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Abstract: The performance of three table grapes multi-scale designs, namely the 4.5kg box, 5kg open-top punnet and 5kg clamshell punnet, was studied. Results showed that vent-hole ratio of empty grape boxes had a significant influence on the resistance to airflow, where the 5kg punnet box with a vent-hole ratio of 6.13±0.04% had a lower pressure drop than the 4.5kg boxes with a lower vent-hole ratio of 3.80±1.74%. The addition of liner films and inner packages changed the pressure patterns, indicating that inner packaging had a great influence on airflow resistance and airflow patterns through multi-scale packages of grapes. Cooling rates of grapes in the 4.5kg multi-packaging was significantly (P <0.05) slower than that of grapes in 5kg punnet multi-packaging, where the 4.5kg box resulted in a seven-eighths cooling time of 30.30–46.14% and 12.69–25.00% more than that of open-top and clamshell punnet multi-packages, respectively. After 35days in cold storage at −0.5°C, grape bunches in the 5kg punnet box combination (open-top and clamshell) had a weight loss of 2.01–3.12%, while the bunches in the 4.5kg box combination had only 1.08% weight loss. The bunch stem dehydration rates were also higher in the 5kg punnet multi-package. These results were attributed to differences in vapour pressure deficit (VPD) measured between the three multi-scale packages, where the VPD inside the 4.5kg multi-packaging was 40.95Pa, while the VPD inside the 5kg open-top and clamshell punnet packaging were 92.97Pa and 100.71Pa, respectively. [Copyright &y& Elsevier]

Abstract: A three-dimensional (3D) finite element model for simulating heat transfer during cooling of irregular-shaped ready-to-eat meat products was developed and validated. The heat transfer model considered conduction as the governing equation, subject to convection, radiation and moisture evaporation boundary conditions. A 3D finite element algorithm developed in Java™ was used to solve the model. The algorithm generated solutions for meshes containing 4-node tetrahedral volume elements and 3-node triangular boundary elements. Product geometries were generated from CT-scan images of the meat products. The model was adapted to receive input parameters that can be easily provided by a meat processors including air relative humidity, air temperature, air velocity, type of casing, duration of water shower, product weight, and estimated core temperature of product prior to entering the cooling chamber. Model validation was conducted in four commercial facilities, under normal processing conditions. Temperatures predicted by the model were in agreement with observed values. Average root-mean-square error (RMSE) was 1.19±0.54°C for core temperatures, 1.73±0.48°C for temperatures 0.05m from core to surface, and 2.01±1.01°C for surface temperatures. The developed heat transfer model was integrated with predictive microbiology models through a food safety website: numodels4safety.unl.edu. The integration can be useful for estimating the severity of cooling deviations and resulting microbiological safety caused by unexpected cooling process disruptions. [Copyright &y& Elsevier]

Abstract: An approximate cheese cylinder is cooled while partially submerged in a flowing brine solution. Microbiological considerations require the cheese to be cooled to 4°C or less prior to packaging. Knowledge of the temperature evolution of the product is desirable from a manufacturing perspective, and we propose a model to describe the temperature time-history of a single cheese cylinder during cooling. The combination of unusual product geometry and the discontinuity in surface temperatures motivate the use of the finite element method (FEM). The FEM solution is used to describe the cooling process, and to ascertain the minimum time necessary for the cheese to attain the required packaging temperature. The FEM solution exhibits excellent agreement with the corresponding experimental findings. The discontinuity in surface temperatures has a significant influence on the cooling regime. Future process optimisation should focus on developing methods to increase the cheese surface area in contact with the brine. [Copyright &y& Elsevier]

A multi-scale three-dimensional computational fluid dynamics (CFD) model was developed to predict airflow, heat and mass transfer in a typical full loaded cool storage. In order to reduce the computational costs, the porous media parameters of the bed of the apples inside the vented containers were extracted using a series of wind tunnel CFD simulations and then applied in the cool storage model. The model was validated against experiments by means of velocity, product temperature, and product weight loss measurements in cool storage. The errors of about 23.2 and 9.1% were achieved for velocity magnitude prediction in the cool storage and the product weight loss after 54 days of cooling in the loaded cool storage, respectively. The model over predicted the cooling rate of the products temperature; however, it showed a good trend of cooling rate. About 11°C difference was observed between the hottest and the coldest product temperatures at half cooling time by experiments that were in good agreement with the simulation results with about 10°C. This difference changes versus time of cooling and reached to about 4°C at the end of the cooling time. The product's temperature heterogeneity was predicted 1.9°C between the 7 and 9 hours of cooling and reduced to 0.6°C at the end of the cooling. The multi-scale model was capable of predicting air velocity, product temperature, and weight loss with reasonable accuracy and was reliable enough for numerical studies on larger domain with high reduction in computational costs. [ABSTRACT FROM AUTHOR]

ABSTRACT The objective of this work was to evaluate integrated processes of cooking and vacuum cooling of mussels. Thus, the following alternatives were assessed: vapor cooking followed by vacuum cooling (VCk-VC) and water immersion cooking followed by vacuum cooling with the samples immersed in the cooking water (ICk-IVC). Such alternatives were compared with a conventional process of vapor cooking followed by water immersion cooling (VCk-IC). The time to cool the samples until 10C was similar for the VCk-VC and VCk-IC processes, while for the ICk-IVC process, the cooling time was much higher. However, the samples submitted to the VCk-VC process presented a cooling weight loss in contrast to the weight gains observed for samples treated using the ICk-IVC and VCk-IC processes. On the other hand, the samples submitted to the VCk-VC process presented lower counts of mesophiles and psychrotrophs during cold storage than samples treated using the conventional process.5, 2011. PRACTICAL APPLICATIONS Mussels are the most abundant cultivated shellfish in Brazil and are marketed as fresh or as processed product. At the initial steps of industrial processing, mussels are cooked and cooled to manual extraction of the meat from the shell. The cooling is classically accomplished by immersion of the cooked mussels in cold water, which is a critical step because cooling water and ice can cause recontamination of the cooked product. In this way, the present paper reported an alternative to process mussels using the vacuum cooling technique. The obtained results showed that the microbiological quality of vacuum-cooled mussels was superior to that of conventional cooled ones. [ABSTRACT FROM AUTHOR]

Abstract: Two important factors affecting the oil uptake in foods during deep fat frying are water content and pressure development. In the past frying studies, the physical pressure has not been measured experimentally but was calculated using computer models, which has resulted in disagreements about its magnitude. The present study tries to explain the complex mass transfer mechanisms taking place during deep fat frying with respect to real time pressure variations inside potato discs and chicken nuggets. Frying experiments were performed at two temperatures of 175°C and 190°C for 200 and 240s for potato discs and chicken nuggets, respectively. The gage pressure increased rapidly above the atmospheric pressure immediately after the samples were introduced into the hot oil. The rise in pressure was greater in potato discs with greater initial moisture content. This was expected due to sudden moisture flash-off. As frying progressed, the temperature inside the samples increased whereas the gage pressure started decreasing and became negative. The onset of negative pressure was observed during initial stages of frying for chicken nuggets, but in the middle of frying for potato discs. The negative pressure values before the product is taken outside the fryer may cause increased oil uptake during frying itself. During the post frying cooling, the pressure further decreased and reached negative values. The negative pressure is expected to have caused rapid absorption of surface oil during both frying and cooling stages. [Copyright &y& Elsevier]

The objective of this research was to study the effects of different milling conditions and postmilling handling procedures on appraised milling quality of rough rice. Rough rice (M202) with moisture content of 11.5 ± 0.2% was used for this study. The samples were milled with a McGill number 3 mill under four milling conditions, including normal milling, milling at high temperature, milling with cooling using ice water, and room temperature water. The milled rice samples were cooled in closed and open plastic containers and in open pans with three temperatures: 15, 23, and 35°C. The effects of milling and postmilling conditions on milled rice temperature, moisture loss, cooling rate, single and multiple fissuring rates, total rice yield (TRY), head rice yield (HRY), whiteness index (WI), and total lipid content (TLC) were evaluated. Results showed that high single and multiple fissuring rates and low TRY and HRY were inherent in improper milling and postmilling conditions. Single fissuring rates were 15.9 and 17.6% and multiple fissuring rates were 3.5 and 7.2% for rice samples milled under normal and high‐temperature conditions, respectively. Cooling methods that used open containers and pans had more moisture losses and further resulted in lowering appraised milling quality than methods that used closed containers. Low‐temperature milling conditions followed by cooling in closed containers significantly reduced single and multiple fissuring rates and improved TRY and HRY by 0.9 and 1.5 percentage points, respectively. The effects of tested milling and postmilling conditions on WI and TLC were not significant. Obtained results constitute valuable information for developing milling and cooling procedures to achieve consistent, accurate, and reliable milling quality appraisals for rough rice. [ABSTRACT FROM AUTHOR]

Abstract: To study the effects of chilling methods and hot-boning on quality parameters of M. longissimus lumborum (LL) of Nelore steers, sixteen left-carcass sides were electrically stimulated and the LL muscles were hot-boned and chilled at −20°C (HBVFC) or 0°C (HBO). Eight control left-carcass sides were cold-boned (AT). All muscles were vacuum-packaged and aged at 0°C for 14d. Shear force and tenderness of the AT-treated muscles were not different from HBO-treated muscles. The shear force values of the HBVFC muscles were higher after 7 and 14d post-mortem (pm) compared to those of the AT muscles, but there was no difference from the HBO muscles. Aging did not reduce the shear force values of the HBVFC muscles. The purge losses of the HBVFC muscles were higher than those of the HBO and AT muscles. The HBVFC muscles were less tender than the HBO and AT muscles at 14d pm. [Copyright &y& Elsevier]

Abstract: After field harvest, baby spinaches are transported to the packing shed where they are cooled by forced air systems. If contaminated, the temperature of spinaches will affect the number of pathogens in the leaves, and effective temperature control is critical to restrict their growth. Hence, the need to assess the impact of cooling practices on the growth of pathogens in leafy greens. The Baranyi model was used to describe the experimental data and build a dynamic model to predict microorganism growth rate in baby spinach leaves as function of temperature. Baby spinach leaves, inoculated with 104 CFU/ml of Salmonella Typhimurium LT2 or 102 CFU/ml of an Escherichia coli cocktail, and were maintained at temperatures ranging from 10 to 37 °C for 30 h. At 10–30 °C, the E. coli strains grew significantly more (∼2–4 log cycles) than the Salmonella strain (∼0.11–2.4 log cycles) while at 37 °C, both bacterial populations increased by ∼6 log cycles for 30 h. The growth kinetics of each microorganism followed the Baranyi model. The maximum bacterial population increased with temperature and the values were similar for both bacteria. The theoretical minimum temperature for growth was 5.88 °C and 4.76 °C for Salmonella and E. coli, respectively. The dynamic model was validated with an experimental linear cooling profile (slow cooling) and could be incorporated into a risk assessment tool to evaluate the growth of pathogens in baby spinach during processing and distribution. [Copyright &y& Elsevier]

Abstract: Amylomaltase-treated starch (ATS) has been described as an excellent fat-replacer in set yoghurt. Its functionality as a creaminess enhancer relates to the ability to form domains, which have melting and yielding characteristics in the mouth. This study was intended to understand the functionality of ATS in stirred yoghurt. Sensory evaluation of reduced fat stirred yoghurt samples showed that the creaminess perception of stirred yoghurt with 1.5% fat and 0.5% ATS was comparable with the reference full fat yoghurt containing 3% fat. This showed that ATS was even more effective as a creaminess enhancer in stirred yoghurt than in set yoghurt. This was related to the higher effectiveness of domain formation during storage after cooling in a dispersed system, as a result of stirring of the yoghurt gel, compared with a gelled set-yoghurt system. [Copyright &y& Elsevier]

Improper food cooling practices are a significant cause of foodborne illness, yet little is known about restaurant food cooling practices. This study was conducted to examine food cooling practices in restaurants. Specifically, the study assesses the frequency with which restaurants meet U.S. Food and Drug Administration (FDA) recommendations aimed at reducing pathogen proliferation during food cooling. Members of the Centers for Disease Control and Prevention's Environmental Health Specialists Network collected data on food cooling practices in 420 restaurants. The data collected indicate that many restaurants are not meeting FDA recommendations concerning cooling. Although most restaurant kitchen managers report that they have formal cooling processes (86%) and provide training to food workers on proper cooling (91%), many managers said that they do not have tested and verified cooling processes (39%), do not monitor time or temperature during cooling processes (41%), or do not calibrate thermometers used for monitoring temperatures (15%). Indeed, 86% of managers reported cooling processes that did not incorporate all FDA-recommended components. Additionally, restaurants do not always follow recommendations concerning specific cooling methods, such as refrigerating cooling food at shallow depths, ventilating cooling food, providing open-air space around the tops and sides of cooling food containers, and refraining from stacking cooling food containers on top of each other. Data from this study could be used by food safety programs and the restaurant industry to target training and intervention efforts concerning cooling practices. These efforts should focus on the most frequent poor cooling practices, as identified by this study. [ABSTRACT FROM AUTHOR]

This article identifies and describes five alternative cooling technologies (magnetic, thermionic, thermoacoustic, thermoelectric, and thermotunnel) and qualitatively assesses the prospects of each technology relative to vapor compression for space cooling and food refrigeration applications. Assessment of the alternatives was based on the theoretical maximum percent of Carnot efficiency, the current state of development, the best percent of Carnot efficiency currently achieved, developmental barriers, and the extent of development activity. The prospect for each alternative was assigned an overall qualitative rating based on the subjective, composite view of the five characteristics. [ABSTRACT FROM PUBLISHER]

Abstract: Anhydrous milk fat and blends containing up to 40% (w/w) rapeseed oil (RO) were crystallized using a slow (0.05 °C min−1) or fast (5 °C min−1) cooling rate. Melting behaviour was examined using differential scanning calorimetry, texture was analysed by parallel plate compression tests, microstructure was studied by confocal laser scanning microscopy, and solid fat content was measured by pulse-NMR. Fast cooling of the blends decreased the peak melting temperature of both high and low melting fractions of milk fat as the content of RO increased, while increasing RO combined with slow cooling did not affect melting behaviour. Solvent effects dominating in fast cooled samples are suggested to be responsible for the change in melting behaviour. The texture of fast cooled samples correlated with solid fat content. In slow cooled samples addition of RO decreased the hardness, which was ascribed to an increase in crystal cluster size. [Copyright &y& Elsevier]

Abstract: In order to describe cooling processes, the thermal diffusivity α and the convective transfer coefficient h must be known. To this end, in general the analytical solution of the diffusion equation with only the first term is fitted to an experimental dataset of the temperature versus time, in which the temperature is measured in a known position. Despite this technique to describe well the major part of the cooling kinetics, this procedure contains a flaw for Fourier numbers less than 0.2 (lag factor). This article presents an algorithm based on optimal removal of experimental points to minimize errors in the determination of α and h. The algorithm was validated for several physical situations, and applied in cucumber cooling. The whole cooling kinetics was simulated with success (chi-square=2.8756×10−3 and determination coefficient=0.9991), including the region responsible by the lag factor. [Copyright &y& Elsevier]

Abstract: The aim of the Part II is to apply the methodology combining deterministic and stochastic approaches to describe the evolution of food products along the cold chain. The proposed methodology, presented in Part I, takes into account different sources of variability (logistics, thermal conditions, consumer behaviour…) and uses deterministic models for equipment and product evolution. First, the data structure of a case study involving the three final links of the cold chain (display cabinet, shopping basket and domestic refrigerator) is presented. Then, the simulation results are analysed in order to highlight the potentialities of the modelling approach. These results are compared with survey data to validate the model. This part also underlines the sources of variability which exert the greatest influence on the microbial load development: the residence time of the product inside the refrigerator and the thermostat setting of the refrigerator. [Copyright &y& Elsevier]

Abstract: The authors have proposed application of ice slurry to a cold storage of foods for widely using the ice slurry. In this study, a new ice slurry utilizing the food additive trehalose was tested using the “harvest method”. The trehalose is expected to suppress ice crystal growth. The freezing characteristics of the trehalose solution were investigated based on a scraping force of ice growing on a carbon steel surface, apparent ice thickness, concentration in ice, observation of formed ice from the side view and behavior of ice during scraping, varying initial concentrations of the solution, amounts of formed ice, supercooling degrees of the solution and temperatures of the cooling surface. Furthermore, a unique freezing characteristic feature of the trehalose solution was clarified by comparing it with an ethylene-glycol solution. [Copyright &y& Elsevier]

Abstract: Many deterministic models have been developed to describe heat transfer in the cold chain and to predict the thermal and microbial evolution of food products. However, different product items will have different evolutions because of the variability of logistic supply chain, equipment design and operating conditions, etc. The objective of this study is to propose a general methodology to predict the evolution of food products and its variability along a cold chain. This evolution is characterized by state variables such as temperature, water content, microbial load, etc. The methodology, presented in part I, is based on deterministic models for equipment and on stochastic laws for different sources of randomness. A Monte-Carlo algorithm is proposed for solving the model equations. The approach will be applied for the three last links of the cold chain: display cabinet, shopping basket and domestic refrigerator in part II of this study. [Copyright &y& Elsevier]

Abstract: This work reports a study of the heat and mass transfer during the freezing of a block of beef in the freezer compartment of a household refrigerator. It takes into account the natural convection in air coupled to the heat conduction and water diffusion in the meat. The nonlinear partial differential equations describing mass conservation, linear momentum, energy and species concentration in two dimensions are solved with the SIMPLE algorithm and the finite volumes method. The results obtained include the unsteady state description of air movement as well as temperature and water concentration in the air, and temperature and water concentration distribution in the meat. The predicted weight loss of the food reaches a value of 1.5%. [Copyright &y& Elsevier]

Abstract: The influence of roasting and storage conditions on free radical contents of individual Arabica coffee beans was examined during storage of whole, half and ground beans in air over a 1-month period. Free radical contents increased with increasing roasting time (roasting degree), but the atmosphere (air vs. N2) used in the roasting and cooling process had little effect. There was a progressive increase in free radical contents with storage time, but the rate was much lower in whole beans than with half and fully ground beans, for which the rate was similar. These results suggest that exposure to O2, rather than physical grinding is the main mechanism for storage-related free radical generation, and strongly indicate that roasted coffee is best kept as whole beans in order to minimise changes during prolonged periods of aerobic storage. Furthermore, they demonstrate that EPR measurements can contribute to understanding the process and storage related changes in coffee. [Copyright &y& Elsevier]

Abstract: Cooked dishes must be cooled rapidly after cooking to avoid significant growth of Clostridium perfringens. French regulations require that produce be cooled from 63 °C to 10 °C in less than 2 h. Cooling is a critical phase for central cooking facilities that need to cool large quantities of food. The food is cooled in blast-chillers before being placed in cold storage. We observed that in France the blast-chiller is usually switched off by operators as soon as a measured temperature is equal to or below 10 °C. This temperature measurement may be taken at any place in the batch. We studied the consequences of this procedure on the distribution of temperatures at the time when cooling is stopped. We did this by monitoring the core temperatures of the foodstuffs during 52 cooling operations carried out in seven central cooking facilities for hospitals or schools. The data allowed us to estimate the characteristics of the distribution of temperatures within batches. Simulations suggest that, when the blast-chiller is switched off after cooling, there can be significant differences between random temperature readings in the batch and the highest temperatures. For 5% of simulations, the difference could be greater than 17 °C. We propose alternative rules to reduce this discrepancy. If such a single measurement was replaced by three measurements, with each of them taken at the centre of a container, this difference would be less than 3.8 °C in 95% of the simulations. The improvement of methods for measuring temperatures is necessary to achieve the cooling durations recommended by the official organizations. [Copyright &y& Elsevier]

The objective of this study was to investigate the effects of conventional chilling (0 to 4 °C), rapid chilling (RC, -20 °C for 30 min, followed by 0 to 4 °C), and short-duration chilling (0 to 4 °C for 30 min, followed by 25 °C) on meat quality and calpain activity of pork muscle longissimus dorsi (LD). The muscle quality characteristics pH, color, cooking loss, pressing loss and tenderness, and calpain activities were measured 0-, 3-, 12-, and 24-h postmortem. Results show that the RC resulted in a faster temperature decline of the muscle, and prevented the meat pH and Commission Internationale de l'Eclairage L* value from declining during postmortem aging. RC also reduced meat cooking loss and pressing loss compared with the other two chilling methods. However, the chilling methods did not significantly affect meat shear force. During the first 24-h postmortem, there was not a noticeable change in the activity of m-calpain. But μ-calpain activity decreased regardless of chilling method. In the rapidly chilled carcasses, μ-calpain activity remained the same 3- and 12-h postmortem. However, in the short-duration chilled and conventionally chilled carcasses, the activity was visibly reduced. At 24-h postmortem, no clear zones on the gel were observed in all three treatments. Practical Application: Conventional and RC methods are commonly used for pork in commercial practice nowadays. Compared with conventional chilling, the effect of RC on quality parameters of pork varies. In recent years, short-duration chilling (SC) is widely used in many Chinese pig slaughtering facilities. However, few researchers have studied the effect of SD on pork quality. Therefore, the present study investigated the effect of different chilling methods on functionalities or quality of chilled pork meat. [ABSTRACT FROM AUTHOR]

The shelf life of mushrooms is very limited since they are susceptible to physical and microbial attack; therefore they are usually blanched and immediately frozen for commercial purposes. The aim of this work was to develop a numerical model using the finite element technique to predict freezing times of mushrooms considering the actual shape of the product. The original heat transfer equation was reformulated using a combined enthalpy-Kirchhoff formulation, therefore an own computational program using Matlab 6.5 (MathWorks, Natick, Massachusetts) was developed, considering the difficulties encountered when simulating this non-linear problem in commercial softwares. Digital images were used to generate the irregular contour and the domain discretization. The numerical predictions agreed with the experimental time-temperature curves during freezing of mushrooms (maximum absolute error <3.2°C) obtaining accurate results and minimum computer processing times. The codes were then applied to determine required processing times for different operating conditions (external fluid temperatures and surface heat transfer coefficients). [ABSTRACT FROM AUTHOR]

Abstract: The proposed FEM model describes natural convective air cooling of cheese curd and cheeses with different sizes, chemical composition and initial temperature, including temperature-dependent functions accounting for the variation of specific heat capacity and thermal conductivity of cheeses. Both the calculated convective heat transfer coefficients (from 3.58 to 15.15W/m2 K) and the ratio between Grashof and square Reynolds numbers confirmed that heat exchange was natural convective. The model permitted to accurately predict the transient temperature change into the cheese, as shown by the mean RMSEs values (from 0.34 to 2.29°C). Higher RMSEs values (up to 3.29°C) were obtained for cheese curds, because some deviations from the assumptions of the model occurred. These higher RMSEs values for cheese curds quantify the importance of compliance with the model’s assumptions to ensure a best fit between the simulated and experimental data. [Copyright &y& Elsevier]

Abstract: Fresh fruits, juices, and beverages have been implicated in human noroviral and hepatitis A virus outbreaks. The purpose of this study was to determine the survival of human norovirus surrogates (murine norovirus, MNV-1; feline calicivirus, FCV-F9; and bacteriophage MS2) in juices (orange and pomegranate juices), juice blends (pomegranate and orange juice) and milk over 0, 1, 2, 7, 14, and 21 days at refrigeration (4 °C). Juices, juice blends, and milk were inoculated with each virus over 21 days, serially diluted in cell culture media, and plaque assayed. MNV-1 showed no reduction in titer after 21 days in orange juice and milk, but moderate reduction (1.4 log) in pomegranate juice from a titer of 5 log10 PFU/ml. However, MNV-1 was completely reduced after 7 days in the orange and pomegranate juice blend. FCV-F9 from a titer of 6 log10 PFU/ml was completely reduced after 14 days in orange as well as pomegranate juice and by ∼3 logs after 21 days in milk at 4 °C. Interestingly, FCV-F9 was completely reduced after 1 day in the orange and pomegranate juice blend at 4 °C. MS2 was reduced by ∼1.28 log after 21 days in orange juice from a titer of 6 log10 PFU/ml, and <1 log after 21 days in milk or pomegranate juice, with juice blends showing minimal reduction (<1 log) after 21 days at 4 °C. These results show the survival pattern of noroviruses that aid in the transmission of foodborne viral outbreaks. The data obtained can be used in quantitative viral risk assessment studies and to develop improved measures to prevent virus survival towards controlling outbreaks. [Copyright &y& Elsevier]

Abstract: The influence of different package vent configurations, including ventilated packages with 1, 3 and 5 vents, on produce temperature distribution during forced convection cooling of produce was investigated by mathematical modeling of simultaneous airflow and heat transfer. Generally, produce cooling uniformity was increased by increasing the number of vents from 1 to 5. Produce cooling heterogeneity increased until about 90 min cooling and subsequently decreased with further cooling in all 3 ventilated packages. The methodology developed in this study can be used as a design tool to provide homogeneous temperature distribution in ventilated packages during forced convection cooling of produce. [Copyright &y& Elsevier]

Abstract: This study examined the growth characteristics of Listeria monocytogenes as affected by a native microflora in cooked ham at refrigerated and abuse temperatures. A five-strain mixture of L. monocytogenes and a native microflora, consisting of Brochothrix spp., isolated from cooked meat were inoculated alone (monocultured) or co-inoculated (co-cultured) onto cooked ham slices. The growth characteristics, lag phase duration (LPD, h), growth rate (GR, log10 cfu/h), and maximum population density (MPD, log10 cfu/g), of L. monocytogenes and the native microflora in vacuum-packed ham slices stored at 4, 6, 8, 10, and 12 °C for up to 5 weeks were determined. At 4–12 °C, the LPDs of co-cultured L. monocytogenes were not significantly different from those of monocultured L. monocytogenes in ham, indicating the LPDs of L. monocytogenes at 4–12 °C were not influenced by the presence of the native microflora. At 4–8 °C, the GRs of co-cultured L. monocytogenes (0.0114–0.0130 log10 cfu/h) were statistically but marginally lower than those of monocultured L. monocytogenes (0.0132–0.0145 log10 cfu/h), indicating the GRs of L. monocytogenes at 4–8 °C were reduced by the presence of the native microflora. The GRs of L. monocytogenes were reduced by 8–7% with the presence of the native microflora at 4–8 °C, whereas there was less influence of the native microflora on the GRs of L. monocytogenes at 10 and 12 °C. The MPDs of L. monocytogenes at 4–8 °C were also reduced by the presence of the native microflora. Data from this study provide additional information regarding the growth suppression of L. monocytogenes by the native microflora for assessing the survival and growth of L. monocytogenes in ready-to-eat meat products. [Copyright &y& Elsevier]

Abstract: The effect of conventional and microwave pasteurization on the main flavonoids present in grapefruit juice and their stability throughout 2months of refrigerated and frozen storage was evaluated. Individual flavonoids were analyzed by HPLC. The results showed that naringin, narirutin, quercetin and naringenin were the most abundant flavonoids in grapefruit juice. In general, although every pasteurization treatment caused a significant reduction in the content of all the studied flavonoids, the treated samples were more stable during storage. While fresh squeezed juice (FS) and conventional pasteurized juice (CP) were better preserved under refrigeration conditions, microwave pasteurized juice (MP) conserved better when frozen stored. In fact, after 2months, frozen MP samples showed the greatest flavonoid retention. From this point of view, microwave treatment can be considered a good alternative to conventional pasteurization. Industrial relevance: Flavonoids are polyphenolic compounds present in fruits and vegetables relevant not only in terms of quality, as they influence the visual appearance and taste, but also from a therapeutical point of view, as they appear to be associated with the prevention of degenerative diseases. The consumption of grapefruit juice is fairly widespread among the population. Traditionally, juices have been pasteurized by heat treatment to prolong their shelf life. However, this process may cause irreversible losses of nutritional quality and antioxidant activity and, in consequence, may affect their health-related properties. In this sense, the use of microwaves can be considered an alternative to conventional thermal pasteurization. Microwave energy was applied as alternative to conventional heating for grapefruit juice pasteurization. The results obtained in this study showed that when the effect of pasteurization process and storage is considered together, the use of microwave energy led to a greater retention of all the analyzed flavonoids, thereby representing a good alternative to conventional pasteurization. In this case, frozen storage of processed product would be recommended to better preserve these compounds. [Copyright &y& Elsevier]

Abstract: Instant rice produced from a conventional process consisting of the cooking, washing and drying steps possesses poorer eating quality compared with that of freshly cooked rice. The objective of this work was therefore to study the effects of cooking, pretreatment and drying methods on microstructure, textural properties and starch digestability of instant rice after rehydration; jasmine white rice was chosen as a test material. Conventional boiling method and electric rice cooking were selected as the methods to prepare cooked rice. In the case of boiling, cooked rice was frozen at −20°C or cooled at 4°C for 24h prior to drying, while the cooked rice from an electric rice cooker was washed with ambient or cool water for 30s prior to drying. After pretreatment the cooked rice was dried either by freeze drying or hot air drying at 80°C. Based on the scanning electron microscopic results it was found that the cooking, pretreatment and drying methods all affected the rice morphology. The hardness and stickiness of instant rice after rehydration were lower for samples prepared from the rice cooker than those of freshly cooked rice, while both textural properties appeared to be improved significantly for the samples from boiling. The texture of the freeze-dried products was not different from that of the air-dried one. The freezing pretreatment provided the texture and glycemic index of instant rice after rehydration similar to those of the freshly cooked rice. On the other hand, the cooling pretreatment resulted in the harder texture and higher glycemic index of the samples. [ABSTRACT FROM AUTHOR]

Abstract: Microcapsules were prepared by spray chilling, using interesterified fat with no trans isomers fatty acids prepared with fully hydrogenated soybean oil and soybean oil in the ratio of 70:30% w/w respectively, and α-tocopherol as active ingredient. For this work we used a design with four trials a proportion of Lipid: Core material (%) 90:10, 80:20, 95:5 and 85:15 coded A, B, C, D respectively, which were subjected to storage for 180 days at three different temperatures (BOD at 22°C and -18°C freezer, in the absence of light and temperature at 25±3°C with light) and X- ray diffraction analysis (0, 60, 120, 180 days) and calorimetric measurements (time zero) were performed. The results showed values of encapsulation efficiency above 90%. Thermograms obtained by DSC, in zero time, showed no differences between the samples. The diffraction patterns obtained by X-ray diffraction, were very similar among the tests and were found the presence of three major peaks in the following angles 2θ = 19.3° d = 4.6A, 2θ = 22.8° d = 3.8A and 2θ = 23.1° d = 3.7A, which appear to be associated with the β polymorphic form. The percentage of crystallinity of the formulations obtained over time was relatively low, below 30% with no significant difference due to storage time and very similar between the tests. [Copyright &y& Elsevier]

Abstract: The aim of this work was to develop and validate a computational fluid dynamic model of the forced-air cooling process of fresh strawberries, and use it as a design tool to develop a cooling system aimed at promoting a rapid, uniform and more energy efficient process. The improved performance of the new design was experimentally confirmed. It not only significantly improved the uniform of the cooling process (essential requirement to decrease post-harvest losses), but it also replicated the cooling time of commercial designs while decreasing the pressure drop across the system by 70%. [Copyright &y& Elsevier]

Rheological properties of chocolate play a relevant role either in process design or texture definition. Nevertheless, only flow properties of molten product or mechanical properties of samples cooled at fixed temperature (usually 20 °C) are measured, whilst testing conditions close to the industrial applications (temperature close to 30 °C) are less common to be used. In this work, chocolate samples (cooled at 1 and 5 °C min) were characterised at 30 °C by using small-amplitude oscillations and low-stress creep tests, aiming at establishing how material properties are related to the chocolate microstructure. The effects of either 3 anhydrous milk fats (AMF), having different melting points, or sugar particle size were evaluated. It was found that addition of AMFs, owing to their solid content, can yield an increase in consistency; however, this effect is less relevant when coarse sugar is used, because of the broader particle size distribution, and it depends on the thermal history because of the different fat crystallisation time. Finally, creep tests resulted to be very sensitive in detecting changes in chocolate rheological properties. [ABSTRACT FROM AUTHOR]

It was aimed to evaluate the efficiency of coatings based on carboximethyl cellulose (CMC) and dextrin applied in 'Tommy Atkins' mango fruit stored for zero, ten and 20 days under refrigeration (12.4±3.1°C and 72±12% RH) and, after this period, submitted to ambient conditions (20.3±3.0°C and 40±7% RH) for three, six, eight and nine days. The CMC 1.0% + dextrin 0.2%, CMC 0.8% + dextrin 0.5% and CMC 0.5% + dextrin 1.0% coatings were compared to the control. The experimental design was completely randomized in factorial 4x7 (coating x storage time), with four replicates constituted by three fruits. The application of CMC 1.0% + dextrin 0.2% or CMC 0.8% + dextrin 0.5% delayed the soluble solids accumulation, the titratable acidity reduction and the skin color evolution, increasing fruit brightness that ensured a better appearance. The responses indicate a delay on maturation that was more evident on CMC 0.8% + dextrin 0.5% treatment. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this work was to develop and evaluate integrated processes of cooking and vacuum cooling of chicken breast cuts in a same vessel aiming at avoiding product manipulation and reducing the processing time. In this context, three integrated processes were compared with respect to weight loss and processing time: (i) vapor cooking followed by vacuum cooling; (ii) water immersion cooking followed by draining the cooking water and vacuum cooling; and (iii) water immersion cooking followed by vacuum cooling with the product immerse in the cooking water. Shorter cooling times were obtained using processes (i) and (ii), where the cooling is performed in non-immersed samples, while smaller weight losses are obtained using process (iii). Consequently, for applications in which weight loss is not an issue, processes (i) and (ii) must be used. Alternatively, process (iii) can be used for obtaining smaller weight losses with a larger cooling time. [Copyright &y& Elsevier]

'Opus' and 'Leon' snap beans were harvested, hydrocooled, held for 2 to 7 days at five temperatures and evaluated for quality attributes. The objectives of this work were to obtain quality curves at chilling and non-chilling temperatures, identify for each temperature which quality attributes limit snap beans marketability, and determine the remaining compositional value at the point the snap beans had reached the minimum acceptable quality for sale. Results from this study showed that temperature had a significant effect on the shelf life and overall quality of snap bean. Snap beans stored at temperatures higher than 10 &degC; were less green, softer and more shriveled, had higher weight loss, and lower acidity, soluble solids, ascorbic acid, and chlorophylls contents than those stored at lower temperatures. When stored at 1, 5, and 10 &degC; 'Leon' snap beans developed chilling injury (CI), whereas no visual symptoms were noticeable in 'Opus' snap beans. Although CI might have indirectly affected the quality of 'Leon' snap beans, it was not considered a sensory quality-limiting factor. Overall, weight loss was the first non-sensory quality attribute to reach the limit of acceptability, whereas firmness was the first sensory quality attribute, followed by color, to reach the limit of acceptability and therefore limited the shelf life of 'Opus' and 'Leon' snap beans cultivars. As a result of excessive water loss and accelerated softening, shelf life of both snap bean cultivars was relatively short, ranging from 1 to 3.5 days, depending on the temperature and cultivar. Furthermore, the compositional value was considerably reduced at the point of poor sensory quality. The high weight loss obtained for beans stored at all temperatures suggests that the use of a film wrap may help create a high relative humidity and therefore reduce water loss, maintain better overall quality, and extend the shelf life of snap beans. Overall, maximum shelf life and best quality were obtained when 'Opus' and 'Leon' snap beans were stored at 10 &degC;. [ABSTRACT FROM AUTHOR]

Abstract: Hydrofluidization is a method of chilling and freezing of foods that uses a circulating system that pumps the refrigerating liquid upwards through orifices and/or nozzles into a refrigerating vessel, thereby creating submerged agitating jets and increasing heat transfer to foods during freezing. The objective of this work was to develop a model to estimate the fluid flow and heat and mass transfer in a hydrofluidization system. A study case of modeling and validating the heat transfer to a single stationary copper sphere of 20-mm diameter impinged by a single round jet of liquid was carried out using computational fluid dynamics. The simulations were performed using parameters such as: velocity of the liquid at the orifice exit (2.36–7.07ms−1), temperature of the liquid refrigerant (−5 to −15°C) and distance between the orifice and the stagnation point of the sphere (1 and 5cm). In general, the errors of the model were in the order of magnitude of the uncertainty of the experimental data of Nusselt number averaged over the sphere surface. Also, the simulated heat transfer and flow field parameters were comparable with those obtained in literature for similar systems. [Copyright &y& Elsevier]

Abstract: Successful modelling of the thermal behaviour of food products requires accurate knowledge of both the thermal properties of the product and the cooling media to which it is exposed to and a correct approach to validation of the model output against experimental temperature histories. This procedure is complicated where there is uncertainty in the location at which temperature is measured in the product. The cooling of a soft cylindrical cheese product that is partially immersed in brine and air is examined. As the cheese is very deformable, it is not possible to exactly identify the measurement location of the temperature-recording thermocouples. The Uniform and Exponential probability distributions were found to best represent the variability in thermocouple location at the centre and surface of the product, respectively. Expressions for the mean measured temperature at the centre and surface that result from the distributed nature of thermocouple location were obtained. These expressions were used to derive equivalent locations in the cheese which should be used when comparing model and experimental temperature predictions. The theoretical approach was also checked against Monte Carlo simulations and there was excellent agreement between them. It was shown that when validating model temperature histories against experimental readings that this phenomenon must be taken into account. [Copyright &y& Elsevier]

In the last period, the mass and heat transfer processes are important subject, especially in the cooling and freezing food product domain. The past years literature' study reveals an increasing interest for controlling and freezing front propagation in these kind practices especially from the energy saving reasons. During the time a series of empirical approaching were developed (Lovatt, Dorodnitsyn). The present paper exposes a particular investigation for such specific processes, in order to succeed in finding out a representation for the freezing conservation technology, in our particular case, the strawberry freezing process. In our previous papers, by considering a series of initial samples with known physics parameters, were applied specific identification procedures on the experimental data sets, in order to succeed in finding a mathematical representation of the bijective link between the neural network nodes `weights approaching and the material physics parameters. In the present paper, it was developed a preliminary numerical model in order to succeed in reaching the temperature evolution' assessment during a free cooling process. For such a complex process as the fruits freezing conservation procedure, the necessary numerical model, for the first order of approximation, was complicated enough. The numerical results and the obtained correlations are encouraging and allow considering this preliminary procedure for such non-linear system to be further developed. In this way, we should improve the freezing front shift assessment in order to succeed in reaching good evolution estimations. In the present paper, we present the preliminary results of our work, pointing our numerical model performances. [ABSTRACT FROM AUTHOR]

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Quality control and monitoring of perishable goods during transportation and delivery services is an increasing concern for producers, suppliers, transport decision makers and consumers. The major challenge is to ensure a continuous 'cold chain' from producer to consumer in order to guaranty prime condition of goods. In this framework, the suitability of ZigBee protocol for monitoring refrigerated transportation has been proposed by several authors. However, up to date there was not any experimental work performed under real conditions. Thus, the main objective of our experiment was to test wireless sensor motes based in the ZigBee/IEEE 802.15.4 protocol during a real shipment. The experiment was conducted in a refrigerated truck traveling through two countries (Spain and France) which means a journey of 1,051 kilometers. The paper illustrates the great potential of this type of motes, providing information about several parameters such as temperature, relative humidity, door openings and truck stops. Psychrometric charts have also been developed for improving the knowledge about water loss and condensation on the product during shipments. [ABSTRACT FROM AUTHOR]

This study investigated the efficacy of sanitized ice for the reduction of bacteria in the water collected from the ice that melted during storage of whole and filleted Tilapia fish. Also, bacterial reductions on the fish fillets were investigated. The sanitized ice was prepared by freezing solutions of PRO-SAN® (an organic acid formulation) and neutral electrolyzed water (NEW). For the whole fish study, the survival of the natural microflora was determined from the water of the melted ice prepared with PRO-SAN® and tap water. These water samples were collected during an 8 h storage period. For the fish fillet study, samples were inoculated with Escherichia coli K12, Listeria innocua, and Pseudomonas putida then stored on crushed sanitized ice. The efficacies of these were tested by enumerating each bacterial species on the fish fillet and in the water samples at 12 and 24 h intervals for 72 h, respectively. Results showed that each bacterial population was reduced during the test. However, a bacterial reduction of < 1 log CFU was obtained for the fillet samples. A maximum of approximately 2 log CFU and > 3 log CFU reductions were obtained in the waters sampled after the storage of whole fish and the fillets, respectively. These reductions were significantly ( P < 0.05) higher in the water from sanitized ice when compared with the water from the unsanitized melted ice. These results showed that the organic acid formulation and NEW considerably reduced the bacterial numbers in the melted ice and thus reduced the potential for cross-contamination. [ABSTRACT FROM AUTHOR]

One of the most popular issues in electrostatic biology is the effects of a high-voltage electrostatic field (HVEF) on the thawing of chicken thigh meat. In this study, chicken thigh meat was treated with HVEF (E-group), and compared to samples stored in a common refrigerator (R-group), to investigate how HVEF affects chicken thigh meat quality after thawing at low temperature storage (−3 and 4 °C). The results showed that there were no significant differences in biochemical and microorganism indices at −3 °C. However, the HVEF can significantly shorten thawing time for frozen chicken thigh meat at −3 °C. After thawing chicken thigh meat and storing at 4 °C, the total viable counts reached the Intl. Commission on Microbiological Specification for Foods limit of 107 CFU/g on the 6 and 8 d for the R- and E-group, respectively. On the 8th d, the volatile basic nitrogen had increased from 11.24 mg/100 g to 21.9 mg/100 g for the E-group and 39.9 mg/100 g for the R-group, respectively. The biochemical and microorganism indices also indicated that the E-group treatment yielded better results on thawing than the R-group treatment. The application of this model has the potential to keep products fresh. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this work was to study survival of Listeria innocua and Listeria monocytogenes in muscle of cod during salt-curing and growth during chilled storage of the rehydrated product. Fresh cod was inoculated with L. innocua and L. monocytogenes at different levels before salt-curing. After salt-curing and rehydration, the levels were within 1 log10 CFU/g lower than prior to salt-curing in all experiments. During the first 5days of storage after rehydration, growth of L. innocua was observed in 1 out of 5 experiments at 4°C, but a 10–100-fold increase were observed in all experiments from day 5 to day 10. The growth started earlier and was more rapid when samples were stored at 7°C. Growth of L. monocytogenes at 4°C appeared to start earlier than for L. innocua, but a 10–100-fold increase was observed also for this bacterium. The lag phases in rehydrated products were longer than in experiments with cod muscle juice. The differences could be explained by a different level of salt stress. This work demonstrates that long term exposure to very high salt concentrations does not eliminate Listeria spp., and that Listeria being present in the fish prior to salt-curing can recover and grow in rehydrated salt-cured cod during chilled storage. [Copyright &y& Elsevier]

Abstract: In this study, the influence of the hot-fill water-spray-cooling process after continuous pasteurization on the number of decimal reductions (γ) and growth parameters (lag time; λ, ratio N f /N o; κ, maximum growth rate; μ) of Alicyclobacillus acidoterrestris CRA 7152 in orange juice stored at 35°C were investigated. Two different inoculum levels of A. acidoterrestris CRA 7152 (102 and 103 spores/mL) in orange juice (110Brix, pH 3.7) and a Microthermics UHT-HTST pilot plant were used to simulate industrial conditions. Results have shown that regardless of the inoculum level (102 or 103 spores/mL), the pasteurization processes were unable to cause even 1 γ. Predictive modeling using the Baranyi model showed that only κ and time to reach 104spores/mL (t104 — time to juice spoilage) were affected by the spore inoculum used (p <0.05). It has been concluded that A. acidoterrestris was able to survive the hot-fill process and to grow and spoil orange juice in 5–6days when the final storage temperature was 35°C. [Copyright &y& Elsevier]

Abstract: The impact of cooling rates (0.40, 1.11, 1.42, 1.64, 2.47 and 3.36°C/min) on starch retrogradation and textural properties of cooked rice was evaluated. The relationship between cooling rates and different properties were determined using Pearson correlation. Starch retrogradation enthalpy (ΔH r) of cooked rice was determined by differential scanning calorimetry, and textural properties were determined by a Texture Analyser. This study showed that the ΔH r value and hardness value had a negative correlation with cooling rate during storage, −0.963⩽ r ⩽−0.716, P <0.01; −0.826⩽ r ⩽−0.706, P <0.05, respectively. However, a positive correlation was found between adhesiveness and cooling rate (0.237⩽ r ⩽0.882, P <0.05). These results indicated that the cooked rice chilled with slower cooling rate retrograded faster than chilled with rapid cooling rate. Therefore, high quality cooked rice can be produced by rapid cooling process. [Copyright &y& Elsevier]

Abstract: The effects of cooling temperature (CT) (0–2, 2–4, or 4–6°C) and hot carcass weight (HCW) (either ⩽10.5 or ⩾12.0kg) on weight loss (WL) and meat quality were evaluated in 60 lamb carcasses of Rasa Aragonesa breed. Carcasses were exposed to CT throughout 90h. WL was assessed at 18, 42, 66, and 90h post-slaughter. pH, colour, instrumental measurement of texture, oxidation, and sensory parameters were evaluated in longissimus thoracis et lumborum aged for 96h following standard methods. Sensory test involved a trained test panel. No significant interactive effects among the parameters evaluated were detected in the study. The lower the CT, the higher the WL after 90h in storage (0.25% lost each 2°C decrease), the higher final pH, and the lower lightness, the higher hue and chroma of the meat. Toughness was higher in meat cooled at 2–4°C than in meat cooled at temperatures above or below this range. Neither oxidation nor sensory variables were affected by CT. Regarding on HCW, light carcasses exhibited higher WL (2.39% versus 2.04% after 90h of cooling), higher final pH, and lower levels of oxidation than did heavier carcasses. Neither colour nor instrumental measurement of texture was affected by HCW. Lamb and fat odour and metallic and acid flavour intensities were significantly greater in the heavier carcasses, although it did not affect overall acceptability. Both CT and HCW should be considered as main effects on lamb quality, especially CT. [Copyright &y& Elsevier]

Abstract: Most industrial food cooling is performed by air blast, water spraying and immersion cooling. Immersion cooling is simple, with low operational cost and leads to food quick cooling. The objective of this work was to investigate the influence of water agitation method (water injection, air injection and water injection coupled to a Venturi ejector) on the average heat transfer coefficient () between food and cooling water. Time–temperature evolutions of a sphere immersed in the cooling media were used to determine the heat transfer coefficients at different positions in a cooling tank. Air injection and water injection coupled with a Venturi ejector significantly increased the heat transfer coefficient between food and cooling water. For the investigated conditions, was increased up to eight times, when air injection was used. However, the complex flow of bubbles and water inside the tank created heterogeneous water agitation, creating zones with different heat transfer coefficients. Furthermore, the use of water recirculation coupled with a Venturi ejector can be very convenient for cases where pressurized air is not available, but the best agitation solution depends on each case. [Copyright &y& Elsevier]

The article presents a science experiment to help students understand the concept of self -heating or self-cooling food products. It provides methodologies used in the experiment which are foundation for problem-based learning (PBL) and framework for inquiry-guided instruction (IGI), and an activity on the applied principles and rationale to self-heating beverages and Meals, Ready to Eat (MREs).

Abstract: The aim of this study was to investigate the impact of superchilling (−2°C) on the evolution of Listeria monocytogenes and organoleptic characteristics of cold-smoked salmon samples. An Hadamard matrix experimental design was carried out on artificially inoculated samples stored at +4°C for 10d and at +8°C for 18d to know the influence of four factors: salt content, strain, cold stiffening and superchilling time, on the level of L.monocytogenes in cold-smoked salmon. The growth of L. monocytogenes in naturally contaminated cold-smoked salmon and the organoleptic properties were investigated under superchilling conditions. Superchilling (−2°C for 28d) had a limited impact on some of the organoleptic properties but the level of L. monocytogenes at the end of the shelf-life (4°C for 10d and 8°C for 18d) could exceed the microbiological criterion set by the European legislation. [Copyright &y& Elsevier]

Abstract: The effect of natural additives, superchilling, and modified atmosphere packaging (MAP) on the shelf-life of Atlantic Salmon (Salmo salar) fillets was investigated. The variables analyzed were: gas concentration (CO2:N2), gas-to-product volume (g/p) ratio and type of natural additive. Experiments were monitored by sensory, chemical, and microbiological analyses. Natural additives did not improve salmon shelf-life. The greatest extension of shelf life was reached by a combination of superchilling and MAP. The samples with the highest CO2 concentration (90%) and g/p ratio of 2.5 showed the highest shelf-life: 22 days vs. 11 days (control sample). Microbial analysis determined the ultimate shelf-life. [Copyright &y& Elsevier]

Abstract: This paper describes a detailed procedure into the investigation of optimised control strategies for CO2 cycles in medium temperature retail food refrigeration systems. To achieve this objective, an integrated model was developed composing of a detailed condenser/gas cooler model, a simplified compressor model, an isenthalpic expansion process and constant evaporating temperature and superheating. The CO2 system can operate subcritically or transcritically depending on the ambient temperature. For a transcritical operation, a prediction can be made for optimised refrigerant discharge pressures from thermodynamic cycle calculations. When the system operates in the subcritical cycle, a floating discharge pressure control strategy is employed and the effect of different transitional ambient temperatures separating subcritical and transcritical cycles on system performance is investigated. The control strategy assumes variable compressor speed and adjustable air flow for the gas cooler/condenser to be modulated to achieve the constant cooling load requirement at different ambient conditions. [Copyright &y& Elsevier]