The objective of this study was to identify the anaerobic compensation point (ACP) required to maximally inhibit aerobic respiration and extend postharvest life of 'Palmer' mangos produced on 'Espada' rootstock in the summer and winter growing seasons in Brazil. The study was composed by two experiments. The first was carried out to determine the ACP (minimum pO2 required to maximally inhibit aerobic respiration) of 'Palmer' mangos during storage at 9 degrees C. The second was carried out to validate the minimum pO2 to store the fruit under dynamic controlled atmosphere (DCA). In the first experiment, the fruit were harvested at the commercial maturity in the summer and winter growing seasons and stored for 49 days at 9 degrees C with 90-95 % relative humidity. Every week, the fruit were hermetically sealed in 20 L containers, where O2, CO2, and ethanol concentrations were monitored during 35 h. The minimum pO2 required to maximally inhibit fruit aerobic respiration was determined at the beginning of ethanol production, which indicates a shift of fruit aerobic to anaerobic respiration (ACP). The minimum pO2 to efficiently inhibit aerobic respiration of 'Palmer' mangos ranged from 0.3 kPa to 4.7 kPa in summer and 1.75-11.15 kPa in winter growing seasons. Fruit harvested in the following growing season and stored in DCA with the minimum pO2 showed lower aerobic respiration, mass loss, as well as better maintenance of skin and pulp color, firmness, soluble solids (SS), titratable acidity (TA), and SS/TA ratio, compared to fruit stored only under refrigerated atmosphere at 9 degrees C for 60 days.

This study presents an in-depth experimental analysis of thermal and airflow behaviour inside large bulk apple bins under typical cold storage conditions. Four instrumented bins were monitored at two vertical levels in a commercial cold room. Temperature sensors tracked fruit cooling in different regions of each bin, while embedded sensors were designed to measure interstitial slow air speeds. Cooling was characterised in two phases: an initial continuous cool-down followed by an intermittent cooling regime. A front bin directly exposed to cold airflow showed rapid cooling at the airflow-exposed face and noticeable temperature fluctuations reflecting ongoing convective cooling. In contrast, a bin located immediately behind the front bin cooled more slowly and experienced no temperature oscillations, indicating cooling dominated by natural convection and conduction. The bin centres cooled much more slowly, highlighting the limitation of cold air penetration. Airflow measurements confirmed that only the front regions of bins received significant forced-air infiltration (approximately 0.08 m s−1), whereas interior zones became essentially air-stagnant, with air speed nearly zero, once the fruit cooled. All bins exhibited minor vertical stratification, with top-layer fruit about 0.1 to 0.2 °C warmer than bottom-layer fruit. These findings provide direct evidence of mixed convection cooling in front bins versus purely free-convective cooling or conduction cooling in sheltered bins. The study's insights emphasise the need for improved airflow distribution in cold rooms. Practical strategies, such as improved bin design and airflow management strategies, are suggested to achieve more uniform cooling.

Monitoring and controlling surface condensation on fruit is a crucial factor to maintain quality and reduce postharvest losses during cold storage. High air humidity can cause liquid water to condensate on the surface of fruits, stimulating the growth of spoilage organisms and contributing to fruit losses. At the same time, short condensation intervals can be beneficial for preventing moisture loss and limit weight loss of the fruit. According to psychometrics, condensation forms whenever the fruit surface temperature falls below the dew point of the surrounding air, a condition defined as the dew point undershot (DPU). Because direct measurement of condensation is challenging; we applied an indirect approach by continuously comparing fruit surface temperature with the calculated air dew point from ambient air temperature and relative humidity sensors. Condensation forms during DPU events and remains on the fruit surface until all condensed water is evaporated. Using this method in a commercial 50 t apple cold room, five distinct mechanisms that triggered DPU and subsequent condensation, were experimentally verified. These conditions include door openings, loading of warm fruit, defrost cycles, ventilation-driven air mixing and slightly cooler bins in the bottom tier. Condensation risk was mostly observed in the highest tier, in the door-side bins and occasionally interior stacks. These insights will provide the necessary basis for targeted monitoring and operational strategies to minimize condensation-related decay while maintaining high humidity to reduce weight loss.

Temperature and humidity strongly influence fruit quality during cold storage. Temperature should be maintained slightly above the freezing point for most fruits, and humidity should be maintained in equilibrium with fruit’s moisture to reduce mass loss, while avoiding condensation on its surface. Besides absolute temperature, the difference between fruit surface and air temperature plays a key role for phase change phenomena such as condensation, evaporation, mass loss, and heat transfer by cooling air. Whereas spatial air temperature distribution in the postharvest cold chain has been covered by several studies, data on humidity distribution are scarce. This time series dataset provides multi-point measurements of fruit surface and air temperature, and air humidity recorded with IoT sensors inside a commercial apple cold room. The changes in these parameters across different locations and storage periods can be used to identify condensation spots and to create a better understanding of cooling processes under high humidity conditions and their optimization.

Postharvest chilling injury (PCI) is a significant limitation in the storage of temperature-sensitive fruits, leading to quality deterioration and reduced marketability. However, low temperatures delay senescence—consistent with the Q10 principle, where metabolic reaction rates change 2–3-fold per 10 °C—and chilling-sensitive fruits experience membrane destabilization, oxidative imbalances, and structural degradation under cold stress. Physiological assessments consistently report elevated electrolyte leakage, increased malondialdehyde accumulation, and reduced membrane fluidity, coupled with disruptions in respiration and cellular energy metabolism. Biochemically, PCI is characterized by enhanced ROS production and a 20–50% decline in key antioxidant enzymes, along with disturbances in calcium signaling and hormone regulation. At the molecular level, chilling-responsive transcription factors such as CBF, CAM, HSF, and WRKY show strong induction, while lipid remodeling and epigenetic modifications further shape cold adaptation responses. Advances in multi-omics, including transcriptomics, proteomics, metabolomics, lipidomics, and volatilomics, have revealed chilling-associated metabolic shifts and regulatory cascades, enabling the identification of potential biomarkers of tolerance. Emerging mitigation strategies, including physical and chemical treatments, as well as CRISPR-based interventions, have shown a 30–60% reduction in PCI in controlled studies. This review synthesizes recent progress in physiology, molecular biochemistry, and postharvest technology to support future research and practical PCI management.

At harvest, the water content of apples and pears is at its maximum, about 83–85

Postharvest cold storage plays a crucial role in maintaining the quality and extending the shelf life of fresh produce, reducing food waste, and supporting a sustainable food supply chain. However, challenges such as non-uniform cooling, energy-intensive refrigeration, and environmental concerns require continuous innovation. Improper cold storage control can lead to uneven ripening and spoilage, highlighting the need for advanced monitoring and control systems. Recent innovations, including smart monitoring systems, Internet of Things (IoT) applications, artificial intelligence (AI)-driven predictive maintenance, and digital twin technology, offer potential solutions. Integrating renewable energy sources and sustainable refrigerants can further enhance environmental sustainability. This review explores key postharvest cold storage technologies, their impact on produce quality, and strategies for improving energy efficiency and sustainability. Future research should focus on optimizing energy-efficient designs and expanding the adoption of intelligent monitoring systems to ensure both economic and environmental benefits.

Volatile compounds, key odors, quality parameters, and the sensory profile of 'Cripps Pink' apples stored for nine months under a controlled atmosphere (CA) and dynamic controlled atmosphere by respiratory quotient (DCA-RQ1.3), with and without the use of 1-methylcyclopropene (1-MCP), were evaluated at 1, 7, and 14 days of shelf life. The volatile compounds were analyzed by gas chromatography-mass spectrometry (GC/MS) and gas chromatography-olfactometry (GC-O), and these results were correlated with sensory attributes throughout the Preferred Attribute Elicitation evaluation. The volatile compounds profile showed that apples stored under CA had higher concentrations of aldehydes, while those under DCA displayed a greater concentration of esters. 1-MCP application led to a reduction in the principal compounds in both storage environments. GC-O showed that CA-stored apples had more odor-impact compounds, specifically 3 alcohols, 6 aldehydes, and 6 esters above 40 % of modified frequency, compared with DCA-stored apples, which had only 1 alcohol, 2 aldehydes, and 3 esters above 40 % of modified frequency. Furthermore, preferred attribute elicitation demonstrated that, by day 7, apples stored under DCA conditions were less crunchy and juicy than those stored under CA. Additionally, apples stored under CA with 1-MCP were characterized by their juiciness, green color, and herbal odor. Thus, 'Cripps Pink' apples exposed to an atmosphere with greater O2 availability had a more complex aroma profile and maintained quality attributes better. However, storage under DCA, despite leading to a higher concentration of ethyl esters, was associated with lower-quality attributes. Applying 1-MCP mitigated the main volatile/odor compounds from both storage atmospheres while maintaining physicochemical parameters. In summary, the volatile profile, key odors, and sensory characterization of 'Cripps Pink' apples depend on the storage atmospheric condition, the use of 1-MCP, and shelf life duration.

The preservation of apples in cold storage relies deeply on understanding the thermal dynamics governing their environment. Within packaging, apples engage in complex thermal interactions, between themselves and the environment, affecting convective and conductive heat transfer pathways. Challenges escalate in industrial cold storage facilities, manifesting as temperature stratification and non-uniform cooling. Nonetheless, a comprehensive understanding of heat transfer dynamics is vital for optimizing cold storage equipment design and enhancing cooling system operation efficacy. Building upon previous studies validating the use of Peltier elements for detecting and quantifying heat flux in individual apples, this research extends its application to industrial cold rooms. By strategically selecting locations within the apple bin and the storage cold room and comparing changes in total heat content obtained by a conventional method and comparing with the Peltier element for its validation. Results of the convective heat transfer coefficient in an upper-layer bin were in the range of 2.7-5.9 Wm(-2) K-1 while in a bin at door level were 5.0-7.0 Wm(-2) K-1. The higher values found in the position near the door can be correlated to the faster air speed experienced between the apples in this position. By applying these values in the transient heat transfer model to predict the fruit core temperature during the cooling process, a relatable prediction was found, with apple temperature difference <0.9 degrees C between predicted by the Peltier element and experimental cooling curves. This study can aid understanding of thermal dynamics in cold storage environments, and support future development for more efficient and sustainable cold storage practices.

'Xenia' is a new and desired pear cultivar in Germany that is already spreading its cultivation to other European countries. The aim of this research was to determine the optimum storage conditions for 'Xenia' pear grown in the South of Germany. 'Xenia' was stored under regular air (RA), controlled atmosphere (CA) with 1.0 kPa O-2 plus <= 0.7 kPa CO2, and 2.0 kPa O-2 plus <= 0.7 kPa CO2 and DCA-storage based on CO2 monitoring (DCA-CD) for 9 months. The storage temperature in all conditions was 0 degrees C. In each storage system tested, pear fruit were divided into two batches: control (untreated fruit) and 1-MCP (pears treated with 1-MCP 300 nL L-1). At storage end, total soluble solids (TSS), glucose, fructose and sorbitol were higher in fruit treated with 1-MCP and stored under DCA. Pears kept in RA-storage showed the highest ethylene production and respiration rate, while those fruit under CA at 2.0 kPa O-2, treated with 1-MCP, and DCA-storage had higher fruit firmness, TSS, titratable acidity, malic acid and greener peel color. The application of 1-MCP at 300 nL L-1 was effective in maintaining the quality of 'Xenia' pear, although its impact was dependent on the storage strategy, as well as this effect was mitigated under conditions with less than 1.0 kPa O-2.

Refrigerated storage is crucial for maintaining the quality and safety of highly perishable and seasonal fresh fruit during the postharvest stage. Heat transfer is the primary factor that affects food decay in the storage period. However, cold storage facilities often face challenges with non-uniform airflow and temperature distribution. Therefore, this study aimed to investigate the impact of different cooling rates on heat transfer. It considered factors such as air velocity, apple surface area, initial apple temperature, air temperature, and application of a coating on apples during cold storage. Tests were conducted using a batch of apples stored in a bin as well as individually. These investigations represent the variability of conditions found within cold storage facilities. The results demonstrated that air velocity plays a significant role in the cooling kinetics of apples. Higher air velocities (>2.0 m s(-1)), at the fan outlet, were found to have a lesser pronounced influence compared to lower velocities (<1.0 m s(-1)). Heat transfer coefficients of a bin of apples ranged from 2.1 to 7.9 W m(-2) K-1, for the corresponding average air speed of 0.05 and 0.31 m s(-1) within the bin. Numerical correlations were generated for the single apple as well for the bin of apples. These findings contribute to a better understanding of how to store fresh produce effectively and suggest that adjusting the airflow in cooling facilities during different cooling phases could be guided by thermal analysis of fresh produce, potentially leading to energy-saving strategies.

The effect of different doses of 1-butanol vapor was evaluated on the overall quality and metabolism of 'Maxi Gala' apples during 14 d of shelf life at 20 degrees C, both immediately after harvest (before storage; BS) and after 7.5 months of storage (AS) in a dynamic controlled atmosphere. In BS and AS experiments, 'Maxi Gala' apples were submitted to the following treatments: without 1-butanol application; application of 80, and 160 mg L- 1 of 1butanol vapor in the fruit headspace, kept for 24 h at 20 degrees C in 24 L hermetic chambers. The metabolism and quality were evaluated at 1, 7, and 14 d of shelf life. In the BS experiment, 1-butanol vapor at 160 mg L- 1 reduced ACC oxidase activity and ethylene production, thereby preserving firmness and maintaining a favorable balance of total soluble solids, acidity, and juiciness over 14 d. These effects resulted in a higher number of healthy and firmer fruit compared with the control treatment. In the AS experiment, 1-butanol vapor at both 80 and 160 mg L- 1 maintained firmness and overall healthy fruit incidence during shelf life. Initially, 1-butanol was accumulated in the fruit but it was progressively metabolized over time. Butyl acetate was the predominant metabolic byproduct, suggesting its potential role in the metabolization of 1-butanol within the fruit. Overall, the application of 1-butanol vapor, either immediately after harvest or following long-term storage, showed potential for preserving fruit quality and extending the postharvest life of 'Maxi Gala' apples under the specific conditions of this study.

This study aimed to evaluate the impact of 1-butanol vapor treatment and compare it with ethanol, 1-methylcyclopropene (1-MCP), and ethylene treatments on ethylene production, respiration rate, color changes, physicochemical quality, and the volatile compounds derived from ethanol and 1-butanol during six days of storage at 20 degrees C. The florets were treated for 24 h at 20 degrees C in airtight chambers. After treatment, the florets were stored at 20 degrees C for six days, and metabolism and quality analyses were conducted after zero, three, and 6 days at 20 degrees C. Treating 'Legacy' broccoli florets with 1-butanol and 1-MCP increased ACC oxidase activity, ethylene production, and respiration rate while preserving better stem firmness and chemical quality, indicating that ethylene action is inhibited by these treatments. 1-Butanol is an effective alternative to delay the yellowing of 'Legacy' broccoli, maintaining better overall quality than 1-MCP and ethanol vapor treatments during six days of storage at 20 degrees C. 1-Butanol was more effective than ethanol in delaying yellowing in 'Legacy' broccoli. The delayed yellowing observed with 1-butanol treatment resulted from higher concentrations of chlorophyll and pheophytin maintenance. The application of 1-butanol and ethanol to 'Legacy' broccoli was dissipated differently by the florets; ethanol was primarily volatilized into the surrounding environment, whereas 1-butanol was bioconverted into butanal and butanoic acid and also volatilized into the surrounding environment. Lastly, the results demonstrated the potential of 1-butanol as an alternative treatment to control yellowing in 'Legacy' broccoli stored at 20 degrees C.

Abstract: This study was carried out to evaluate the changes in maturity and quality of ‘Monalisa’ apple fruit at harvest and after storage and to determine maturity indices for the optimum harvest time. Experimental treatments were harvesting time, storage atmosphere and duration and 1-MCP exposure. Fruit from multiple harvest date and three harvest years were stored at 0.8 oC in air or controlled atmosphere for 3, 5, 6 or 9 months. Half of the fruit were treated with 1-MCP in two years. The increase in ethylene production, respiration, starch degradation and soluble solids content, and the decline in flesh firmness and titratable acidity during on-tree maturation followed the expected pattern of early season cultivars such as Gala, the ‘Monalisa’ progenitor. After storage, late harvested fruit had higher severity of decay, and physiological disorders compared to early harvested fruit. Skin browning was the predominant disorder in ‘Monalisa’, which was affected by harvest maturity, 1-MCP treatment, storage atmosphere and duration. The results showed that ‘Monalisa’ apple intended for immediate marketing should be harvested between 131 to 149 days after full bloom, with starch index ranging from 3.3 to 7.5 (1-9 scale), flesh firmness from 87.1 to 69.3 N, soluble solids content from 12.7 to 14.7 %, and titratable acidity from 0.66 to 0.56 %. ‘Monalisa’ apple intended for mid- and long-term storage should be harvested earlier between 124 to 131 days after full bloom, with starch index ranging from 2.4 to 3.4, flesh firmness from 90.7 to 86.2 N, soluble solids content from 12.7 to 14.3 %, and titratable acidity ranging from 0.67 to 0.59 %.

The aim of this work was to evaluate the effect of CA and DCA on sugars, tricarboxylic acid cycle (TCA), anaerobic metabolism and some volatile compounds of ‘Elstar’ and ‘Nicoter’ apples. This study also aimed to evaluate the effect of ethylene action blocking by 1-MCP (0.650 ppm). The storage conditions tested for both cultivars were (1) CA; (2) DCA-CF; (3) DCA-RQ 1.3; (4) DCA-RQ 1.5; (5) DCA-CD 1.1; and (6) DCA-CD 1.3. The lowest oxygen limit (LOL) was higher for the ‘Nicoter’ apples, and the three DCA methods were able to detect this difference between the cultivars. Sorbitol had a trend of accumulation when the fruit was stored under DCA-RQ and DCA-CD, especially in higher RQ and CD, showing a negative Pearson correlation with the oxygen partial pressure over the storage period. The 1-MCP treatment induced sorbitol accumulation even when the fruit was stored under CA. The TCA intermediaries, such as citrate, 2-oxoglutarate, succinate, fumarate and oxaloacetate, were the most affected by the atmosphere conditions and the 1-MCP treatment for both cultivars. Malic acid was more affected by the storage time than the atmosphere conditions. Succinate and fumarate had an accumulation trend when the fruit was stored under DCA-RQ.

This study investigated the effects of pre-harvest calcium (Ca) application on apple fruit ascorbic acid (AsA) concentration and mineral contents in the cultivars ‘Braeburn’, ‘Fräulein’, ‘Pinova’, ‘Topaz’ and ‘Elstar’, and core browning (CB) susceptibility in ‘Braeburn’ and ‘Fräulein’ during controlled atmosphere (CA) storage (1 °C, 1 kPa O2 plus ≤ 1 kPa CO2). Approximately eight pre-harvest Ca applications were applied during the growing season for ‘Braeburn’ and ‘Fräulein’ cultivars and one application in “spring” for ‘Pinova’, ‘Topaz’ and ‘Elstar’. In addition, data from five consecutive harvest seasons was used to assess the relationship among AsA, mineral content, and CB for ‘Braeburn’. Results showed that the impact of pre-harvest Ca was variable among cultivars; fruit Ca concentration was increased and the K/Ca ratio was reduced only in ‘Fräulein’ fruit, and AsA was increased only in ‘Braeburn’ fruit, especially in the inner cortex tissue where CB occurs. For ‘Pinova’, ‘Elstar’ and ‘Topaz’, Ca concentration was slightly higher in untreated fruit compared to Ca-treated fruit (p < 0.07). AsA increased after storage, remaining higher in ‘Braeburn’ fruit treated with Ca, especially in the outer cortex tissue. Pre-harvest Ca reduced CB in ‘Fräulein’, but CB incidences in ‘Braeburn’ were too severe (> 84%) and unaffected by Ca application. Analysis of the data from five consecutive harvest seasons showed that ‘Braeburn’ CB incidence related positively with Ca (r = 0.97, p < 0.05) and negatively with the AsA/Ca ratio (r = −0.71, p > 0.05). Our results suggest that the positive effect of pre-harvest Ca application in reducing CB incidence in ‘Braeburn’ apple, as reported by previous studies on ‘Braeburn’ apple, may be associated with increased AsA concentration, possibly due to higher synthesis and/or reduced degradation, rather than due to higher total fruit Ca concentration.