EFFECTS OF 1‐METHYLCYCLOPROPENE AND MODIFIED ATMOSPHERE PACKING ON POSTHARVEST LIFE AND QUALITY IN TOMATOES

ABSTRACT

The effects of 1‐methylcyclopropene (1‐MCP), modified atmosphere packaging (Xtend, StePac L.A. Ltd., Tefen, Israel) and their combination were investigated on storage and quality maintenance of tomatoes cv. “Perla” harvested at two maturity stages. 1‐MCP treatment was performed in 1,000 nL/L doses for 24 h while untreated fruits were considered as control. Fruits were stored at 12C with 90% relative humidity for 21 days. Weight loss, skin color, elasticity, lycopene, ascorbic acid, soluble solid content (SSC), titratable acidity (TA) and SSC/TA were evaluated with the intervals of 7 days. MAP with and without 1‐MCP reduced weight loss and maintained to elasticity compared with control and 1‐MCP alone. Nevertheless, 1‐MCP or its combination with MAP significantly delayed changes in parameters related to fruit ripening, such as skin color, lycopene, TA and SSC/TA increase in both ripening stages. Overall results indicated that the combination of 1,000 nL/L 1‐MCP and modified atmosphere package was the most effective treatment in both ripening stages.

PRACTICAL APPLICATIONS

Tomato is a climacteric fruit and its ripening depends on ethylene production physiology. 1‐Methylcyclopropene (1‐MCP) prevents ethylene action by blocking ethylene receptors and extends the storage life of tomatoes. Modified atmosphere packaging (MAP) of fresh fruits and vegetables refers to the still evolving technique of matching the respiration of the product with the O₂ and CO₂ permeability of packages in order to modify the oxygen and carbon dioxide concentrations of the atmosphere to desired levels within the package. Recent studies revealed that combined applications of 1‐MCP and MAP have significant effects on maintaining storage quality of banana, litchi and plums. This study was conducted on the investigation of the effects of 1‐MCP and MAP combination on storage duration and quality of tomatoes harvested at different maturity stages.     

供应链中生鲜果蔬品质劣变机制、共性管控及智能检测技术研究进展

供应链中生鲜果蔬由于呼吸作用、蒸腾作用和乙烯释放等因素,持续消耗有机物质(如糖和淀粉),导致生鲜果蔬品质降低。在整个供应链中,生鲜果蔬的生理、生化变化受内在因素(种类与品种、产地与采收期、成熟度或生长期)和环境因素(如温度、湿度、O₂和CO₂体积分数、乙烯体积分数、挤压、撞击、振动等)的影响。目前,供应链中应用了许多采后技术来提高品质和保留率,以减少生鲜果蔬的品质劣变,提高其市场竞争力。作者简要介绍了供应链中生鲜果蔬品质劣变(如霉变、萎蔫、褐变、软化、黄化等)机制、生鲜果蔬品质劣变影响因素,以及通过采用共性管控技术减缓生鲜果蔬的品质劣变,并综述了智能标签在生鲜果蔬新鲜度检测中的研究进展。     

Impact of Mixtures of Different Fresh‐Cut Fruits on Respiration and Ethylene Production Rates

Packaging and storage of fresh‐cut fruits and vegetables are a challenging task, since fresh produce continue to respire and senesce after harvest and processing accelerates the physiological processes. The response on respiration and ethylene production rates of fresh produce to changes in O₂ and CO₂ concentrations and temperature has been extensively studied for whole fruits but literature is limited on processed and mixed fresh‐cut fruits. This study aimed to investigate the effects of mixing various proportions of fresh‐cut fruits (melon chunks, apple slices, and pineapples cubes) on respiration and ethylene production rates and to develop predictive models for modified atmosphere packaging. The experiment was designed according to a simplex lattice method and respiration and ethylene production rates were measured at 10 °C. Results showed that single component pineapple cubes, apple slices, and melon chunks, in this order, had significant constant coefficients (P = 0.05) and the greatest impact on respiration rate while the interactive binary and tertiary coefficients were insignificant. For ethylene production rates, single component apple slices, melon chunks, and pineapple cubes, and their 3‐component mixtures, in this order, had significant constant coefficients (P = 0.05) while binary coefficients were insignificant. Mathematical models were developed and validated; the cubical model was the best to describe the influence of proportion of fruit on respiration and ethylene production rates, however, considering simplicity the linear part of the model is recommended to quantify respiration and ethylene production rates of mixed fresh‐cut fruits.     

Recent advances in modified atmosphere packaging and edible coatings to maintain quality of fresh-cut fruits and vegetables

Processing of fruits and vegetables generates physiological stresses in the still living cut tissue, leading to quality deterioration and shorter shelf life as compared with fresh intact produces. Several strategies can be implemented with the aim to reduce the rate of deterioration of fresh-cut commodities. Such strategies include low temperature maintenance from harvest to retail and the application of physical and chemical treatments such as modified atmosphere packaging (MAP) with low O₂ and high CO₂ levels and antioxidant dips. Other technologies such as edible coatings with natural additives, new generation of coatings using nanotechnological solutions such as nanoparticles, nanoencapsulation, and multilayered systems, and nonconventional atmospheres such as the use of pressurized inert/noble gases and high levels of O₂ have gained a lot of interest as a possibility to extend the shelf life of minimally processed fruits and vegetables. However, the high perishability of these products challenges in many cases their marketability by not achieving sufficient shelf life to survive the distribution system, requiring the combination of treatments to assure safety and quality. This review reports the recent advances in the use of MAP, edible coatings, and the combined effect of both technologies to extend the shelf life of fresh-cut fruits and vegetables.     

SEQUENTIAL TREATMENTS OF HOT WATER AND MODIFIED ATMOSPHERE PACKAGING IN CHERRY TOMATOES

ABSTRACT

The effects of hot water treatment (HWT) and modified atmosphere packaging (MAP) on the storage and fruit quality of cherry tomatoes (Lycopersicon esculentum Mill. cvs. “Alona” and “Naomi”) were investigated. For this purpose, light‐red cherry tomato fruits were dipped in hot water (54C for 5 min) and subsequently stored in plastic film materials with various O₂ and CO₂ permeabilities. The cultivars used in the study were stored in a cold room at 5–7C and 90 ± 5% relative humidity (RH). The changing gas composition within the films and quality changes of the fruits were evaluated during the storage period. At the end of the study, HWT combined with MAP produced better results than MAP alone in both cultivars. Therefore, the HWT + MAP treatment proved effective with regard to fruit quality and delaying the maturity of cherry tomatoes during storage. HWT + 50 micropolyethylene (μPE) treatment produced the best result in the two cultivars at the end of the 28‐day storage with respect to the parameters evaluated in the study.

PRACTICAL APPLICATIONS

Tomato is considered a climacteric fruit, in which ripening is accompanied by a peak in respiration and a concomitant sharp increase in ethylene production, which accelerates quality loss through the physicochemical changes related to this process, such as softening and color evolution. Postharvest heating is a noncontaminating physical treatment that delays the ripening process, reduces chilling injury and controls the activity of pathogens. Because of these beneficial effects, heat treatments are currently used commercially for quality control of fresh products. Modified atmosphere packaging is another technique that has been used to prevent or retard postharvest fruit ripening and its associated biochemical and physiological changes by favorably altering the O₂ and CO₂ levels around the products. In recent years, the use of combined techniques in the postharvest handling of fresh products is increasing, and numerous authors have obtained good results using a combined treatment. Diseases have the potential to destroy the market value and utility of large amounts of fresh tomato annually. The present work evaluated a prestorage conditioning treatment to protect against these losses. The results will allow the long storage of cherry tomato, benefiting the growers, exporters, shippers and distributors of this horticultural product.

     

Modified Atmosphere Packaging of Pomegranate Fruit and Arils: A Review

Ongoing global drive for a healthier diet has led to a rise in demand for convenient and fresh food produce, with high nutritional value and free of additives. Minimally fresh processed fruits and vegetables, satisfies the consumers’ perception of a high nutritional quality and convenience produce. Minimally processed fruit and vegetables are susceptible to increased deterioration in quality and microbial infestation due to increase in endogenous enzymatic processes and respiration rate. Modified atmosphere packaging (MAP) technology offers the possibility to retard produce respiration rate and extend the shelf life of fresh produce. However, it is important to correlate the permeability properties of the packing films with the respiration rate of the produce, in order to avoid anaerobic conditions which could lead into fermentation of produce and accumulation of ethanol. Hence, mathematical prediction modelling is now widely applied in the design and development of effective MAP technology in both whole and minimally processed fresh produce. With increasing global interest in postharvest handling and nutrition value of pomegranate, MAP of minimally processed pomegranate arils offers additional innovative tool for optimal use and value addition, including the utilization of lower-grade fruit with superficial peel defects such as; cracks, splits, and sunburnt. This review paper highlights the current status and applications of modified atmosphere packaging in whole fruit and minimally processed pomegranate arils and identifies future prospects.     

Innovative processes and technologies for modified atmosphere packaging of fresh and fresh-cut fruits and vegetables

Modified atmosphere packaging (MAP) technology has been commercially viable since the 1970s. Currently, MAP is extensively used worldwide to preserve the quality and extend the shelf-life of whole fresh fruits and vegetables, but is also increasingly used to extend the shelf-life of minimally processed fresh fruit and vegetables. This review discusses new processes and technologies that can be used to improve quality preservation and consumer acceptability of minimally processed produce where high respiration rates and challenging degradation processes operate. New packaging innovations are enabling producers and retailers to further maintain quality for longer. Innovative approaches to extend shelf-life include active MAP with differentially permeable films, films that incorporate antimicrobial properties, edible coatings that confer barriers properties, and the use of non-traditional gases to modify respiration. Intelligent packaging using integrated sensor technologies that can indicate maturity, ripeness, respiration rate and spoilage are also appearing. This review demonstrates that preservation technologies and associated packaging developments that can be combined with modified atmosphere are constantly evolving technology platforms. Adoption of combinations of technology improvements will be critical in responding to commercial trends towards more minimally processed fresh-cut and ready-to-eat fruit and vegetable products, which require specialized packaging solutions.     

Nondestructive and Continuous Monitoring of Oxygen Levels in Modified Atmosphere Packaged Ready‐to‐Eat Mixed Salad Products Using Optical Oxygen Sensors,and Its Effects on Sensory and Microbiological Counts during Storage

The objective of this study was to determine the percentage oxygen consumption of fresh, respiring ready‐to‐eat (RTE) mixed leaf salad products (Iceberg salad leaf, Caesar salad leaf, and Italian salad leaf). These were held under different modified atmosphere packaging (MAP) conditions (5% O₂, 5% CO₂, 90% N₂ (MAPC—commercial control), 21% O₂, 5% CO₂, 74% N₂ (MAP 1), 45% O₂, 5% CO₂, 50% N₂ (MAP 2), and 60% O₂, 5% CO₂, 35% N₂ (MAP 3)) and 4 °C for up to 10 d. The quality and shelf‐life stability of all packaged salad products were evaluated using sensory, physiochemical, and microbial assessment. Oxygen levels in all MAP packs were measured on each day of analysis using optical oxygen sensors allowing for nondestructive assessment of packs. Analysis showed that with the exception of control packs, oxygen levels for all MAP treatments decreased by approximately 10% after 7 d of storage. Oxygen levels in control packs were depleted after 7 d of storage. This appears to have had no detrimental effect on either the sensory quality or shelf‐life stability of any of the salad products investigated. Additionally, the presence of higher levels of oxygen in modified atmosphere packs did not significantly improve product quality or shelf‐life stability; however, these additional levels of oxygen were freely available to fresh respiring produce if required. This study shows that the application of optical sensors in MAP packs was successful in nondestructively monitoring oxygen level, or changes in oxygen level, during refrigerated storage of RTE salad products.     

Effects of temperature on Agrocybe chaxingu quality stored in modified atmosphere packages with silicon gum film windows

The effects of three storage temperatures (1, 3, and 5 °C) were determined on the quality of the edible mushroom Agrocybe chaxingu stored in modified atmosphere packages (MAP) with and without (control) silicon gum film windows. Results showed that the storage temperature had clear effects on headspace gas concentrations of O₂, CO₂ and ethylene, sensory characteristics, respiration rate, ascorbic acid content, soluble solid content and electrolyte leakage. The higher storage temperature (5 °C) resulted in more rapid changes in the different quality parameters for the stored mushroom except in the case of storage at 1 °C where chilling injury occurred. The MAP with silicon gum film windows at 3 °C provided the best atmosphere for mushroom A. chaxingu as shown by a fact that the MAP packs with windows at 3 °C had better quality than the control.     

国内新鲜食品气调包装技术研究现状

气调包装是一种重要的食品保鲜方法,可以有效延长产品的货架期。使用气调包装技术保鲜食品时,影响保鲜效果的因素主要有三个,一是包装气体的初始组分,二是保鲜过程中包装气体的变化,三是保鲜的温湿度条件。总结目前常用的两种果蔬呼吸模型,并分析其适用范围。总结出保鲜新鲜果蔬、鲜切蔬菜和肉类产品的初始气体组分。介绍不同包装膜对包装内外气体交换的影响。概述气调包装温湿度的相关研究。最后,对气调包装技术研究提出建议。     

Recent Application of Modified Atmosphere Packaging (MAP) in Fresh and Fresh-Cut Foods

Modified atmosphere packaging (MAP) has been applied in the food industry for about 90 years to extend shelf life and maintain quality of fresh and fresh-cut foods. Recently, MAP has experienced a rapid development in both scientific and industrial communities, which was one of the most appropriate and practical technologies for packaging fresh and fresh-cut produce. This paper reviews some recent developments of newly emerged MAP systems such as high-oxygen MAP, controlled MAP, and intelligent MAP and provides an overview of MAP applications for fresh and fresh-cut fruits, vegetables, mushrooms, meat, and aquatic products.     

Modeling of Active Modified Atmosphere Packaging of Endives Exposed to Several Postharvest Temperatures

Endives were sealed in low‐density polyethylene flexible pouches containing or not containing individual oxygen or carbon dioxide scavenger sachet and stored at 5 °C and 20 °C. A mathematical model has been applied to predict gas changes for these passive and active modified atmosphere packaging (MAP). The model took into account the respiration rate of endives, the transmission rate of gases through the film, the absorption kinetics of gas scavengers, and the temperature influence of all these parameters. Whatever the temperature, the model was successfully validated with root mean square error values still lower than 1 kPa and thus represented a real tool to improve the design of MAP for fresh fruits and vegetables. Oxygen scavengers reduced by half the transient period duration (50 h compared with 100 h without scavengers) and did not modify the gas equilibrium composition, suggesting a beneficial influence on keeping the quality of the product. The carbon dioxide scavengers’ influence was limited and needs further study with carbon dioxide‐sensitive products.     

Effects of heat treatment on atmospheric composition and color of peeled white asparagus in modified atmosphere packaging

Freshly harvested spears of white asparagus were subjected or not to heat treatment by immersion in a hot water bath at 55 °C for 3 min, then left unpeeled or were peeled before wrapping in 16 µm stretch film and stored at 3 °C for 6 days. During storage, the atmosphere within the packages was sampled for O₂, CO₂ and C₂H₄ determination, while spear fresh weight, color and anthocyanin content at the 3 cm apical peel segments were determined before and after storage. The results showed that CO₂ concentration in packages of white asparagus spears was not greatly influenced by peeling or heat treatment. On the other hand, a higher package O₂ depletion of treated (peeled or heated) spears was observed. Peeling also resulted in an increase of ethylene peak concentration, indicating wound-induced ethylene production, which was suppressed by heat treatment. The initial color of the whole spear was retained, while the appearance of a violet coloration on the spear tip was prevented by heat treatment in both unpeeled and peeled spears.Industrial relevancePeeled white asparagus has drawn the attention of industry as a novel lightly processed product. The combination of heat treatment with modified atmosphere packaging (MAP) could be used to improve the storage life of this product. Moreover, both peeling and heat treatment cause changes in ethylene production and respiration rate of asparagus spears and this information could be useful for development of novel application to MAP design for lightly processed (peeled) white asparagus.     

Effect of initial oxygen concentration and film oxygen transmission rate on the quality of fresh‐cut romaine lettuce

Modified atmosphere packaging (MAP) is widely used to maintain the quality of fresh‐cut produce by matching the oxygen transmission rate (OTR) of the packaging film to the respiration rate of the packaged product. The effect of the interaction between film OTR and the initial headspace O₂ on quality of fresh‐cut vegetables has not previously been reported. Romaine lettuce leaves were sliced, washed, dried and packaged with film OTRs of 8.0 and 16.6 pmol s^?1 m^?2 Pa^?1, and with initial headspace O₂ of 0, 1, 2.5, 10 and 21 kPa. Packages were hermetically sealed and stored at 5 °C for up to 14 days. For samples packaged in 16.6 OTR film, increasing the initial headspace O₂ concentration delayed O₂ depletion within the packages, hastened the onset and increased the intensity of discoloration, and inhibited the development of CO₂ injury, acetaldehyde and ethanol accumulation, off‐odors and electrolyte leakage. With 8.0 OTR‐packaged lettuce pieces, ≤1 kPa initial headspace O₂ treatments induced an essentially anaerobic environment within the packages and increased acetaldehyde and ethanol accumulation and off‐odor development. Increasing the initial O₂ concentration above 1 kPa in 8.0 OTR packages transiently increased O₂ concentrations and reduced fermentative volatile production, off‐odors, electrolyte leakage and CO₂ injury. Regardless of initial headspace O₂ concentration, all 16.6 OTR‐packaged samples had severe discoloration after 14 days of storage. Quality was better maintained in 8.0 OTR‐packaged lettuce pieces as the initial headspace O₂ concentration was increased. A 21 kPa initial O₂ treatment of 8.0 OTR‐packaged lettuce maintained good quality throughout storage and had the best overall quality score. Copyright © 2005 Society of Chemical Industry     

The effects of active and passive modified atmosphere packaging on the survival of Salmonella enterica serotype Typhimurium on washed romaine lettuce leaves

Modified atmosphere packaging (MAP) is commonly used to preserve the quality of ready-to-eat lettuce by inhibiting oxidative browning and growth of microbial populations. The efficacy of MAP is improved by the initial displacement of air with a gas mixture of a desirable composition (active MAP). The present work focused on the effects of MAP on indigenous microbial populations and the survival of Salmonella enterica on the surface of the lettuce. Chlorine-washed leaves of romaine lettuce were inoculated with S. enterica serotype Typhimurium or not inoculated and packaged in one of the three systems: (a) passive MAP in polyethylene bags; (b) active MAP in the same bags with a gas mixture of 10% O₂, 10% CO₂, and 80% N₂; and (c) control without MAP. Active MAP ensured the more rapid establishment of a steady-state atmosphere and favorable conditions during the transitional period preceding the steady state. The active MAP had an antimicrobial effect on indigenous lettuce microflora, but not on Salmonella and even favored the survival of the pathogen, possibly due to the elimination of its natural antagonists. The effects of the passive MAP were less pronounced. The results obtained draw attention to potential safety risks of ready-to-eat fresh produce kept in active MAP and require further investigation.     

The use of carbon dioxide in the processing and packaging of milk and dairy products: A review

The upswing in consumer demand for fresh and high quality preservative‐free foods has led to the development of modified atmosphere packaging (MAP). Increasingly, MAP is being used with high carbon dioxide (CO₂) concentration as well as CO₂/N₂ gas mixes. Modified atmosphere packaging or ‘gas flushing’ as it is also known is an increasingly popular technique used to extend the shelf life (both quality and safety) of a number of dairy products. Carbon dioxide is an active constituent of MAP, naturally present in freshly drawn raw milk. Addition of CO₂ to raw milk or flushing the package headspace has proved to be a simple and cost‐effective method, depending upon the initial microbiological quality of the food product. Carbon dioxide addition through MAP or direct injection as an economically affordable shelf life extension strategy is used commercially worldwide for some dairy products. The development of food packaging machines with integrated gas flushing capabilities and the supply of ‘food grade’ gases allow dairy foods manufacturers to enhance the quality of their products. This review presents a broad spectrum of current research and the current trends with respect to CO₂ as a natural microbial hurdle with special focus on its precise mechanism and its role in quality improvement of dairy products.     

褪黑素在果蔬采后品质劣变中的调控作用

褪黑素是广泛存在于生物体内的一种吲哚类色胺, 具有调控果蔬衰老、清除活性氧自由基、防止抗氧化酶钝化等作用。最新研究发现褪黑素可以显著延缓果蔬采后由呼吸作用、乙烯释放、蒸腾作用、自由基代谢等代谢活动导致的品质劣变。本文从果蔬采后品质劣变角度综述了褪黑素对果蔬采后生理的调节作用, 从导致品质劣变的关键生理活动包括呼吸作用、乙烯合成、蒸腾作用、酶促褐变、膜脂氧化、抗性激活等方面阐述了外源褪黑素的调控机制, 系统阐述了外源褪黑素对果蔬品质的影响, 包括感官品质、糖酸代谢、风味变化等, 以期为褪黑素在保持果蔬采后品质及相关贮藏保鲜新技术的应用奠定一定的理论基础和技术支持。     

Shelf-Life Extension of Fresh Tuber aestivum and Tuber melanosporum Truffles by Modified Atmosphere Packaging with Microperforated Films

ABSTRACT: The aim of this study was to design a modified atmosphere packaging suitable for Tuber melanosporum and Tuber aestivum truffles that extend their shelf life and their availability as a fresh product. Their respiration rates were determined by O₂ depletion and CO₂ formation in closed systems performed at different temperatures: 4, 10, and 23 °C. The results were fitted by exponential equations and derivatives of these equations were used to obtain the experimental respiration rates. Our results revealed high respiration rates in both species of truffles and respiratory quotients (RQ) higher than 1 in all the cases studied. A linear dependence of respiration rate, both R_O2 and R_CO2, on O₂ concentration was revealed. A mathematical model was used to predict the evolution of the gaseous composition at 4 °C in the interior of polypropylene trays (250 mL) heat sealed with 4 microperforated films of different transmission rates. A microperforated film with 2 holes (90 × 50 μm) was selected to produce an internal atmosphere of 15%CO₂/7%O₂ at 4 °C. The predicted atmosphere composition was confirmed by the experimental results. The quality and microbiological characteristics of fresh truffles, packaged in these conditions, revealed that the microbial counts of pseudomonads and Enterobacteriaceae were decreased, the weight loss was reduced, the typical hard texture was maintained, and the development of mycelium growth was delayed, enabling good scores for aroma and flavor, and therefore prolonging the shelf life of T. melanosporum and T. aestivum truffles to 28 and 21 d, respectively. Practical Application: This study describes the benefits of using MAP with microperforated films in the postharvest storage of Tuber melanosporum and Tuber aestivum fresh truffles. The shelf life of T. aestivum is prolonged to 21 d and of T. melanosporum to beyond 28 d increasing the possibilities for a foreign market.     

Postharvest storage of Giant Cavendish bananas using ethylene oxide and sulphur dioxide

The potential of ethylene oxide (EO) and sulphur dioxide (SO₂) to prevent ethylene‐stimulated fruit ripening was assessed using Giant Cavendish bananas. Studies were carried out in a cold room at 15 °C and terminated after 6 weeks. Product quality was assessed via visual observations and physiological assessments. Fruits were exposed to EO concentrations in the range 0–400 ppm for 12 h followed by storage in regular atmosphere (RA). Results showed that EO delayed ripening at 50 and 100 ppm for single exposure and at 50 and 200 ppm for repeated exposure. Treatment with 2 and 8 µg kg^?1 SO₂ was efficient in extending the shelf life of bananas for 4 weeks in RA and for 6 weeks under controlled atmosphere (CA). SO₂ preserved the quality of bananas and reduced the incidence of fungal infections during storage; however, a concentration of 15 µg kg^?1 shortened the shelf life. Fruits treated with low concentrations of EO and SO₂ had harvest‐fresh appearance, good colour, minimum mould and excellent marketability compared with controls and store‐bought references. EO and SO₂ are not approved for use on fresh fruits, with the exception of the use of SO₂ on grapes and citrus fruits. © 2003 Society of Chemical Industry