping container (reefer) is one of the key segments of the fresh produce cold chain in addition to pre-cooling, storage, handling at distribution centres and refrigerated display. Uniform distribution of air inside reefers is very important to ensure uniform cooling of the produce (Tanner and Amos, 2003). Temperature, if not properly controlled, rises due to heat production by the commodity and other heat sources such as fan motors, heat infiltration from outside, solar radiation, etc. ...
... Temperature, if not properly controlled, rises due to heat production by the commodity and other heat sources such as fan motors, heat infiltration from outside, solar radiation, etc. In addition, chilling injury and/or hot spots due to non-uniform cooling lead to produce quality loss (Jedermann et al., 2013;Tanner and Amos, 2003). Hence, it is very important to control temperature inside reefer to preserve produce quality and reduce loss (Vigneault et al., 2009). ...
This paper developed and validated a computational fluid dynamic (CFD) model of airflow and produce cooling inside a fully loaded refrigerated shipping container (reefer) based on porous medium approach. Wind tunnel tests were used to obtain the pressure drop characteristics of palletized stack of apple fruit. Detailed structure of the T-bar floor of the reefer and resistance to airflow of wooden pallets were included in the model. Airflow and temperature data obtained from a fully loaded, full-scale reefer were used to validate the model. The model successfully reproduced the airflow and temperature profiles inside the reefer, and in addition, high and low cooling regions were identified. At 24 h, the average temperature inside the reefer reached 2.7 °C (exp.) and 2.8 °C (numerical) from an initial 9.5 °C with an overall standard deviation of 1.70 °C (exp.) and 2.32 °C (numerical). Model predictions were acceptably accurate with an average error of 26 and 18% in predicting airflow and temperature, respectively. The absence of vent-hole on the bottom face of the packaging box caused non-uniform airflow and a highly heterogeneous cooling. These demonstrated the importance of packaging design that take into account the airflow path inside reefers.
... Both empirical and theoretical studies have been carried out to study the thermal variations and airflow during perishable goods shipping, showing that, in almost any transport situation, local temperature deviations are always present. From the literature reports are indicated deviations of roughly 5°C or more depending on the transport conditions (Moureh and Flick, 2004;Punt and Huysamer, 2005;Rodriguez-Bermejo et al., 2007;Tanner and Amos, 2003). ...
... For this reason, Computational Fluid Dynamics (CFD) tools are widely used (Scott, 1997;Xia, 2002;Wang, 2003). Some trials carried out to optimize the thermal conditions of palletized fruits shipped from New Zealand to Belgium, recording the temperature by means of thermocouples (Tanner and Amos, 2003) showed that reaching a temperature level above the recommended value is a frequent circumstance; furthermore this leads to a great quality decrease, particularly in terms of firmness loss. ...
The Italian orange fruit export development outside EU countries has required commercial agreements regarding the restriction of parasites spread especially Mediterranean fruit fly. The correct use of cold treatment during the shipment is used to satisfy this requirement. This paper reports the results of a simulated refrigerated transport of citrus fruits (14600 kg of ‘Tarocco’ oranges) in a 40ft refrigerated container. Temperatures have been monitored inside the refrigerated container in different positions of the load (in the air, in the pallet and in the fruits) using 40 innovative direct-to-digital temperature probes. Moreover, an innovative package (with an increased vented surface) was compared to the standard boxes. Results show that the difference of average temperature between the temperature probes in head space was less than 0.5°C. Temperature peaks showed the on/off cycle of the automatic defrosting system. Though temperature probes placed on the floor showed a good homogeneity, the air temperature reached a minimum level of about -0.8°C, near the cold air outlet, which is considered too low for the oranges cold storage. The vented boxes allowed a more rapid cooling, lowering the overall thermal resistance of fruit boxes, and so making fruits mostly affected by the cold air temperature near the air cooler outlet.
... The transport of palletized bananas from Central America to Europe in reefer containers has been daily business for more than one decade now, but there is still a large number of containers holding products that arrive in a poor condition due to inadequate temperature management during transport (Billing et al., 1998;Tanner and Amos, 2003). A better understanding of temperature-related problems will have great advantages for the transport chain of bananas. ...
... Initial tests with data loggers placed between the bananas at different positions in the container showed that there are large differences in the velocity of the cooling process ( A comparison of 5 temperature mappings in sea containers, carried out between 2008 and 2010 (Jedermann et al., 2010), showed that there is no unique position for the hot spot with the slowest decline in temperature. Other authors have come to the same result that it is quite difficult to predict the development and location of hot spots (Tanner and Amos, 2003;Moureh and Flick, 2004). Many studies are available about the modeling of air distribution in refrigeration rooms, in refrigerated trucks, vessels and containers (Rodriguez-Bermejo et al., 2007) using Computational Fluid Dynamics (CFD) and other tools. ...
Losses of product quality during the sea transport of bananas in containers are related to the emergence of hot spots. In order to analyze critical conditions, a spatial temperature profile was recorded ashore in a container loaded with banana pallets. The identification of a structured system model showed that it is possible to reduce the information on the measured temperature curves to a set of only two index values. These can be interpreted as factors for coupling to the air stream and for the amount of heat generated by biological processes per banana box. The width of gaps between pallets was identified as the major influence on the spatial temperature profile. Boxes from which the unwanted banana ripening heat cannot be channeled away by the cooling unit can be detected by the quotient of the index values.
... Consequently, many exporters prefer using refrigerated sea containers. These containers are self-contained units that provide better control over produce conditions while offering a more cost-effective solution for transporting large quantities (Tanner & Amos, 2003). ...
Fruits and vegetables are essential for human health, providing vital nutrients and phytochemicals. However, significant losses occur during transportation, particularly in countries like India, which is the second-largest producer but faces 25-30% losses due to transport and storage inefficiencies. Globally, about one-third of food products are lost annually, costing $8.3 billion and affecting food security. The Farm to Fork Strategy seeks to improve the sustainability and efficiency of the food supply chain. This article reviews current transportation methods and challenges, highlighting advancements in refrigeration and packaging, and the integration of RFID technology to enhance traceability and reduce post-harvest losses. Effective implementation can improve the quality and shelf life of produce, benefiting both producers and consumers.
... For example, the barrier property of the packaging material estimated using mean values is increased by a certain % assumed to compensate for the variability in the information used. However, these adjustments have no quantitative support leading to under-or overprocessing risks (Caballero-Cerón, Guerrero-Beltrán, Welti-Chanes, Mújica-Paz, & Torres, 2015;Chotyakul, 2009;Garcia Cortes et al., 2022;Halder, Datta, & Geedipalli, 2007;Marks & Coleman, 2005;Rodríguez-Martínez et al., 2020;Salgado et al., 2017;Serment-Moreno et al., 2015;Tanner & Amos, 2003;Torres & Wu, 2018). This problem can be solved by design calculations considering the statistical variability of product, process, and environmental factors. ...
... Both empirical and theoretical studies have been carried out to study the thermal variations and airflow during perishable goods shipping, showing that, in almost any transport situation, local temperature deviations are always present. From the literature reports, deviations of roughly 5°C or more depending on the transport conditions [56] are indicated. ...
... This is quite challenging due to various sources of heat generation inside the shipping container, like motors, heat penetration from outside, radiation, and produce respiration (Getahun et al., 2017a). Moreover, a considerable drop in temperature may give rise to chilling injuries (Jedermann et al., 2013;Tanner & Amos, 2003). Accordingly, it becomes exigent to maintain the desired temperature inside various zones of refrigerated container (reefer) throughout the supply chain. ...
Prediction and analysis of temperature‐based quality evolution of those perishables subjected to extreme temperatures in a shipment can guide the stakeholders and decision‐makers regarding the final quality of shipment and export mode. This study aims to forecast the temperature heterogeneity among the perishables packed in a standard ventilated carton for sea‐borne cold chain and airways export, using Computational Fluid Dynamics (CFD) simulation. The biochemical processes affecting the fruit quality are also evaluated, and the overall quality is predicted with the help of the Kinetic rate law model. The case of an Indian mango export to United States is considered for the present study, and a preferable export mode is suggested. The model is experimentally validated with a discrepancy of 1.516 K (RMSE) and 9.504% (MAPE), respectively. The findings indicate more heterogeneous temperature distribution in the case of seaways export (nearly 3 K) compared to airways (1.5 K). The temperature‐dependent quality attributes, following different kinetics, decays by 46% and 89.6% on the 10th day of seaways export. This observation indicates that the mangoes will be spoiled in transit as seaways export to United States takes around 28 days. From these observations, under the given transit conditions, it is recommended to export mangoes via airways to the United States from India, which takes about 3 days.
Practical Applications
Monitoring the temperature of perishables is an indispensable part of cold chain export for maintaining their quality and extending their shelf life. This study proposes a virtual or simulation‐based approach to analyze the cooling behavior of individual mangoes and hence predict the evolution of its various quality attributes, passing through different stages of the cold chain. The technique used is quite promising in predicting the export potential and export mode of the produce before the actual export process takes place, thus preventing excessive in‐transit loss. The method mentioned above is applied in an illustrative case study of Indian mango export to the United States. Its application can be further extended to the export of other perishables to various importing countries.
... Refrigerated containers (RCs) offer a controlled environment for preserving fresh produce quality during transit. Significant temperature variations in palletised stowage resulting from poor airflow distribution inside the RC is a long-standing major challenge in the global fresh produce supply chain (Tanner & Amos, 2002;Punt & Huysamer, 2005). Improving the airflow distribution and temperature control calls for extensive full-scale experiments. ...
Cold air is used to maintain fresh produce quality in refrigerated containers (RCs). Using a physical scale model (PSM) to create similar physical arrangements could enhance understanding of airflow patterns in RCs, without the prohibitive costs of researching on a full scale. However, similarity in the hydro/aerodynamic conditions within the RC is required. As a step towards a PSM of a RC, this work validates whether a smaller PSM of a pallet in a refrigerated space mirrors the performance of a larger PSM. The experimental conditions of the two models were scaled both by dimension and Reynolds number (Re). The smaller PSM successfully predicted the flow characteristics of the larger PSM. The mean absolute percentage difference between Re measured in both models ranged from 3.0 – 29.6%. In the future, we will evaluate the temperature control performance for pallets within a RC using a PSM.
... The temperature variations are also affected by the location of the evaporator, the direction of supply and intake of cold air, and the arrangement of the cargo [12]. The quality of fresh produce can be deteriorated by this variation during transportation [13]. Therefore, monitoring the overall temperature distribution in the refrigerating body is necessary. ...
The main purpose of cold chain is to keep the temperature of products constant during transportation. The internal temperature of refrigerated truck body is mainly measured with a temperature sensor installed at the hottest point on the body. Hence, the measured temperature cannot represent the overall temperature values of transported products in the body. Moreover, the airflow pattern in the refrigerated body can vary depending on the arrangement of loaded logistics, resulting temperature differences between the transported products. In this study, the airflow and temperature change in the refrigerated body depending on the loading patterns of box were analyzed using experimental and numerical analysis methods. Ten different box loading patterns were applied to the body of 0.5 ton refrigerated truck. The temperatures inside boxes were measured depending on the loading patterns. CFD modeling with two different turbulence models (k-ε and SST k-ω) was developed using COMSOL Multiphysics for predicting the temperatures inside boxes loaded with different patterns, and the predicted data were compared to the experimental data. The k-ε turbulence model showed a higher temperature error than the SST k-ω model; however, the highest temperature point inside the boxes was almost accurately predicted. The developed model derived an approximate temperature distribution in the boxes loaded in the refrigerated body.
... This approach assumes the stack as a porous medium and eliminates the complex geometry of stacked packaging systems [16,23,99] Refrigerated transport Fruit are transported in reefers that are maintained at recommended temperature and relative humidity of particular fruit. Aim is to minimise detrimental physiological and biological changes in fresh fruit [31,32,100,101] Refrigerated storage Fruit are kept in a room maintained at the recommended temperature and relative humidity for a particular fruit. Aim is to minimise detrimental physiological and biological changes in fresh fruit [34,40,102,103] Refrigerated retail display Fruit are displayed in cabinets on shelves maintained at the recommended temperature and relative humidity conditions. ...
The thermophysical data of fruit is vital to the study and optimization of postharvest handling processes. However, data available in the literature are not always consistent and must not be used directly. It is crucial to examine the accuracy and reliability of the property data. Also, models to predict the thermal properties of fruit are not distinctly identified and included in the list of models for food materials. The aim of this review is to show the gaps in fruit properties data with emphasis on those properties that are important during postharvest handling. This paper also presents a review of the measurement and prediction techniques for the thermophysical properties of fruit. Fruit thermophysical properties vary with temperature, moisture content, cultivar, and even between the various parts of the same product. The presented review is a valuable input for developing mathematical models that predict cooling rate, cooling time, cooling uniformity and refrigeration energy usage during postharvest handling processes (e.g. precooling and cold storage), as well as for applications related to prediction and monitoring of temperature induced fruit quality changes.
... In the majority of food refrigeration systems, heat is transferred primarily by convection: air temperature and its homogeneity are directly governed by the patterns of airflow. Different studies have shown a significant level of spatial temperature variability in some food refrigeration systems ( Estrada-Flores et al., 2002 ;Amos and Tanner, 2003 ;Tanner and Amos, 2003 ) with non-uniform airflow as a major cause of this variability. The air distribution system must provide sufficient airflow to absorb energy from heat sources (walls, door and often products itself) to avoid unacceptable temperature increase. ...
The average cooling demand of a refrigerated vehicle depends on the external conditions and on the journey's profile, such as ambient temperature, air velocity, vehicle speed etc. In order to understand the dynamic heat load on the system and predict the peak of cooling demand, a fully dynamic model of the insulated box of a refrigerated vehicle was developed and experimentally validated. Experimental data was collected during test of a vehicle following the International Agreement for the Transport of Perishable (ATP) test. The model validation demonstrates the capability of the model to correctly predict the evolution of the internal box air temperature in both transient and steady-state conditions. The trend of dynamic load, peak of cooling demand, influence of the solar absorption coefficient and influence of the walls thermal mass on the cooling energy demand during a typical mission are also simulated.
... The release of ethylene, however, is in extremely low concentrations (parts per billion (ppb) levels); hence, it is always undetected until significant damage to fruit consignment is caused. It is reported that, in order to predict early ripening in a container, an analytical system is required for detecting ethylene gas with a concentration as low as 50 ppb [4,5]. ...
In this paper, a novel ceramic preconcentrator is manufactured using aluminum nitride (ALN) ceramics. The preconcentrator consists of a heater, a preconcentrator body, a gas inlet and a gas outlet. The adsorption material, Carbosieve SII, is loaded into the preconcentrator. The preconcentrator is integrated with a previously developed micro gas chromatographic system filled with ethylene. When operated, adequate ethylene gas is adsorbed into the preconcentrator. The application of heat pulse also successfully desorbs the ethylene gas. Tests are conducted with ethylene gas at concentrations of 10 ppm, 5 ppm and 2.5 ppm and 400 ppb, respectively. The system is also tested with ethylene gas from ripening bananas over a period of three days. No interference signal is observed in the chromatogram because of other ripening gases (e.g., carbon dioxide, oxygen, alcohol) and humidity. A detection limit of 25 ppb is realized with this system. The developed preconcentrator has several applications, e.g., in food industry and environmental monitoring.
... Measuring carbon dioxide, humidity, and temperature is relatively straightforward, and commercially sensors are available to detect them. However, to develop a system that detects ethylene gas in ppb showing no cross-sensitivity toward carbon dioxide is still a challenge [3][4][5]. ...
Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented here for the detection of ethylene gas. The gas chromatographic system was assembled using a preconcentrator, a printed 3D printed gas chromatographic column, a humidity sensor, solenoid valves, and an electrochemical ethylene gas sensor. Ambient air was used as a carrier gas in the gas chromatographic system. The flow rate was fixed to 10 sccm. It was generated through a mini-pump connected in series with a mass flow controller. The metal oxide gas sensor is discussed with its limitation in ambient air. The results show the chromatogram obtained from metal oxide gas sensor has low stability, drifts, and has uncertain peaks, while the chromatogram from the electrochemical sensor is stable and precise. Furthermore, ethylene gas measurements at higher ppb concentration and at lower ppb concentration were demonstrated with the electrochemical ethylene gas sensor. The system separates ethylene gas and humidity. The chromatograms obtained from the system are stable, and the results are 1.2% repeatable in five similar measurements. The statistical calculation of the gas chromatographic system shows that a concentration of 2.3 ppb of ethylene gas can be detected through this system.
... Both empirical and theoretical studies have been carried out to study the thermal variations and airflow during perishable goods shipping, showing that, in almost any transport situation, local temperature deviations are always present. From the literature reports, deviations of roughly 5°C or more depending on the transport conditions [56] are indicated. ...
Citrus is a fruit crop grown in different Mediterranean countries. Generally, harvested fruits are used for fresh consumption or are processed (mainly to produce juices). In this chapter, the authors discuss the state of art on citrus postharvest with a scientific approach, evaluating the current knowledge about the physiology and pathology of citrus fruits and the main causes of deterioration. In addition, the authors explain the main facilities for the cold storage of citrus fruit with particular reference to the rapid-cooling techniques and treatments needed prior to shipment of citrus fruits (refer shipment). In the last part of the chapter, the non-destructive methods for the quality evaluation are presented.
... In these cases full containers may be required to conduct a useful experiment (e.g. Tanner and Amos, 2003;Defraeye et al., 2015b), resulting in considerable cost for a single replicate. Hence, cost becomes a limiting constraint when studying these systems (Tanner et al., 2002a;Ambaw et al., 2013). ...
Forced air cooling studies are hindered by the practical difficulties and cost associated with pallet scale investigations. Produce simulators are a potential solution for overcoming some of these difficulties. Despite their common use in precooling research, there are a lack of design guidelines for such simulators in the literature which in some case has led to their inappropriate use. This review examines previous use of produce simulators in produce cooling studies in the context of transport phenomena theory. This allows constraints to be proposed which facilitate the design of produce simulators that can replicate transport phenomena in horticultural produce. These include the requirements of geometric and thermal property matching as well as the practical constraints imposed on produce simulators. It is suggested that future computational modelling work is well suited to the establishment of produce simulator design guidelines which incorporate complex effects such as the impact of variation in produce geometry on flow. The material engineering challenges posed by produce simulators are also discussed.
... One customer used the Xsense system to monitor temperature in real time during transit of stone fruit during the 2008 and 2009 season. Temperature distribution within trucks is known to be uneven and large gradients in temperatures may exist (Moureh and Flick, 2004;Tanner and Amos, 2003). There are hot and cold spots in the same truck and typically pallets located in the first and last rows are exposed to low temperatures and those pallets in the middle of the truck are exposed to higher temperatures. ...
Huge amounts of fresh produce go to waste as a result of poor handling and temperature control through the supply chain. The current paper describes different means of reducing wastage including good sanitation/disinfection and temperature management at the packing house, usage of modified atmosphere packaging, real time monitoring of temperature at the pallet level throughout the supply chain for corrective actions should temperature stray from predetermined limits, and embedded shelf life models that enable First Expired First Out management. The key for sustained reduction in wastage is integration of all of the aforementioned means in a systems approach and collaboration between different parties in the supply chain.
... In fact, little is known in general about the actual cooling process inside reefer containers (or refrigerated trucks) during transport. Associated experimental or numerical studies have been rather limited (Hoang, Laguerre, Moureh, & Flick, 2012;James, James, & Evans, 2006;Jedermann et al., 2013Jedermann et al., , 2014Jim enez-Ariza et al., 2014;Moureh & Flick, 2004;Moureh, Menia, & Flick, 2002;Moureh, Tapsoba, Derens, & Flick, 2009;Rodríguez-Bermejo, Barreiro, Robla, & Ruiz-García, 2007;Tanner & Amos, 2003;Tapsoba, Moureh, & Flick, 2006. This research mainly focussed on airflow/temperature distributions and uniformity instead of product cooling rate. ...
More integrated evaluation of cold chain performance is key for developing a more resource-efficient, energy-smart food supply chain. The present study applies this rationale to evaluate the ambient loading protocol for overseas export of citrus fruit in refrigerated containers. Ambient loading implies that fruit, packed into ventilated boxes, are directly precooled in the container. This technique provides several economic and logistical advantages but is particularly challenging for phytosanitary cold disinfestation treatments. For such an integral approach, multiple relevant product and process parameters were monitored throughout the cold chain, such as fruit cooling rate, quality parameters, shelf life, pest disinfestation efficacy, and their spatial uniformity throughout the cargo load. Also energy consumption of the refrigeration unit was measured. The performance of the standard ambient loading practice was compared to two novel airflow strategies: the channelling configuration, which reduced airflow bypass between pallets, and the horizontal configuration, which forced air horizontally through the pallets. Standard ambient loading was able to cool the produce within about 3. d to the seven-eighths cooling time. The channelling configuration exhibited similar cooling behaviour but the fruit lost less moisture, lasted longer in shelf life conditions and had a better quality. The horizontal configuration performed worse on all aspects. The cooling performance of the container clearly depended on the way in which it was stowed and convectively cooled. This more holistic evaluation of the cooling strategy unveiled several trade-offs and allowed a multi-parameter evaluation of technological improvements to cold chain practices.
... In fact, little is known in general about the actual cooling process inside reefer containers (or refrigerated trucks) during transport. Associated experimental or numerical studies have been rather limited (Hoang, Laguerre, Moureh, & Flick, 2012;James, James, & Evans, 2006;Jedermann et al., 2013Jedermann et al., , 2014Jim enez-Ariza et al., 2014;Moureh & Flick, 2004;Moureh, Menia, & Flick, 2002;Moureh, Tapsoba, Derens, & Flick, 2009;Rodríguez-Bermejo, Barreiro, Robla, & Ruiz-García, 2007;Tanner & Amos, 2003;Tapsoba, Moureh, & Flick, 2006. This research mainly focussed on airflow/temperature distributions and uniformity instead of product cooling rate. ...
Packaging Oranges Precooling Export As an alternative to forced-air precooling, warm loading of citrus fruit into refrigerated containers for cooling during marine transport was explored. This practice could provide several logistic and economic savings. Although successful for resilient citrus fruits, the cooling process and performance of ambient loading have not been explored in a systematic manner. There is still a considerable potential to optimise the implementation of the technique and to apply it to more sensitive citrus or other fruits. Calculations identified the required cooling capacity of a refrigerated container as a function of the envisaged fruit cooling time, and these were complemented by a full-scale experiment. Although a refrigerated container was theoretically able to cool the produce in less than 5 days, the experiment showed that these cooling rates are not currently achieved in practice, bearing in mind that step-down cooling was applied. Future improvements in the technique point towards an improved box design and better stacking on the pallet, and to reducing airflow short-circuits between pallets.
... En las vitrinas de 2 locales de venta minorista, para productos provenientes de la fábrica Nº 4, los sensores de temperatura marcaron 7° y 13°C respectivamente, pero al registrar la temperatura en el interior de éstas sólo se registró una temperatura levemente sobre la norma (7,7°C) lo que no resultaba significativo. Sin embargo, diversos estudios demuestran que en algunos sistemas de refrigeración existen diferencias significativas en la variación espacial de temperatura (13,14) y estas mediciones puntuales podrían no reflejar la distribución real de temperatura dentro de las vitrinas. Esto se debe a que el frío se distribuye de manera desigual dentro de una cámara de refrigeración según sea el sistema utilizado, el nivel de carga e incluso la disposición de los productos (13), por lo que las variaciones observadas pudieron deberse a alguno de estos factores. ...
The food health regulations from Chile control their manufacturing, distribution and storage. Due to the lack of published data on the implementation of the regulations, we evaluated the continuity of the cold chain in five factories of sausages, using pate and cheese head as control products. The results showed deficiencies in the maintenance of cold chain, mainly in the distribution and retailing of products. In addition, statistically significant differences (Student t test) were detected between the bacterial count of initial sample (at the factory) and final (after 5 days, p<0.05), indicating the breakdown of the cold food chain and the increase in microbial load. Since food preservation has a direct impact on public health of the population, further studies are needed to evaluate the cold chain operation in Chile.
... disinfestation (1°C) is well below the minimum temperatures recommended to avoid chilling injury in oranges (Erkan and Pekmezci 2000;Schirra et al. 1997;Edwards et al. 1994) and other citrus (Schiffmann-Nadel et al. 1971;Purvis 1985;Underhill et al. 1999) and is exacerbated by the variability of temperature control and gradients within shipping containers. Tanner and Amos (2003), for example, monitored the internal temperature of a 40-foot length refrigerated container (temperature set point -0.5°C) loaded with pallets of kiwifruit bound from Australasia to Europe and found significant variability, both spatially across the container width (>4°C) and temporally during defrost cycles and transport over the equatorial zone (1.5°C). Therefore, a distinct disadvantage of the use of cold disinfestation procedures and the use of storage containers per se is the increased inherent risk of fruit developing chilling injury. ...
The navel orange cultivar Lanes Late is an important export commodity for the Australian citrus industry with key markets in Asia and the United States of America. Low temperatures during storage and transport are used to extend postharvest life and for the purpose of insect disinfestation, making fruit more prone to chilling injury. The effects of low temperature and storage duration on the development of chilling injury were therefore examined. Cartons of about 100 fruit were stored at 3, 1 or –1°C for 0, 10, 20 or 30 days before transfer to a 22°C post-storage observation room. Fruit were assessed for chilling injury at transfer and every 10 days post-storage for 30 days. At all observation times the main effects of temperature and storage duration on the incidence of chilling injury and chilling injury index were significant with no interaction. The highest incidences of chilling injury were observed for fruit stored at –1°C (21%) and for 30 days (28%). Similarly, the chilling injury index was greatest for fruit stored at –1°C (0.47) for 30 days compared with fruit stored at 3 and 1°C (0.34 and 0.27, respectively). The incidence of chilling injury and the chilling injury index increased 2.1- and 3.0-fold, respectively, between the 10 and 30 day post-storage observations. Moisture loss was positively correlated with the chilling injury index (R² = 0.53; P<0.001), supporting the hypothesis that moisture loss and time are important determinants of the expression of chilling injury. Based on this study, it is recommended that fruit storage and transit time be kept to ≤20 days and transport temperatures are maintained at ≥1°C. The expression of chilling injury could be minimised by reducing the post-storage handling time when moisture loss is expected to be highest.
... Perishable food products are at risk of suffering various damages along the cold chain. The parties involved should control and monitor the conditions of goods in order to ensure their quality for consumers and to comply with all legal requirements (Tanner and Amos, 2003). ...
IntroductionThe nature of perishable foodsWarehousing operationsDistribution processNew technologies in warehousing and distributionConclusions and future trendsReferences
Innovation during the last few decades has allowed great advances to be made in the quality and range of fresh produce enjoyed in places far from the site of production. However, such is the complexity of organizing the preparation and transportation of perishable commodities that, occasionally, a consignment may arrive in poor condition or even be a total loss. The cargo receiver loses money and therefore needs to make a claim. Consequently, it becomes necessary to identify the cause(s) of deterioration. This chapter outlines the background and procedure involved in investigating losses in refrigerated fruits and vegetables carried by sea, but similar principles could be applied to consignments transported by air, road, or rail. Detailed evidence, collected during outturn surveys and from documents, can be used to determine whether the deterioration can be traced to preshipment or shipboard factors, or a combination of both. Two case studies are presented.
An improved internal structure is proposed to improve the distribution of cooling capacity in refrigerated container. Firstly, a computational fluid dynamics model was established and the fruit stacks was simplified to be porous medium. The flow resistance coefficient was obtained by combining theory and numerical simulation and then verified. Secondly, three baffles were added to reduce the loss of cold airflow by blocking the airflow through air-gaps. The velocity and temperature of the previous refrigerated container and the improved refrigerated container were obtained and compared. The cold airflow distribution in the improved refrigerated container is more uniform. The improvement of vertical velocity in all stacks is in the range of 5.24% – 425.04%. The cooling performance of the two refrigerated containers were also obtained. The variation of temperature distribution is within ±1 °C and the cooling time is also reduced by at least 22.9% in the improved refrigerated container. Finally, the proposed structure showed good applicability for different fruits and vegetables. For all produce tested, the decrease ratio of temperature rise in the improved refrigerated container relative to the previous refrigerated container ranges from 34.0% to 59.5%.
When preserving perishable goods, maintaining a constant temperature over the cold supply chain is essential. Therefore, refrigerated vehicles are an important part of the cold supply chain system. However, many traditional refrigerated cargo systems are not designed to support the homogeneity of the temperature inside cargo trailers. Indeed, refrigerating equipment is usually placed on one side of transportation systems as this is considered to be more practical. Such a configuration thus leads to significant temperature differences in the two distinct parts of a refrigerated cargo trailer, which might affect the quality, safety, and shelf life of perishable foods. This research aims to improve the temperature distribution of refrigerated trailers. In this study, it is highlighted that in the most commonly used traditional refrigerated trailer models, lower air velocity and higher product temperature are observed at the rear. There is also a partial product chilling risk at the front of the refrigerated trailer. This study investigates and reports significant differences among the three airflow design models of refrigerated cargo systems by applying turbulence flow, heat, and mass transfer models. The analyses of these three models reveal that significant improvement could be achieved by applying the proper arrangements of inlets on the ceiling of the trailer body.
During transportation of fruits and vegetables, factors such as temperature, air exchange, humidity levels, packaging design and stacking arrangements in the reefer (refrigerated shipping container) are extremely important to maintain the cold chain. In this study, the airflow distribution inside two types of refrigerated shipping containers (T-bar floor and flat floor) used for transporting fresh fruit handling were investigated. Computational fluid dynamics (CFD) model of airflow was developed and experimentally validated. Measurements of air velocities were taken from 222 sample positions inside a full-size reefer. The validated model was then implemented to study the effects of container designs and operational conditions on airflow pattern and distribution. High and low evaporator speed scenarios of the two reefer designs (T-bar floor and flat floor) were investigated. The result showed that airflow distribution in the two container designs were markedly different. Good agreement was found between measured and predicted values of air velocities. The air exchange rate in the rear part of the reefers for the two designs were compared. For the flat floor reefer, the air exchange was 0.2 m³ h⁻¹ while for the T-bar floor, it was 0.6 m³ h⁻¹. Also, in the primary recirculation region, (between 3 and 8 m from the inlet side) the average vertical air velocity was higher in the T-bar floor reefer (0.04 m s⁻¹) than in the flat floor reefer (0.01 m s⁻¹). As a result, reefer with T-bar floor design exhibited a noticeable reduction of air recirculation zone and enhanced uniform vertical air movement compared to the reefer with flat floor design.
The field of postharvest horticulture has traditionally focused on establishing the 'optimal' combination of harvest timing, postharvest treatments and storage technologies which results in the greatest longevity of fresh products. While much has been achieved in reducing crop losses and facilitating global trade of fresh produce, product losses in the postharvest environment which impact on industry profitability still occur, including in 'developed' industries. Many of these losses in established industries are a result of the inherent variability which is observed between batches of the same product. An improved ability to predict storage outturn would allow improved 'inventory management' so particular batches of product could be targeted to the most appropriate market and maximize industry profitability. Irrespective of whether the mode of product failure is decay, chilling injury or development of advanced senescence, the ability to understand the physiology underlying batch variability and predict the behaviour of each batch would be a powerful tool in stock management. A number of different postharvest approaches including metabolomics, mathematical modeling, non-destructive testing and accelerated libraries have the potential to contribute to improved prediction of storage out-turn. This paper provides examples of each of these approaches and suggests the potential for synergies in ideology and data handling methodologies which may apply across all horticultural industries.
A promising cold-chain protocol is explored as an alternative to the commonly-used forced-air pre-cooling (FAC) of citrus fruit prior to shipping: ambient loading of fruit in reefer containers for cooling during long-haul marine transport. Despite the multiple logistical and economical savings it provides, the potential of “ambient loading” of fruit in reefer containers has been left largely unexplored. The present study targets this aspect, but also cooling by vertical airflow in general. Computational fluid dynamics (CFD) is used to identify differences in cooling rate and uniformity between individual boxes at different heights on a pallet and between individual fruit within a single box. Simulations show that low airflow rates, typical for refrigerated containers, do not only induce slower fruit cooling, compared to FAC airflow rates, but also the cooling heterogeneity between different layers of boxes (in height) and between individual fruit in a single box is larger. In addition, the presence of gaps between pallets invokes airflow short-circuiting, leading to highly reduced fruit cooling rates. Finally, strategies for future improvement of the ambient loading protocol are proposed, which in the first place should target faster and more uniform cooling.
Supply network management is a challenging task due to the complexity, the dynamics, and the distribution of logistics processes. Automated process control thus requires to reduce the computational complexity and to cope with the dynamics locally. The paradigm of autonomous control in logistics means that control of logistics processes is delegated to the participating objects. As an example, shipping containers may themselves plan and schedule their way through logistics networks in accordance with objectives imposed by their owners. This work (Schuldt, Multiagent coordination enabling autonomous logistics. Springer, Heidelberg, 2011) solves the implementation of autonomous control with multiagent technology. This multiagent-based solution has been used in a realistic simulation of the container logistics processes of major European retailer of consumer products. The validation shows that autonomous control is actually possible and that it outperforms the previous centralised dispatching approach by significantly increasing the resource utilisation efficiency. Moreover, the multiagent system relieves human dispatchers from dealing with standard cases, giving them more time to solve exceptional cases appropriately.
In conventional temperature measurement using a sound probe, the operation beginnings of two acoustic sensors must be completely synchronized to measure time of flight (TOF), t(f), because the precision of synchronization determines TOF measurement accuracy. A wireless local area network (LAN) is convenient for constructing a sensing grid; however, it causes a fluctuation in the delay of millisecond order. Therefore, it cannot provide sufficient precision for synchronizing acoustic sensors. In previous studies, synchronization was achieved by a trigger line using a coaxial cable; however, the cable reduces the flexibility of a wireless sensing grid especially in larger-scale measurement. In this study, an asynchronous-type sound probe is devised to compensate for the effect of the delay of millisecond order caused by the network. The validity of the probe was examined, and the air temperature distribution was measured using this means. A matrix method is employed to obtain the distribution. Similar results were observed using both asynchronous-type sound probes and thermocouples. This shows the validity of the use of a sensing grid with an asynchronous-type sound probe for temperature distribution measurement even if the trigger line is omitted. (C) 2009 The Japan Society of Applied Physics
The measurements of wind velocity and direction using an acoustic reflection against a wall are described. We aim to measure the spatial mean wind velocity and direction to be used for an air-conditioning system. The proposed anemometer consists of a single wall and two pairs of loudspeakers (SP) and microphones (MIC) that form a triangular shape. Two sound paths of direct and reflected waves are available. One is that of the direct wave and the other is that of the wave reflected on the wall. The times of flights (TOFs) of the direct and reflected waves can be measured using a single MIC because there is a difference in the TOF between direct and reflected waves. By using these TOFs, wind velocity and direction can be calculated. In the experiments, the wind velocities and directions were measured in a wind tunnel by changing the wind velocity. The wind direction was examined by changing the setup of the transducers. The measured values using the proposed and conventional anemometers agreed with each other. By using the wave reflected against a wall, wind velocities and directions can be measured using only two pairs of transducers, while four pairs are required in the case of conventional anemometers.
4.6.1. Introduction RFIDs, sensor networks and low-power microcontrollers are increasingly applied in logistics. They are char-acterized by restrictions on calculation power, communication range and battery lifetime. In this article we consider how these new technologies can be utilized for autonomous cooperation and how these processes could be realized on systems with limited resources. Besides tracing of the current freight location by RFID technologies, the monitoring of quality changes that occur during transport is of growing importance. The demand for improved and comprehensive supervision of goods could be best fulfilled by distributed autonomous systems. The 'intelligent container' as autonomous supervision system The prototype of our 'intelligent container' demonstrates how autonomous control could be implemented on a credit-card sized processor module for integration into standard containers or transport vehicles (Figure 1). The processor provides a platform for local interpretation and pre-processing of sensor information. The sys-tem automatically adapts to the specific requirements of the transport good. An extended electronic con-signment note that is implemented as software agent contains individual transport-and monitoring instruc-tions. RFID technologies are used to control the transfer of this mobile freight agent. The implementation of the local data pre-processing and an example quality model for vegetables are described in section 2. If the supervision system predicts that the freight quality will drop below an acceptance threshold before arrival, it contacts the transport manager. The extended agent platform for further transport planning is shortly intro-duced in section 3.
In this paper, we describe a two-axis anemometer with an acoustic reflector using a single pair of a loudspeaker (SP) and a microphone (MIC). The two-axis anemometer proposed in this study consists of a SP, a MIC and an acoustic reflector, which form a right-angled isosceles triangle. This anemometer can measure spatial mean wind velocity and direction by calculating each wind component along the coordinate axis defined in each propagation path; this anemometer is targeted for use in air-conditioning systems of high efficiency. The sound probe consists of a SP, a MIC, an acoustic reflector and each propagation path. By using the acoustic reflector, an additional sound path becomes available. In this case, the time of flight (TOF) can be measured using a single SP-MIC pair because of the difference in TOF between direct and reflected waves. Some experiments were carried out in a wind tunnel to measure wind velocity and direction at various wind velocities. The sound probe is placed on a turntable in a wind tunnel. Although the actual wind direction is constant, the apparent direction relative to the sound probe can be changed by rotating a turntable. The measured wind velocities and directions in the experiments showed only small changes with the wind direction change. The feasibility and accuracy of the proposed two-axis anemometer for wind velocity and direction measurements were confirmed.
Bactrocera invadens (Diptera: Tephritidae) has spread rapidly across Africa and currently poses a phytosanitary threat to the fruit industry of South Africa. In reaction a cold mitigating treatment to provide phytosanitary security to importing countries was developed in Nairobi, Kenya. Using laboratory reared fruit flies, the rate of development in 'Hass' avocado (Persea americana Miller) was determined at 28 degrees C. Fruit ripeness or softness was found to be a factor improving larval fruit fly survival. Using this information the egg and larval developmental stages were subjected to 2 degrees C cold treatment and it was found that the third instars were the most cold tolerant life stage and that it was expected that between 16 and 17 d treatment would provide phytosanitary security. There were no survivors in the treatment of an estimated 153,001 individuals in four replicates at an average fruit pulp temperature of 2 degrees C satisfying the Probit 9 level of efficiency at a confidence of >95%. These data provide evidence that a continuous cold treatment of 1.5 degrees C or lower for 18 d would provide phytosanitary security in that any consignment entering an importing country poses no risk of accidental importation of B. invadens.
A study was carried out to evaluate temperature variation and quality deterioration of packaged cod fillets as influenced by the box type used and their position on pallets under dynamic temperature storage. Storage life of thermally abused fillets was compared to that of fillets stored at steady temperature. Thermal performance of fish boxes, made of corrugated plastic on one hand and expanded polystyrene on the other hand, was also compared. Fillet temperature at multiple positions on the pallets along with environmental temperature and humidity were monitored during storage. Differences in product temperature of up to 10.5 °C were recorded on the thermally abused pallets stored for 6.4 h at mean ambient temperature of 18.5 °C. A reduction in storage life of 1.5–3 days was observed depending on the box position on the abused pallets compared to steady temperature storage.Highlights► We study temperature variation and quality deterioration of palletised cod fillets. ► Up to 10.5 °C product temperature difference was recorded on thermally abused pallets. ► Thermal load reduced shelf life by 1.5–3 days depending on box position. ► Quality loss was faster in the sensitive corner boxes than in the centre boxes.
The improvement of the banana supply chain in order to provide better quality and to compensate for biological variance is still a challenging issue. This paper describes the online-monitoring and supervision of spatial deviations by the Intelligent Container, which is a crucial pre-requisite to improve the transport conditions. Spatial temperature deviations data were collected during sea-transportation of two containers and analysed with regard to differences over the container length, effects of power interruptions, differences between two containers of same type and year of manufacture and deviations inside one cardboard box. Furthermore, the accuracy of a simple setup with only 4 sensors was compared with a setup with 16 sensors distributed over 4 pallets. 1. The banana challenge When banana fruit ripening is triggered, enzyme activity accelerates the conversion of starch to sugar generating up to 800 Watt of heat per ton [Ker04]. Beyond a certain point of ripening of fruit, few modes of cool transport can maintain optimum carrying conditions with out damage to sensitive fruit. By understanding the evolution of biological variance from field to store and being able to monitor in time-spatial representative indicators of fruit ripening during transport or storage, a practical model for managing quality needs to be developed. Key outcome of this innovation is to find reliable indicators that allow decisions to be made along the supply chain that can reduce the chance of waste and improved customer satisfaction. Integrated online monitoring of the environment in the immediate surrounding of the fruit should aim to sense and predict the changes in fruit ripening connected to the internal dynamics of a transport unit of fruit. The greatest risk in banana supply chain is the loss of fruit due to untimely ripening as a result of post harvest decay or fruit physiological factors. Ripening triggers in the field, the packing plant, during transport to the port, and refrigeration in the ship/container. Uncontrolled biological processes during the ripening in Europe or during the final stages of distribution to the consumer also increase this risk. These triggers may take the form of stress to the plant or fruit, variations between hot and cool temperatures in critical periods of time, or mechanical/pathogen damage to the fruit. Awareness and key actions based on reliable/representative indicators can significantly reduce the losses; this results in an energy efficient supply chain as well as meeting quality expectation of the customer/consumer. Since Tropical banana production is a continuous process all year round, identification of problems as soon as possible in the chain can improve the reaction time to avoid repeating the same mistakes.