1‐METHYLCYCLOPROPENE DELAYS POSTHARVEST RIPENING AND REDUCES DECAY IN HAMI MELON

ABSTRACT

The effects of 1‐methylcyclopropene (1‐MCP) on postharvest ripening and fruit decay in Hami melon were investigated. Melons were treated with 0, 0.1, 1, or 5 µL/L 1‐MCP at 25C for 24 h and then stored at 25C for 16 days. 1‐MCP treatment significantly inhibited respiration rate and ethylene production and delayed their climacteric rise. The treatment also significantly inhibited the decrease of firmness and the increase of electrolyte leakage. Moreover, treatment with 1 or 5 µL/L 1‐MCP maintained significantly higher total soluble solids, vitamin C and chlorophyll contents. In addition, 1‐MCP treatment significantly delayed the incidence of fruit decay and inhibited the increase of decay index. The efficacy of 1‐MCP on delaying postharvest ripening and controlling fruit decay increased with increasing concentration. These results indicate 1‐MCP treatment has great potential to extend shelf‐life and maintain quality in Hami melon during distribution at ambient temperature.

PRACTICAL APPLICATIONS

1‐Methylcyclopropene (1‐MCP) has been commercially used to delay postharvest ripening and extend the storage life on some climacteric fruits. Hami melon has a very short shelf‐life mainly due to fruit ripening and decay, which causes significant economic losses. In this study, a postharvest application of 1‐MCP significantly delayed ripening and reduced fruit decay while maintaining overall quality during storage at 25C. The results will allow long‐distance transportation and marketing of Hami melon and benefit growers, shippers and distributors of this melon fruit.     

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     

Shelf life of ready to use peeled shrimps as affected by thymol essential oil and modified atmosphere packaging

In this work the influence of different packaging strategies on the shelf life of ready to use peeled shrimps was investigated. First, the effectiveness of the coating (Coat) and the active coating loaded with different concentrations of thymol (Coat-500, Coat-1000, and Coat-1500) on the quality loss of the investigated food product packaged in air was addressed; afterwards, the thymol concentration that had shown the best performance was used in combination with MAP (5% O₂; 95% CO₂). Microbial cell load of main spoilage microorganisms, pH and sensorial quality were monitored during the refrigerated storage. Results of the first step suggested that the sole coating did not affect the microbial growth. A slight antimicrobial effect was obtained when the coating was loaded with thymol and a concentration dependence was also observed. Moreover, the active coating was effective in minimizing the sensory quality loss of the investigated product, it was particularly true at the lowest thymol concentration. In the second step, the thymol concentration (1000 ppm) that showed the strike balance between microbial and sensorial quality was chosen in combination with MAP. As expected, MAP significantly affected the growth of the mesophilic bacteria. In particular, a cell load reduction of about 2 log cycle for the samples under MAP respect to that in air was obtained. Moreover, the MAP packaging inhibited the growth of the Pseudomonas spp. and hydrogen sulphide-producing bacteria. The MAP alone was not able to improve the shelf life of the uncoated samples. In fact, no significant difference between the control samples packaged in air and MAP was observed. Whilst, the use of coating under MAP condition prolonged the shelf life of about 6 days with respect to the same samples packaged in air. Moreover, when the MAP was used in combination with thymol, a further shelf life prolongation with respect to the samples packaged in air was observed. In particular, a shelf life of about 14 days for the active coating under MAP compared to the same samples in air (5 days) was obtained.     

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.     

Combined effect of active coating and modified atmosphere packaging on prolonging the shelf life of low-moisture Mozzarella cheese

In this work, the effect of active coating on the shelf life of low-moisture Mozzarella cheese packaged in air and modified atmosphere (MAP) was studied. The active coating was based on sodium alginate (2%, wt/vol) and potassium sorbate (1%, wt/vol). The MAP was made up of 75% CO₂ and 25% N₂ (MAP1), 25% CO₂ and 75% N₂ (MAP2), or 50% CO₂ and 50% N₂ (MAP3). The product quality decay was assessed by monitoring microbiological and sensory changes during storage at 4, 8, and 14°C. Results showed that the combination of active coating and MAP was able to improve the preservation of low-moisture Mozzarella cheese. Specifically, the shelf life increased up to 160 d for samples stored at 4°C, and 40 and 11 d for those at 8 and 14°C, respectively. A faster quality decay for untreated samples packaged in air was observed. In particular, the Pseudomonas spp. growth and the appearance of molds were responsible for product unacceptability. The combination of active coating and MAP represents a strategic solution to prolong the shelf life of low-moisture Mozzarella cheese and to ensure the safety of the product under thermal abuse conditions.     

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.     

Synergistic Effect of Sodium Chlorite and Edible Coating on Quality Maintenance of Minimally Processed Citrus grandis under Passive and Active MAP

Edible coating has been an innovation within the bioactive packaging concept. The comparative analysis upon the effect of edible coating, sodium chlorite (SC) and their combined application on quality maintenance of minimally processed pomelo (Citrus grandis) fruits during storage at 4 °C was conducted. Results showed that the combination of edible coating and SC dipping delayed the microbial development whereas the sole coating or dipping treatment was less efficient. The synergetic application of edible coating and SC treatment under modified atmosphere packaging (MAP, 10% O₂, 10% CO₂) was able to maintain the total soluble solids level and ascorbic acid content, while reduce the weight loss as well as development of mesophiles and psychrotrophs. Nonetheless, the N, O‐carboxymethyl chitosan solely coated samples showed significantly higher level of weight loss during storage with comparison to the untreated sample. Furthermore, the combined application of edible coating and SC dipping under active MAP best maintained the sensory quality of minimally processed pomelo fruit during storage.     

Effect of pre‐ripening chilling temperatures on ripening,shelf life and quality of bananas treated with 1‐methylcyclopropene

Ethylene production, shelf life and fruit quality of Cavendish bananas (cv. Williams), held at different pre‐ripening storage temperatures (5 °C, 10 °C or 15 °C) prior to ethylene and/or 1‐methylcyclopropene (1‐MCP) application, were determined and compared. Levels of ethylene production during ripening were highest for control fruit that had been stored at 5 °C followed by 10 °C and then 15 °C. 1‐MCP treatment (at 300 nL L^?1) had no effect on ethylene production of fruit that had been stored at 10 °C by day 10 of storage, but ethylene production was significantly higher for fruit that had been stored at 15 °C and lower for those stored at 5 °C before 1‐MCP treatment. 1‐MCP also increased shelf life to a greater extent when applied to fruit that had been stored at 10 °C or 15 °C. Even though 1‐MCP had no significant effect on under peel chilling injury, it increased discolouration significantly, regardless of storage temperature. Firmness of 1‐MCP‐treated fruit decreased significantly compared to the control when fruit were held at 5 °C or 15 °C prior to ripening (and 1‐MCP application) but had no effect on fruit stored at 10 °C before ripening. These results indicate that pre‐ripening storage temperature affects ripening, shelf life and quality in both ethylene and 1‐MCP‐treated bananas.     

Extending the shelf‐life of bananas with 1‐methylcyclopropene and a chitosan‐based edible coating

BACKGROUND: The marketability of bananas over long distances has been limited due to their highly perishable nature and sensitivity to ethylene. To increase the shelf‐life several alternatives have been tested in attempts to maintain quality characteristics. We evaluated the effects of 1‐methylcyclopropene (SmartFresh^SM, 1‐MCP) and a chitosan‐based edible coating (FreshSeal^®, EC), applied alone or combined, on bananas at ripeness stage 3. All fruits were stored for 8 days at 22 °C, 85% RH. Color development, weight loss, firmness, physiological, sensory and chemical variables were evaluated. RESULTS: After 3 days, control and EC‐treated fruits were completely yellow (°Hue = 90), while 1‐MCP treated fruits alone and combined with EC were still showing some green colorations on tips and neck of fingers. After 7 days, fruits treated with the combination (EC + 1‐MCP) reached a Hue value of 90. Firmer fruits were observed with 1‐MCP alone or combined with EC. A decrease of 0.15% titratable acidity and an increase of 8°Brix were observed in all treatments during the experiment. The incidence of sugar spots was delayed and diminished on fruits treated with 1‐MCP either alone or combined. Sensory results showed no adverse effects by using the 1‐MCP or the edible coating. CONCLUSION: The combined treatment of EC + 1‐MCP could be used to extend the commercial life of bananas for up to four more days. Copyright © 2009 Society of Chemical Industry     

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.     

Effect of modified atmosphere packaging on the growth of spoilage microorganisms and Listeria monocytogenes on fresh cheese

Queso Fresco has a limited shelf life and has been shown to support the rapid growth of Listeria monocytogenes during refrigerated storage. In addition to improving quality and extending shelf life, modified atmosphere packaging (MAP) has been used to control the growth of pathogenic microorganisms in foods. The objectives of this study were to determine the effects of MAP conditions on the survival and growth of spoilage microorganisms and L. monocytogenes during storage of Queso Fresco manufactured without starter cultures. For L. monocytogenes experiments, cheeses were surface inoculated at ～4 log₁₀ cfu/g before packaging. Inoculated and uninoculated (shelf life experiments) cheeses were placed in 75-µm high-barrier pouches, packaged under 1 of 7 conditions including air, vacuum, or combinations of N₂ and CO₂ [100% N₂ (MAP1), 30% CO₂:70% N₂ (MAP2), 50% CO₂:50% N₂ (MAP3), or 70% CO₂:30% N₂ (MAP4), 100% CO₂ (MAP5)], and stored at 7°C. Samples were removed weekly through 35 d of storage. Listeria monocytogenes counts were determined for inoculated samples. Uninoculated samples were assayed for mesophilic and psychrotolerant counts, lactic acid bacteria, coliforms, and yeast and mold. In general, cheeses packaged under conditions consisting of higher contents of CO₂ had lower pH levels during storage compared with those stored in conditions with lower levels or no CO₂ at all. Similarly, the antimicrobial efficacy of MAP in controlling spoilage microorganisms increased with increasing CO₂ content, whereas conditions consisting of 100% N₂, vacuum, or air were less effective. Mean L. monocytogenes counts remained near inoculation levels for all treatments at d 1 but increased ～2 log₁₀ cfu/g on cheeses packaged in air, vacuum, and 100% N₂ (MAP1) conditions at d 7 and an additional ～1.5 log₁₀ cfu/g at d 14 where they remained through 35 d. In contrast, treatments consisting of 70% CO₂ (MAP4) and 100% CO₂ (MAP5) limited increases in mean L. monocytogenes counts to <1 log₁₀ cfu/g through 14 d and ～1.5 log₁₀ cfu/g by d 21. Mean L. monocytogenes counts increased to levels significantly higher than inoculation (d 0) on cheeses stored in MAP2 and MAP3 on d 21, on d 28 for MAP4, and on d 35 for cheeses stored under MAP5 conditions. Overall, significant treatment × time interactions were observed between air, vacuum, and MAP1 when each was compared with MAP2, MAP3, MAP4, and MAP5. These data demonstrate that packaging fresh cheese under modified atmospheres containing CO₂ may be a promising approach to extend shelf life while limiting L. monocytogenes growth during cold storage.     

Quality of fresh‐cut baby spinach grown under a floating trays system as affected by nitrogen fertilisation and innovative packaging treatments

BACKGROUND: Alternative techniques for cultivation of leafy vegetables such as a floating tray system and unconventional gas mixtures for post‐harvest active modified atmosphere packaging (MAP) could be of interest in the minimally processed vegetable industry. RESULTS: The combined effect of three pre‐harvest fertilisation doses (8, 12 or 16 mmol N L^?1) and three post‐harvest MAP conditions (passive, super‐atmospheric or N₂O‐enriched) on the main quality attributes of fresh‐cut baby spinach leaves throughout 10 days at 5 °C was studied. After 8 days of shelf life, spinach leaves fertilised with 8 and 16 mmol N L^?1 and stored under N₂O‐enriched MAP showed the lowest microbial growth, with good sensory quality. Such combined treatments also preserved the total antioxidant capacity sampled at harvest (8 g ascorbic acid equivalent antioxidant capacity kg^?1 f.w.). A decrease of 10–20% in total vitamin C content regardless of N fertilisation and packaging treatment was found during shelf life. Total phenolics content at harvest was 2 g gallic acid equivalents kg^?1 f.w., which was slightly decreased or preserved during shelf life while total chlorophylls were preserved for all treatments assayed around 550 mg kg^?1 f.w. CONCLUSION: No clear effect of fertilisation doses was observed during post‐harvest storage on overall quality of fresh‐cut baby spinach leaves, while N₂O‐enriched atmospheres seems to be a promising alternative to passive MAP for extending shelf life. Copyright © 2010 Society of Chemical Industry     

The effects of natural antioxidants and lighting conditions on the quality of salmon (Salmo salar) fillets packaged in modified atmosphere

The effect of lighting conditions (darkness, a low‐UV colour‐balanced lamp and supermarket fluorescents), along with the application of natural antioxidants (rosemary extract and ascorbic acid) on shelf‐life of salmon (Salmo salar) fillets packaged in modified atmosphere and stored at 1 ± 1 °C was studied. Darkness and lighting with low‐UV colour‐balanced lamps led to an extension of shelf‐life compared with conventional light, as assessed by a* values, lipid oxidation (TBARS value) and sensory evaluation. The application of natural antioxidants on the surface of MAP salmon fillets gave rise to a delay of lipid oxidation as well as an improvement of the sensory quality, mainly in the case of conventional lighting conditions. Copyright © 2005 Society of Chemical Industry     

Irradiation as a novel approach to improve quality of Tropaeolum majus L. flowers: Benefits in phenolic profiles and antioxidant activity

Edible flowers are increasingly used in food preparations, requiring new approaches to improve their conservation and safety. Food irradiation, particularly electron beam and gamma irradiation, is legally recognized to extend shelf life, improve hygienic quality and disinfest foods. Garden nasturtium (Tropaeolum majus L.) flowers are widely used in food preparations, being also known for their antioxidant properties and high content of phenolics. The purpose of this study was to evaluate the dose–response effects of gamma and electron beam irradiation (unirradiated and doses of 0.5, 0.8 and 1 kGy) on its antioxidant activity and phenolic compounds. Kaempferol-O-hexoside-O-hexoside was the most abundant compound, while pelargonidin-3-O-sophoroside was the major anthocyanin. The flowers showed high antioxidant activity, in particular as reducing agents. The interaction among the effects of irradiation dose and irradiation technology was a significant source of variation for all parameters. In general, irradiated samples gave higher antioxidant activity, maybe due to their higher amounts of phenolic compounds. Anthocyanins were the sole compounds negatively affected by irradiation. These differences were reflected in the linear discriminant analysis, which allowed the perfect separation of the applied doses, as also both irradiation technologies. Accordingly, irradiation represents a feasible technology to preserve the quality of edible flowers.Industrial relevanceThe increasing application of edible plants in several food commodities demands new technological approaches to improve their distribution and marketing as fresh products. Prolonging post-harvest storage, while preserving the whole quality of plants, these facts will benefit their industrial development, as well as the consumers' health. This study applied irradiation technologies, using electron-beam and gamma-irradiation in different doses, to a widespread and highly appreciated edible flower species, T. majus, and demonstrated that these technologies/doses did not compromise the phenolic compounds composition and antioxidant activity.     

Combined effects of a natural Allium spp. extract and modified atmospheres packaging on shelf life extension of olive‐based paste

This study aimed to extend the shelf life of non‐thermally stabilised olive‐based paste by adding different concentrations (0.2, 0.5, 1.0 g kg^?1) of a natural Allium spp. extract and/or by using different packaging atmospheres (MAP1, 75% Ar‐23% CO₂‐2% H₂; MAP2, 70% N₂‐30% CO₂) during refrigerated storage. Higher amounts of the natural extract gave the highest level of microbial inhibition, increased hardness, a greater release of aldehydes, esters, and ketones, and a better colour preservation when used with MAP1. The natural extract and MAP, either alone or in combination, produced no sensory defects (except for the control in MAP2), but a greater loss of typical olive flavour. The addition of the natural extract used with an appropriate MAP, can retain the quality attributes and extend shelf life for approximately 14 days longer than the control (without natural extract and MAP), and a better performance is achieved by using greater amounts of natural extract and MAP1.     

The effects of natural antioxidants and lighting conditions on the quality characteristics of gilt‐head sea bream fillets (Sparus aurata) packaged in a modified atmosphere

The effects of lighting conditions and the application of natural antioxidants (rosemary extract and ascorbic acid) on the shelf‐life of gilt‐head sea bream fillets (Sparus aurata) packaged in a modified atmosphere (MAP) and stored at 1 ± 1 °C were studied. Lighting with low‐UV colour‐balanced lamps led to an extension of shelf‐life compared with that under supermarket fluorescent tubes, as assessed by lipid oxidation (TBARS value) and sensory evaluation. The application of antioxidants to the surface of MAP fillets delayed lipid oxidation besides improving the sensory quality. Rosemary extract was more effective than ascorbic acid in delaying lipid oxidation under both kinds of lighting. The effect of ascorbic acid was greater in the samples illuminated by low‐UV tubes than in those stored under conventional lighting. However, the effectiveness of rosemary extract was similar in both kinds of lighting conditions. Copyright © 2004 Society of Chemical Industry     

Microencapsulated Lactobacillus reuteri combined with modified atmosphere as a way to improve tuna burger shelf life

In this study, tuna burgers were subjected to a bio‐preservation treatment combined with modified atmosphere packaging (MAP) in order to prolong the shelf life. After L. reuteri production of reuterin, the antimicrobial compound was microencapsulated and then added to tuna burger formulation. Reuterin content was analysed before and after the spray drying treatment, thus assessing its final concentration. Then, the effects of spray‐dried reuterin on tuna burgers quality were investigated with success on samples packaged under both ordinary and MAP conditions. The efficacy of bio‐control was evident in all the samples. For burgers stored in air, a shelf life of about 7.63 days was recorded for the active samples with respect to the 5.78 days of the reuterin‐free samples. Under MAP, a similar reuterin effectiveness was recorded but a general shelf life improvement was reached, accounting for about 13 days in the active samples and 12 days in the reuterin‐free samples.     

Shelf‐Life Extension of Chill‐Stored Beef Longissimus Steaks Packaged under Modified Atmospheres with 50% O2 and 40% CO2

This study was conducted to compare the shelf‐life of beef steaks stored in different packaging conditions: overwrapped (OW) packaging and 2 modified atmosphere packaging systems (MAP): 80% O₂ MAP (80% O₂/20% CO₂) and 50% O₂ MAP (50% O₂/40% CO₂/10% N₂). Steaks were stored at 2 °C for 20 d. Headspace gas composition, microbial counts, color stability, pH, purge loss, and lipid oxidation were monitored. Among the packaging types, 50% O₂ MAP was superior to OW packaging and 80% O₂ MAP in delaying bacterial growth and extending shelf‐life to 20 d. 50% O₂ MAP also gave steaks an acceptable color during storage. No significant differences were observed in color stability of steaks packaged in both 50% O₂ MAP and 80% O₂ MAP. This study reveals 50% O₂ MAP is a realistic alternative to preserve beef steaks efficiently.     

Effect of processing and packaging conditions on quality of refrigerated potato strips

Abstract: Although sulfiting agents are commonly used in the fresh‐cut potato industry, concerns about further regulatory restrictions on sulfite use and consumer fear of sulfite‐treated foods have lead to increased research in alternative processing methods. The objective of this study was to determine processing and packaging techniques to achieve a safe and high‐quality potato strips with a 4 wk minimum refrigerated shelf life. Potato strips were 1st blanched at low temperature (60 °C) in 0.5% CaCl₂ solution for 20 min and then 2nd blanched at high temperature (approximately 98 °C) in water for 5 min. Blanched strips were packaged in a near‐aseptic environment or treated in‐package with gaseous ozone, sodium metabisulfite (SM) solution, or FIT Fruit and Vegetable Wash? (Procter and Gamble Co., Cincinnati, Ohio, U.S.A.) and then stored at 7 ± 1 °C for 28 d. No significant difference was observed in lightness of near‐aseptically packaged fries, FIT‐treated fries, and frozen fries; however, less color difference was determined in near‐aseptically packaged fries and FIT‐treated fries compared to frozen fries. Gaseous ozone treatment decreased color quality of potato strips, significantly. The highest after‐frying peak force was observed in FIT‐treated strips. There was no significant difference in oil absorption of refrigerated and unprocessed strips. These results indicate that either near‐aseptic packaging or in‐package FIT treatment are the better alternatives for blanched potato strips to extend shelf life and maintain quality. Practical Application: In this study, several processing conditions and packaging methods were evaluated to improve quality and extend shelf life of refrigerated potato strips. Results indicate that the combination of 2‐step blanching and near‐aseptic packaging was an effective nonchemical processing method, giving 28 d refrigerated shelf life. Similarly, FIT Fruit and Vegetable Wash? proved to be an effective chemical alternative to sulfites and avoids the allergen concern.     

Tuna Burgers Preserved by the Selected <Emphasis Type="Italic">Lactobacillus paracasei</Emphasis> IMPC 4.1 Strain

The use of protective microbial strains in combination with modified atmosphere packaging (MAP) and refrigerated storage on the shelf life of tuna burgers was investigated. Preliminary, the protective ability of three lactic acid bacteria (LAB) cultures (Lactobacillus casei, Lactobacillus paracasei, and Lactobacillus plantarum) have been assessed on ready-to-cook tuna burgers. Among them, L. paracasei showed the best preserving performance and significantly controlled both aerobic mesophilic bacteria and Pseudomonas spp. growth. Subsequently, the efficacy of the selected LAB culture under MAP conditions (5% O₂ and 95% CO₂) was assessed evaluating microbial and sensory quality, as well as volatile aldehyde content. Results indicated that the shelf life of burgers containing L. paracasei and packaged under MAP was 4 days longer than the control (shelf life about 6 days) and that the applied procedure represents an effective approach for the mild preservation of fish products.