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Abstract Background Vacuum cooling (VC) is a cooling technology for moist and porous foodstuffs with superiority in cooling rate, uniformity and hygiene, and low energy consumption. However, there are still some disadvantages that weaken the competitiveness of industrial applications such as the inevitable mass loss and uneven cooling in different parts of leafy vegetables. In order to improve the performance of VC, many efforts have been performed. Scope and approach In this review, the basic information of VC and the main applications for fruit, vegetables and meat products as well as limitations are described first. Improvements for enhancing performances of this technology in terms of operation processes including pre-treatment, technical optimization and integration, as well as equipment upgrade, and optimized operation conditions such as final pressure and pressure reduction rate are discussed. In addition, the limitation and further prospects of VC in the food industry are also mentioned. Key findings and conclusions The findings presented in this review demonstrated that optimizing operation processes and controlling operation conditions can effectively improve the performance of VC including mass loss, cooling rate and energy consumption and temperature distribution. However, many enhancing strategies still have limitation for applied in the food industry. Future trends of VC are the study of moisture migration characteristics based on food microstructure and multi-functional optimization of VC process or system. It is hoped that the current review can provide some guidance for further developments of the VC technology. Highlights • Contemporary applications of vacuum cooling to foods are presented. • Limitations in application and performance of vacuum cooling are discussed. • Innovative operation processes to improve vacuum cooling technology are assessed. • Strategies to refine operation conditions of vacuum cooling are outlined. • Key research trends comprise moisture migration and multi-functional optimization. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the ability of Bacillus cereus spores to germinate and grow in order to determine a safe cooling rate for cooked rice, beans, and pasta, rice-chicken (4:1), rice-chicken-vegetables (3:1:1), rice-beef (4:1), and rice-beef- vegetables (3:1:1). Samples were inoculated with a cocktail of four strains of heat-shocked (80°C for 10 min) B. cereus spores (NCTC 11143, 935A/74, Brad 1, and Mac 1) to obtain a final spore concentration of approximately 2 log CFU/g. Thereafter, samples were exponentially cooled through the temperature range of 54.5 to 7.2°C in 6, 9, 12, 15, 18, and 21 h. At the end of the cooling period, samples were removed and plated on mannitol egg yolk polymyxin agar. The plates were incubated at 30°C for 24 h. The net B. cereus growth from spores in beans was <1 log after 9 h of cooling, but the pathogen grew faster in rice and pasta. In combination products, the net growth was as follows: 3.05, 3.89, and 4.91 log CFU/g in rice-chicken; 3.49, 4.28, and 4.96 log CFU/g in rice-beef; 3.50, 4.20, and 5.32 CFU/g in rice--chicken--mixed vegetables; and 3.68, 4.44, and 5.25 CFU/g in rice--beef--mixed vegetables after 15, 18, and 21 h of cooling, respectively. This study suggests safe cooling rates for cooling cooked rice, beans, pasta, rice-chicken, rice-chicken-vegetables, rice-beef, and rice-beef-vegetables to guard against the hazards associated with B. cereus. [ABSTRACT FROM AUTHOR]

Food freezing is one of the most energy-intensive technologies used to preserve food products in domestic manufacturing operations. To acquire the heat load profile during freezing process, measurements and simulation have been conducted on a running refrigerated warehouse as part of a large cold storage. Continuous temperature measurements have been taken in the chosen room and rooms around it, as well as the outdoor temperature and the evaporation temperature in air coolers. The dynamic heat gain from warehouse structures and air coolers was simulated based on the measured temperatures and operation mode of refrigeration system. An verified food freezing model was applied to model the heat load of food products to analyze the influence of air temperature on freezing process. Results show that the heat load through warehouse structures has little impact on room temperature compared to the heat load of air coolers and food products. Due to the large transients induced by on/off control strategy of refrigeration system, the refrigeration capacity changes greatly during freezing process which has the same trend as the heat load of food products. It can be concluded the heat load of refrigerated warehouse varies greatly at different stages of freezing process. Different control strategies of refrigeration system need to be applied at different stages of food freeing from energy-saving point. [ABSTRACT FROM AUTHOR]

In recent years, the temperature of processed olives in many olive-growing areas was often close to 30 °C, due to the global warming and an early harvesting period. Consequently, the new trends in the extraction process have to include the opportunity to cool the olives or olive paste before processing to obtain high quality EVOO. A tubular thermal exchanger was used for a rapid cooling treatment (CT) of olive paste after crushing. The results did not show a significant difference in the oil yield or any modifications in the legal parameters. The cooling process determined a significant improvement of phenolic compounds in all the three Italian cultivar EVOOs analyzed, whereas the volatile compounds showed a variability largely affected by the genetic origin of the olives with C 6 aldehydes that seem to be more stable than C 6 alcohols and esters. [ABSTRACT FROM AUTHOR]

In this study we investigated the combined effect of shearing and cooling rate in the rheology of organogels developed in high oleic safflower oil by ( R )-12-hydroxystearic acid (HSA), its primary amide derivative [( R )-12-hydroxyoctadecanamide, HOA], and the N -octadecyl derivative of HOA [( R )- N -octadecyl-12-hydroxyoctadecanamide, OHOA]. The experimental set up to develop the organogels involved: 1). The use of quiescent (0 s − 1 ) or shearing (300, 600, and 1200 s − 1 ) conditions during cooling the gelator solutions (2%) just until achieving the gelator's melting temperature (T M ) in the vegetable oil, to then continuing the cooling under static conditions until achieving 15 °C) The use of cooling rate protocols involving a constant cooling rate of 1 °C/min (CR 1 ) or 10 °C/min (CR 10 ) in the shearing and static stages, or variable cooling rates in each stage (i.e., VR 1–10 or VR 10–1 ). The elasticity of the organogels ( G ′) was measured while cooling under static conditions, once the systems achieved 15 °C, and after 60 min at this temperature. The rheological results obtained at 15 °C showed a cooling rate and molecular weight-dependent effect of shearing on G ′. We propose that the molecular relaxation time of gelator molecules, and its increase as molecular weight increases and as temperature decreases, plays an important role on the gelator's susceptibility to go through a shear induced crystallization process. Therefore, high molecular weight molecules like OHOA (551.97 Da) would remain stretched by shearing longer times than HSA (300.49 Da) and HOA (299.49 Da). Thus, when shearing was applied while cooling at the higher cooling rate (i.e., CR 10 and VR 10–1 ), the stretched OHOA molecules would lead to the development of mesophase precursors that upon further cooling under quiescent conditions, crystallize developing a well-structured organogel. In contrast, stretched low molecular weight molecules (i.e., HSA and HOA) with shorter relaxation time would dissolve back to the isotropic state during cooling. Additionally, the rheological results of HSA and HOA organogels suggested that the shear induced crystallization process might be dependent on the gelator polarity also. These results show that the application of shear and the extent of its application as temperature decreases until achieving T M , have important implication on the self-assembly of gelator molecules, and therefore in the organization and rheology of the three-dimensional crystal network of the organogel. [ABSTRACT FROM AUTHOR]

The aim of this study was to gain a better understanding of the tenderisation mechanism associated with very fast chilling (VFC) of beef muscle. Hot-boned striploins from 36 carcasses were allocated to a treatment (control, delayed or immediate chilling below 0 °C), and each striploin was divided into three equal portions and allocated to a time post-mortem (2, 5 or 14 d). Immediate chilling resulted in lower peak force values at 2 d post-mortem and lower particle size after 5 d post-mortem. Both chilling treatments significantly improved the WHC by reducing drip loss and cooking loss. Sarcomere lengths were not affected by chilling treatments, although fragmentation and cleavage of muscle fibres were evident along the fibre length, possibly contributing to the reduction in peak force values at 2 d post-mortem. Both delayed and immediate chilling resulted in a higher pH at 4 and 24 h post-mortem, and colour parameters were modified. These results suggest that VFC has potential for accelerating tenderisation early post-mortem by a combination of biochemical and biophysical effects. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Desiccant wheel based air handling units are of great interest in drying processes, such as in the pharmaceutical and food industries, due to the significant energy savings that can be achieved compared to conventional systems. Units based on desiccant wheels are usually optimized in peak conditions, while little attention is given to operation at part load and off design conditions. The aim of this work is to analyze the effects of different control strategies of desiccant wheels on regeneration heat consumption. The analysis is performed through a phenomenological desiccant wheel model, which is validated with experimental data collected in typical working conditions of the drying room investigated in this work. Five control strategies are proposed, highlighting that each one leads to significantly different heat consumption. Finally, an additional simplified control is introduced, showing that it can effectively reduce thermal power consumption compared to conventional control strategies. [ABSTRACT FROM AUTHOR]

Regulation of sugar metabolism in potato tubers stored at low temperatures has significant ramifications for producers and consumers of potato chips and French fries. Low-temperature storage reduces losses due to sprouting and disease but induces undesirable accumulation of the reducing sugars glucose and fructose. These sugars react with free amino acids during frying to produce dark-colored and bitter-tasting products that have elevated levels of acrylamide, a suspected human carcinogen. Elevated amounts of tuber glucose and fructose are produced when vacuolar acid invertase (VInv) hydrolyses sucrose derived from starch degradation. In this study, wild-type tubers and tubers in which VInv expression was reduced by RNA interference were used to study the temperature-dependent regulation of sugar accumulation and expression of carbohydrate metabolism genes during and after the cooling of tubers to 9 or 3 °C. It was found that transcriptional control of genes central to carbohydrate metabolism occurred in three overlapping phases. First, early in cooling, slight increases in VInv and β-amylase expression occurred. Second, at lower temperatures, large decreases in AGPase and GBSS expression were observed. Finally, when tubers reached 3–5 °C, large increases in β-amylase expression were observed, coinciding with large increases in sucrose in all genotypes and large increases in glucose and fructose in tubers with high VInv expression. Suppression of VInv expression did not alter the expression of β-amylase , AGPase , GBSS , or other genes, indicating that there was little or no feedback from reducing sugars to transcriptional control of carbohydrate metabolism. Invertase activity of WT tubers stored at 9 °C was comparable to that of WT tubers stored at 3 °C, but reducing sugars were markedly higher at the lower temperature. Taken together, these data support a model in which reducing sugar accumulation is controlled both by temperature-regulated changes in sucrose accumulation, resulting from increased starch degradation by β-amylase and decreased starch resynthesis by AGPase and GBSS, and by differences in VInv activity that persist throughout storage. [ABSTRACT FROM AUTHOR]

Food processing has significant simultaneous requirements of cooling, warm water and hot water. In order to reduce energy consumption and greenhouse gases emission, one type of NH 3 heat pump and two types of transcritical CO 2 heat pumps are proposed. These natural refrigerant heat pumps can supply not only cooling, but also warm water and hot water simultaneously. The characteristics and performance of the heat pumps are analyzed and simulated. Annual primary energy saving and annual operation cost saving are predicted for California, Wisconsin, New York, and Florida. Research results show that the maximum possible value of annual primary energy-saving rates using the CO 2 heat pumps ranges from 56% to 65%, and using the NH 3 heat pump is approximately 44%; the maximum possible value of annual operation cost saving rates using the CO 2 heat pumps ranges from 50% to 66%, and using the NH 3 heat pump is from 20% to 47%. [ABSTRACT FROM AUTHOR]

The effect of tempering (20, 30 and 40 °C) and the cooling rate (0.5 and 2 °C/min) on physical properties and stability of whipping and whipped cream was investigated. Rheological behavior and light microscope observations showed that tempering at 30 °C and fast cooling created convenient condition for forming partial coalescence between fat globules in whipping cream. This special linkage helped to prevent serum leaking out of whipped cream when storing them at low temperature (4 °C). However, tempering at 20 °C would have been a more appropriate choice to stabilize structure of products through balance different types of partial coalescence in whipped cream during storage. [ABSTRACT FROM AUTHOR]

The antimicrobial impact of purified and natural sources of both nitrite and ascorbate were evaluated against Clostridium peifringens during the postthermal processing cooling period of deli-style turkey breast. The objective of phase 1 was to assess comparable concentrations of nitrite (0 or 100 ppm) and ascorbate (0 or 547 ppm) from both purified and natural sources. Phase II was conducted to investigate concentrations of nitrite (50, 75, or 100 ppm) from cultured celery juice powder and ascorbate (0, 250, or 500 ppm) from cherry powder to simulate alternative curing fonnulations. Ground turkey breast (75% moisture, 1.2% salt, pH 6.2) treatments were inoculated with C. perfringens spores (three-strain mixture) to yield 2.5 log CFU/g. Individual 50-g portions were vacuum packaged, cooked to 71.1°C, and chilled from 54.4 to 26.7°C in 5 h and from 26.7 to 7.2°C in 10 additional hours. Triplicate samples were assayed for growth of C. perfringens at predetermined intervals by plating on tryptose-sulfite-cycloserine agar; experiments were replicated three times. In phase I, uncured, purified nitrite, and natural nitrite treatments without ascorbate had 5.3-, 4.2-, and 4.4-log increases in C. perfringens, respectively, at 15 h, but

This paper presents the results of a cold chain field study in France in 2013 carried out in the framework of a European project named Frisbee. A comparison with the results obtained in a previous field study in France in 2002 was presented. These two studies enabled us to have a real picture of the cold chain because temperature monitoring was carried out in a manner not visible to operators and consumers. These studies concern the cold chain of chilled products from the production plant to storage in a domestic refrigerator. The Frisbee field study confirms the results observed in previous work that the most sensitive links are transportation after purchase and particularly storage in a household refrigerator. Despite the regulation imposed by the French authorities since 2002 to indicate the cold zone in refrigerators where sensitive products should be placed, the preservation of products at home is still problematic. [ABSTRACT FROM AUTHOR]

Flowrate and distribution of air is a critical design factor in the cooling, refrigeration and drying of horticultural food products. These operations rely on a constant supply of air distributed throughout bulk arrangements of the produce. Local distribution of the air is critical to optimising the design and efficiency of these processes. Identification of the key parameters affecting the airflow distribution has been done either experimentally (using intrusive point-wise or bulk measurement techniques) or numerically. The detailed information provided by the use of computational fluid dynamic models has facilitated unique opportunities to investigate alternative system designs, without the need for expensive and time consuming experiments. This study provides a review of the techniques available to measure airflow (thermal and rotatory vane anemometry, pressure differential devices, tracer gases, LDA and PIV). Their advantages and disadvantages (accuracy, resolution, application range, cost, and ease of use) as well as their application in the validation of numerical models are reviewed. The novel and scientifically based design guidelines developed by a better understanding of the airflow behaviour within the system for each of the operations under study are also presented. [ABSTRACT FROM AUTHOR]

Data are lacking on the temperature changes of food during transport without the use of refrigerated trucks. The purpose of this study was to evaluate the ability of several insulated and noninsulated containers with or without frozen gel packs to keep perishable and refrigerated foods within the temperature safe zone in relationship to duration of transport. The study was designed to duplicate the practices exhibited by customers purchasing perishable food products from a cash-and-carry business. Approximately 40 perishable food items were evaluated. Four types of containers were tested: a mylar foil bag, a commercial insulated bag, a generic insulated bag, and a commercial insulated blanket. Mixed foods were placed into these containers with or without frozen gel packs, transported in unrefrigerated vehicles, and monitored for 4 h for temperature changes. Two environmental temperatures, room temperature of 21.1°C and a stress temperature of 37.8°C, were evaluated. The internal temperature and surface temperature of the food products in these containers increased slowly but remained well below the U.S. Food and Drug Administration Food Code requirements. The various containers were similar in their ability to retain coolness. The presence of frozen gel packs dramatically enhanced the cold-holding capacity of the containers. The temperature of foods increased more rapidly when stressed in a heated environment. The containers tested used with the frozen gel packs can keep the surface and internal temperatures of various perishable foods (starting at 4.4°C or less) within the Food Code recommendation of under 21.1°C for 4 h. Cash-and-carry businesses should strongly encourage their retail customers to utilize these containers with frozen gel packs to safely transport perishable foods. [ABSTRACT FROM AUTHOR]

Highlights: [•] The new package designs showed an improved cooling rate and cooling uniformity. [•] The new package designs reduce the energy load due to their lower aerodynamic resistance. [•] Package design is a cost-effective way for improving forced-convective precooling. [•] Basic information on the packages was obtained to guide future cold-chain design decisions. [ABSTRACT FROM AUTHOR]

Abstract: The cook-chill operation, a widely used process within central cooking facilities, implies that cooked dishes have to be quickly cooled down immediately after cooking in order to prevent any food-borne diseases due to Clostridium perfringens. The food service operators are obliged to validate the efficiency of the cooling process in the context of their HACCP plan. To perform this cooling process, they can either ensure compliance with some reference criterion (maximal cooling duration) or demonstrate that the cooling operation is safe by carrying out prior tests. This document presents an experimental method to validate the sanitary efficiency of the cooling process. In the studied kitchen the food was cooked and, successively, distributed into plastic containers, cooled down in blast-chiller and then stored in cold room. The tests consisted in monitoring food temperature at the center of the containers from the end of cooking until the beginning of cold room storage. The measurements were performed during 6 cycles of food preparation. From the monitored time–temperature profiles, thermal cooling equations were established for modeling. Each parameter of these thermal equations was linked with a distribution fitted with the experimental data. Then these thermal equations were coupled with predictive microbiology equations. A probabilistic calculation of the C. perfringens potential growth was carried out by using @Risk software. The proposed method required only simple monitoring equipments and could be easily implemented in central kitchens under the usual working conditions. The cooling conditions in the studied kitchen could be considered as satisfactory because the calculations give only a 0.4% probability that the C. perfringens potential growth was equal or greater than 1 log10 cfu/g. [Copyright &y& Elsevier]

Highlights: [•] CFD models of 1-MCP transport based on detailed geometries of boxes and individual fruit have been developed. [•] Models and measurements showed uniform distributions of the gas in air throughout the treatment period. [•] The level of air circulation in room cooling process is sufficient to uniformly distribute the 1-MCP in the air. [•] Wooden boxes significantly deplete the active substance from the treatment atmosphere. [•] The study suggests dose reduction. [Copyright &y& Elsevier]

Highlights: [•] Optimization of hard candy cooling stage. [•] Development of a NLP mathematical model to obtain optimal operating policies. [•] Quality constraints and operating cost are considered. [•] Operating conditions and production planning are obtained for three operating modes. [•] The model is useful to be applied in other hard candy lines. [Copyright &y& Elsevier]

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]

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]

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]

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]

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: 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: 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]

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]

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]

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]

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]