Search

Blueberry is widely grown around the world, and the United States is the leading producer. A strategy to maintain fruit quality during commercial handling is rapid cooling using the forced-air system. Hydrocooling (HY) is an effective cooling method widely used for many crops and has potential as a cooling method for blueberry. The objective of this study was to compare the cooling efficiency of conventional forced-air cooling (FA), the current commercial method, with immersion HY alone or HY in combination with FA (HY + FA), and to determine effects on blueberry fruit quality during subsequent cold storage. ‘Emerald’ and ‘Farthing’ southern highbush blueberry were commercially harvested and packed into plastic clamshell containers. FA was accomplished by simulating commercial conditions using a small-scale unit within a cold room at 1 °C/80% relative humidity (RH) until 7/8 cooling was achieved (27 minutes). For HY, fruit in clamshells (125 g) were immersed in chlorinated ice water (200 ppm free Cl−1, pH = 7.0) and 7/8 cooling occurred in 4 minutes. For HY + FA, fruit were 7/8 hydrocooled then transferred to FA for 30 minutes to remove free water from the fruit. After the cooling treatments, clamshells were evaluated weekly for selected quality parameters during 21 days storage at 1 °C. For HY treatment, the 1/2 cooling time was 1.13 minutes for ‘Emerald’ and 1.19 minutes for ‘Farthing’, whereas for FA treatment, the 1/2 cooling times were 4.5 and 6.8 minutes, respectively. For ‘Farthing’, cooling method did not affect fruit firmness; after 21 days, there was a slight softening in fruit from all treatments. However, ‘Emerald’ fruit cooled by HY + FA were softer than those from either HY or FA after 14 days of storage. For all cooling methods ‘Emerald’ was less acidic (0.3% citric acid) and was sweeter [10.2% soluble solids content (SSC)] than ‘Farthing’ (0.6% citric acid, 9.4% SSC). There were no differences in bloom among cooling methods. Bloom ratings for ‘Emerald’ remained >4.5 (70% to 80% coverage) whereas that for ‘Farthing’ cooled by HY or HY + FA was 3.7. Anthocyanin concentration in ‘Emerald’ fruit from HY + FA cooling method decreased by 33% during 21 days of storage, whereas that for ‘Farthing’ remained constant (8.3 mg cyanidin-3-Glicoside/g) irrespective of treatment during storage. Compared with ‘Farthing’, ‘Emerald’ was more sensitive to HY, where ≈15% of fruit developed visual skin breaks (split) after 7 days storage. HY shows potential as an alternative method to rapidly and thoroughly cool southern highbush blueberries such as ‘Farthing’, thus, maintaining fruit quality, while introducing a rinsing and sanitizing treatment. HY needs to be tested on commercial cultivars to determine the incidence of fruit splitting.

A 3-D computational fluid dynamics (CFD) model was developed to describe and predict the temperature profiles of palletised polylined kiwifruit packages undergoing forced-air cooling. The geometrical configuration of the kiwifruit, polyliner and cardboard box were explicitly modelled. The model included the effects of natural convection on the airflow behaviour and heat transfer process occurring within the packed fruits inside the polyliner. The capability of the model to predict the fruit temperatures in each package was quantitatively validated against experimental data. A laboratory scaled experimental rig was used to monitor the forced-air cooling process of a half pallet of kiwifruit boxes under controlled operating conditions. The numerical model was able to predict cooling times within experimental error. Cooling within the pallet was primarily influenced by air temperature and to a lesser extent airflow distribution into each package. A maximum recommended volumetric flowrate through the pallet of 0.34 L kg(-1) s(-1), far lower than flowrates recommended for the cooling of non-polylined produce, was identified. Successive increases to the flowrate, particularly beyond 0.34 L kg(-1) s(-1), resulted in increasingly diminished reductions (< 12%) to cooling rate. Within the polyliner there was a low transfer of energy between kiwifruit and kiwifruit surrounding air. Instead cooling was reliant on the air temperature flowing over the top of the polyliner. (C) 2016 Elsevier B.V. All rights reserved. publisher: Elsevier articletitle: Modelling the forced-air cooling mechanisms and performance of polylined horticultural produce journaltitle: Postharvest Biology and Technology articlelink: http://dx.doi.org/10.1016/j.postharvbio.2016.05.008 content_type: article copyright: © 2016 Elsevier B.V. All rights reserved. ispartof: Postharvest Biology and Technology vol:120 pages:23-35 status: published

Kimchi cabbage ‘Choon Gwang’ cultivar that was grown in highlands in Gangneung was subjected to predrying, room cooling, and forced air cooling, and then packed with/without 0.02 ㎜ HDPE film to investigate the effect of postharvest treatment on quality characteristics during 8 weeks storage at 2℃ (RH 90 ± 5%). Weight loss in forced air cooling and room cooling was lower than 3-4% with 0.02 ㎜ HDPE film liner treatment during storage. However, it was only below 10% in room cooling without liner treatment and forced air cooling without liner treatment led to the highest weight loss, above 15%. Conversely, the control had lower weight loss than the others. SSC was 2-4°brix for all treatments and there was no difference between postharvest treatments and liner treatments. Color index and firmness both showed no differences with/without 0.02 ㎜ HDPE film and postharvest treatments. In sensory evaluation, forced air cooling with liner treatment was effective, with the highest score, especially in appearance and crispness. After 6 weeks, control kimchi cabbage without liner treatment was damaged seriously in appearance and the internal color had changed to brown. Room cooling and predrying with liner treatment changed the start of internal browning to after 8 weeks storage.

Leafy greens including baby spinach are particularly prone to rapid dehydration. After harvest, leafy greens should be refrigerated as soon as possible to remove the heat from the field in order to decrease respiration rate and increase shelf-life. Delays between harvest and cooling should be avoided, especially during warm weather to avoid water loss. There is a wide range of precooling systems available for using in fresh produce. However, the best precooling system for baby leaves as raw material for the fresh-cut industry has not been well established. The aim of this study was to compare four precooling systems including room cooling (RC), forced air cooling (FAC), hydro cooling (HC) and vacuum cooling (VC) for their effects on quality and shelf-life of baby spinach. Two separate trials, one in winter and another in spring were carried out. Leaf water content increased after cooling in HC and VC but more significantly in winter while in spring, differences among treatments were not significant. The colour measured as chroma was more vivid in HC and VC just after processing but after storage, no differences among precooling treatments were observed. In winter, there were no significant differences in the respiration rate among precooling systems. However, in spring, HC and VC decreased respiration rate and modified less the headspace gas composition of the packages. Pseudomonas counts significantly decreased in HC and VC due probably to the washing effect of the leaf surface without promoting the growth of spoilage microorganisms. Surprisingly, visual quality was significantly lower in VC compared with the rest of precooling treatments due to the higher degree and number of damaged leaves. In conclusion, selection of the precooling system is critical during warm weather because of the high temperature at harvest. Hydro cooling is a good precooling system for baby spinach in spring as it decreases rapidly leaf temperature, decreasing respiration rate and extending shelf life. However, in winter, precooling systems are not as critical because the temperature at harvest was similar to the temperature reached after precooling.

Kimchi cabbage ‘Choongwang’ cultivar is mainly cultivated during summer in Gangneung area. ‘Choongwang’ cultivar was harvested in late July, applied with predrying, room cooling, and forced air cooling, and then packaged with/without 0.02 mm HDPE film to estimate the effect of postharvest treatment on quality characteristics (weight loss, trimming loss, firmness, SSC, color index, sensory evaluation) during 8 week storage at 2°C. Kimchi cabbage without 0.02 mm HDPE film showed high weight loss up to 13-20% while those of with liner were significantly lower. Also forced air cooling among the postharvest treatments was effective to reduce both weight loss and trimming loss. Appearance and freshness in sensory evaluation were the important factors in estimating good quality during storage. Liner treatment with forced air cooling showed highly significant for maintaining appearance and freshness (P ≤ 0.01). Color index was no differences between with/without 0.02 mm HDPE film and postharvest treatments. After 6 weeks storage in without 0.02 mm HDPE film with room cooling or control appearance was severely damaged and also internal browning was found. While in with 0.02 mm HDPE film internal browning was found after 8 weeks storage, just in room cooling or predrying treatment.

The SO 2 technology is the current practice for storage of table grapes. While it has been under scrutiny in the last decade and there is a constant demand for alternative technologies, it remains the only established method for extended storage of table grapes. We present 3 tools which improve the efficiency, longevity and accuracy of storage of grapes with SO 2 . Most of the industry is packaging grapes in cartons containing liners in which dual release SO 2 sheets are placed on the grapes. This packaging confines the SO 2 to the clusters but it compromises the efficiency of forced air cooling. The alternative method is to avoid the use of liners and to wrap the pallet with polyethylene stretch film. This process reduces forced-air cooling time, saving energy and a considerable amount of plastic packaging material. The level of SO 2 in the pallet is low because the pallet's bottom is open and the quality of the rachis is high because the humidity in the pallet is high as well. Adoption of this technology for extended storage of 'Red Globe' grapes stored in plastic boxes, by closing the bottom of the pallets, proved to be problematic due to high levels of SO 2 and short duration of release. By placing the SO 2 releasing sheets in plastic bags containing holes in the bottom, it was possible to extend the storage from 3 month to 4.5 month with satisfactory quality and levels of sulfites within the grapes that did not exceed the threshold of 10 mg kg -1 . To improve the quality of the process we developed an analytical method to measure the rate of SO 2 released from the SO 2 sheets. These 3 methodologies are practiced on a commercial scale enabling storage of table grapes of consistent quality.

Red hot chili cv. 'Superhot' is widely produced in Thailand and exported to many regions. The exporting value of red hot chili increases year by year and rises over 100 million baht per year. However, the problem during the export of red hot chili is darkening at the pedicel area due to water loss from stomata opening. Pre-cooling has been introduced for keeping the quality in various commodities. The purpose of this research was to investigate the effect of different pre-cooling techniques on stomata closing. Red hot chili were purchased from an exporting company in Nakornrachasima Province, Thailand then pre-cooled by using hydro-cooling at 0, 2 and 4°C or forced-air cooling at 4°C with various air velocities (1, 3 and 5 m/s). Control treatment was performed with non-pre-cooled chili. Stomata of red hot chili were monitored under scanning electron microscopy. Stomata apertures were observed only at the pedicel surface and were absolutely absent on the fruit surface. Hydro-cooled chili at 0 and 2°C resulted in significantly closing stomata while the same process at 4°C was only partially closing them. In contrast, forced-air cooled chili at all air velocities did not close stomata apertures in comparison with the control treatment. Hydro-cooled chilies maintained a better external quality than forced-air cooled fruit judged by the degree of pedicel darkening. The darkening was significantly reduced by hydro-cooling whereas slightly decreased by forced-air cooling. These results suggest that hydro-cooling is a suitable technique for keeping the quality of red hot chili after harvest.

Hydrocooling was evaluated as an alternative to forced-air cooling for strawberry (Fragaria × ananassa) fruit. `Sweet Charlie' strawberries were cooled by forced-air and hydrocooling to 4 °C and held in different storage regimes in three different trials. Quality attributes, including surface color, firmness, weight loss, soluble solids, and ascorbic acid content, pH and total titratable acidity, were evaluated at the full ripe stage. Fruit hydrocooled to 4 °C and stored at different temperatures for 8 or 15 days showed overall better quality than forced-air cooled fruit, with significant differences in epidermal color, weight loss, and incidence and severity of decay. Fruit stored wrapped in polyvinylchloride (PVC) film after forced-air cooling or hydrocooling retained better color, lost less weight, and retained greater firmness than fruit stored uncovered, but usually had increased decay. There is potential for using hydrocooling as a cooling method for strawberries.

The application of techniques of simulation of cooling processes may become an important and practical tool as it allows predicting with great approximation the response of the horticultural crops to the cooling process. This work presents a mathematical model and numeric simulation to describe the cooling process of a solid particles bed of different geometry, considering the dimensions of commercial packages. The equations that describe the balance of mass and energy for the product and for the cooling mean are resolved applying the Finite Volume Method. The numeric results are compared to experimental data obtained during the cooling process of orange (Citrus sinensis Osbeck L. 'Valencia') and banana (Musa cavendishi 'Prata') which were cooled in a forced-air tunnel at temperatures 1°C and 7°C, respectively (air velocity ≅ 1 m/s; Q = 0.54 m 3 /s). The result of the distributions of air temperature and of the product temperature along the bed of fruits is presented and discussed in this work.

Delays in initiating the cooling of freshly harvested `Chandler' strawberries (Fragaria ×ananassa) were compared with prompt cooling to determine how such handling affected development of postharvest decays during subsequent storage and marketing. Strawberries at the three-quarter to full red ripeness stages were harvested four times between mid-June and late July, inoculated with Botrytis cinerea or Rhizopus stolonifer and then handled to simulate prompt or delayed precooling prior to storage. This was done by incubating fruit at 35 °C (95.0 °F) and 70% to 80% relative humidity (RH) for 1 or 6 hours. The fruit were then forced-air cooled to 5 °C (41.0 °F) in 1 hour and stored for 7 days at 2 °C (35.6 °F) and 85% to 95% RH, plus displayed in a simulated market at 20 °C (68.0 °F) and 85% RH for 1 day. Decay incidence increased as the season progressed. For non-inoculated fruit, prompt cooling reduced the incidence of decay by an average of 25% and the decay severity by ∼24%. With inoculated fruit, prompt cooling resulted in 15% and 29% decreases in the incidence and severity, respectively, of rhizopus rot compared to delayed cooling, and 5% and 22% decreases in the incidence and severity, respectively, of botrytis rot. Overall, the incidence of botrytis and rhizopus fruit rot averaged 60% and 85% in the prompt and delayed cooling treatments, respectively. Although prompt cooling is important for minimizing postharvest decay of strawberries, temperature management alone may not sufficiently control postharvest decay when decay pressure is high.

The effect of forced-air cooling on plums ( Prunus salicina Lindl., cv. Santa Rosa), applied before or after mechanical damage, and then stored at 1 °C for 4 days, was studied. CO 2 production rate, weight loss, firmness (force–deformation ratio and flesh fruit deformation) and colour were investigated. In another set of ‘Santa Rosa’ fruit without a pre-cooling treatment (damaged and non-damaged), CO 2 production rate was examined. Forced-air cooling led to a reduction in the respiration rate of mechanically damaged plums. Damaged fruit before pre-cooling showed a respiration rate double that of damaged fruit after pre-cooling during storage. Damaged plums before pre-cooling showed higher weight losses, lower firmness (for both force–deformation ratio and flesh fruit firmness parameters), and lower chroma values than damaged fruit after pre-cooling. Pre-cooling ‘Santa Rosa’ plums after harvesting and before manipulation (transportation to packing-house, handling in packing-house, during storage or transportation) can help to maintain fruit quality and prolong shelf life.

The aim of the present study was to precool cauliflower using forced-air, vacuum and high and low flow hydro cooling methods. The weight of the precooled cauliflower heads (5000±5 g) was measured before they were placed in standard plastic crates. Cauliflower heads, whose initial temperature was 23.5 ± 0.5 °C, were cooled until the temperature reached at 1 °C. During the precooling process, time-dependent temperature and energy consumption were measured, and during vacuum precooling, the decreasing pressure values were recorded, and a curve of time-dependent pressure decrease (vacuum) was built. The most suitable cooling method to precool cauliflower in terms of cooling time and energy consumption was vacuum, followed by the high and low flow hydro and forced-air precooling methods, respectively. The highest weight loss was observed in the vacuum precooling method, followed by the forced-air method. However, there was an increase in the weight of the cauliflower heads in the high and low flow hydro precooling method. The best colour and hardness values were found in the vacuum precooling method. Among all methods tested, the most suitable method to precool cauliflower in terms of cooling and quality parameters was the vacuum precooling method. © 2014, Sociedade Brasileira de Ciencia e Tecnologia de Alimentos, SBCTA. All rights reserved.

The effects of postharvest cooling rates and physical damage to tips, on the incidence of tip rot and other quality attributes of asparagus spears (Asparagus officinalis L. ‘New Zealand Beacon Syn 2'), harvested early and late in the season, were investigated. The half cooling times were 1 1/2 min, l 1/2 h, and 53/4 h for hydrocooled, forced‐air cooled, and passively cooled spears, respectively. Apical tissue cooled more rapidly than middle and basal zone tissues. Incidence of tip rot, and visible quality and toughness of asparagus spears, was not affected by the method of cooling, or delays after harvest of up to 12 h at ambient temperatures before hydrocooling. However, overall spear quality was marginally higher, and weight loss significantly less, in hydrocooled spears than in forced‐air or passively cooled spears. It is recommended that spears are hydrocooled or forced‐air cooled within 4–12 h of harvest. In this study, the incidence of tip rot was not linked to the time of harvest within a ...

Forced-air cooling rates of highbush blueberries (Vaccinium corymbosum L.) packaged in 6-oz (177-mL) or 1-pt (473-mL) clamshell containers were affected by positions of vent holes in corrugated flats. Most rapid cooling occurred in flats with vents across the top of the flat. Additional vents aligned in front of clamshells resulted in more rapid and uniform cooling than vents placed between clamshells. Vent holes in the bottom of flats had no effect on cooling rates. Clamshells cooled more slowly in the front of the pallet where cold air entered than in the back of the pallet where cold air exited. Fruit in 6-oz clamshells cooled faster than fruit in 1-pt clamshells.

‘Chandler’, ‘Oso Grande’ and ‘Sweet Charlie’ strawberries were forced-air precooled after delays of 0 or 6 h at 30 °C to study the effect of delaying precooling on physical and chemical quality characteristics of strawberry fruit. Fruit pulp temperatures were equilibrated to 30 °C prior to the start of each experiment to minimise water loss differences between treatments. Evaluations were made after storage for one week at 1 °C plus one day at 20 °C. Delaying the start of precooling resulted in about 50% greater water loss than in control fruit, which was evident as increases in superficial shrivelling. Tissue firmness values were also 14–22% lower in fruit from the delayed treatment. Fruits were darker (lower L ∗ value), less bright (lower chroma) and apparently less red (lower a ∗ value) with the cooling delay, although hue angle was also lower, which may reflect the occurrence of browning. No significant differences in pH were observed in these experiments, but titratable acidity was slightly lower with the delay to cooling. Delaying precooling also caused increased losses of ascorbic acid, soluble solids, fructose, glucose and sucrose compared to controls. In spite of differences related to harvest time and the variability among cultivars, the general responses were quite similar and illustrate the importance of rapid precooling and subsequent storage at low temperature for maintenance of acceptable appearance, texture and nutritive value of strawberries.

The objective of this study was to investigate the drying characteristics, milling quality, and disinfestation effectiveness of rough rice under infrared (IR) radiation heating. Freshly harvested medium grain rice (M202) samples with low (20.6%) and high (25.0%) moisture contents (MC) were used for this study. Single-layer rough rice samples (non-infested and infested with the adults and eggs of lesser grain borers (Rhizopertha dominica) and angoumois grain moths (Sitotroga cerealella) were heated for various durations using a catalytic infrared emitter. The effects of tempering treatment and natural and forced air cooling methods on moisture removal, milling quality and disinfestation were also determined. High heating rate and corresponding high moisture removal were achieved by using the IR heating. After heating, tempering increased moisture removal during cooling and improved milling quality of the rice samples. For example, 60 s of IR heating of 20.6% MC rice resulted in 61.2°C rice temperature, 1.7 percentage MC removal during the heating period and additional 1.4% MC removal after tempering and natural cooling. The rice also had 1.9 percentage higher head rice yield than control sample dried with room air. The heating and tempering treatment also completely killed the tested insects. However, rice samples without tempering or cooled with forced air after tempering had much lower milling quality than the control. Simultaneous drying and disinfestation with high rice milling quality can be achieved by using the catalytic IR to heat the rough rice to 60°C followed by tempering and slow cooling.

Effect of maturity at harvest and forced-air cooling (FAC) on postharvest quality and physiology of apricot cv 'Precoce de Tyrinthe' were investigated. Apricots were harvested at 2 different stages: minimum maturity, MI (9% SSC, orange color except on suture) and ideal harvest maturity, MII (10% SSC, completely orange color). Within a few hours after harvest: (i) half of the fruits of each maturity stage were placed in a cold room at 0-1°C and 90% RH and (ii) the other half was forced-air cooled at 600 cfm. All apricots were stored at 0°C for 7 days and then transferred to 20°C for up to 8 days. Another group of apricots was kept at 20°C immediately after harvest to observe post-harvest changes. Apricots were analyzed for firmness, SSC, titratable acidity, color (hue angle), respiration, weight loss and evaluated for taste. For both stages of maturity, FAC at 0°C increased the shelf-life and improved the appearance of apricots when compared to room cooling at 0°C. The 7/8 cooling time of apricots ranged from 86 min. to 225 min. for FAC and was 431 min for room cooling (RC). Apricots could be forced-air cooled to 0°C and then transported for a period of 7 days in a refrigerated truck while maintaining their quality after additional 6 to 8 days at 20°C.

‘Sweet Charlie’ strawberries were wrapped with PVC polymeric film, and forced-air precooled after delays of 0, 6 or 8 hours at 30 °C to study the effect of delaying precooling on physical and chemical quality characteristics of the strawberry. Non-wrapped fruits were used as a control. Evaluations were performed after storage for one week at 1 °C plus one day at 20 °C. Delaying the precooling resulted in less attractive fruits and loss of quality characteristics. Wrapped strawberries maintained better appearance and quality than nonwrapped berries.

`Sweet Charlie' strawberries (Fragaria ×ananassa Duch.) harvested at full ripe stage were 7/8-cooled by forced-air or hydrocooling to 4C, then held with or without a PVC film wrap in one of three storage regimes: 1) 7 days at 1C plus 1 day at 20C; 2) 7 days at 1C plus 7 days at 7C plus 1 day at 20C, or; 3) 7 days at 1C plus 5 days at 15C plus 2 days at 7C plus 1 day at 20C. Quality attributes, including surface color, firmness, weight loss, soluble solids and ascorbic acid content, pH, and titratable acidity, were evaluated after storage. Hydrocooled berries were better in overall quality, with better color retention, less weight loss, and lower incidence and severity of decay compared to forced-air-cooled berries. Strawberries wrapped in PVC film retained better color and had less weight loss and greater firmness, but greater incidence and severity of decay than berries stored uncovered. These results indicate good potential for using hydrocooling as a cooling method for strawberries.

Snap beans were room cooled (RC) or forced-air cooled (FA) in a 4.5°C commercial cold storage room, or hydrocooled (HC) in a commercial flume-type unit with 4°C water containing 175 ppm NaOCl. The beans were packed in wirebound wooden crates (WC) or waxed corrugated fiberboard cartons (FC) before (RC, FA) or after (HC) precooking and stored one week at 10°C before evaluation. Ascorbic acid, chlorophyll and fiber contents did not differ among treatments, while moisture content and per cent unshrivelled beans were lowest in FA and highest in HC, and lower in WC than in FC containers. HC reduced development of mechanical damage symptoms (browning) and decay compared to RC and FA. The former effect was attributable to the presence of NaOCl rather than leaching or increased cooling rate in HC. HC beans packed in FC had the highest per cent sound beans and lowest per cent beans showing mechanical damage symptoms of all the treatment combinations tested.

BROCCOLI was cooled using forced air and hydro-cooling on a laboratory scale. Moisture loss and cooling rate were compared for the two methods. Less than one percent of the original broccoli weight was lost during cooling tests using air at or above 95% relative humidity. There was no significant difference in weight loss between forced air cooling and hydrocooling with comparable cooling media temperatures (within 0.5 °C or 1 °F) when measured 15 h after cooling. A single semilog plot of nondimensionalized average pulp temperature versus cooling time, with a slope of —0.022 min~S described the cooling rate for all tests including hydrocooling and forced air cooling at six different conditions.

FIELD grown bare root tomato transplants packed in commercial shipping crates were precooled in a batch type precooler by forced air cooled with liquid carbon dioxide (L-C02). The precooled transplants were shipped via commercial truck from Tifton, GA to Fremont, OH. Some of the precooled and nonprecooled transplants were immediately planted in the field upon reaching destination and some were planted after 5 days of storage either at ambient or at 7°C temperatures. The technique of precooling using L-C02 was successful but there was nonuniform cooling between crates. The precooled transplants went through a heating and cooling cycle in transit because of the heat load of nonprecooled transplants. The survival and fruit yield data indicated that the performance of precooled and nonprecooled transplants was similar when they were not stored. The performance of stored transplants was worse than unstored transplants and the performance of precooled-stored transplants was worse than nonprecooled-stored transplants. Successive heating and cooling of precooled tomato transplants caused damage.