Development of user-friendly software for design of modified atmosphere packaging for fresh and fresh-cut produce

Enhancing Gas Transmission Rate of PBS/PBAT Composite Films: A Study on Microperforated Film Solutions for Mango Storage

This study focused on improving the mechanical properties of the poly(butylene succinate) (PBS) film by incorporation of poly(butyrate adipate terephthalate) (PBAT). At 20 wt % PBAT, elongation in the transverse direction improved by 373% while maintaining high tensile strength (27 MPa) and Young's modulus (262 MPa). The PBS80/PBAT20 composite film exhibited optimized mechanical properties. The absorbance coefficient of microperforated film at 980/cm for the 80PBS/20PBAT mix, corresponding to the 10.2 μm CO2 laser wavelength, was 65/cm, indicating high film capability to absorb energy from the CO2 laser. The introduction of microholes enhanced the gas permeability of the PBS/PBAT film. As fluences increased from 187 to 370 J/cm2, there was a notable increase in microhole area in 80PBS/20PBAT film from 19,375 to 46,421 μm2. Concurrently, the gas transmission rate for a singular hole increased from 45 to 210 cm3/d for the oxygen transmission rate (OTR) and from 115 to 220 cm3/d for the CO2 transmission rate (CO2TR). For mango packed in microperforated 80PBS/20PBAT films, the O2 levels inside the package gradually dropped and remained at 14.2% in PBS80/PBAT20-MP1 (OTR ∼ 68,900 cm3/m2·d) and 16.7% in PBS80/PBAT20-MP2 (OTR ∼ 131,900 cm3/m2·d), while CO2 content increased to 6% for PBS80/PBAT20-MP1 and 4% for PBS80/PBAT20-MP2 throughout 33 days. On day 2 of storage in the nonperforated package, O2 content dropped to 2% while CO2 content rose to 22%. Mango packed in the 80PBS/20PBAT film package exhibited an unsatisfactory freshness quality due to the detection of a fermentative odor on day 5 of the storage period. Total soluble solids, color, and weight loss of mango remained stable during storage in all microperforated films. Results demonstrated that the mango shelf life was significantly extended by 35 days using 80PBS/20PBAT-MP1. Laser perforation offered a practical method for improving gas transmission rates (OTR and CO2TR) of 80PBS/20PBAT film for mango packaging.

Polypropylene/Poly(butylene adipate-co-terephthalate) Breathing Film for Inhibiting Pseudomonas and Maintaining Microbial Communities and Postharvest Quality of Allium mongolicum Regel during Storage

Allium mongolicum Regel (A. mongolicum) is a healthy edible plant but highly perishable with a short shelf life of 1-2 d. Modified atmosphere packaging (MAP) could inhibit the postharvest senescence and decay of the vegetables. Thus, the aim of this study was to apply MAP with different gas permeabilities to the storage of A. mongolicum and evaluate its effects on maintaining microbial communities and the postharvest quality of A. mongolicum. The results showed that polypropylene/poly(butylene adipate-co-terephthalate) (PP/PBAT, abbreviated as PAT) MAP was suitable for the storage of A. mongolicum by establishing an optimal atmosphere of 0.5-0.6% O2 and 6.2-7.1% CO2 in the bag. It could delay the postharvest senescence of A. mongolicum and maintain its quality by slowing down its respiration rate and weight loss, reducing cell membrane permeability and lipid peroxidation, maintaining the cell wall, and reducing infection and the growth of microorganisms. However, A. mongolicum in HPT was more perishable than that in PAT during storage. Pseudomonas was found to be the main spoilage bacteria, and they could also be effectively inhibited by PAT-MAP. The next-generation sequencing results also showed the growth of Escherichia-Shigella, Clostridium sensu stricto 1, Streptococcus, Aureobasidium, Didymella, and Fusarium, responsible for A. mongolicum decay or human disease, was well inhibited by PAT-MAP. The results suggested that PAT-MAP could be used to maintain microbial diversity and the postharvest quality of A. mongolicum under cold storage conditions. It provided a feasible solution for the preservation, food quality, and safety control of A. mongolicum.

Development of a Controlled-Ventilation Box for Modified-Atmosphere Storage of Fresh Produce

Adjusting beneficial gas concentrations in real time in response to changing storage conditions is important for fresh produce, especially throughout the supply chain when temperature abuse occurs frequently. In this study, a controlled-ventilated box for bulk transportation of fresh produce was demonstrated and tested under variable temperatures. The presented system comprised a rigid container with a miniature blower installed in the opening of its wall for facilitating the gas exchange and an additional wall opening with a metal tube protruding into the inner container's space. The in-package atmosphere was formed by the balance between the respiratory activity of the produce and the influx of fresh air through the wall openings, regulated by switching the blower ON or OFF. The mass transfer coefficient for metal tubes of different dimensions was measured under modified atmosphere featuring 15% CO₂ and 5% O₂ at 10 °C. The addition of an air blower increased the mass transfer coefficient by at least 100 times. A further storage trial with cherries was successfully performed at 10 °C and 20 °C. The demonstrated trial featured some significant inputs to increase the knowledge about better storage of fresh produce throughout the supply chain and storage.

Integrative programming for simulation of packaging headspace and shelf life of fresh produce

Fresh horticultural products are exposed to different environmental conditions from farm to fork. Barrier properties of packaging and physiological behaviour of produce, namely respiration and transpiration can affect headspace conditions surrounding produce and consequently remaining shelf life. Packaging material also plays a role in heat and mass transfer, such as thermal conduction and permeation of O2, CO2 and water vapour. All of these behaviours are integrated together in the form of ordinary differential equations and solved using numerical methods in MATLAB. • The simulation program is useful for designing the size and number of perforations to achieve equilibrium modified atmosphere alone or in combination with packaging material having a higher water transmission rate or active moisture absorber. • The simulation program is also useful for predicting the shelf life of fresh produce under the actual supply chain conditions. • The simulation program provides a flexible system to input predefined supply chain conditions and the properties of fresh produce and packaging material, thus, minimizing the costly and time consuming experimental procedures for selecting the optimum packaging material for fresh produce.

Fresh Mushroom Preservation Techniques

The production and consumption of fresh mushrooms has experienced a significant increase in recent decades. This trend has been driven mainly by their nutritional value and by the presence of bioactive and nutraceutical components that are associated with health benefits, which has led some to consider them a functional food. Mushrooms represent an attractive food for vegetarian and vegan consumers due to their high contents of high-biological-value proteins and vitamin D. However, due to their high respiratory rate, high water content, and lack of a cuticular structure, mushrooms rapidly lose quality and have a short shelf life after harvest, which limits their commercialization in the fresh state. Several traditional preservation methods are used to maintain their quality and extend their shelf life. This article reviews some preservation methods that are commonly used to preserve fresh mushrooms and promising new preservation techniques, highlighting the use of new packaging systems and regulations aimed at the development of more sustainable packaging.

The microperforated packaging design and evaluation of shelf life of fresh-sliced mushrooms

Fresh mushrooms have a very short shelf life, of 1 – 3 days because of their high respiration rate and lack of cuticles that protect the plant from external factors. In the case of fresh-sliced mushrooms, they will be more susceptible to spoilage reactions due to the increase in respiration rate as a result of a broader surface area. Conventional packaging materials can not meet the requirements for modified atmosphere packaging of fresh-sliced mushrooms. One of the techniques to extend the fresh-cut produce shelf life is the passive modification of modified atmosphere packaging technology. For highly respiring fresh-cut produce such as fresh-sliced mushrooms, the permeability properties of the polymeric materials might not be enough to provide an equilibrium gas concentration in the passive modification of modified atmosphere technology. In this case, the microperforated packaging materials can be used for passive modification of fresh-cut produce. But the microperforation process needs a design for the application of the appropriate number and diameter of microholes to meet the requirements of passive modified atmosphere packaging. For this reason in this research, the design of the microperforation process to be used in passive modified atmosphere packaging was based on the diameter and the number of microholes, and the shelf life of fresh-sliced mushrooms was determined. The samples were stored at 15 °C/80% RH, and pH, color, weight loss, textural, sensorial, and microbial analysis were performed periodically during storage. It was determined that the empirical equation used in this research can be applied to microperforated packaging design for fresh-sliced mushrooms. The shelf life of the fresh-sliced mushrooms packaged with microperforated packaging material was 8 days, while it was less than 7 days (4, 5, or 6 days) when packaged with non-microperforated packaging material. This result shows that the use of microperforated packaging material is effective in extending the shelf life of fresh-sliced mushrooms.

Curcumin-Based Photodynamic Sterilization for Preservation of Fresh-Cut Hami Melon

Fresh-cut fruits and vegetables are the main sources of foodborne illness outbreaks with implicated pathogens such as Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes. This study aimed at investigating the influence of two key parameters (concentration of curcumin and illumination time) on the effects of curcumin-based photodynamic sterilization on the preservation of fresh-cut Hami melons. The results indicated that illumination with 50 μmol/L curcumin for 60 min using a blue LED lamp reduced the total aerobic microorganism count by ~1.8 log CFU/g in fresh-cut Hami melons. Besides this, the effects of photodynamic sterilization on the soluble solids content, color, water content, firmness, and sensory indices of the fresh-cut Hami melons were also evaluated. Compared to the control group, photodynamic sterilization can effectively delay the browning rate and maintain the luminosity, firmness, water content, and soluble solids content of fresh-cut Hami melon. The sensory quality was indeed preserved well after 9 days of storage in a fridge. These results showed that photodynamic sterilization is an effective and promising technology to prolong the shelf life of fresh-cut Hami melons.

Nanostructured poly(l-lactic acid)-poly(ethylene glycol)-poly(l-lactic acid) triblock copolymers and their CO2/O2 permselectivity

Biodegradable poly(l-lactic acid)-poly(ethylene glycol)-poly(l-lactic acid) (PLLA-PEG-PLLA) copolymers were synthesized by ring-opening polymerization of l-lactide using dihydroxy PEG as the initiator. The effects of different PEG segments in the copolymers on the mechanical and permeative properties were investigated. It was determined that certain additions of PEG result in composition-dependent microphase separation structures with both PLLA and PEG blocks in the amorphous state. Amorphous PEGs with high CO₂ affinity form gas passages that provide excellent CO₂/O₂ permselectivity in such a nanostructure morphology. The gas permeability and permselectivity depend on the molecular weight and content of the PEG and are influenced by the temperature. Copolymers that have a higher molecular weight and content of PEG present better CO₂ permeability at higher temperatures but provide better CO₂/O₂ permselectivity at lower temperatures. In addition, the hydrophilic PEG segments improve the water vapor permeability of PLLA. Such biodegradable copolymers have great potential for use as fresh product packaging.

Mechanistic model coupling gas exchange dynamics and Listeria monocytogenes growth in modified atmosphere packaging of non respiring food

A mechanistic model coupling O2 and CO2 mass transfer (namely diffusion and solubilisation in the food itself and permeation through the packaging material) to microbial growth models was developed aiming at predicting the shelf life of modified atmosphere packaging (MAP) systems. It was experimentally validated on a non-respiring food by investigating concomitantly the O2/CO2 partial pressure in packaging headspace and the growth of Listeria monocytogenes (average microbial count) within the food sample. A sensitivity analysis has revealed that the reliability of the prediction by this "super-parametrized" model (no less than 47 parameters were required for running one simulation) was strongly dependent on the accuracy of the microbial input parameters. Once validated, this model was used to decipher the role of O2/CO2 mass transfer on microbial growth and as a MAP design tool: an example of MAP dimensioning was provided in this paper as a proof of concept.

Development and validation of a comprehensive model for map of fruits based on enzyme kinetics theory and arrhenius relation

MAP is a dynamic system where respiration of the packaged product and gas permeation through the packaging film takes place simultaneously. The desired level of O2 and CO2 in a package is achieved by matching film permeation rates for O2 and CO2 with respiration rate of the packaged product. A mathematical model for MAP of fresh fruits applying enzyme kinetics based respiration equation coupled with the Arrhenious type model was developed. The model was solved numerically using MATLAB programme. The model was used to determine the time to reach to the equilibrium concentration inside the MA package and the level of O2 and CO2 concentration at equilibrium state. The developed model for prediction of equilibrium O2 and CO2 concentration was validated using experimental data for MA packaging of apple, guava and litchi.

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.

PRACTICAL APPLICATION

This research helps to quantify the ethylene production and respiration rates of multicomponent mixed fresh-cut fruit, which then can be used for packaging design of fresh-cut produce.

Postharvest treatments of fresh produce

Postharvest technologies have allowed horticultural industries to meet the global demands of local and large-scale production and intercontinental distribution of fresh produce that have high nutritional and sensory quality. Harvested products are metabolically active, undergoing ripening and senescence processes that must be controlled to prolong postharvest quality. Inadequate management of these processes can result in major losses in nutritional and quality attributes, outbreaks of foodborne pathogens and financial loss for all players along the supply chain, from growers to consumers. Optimal postharvest treatments for fresh produce seek to slow down physiological processes of senescence and maturation, reduce/inhibit development of physiological disorders and minimize the risk of microbial growth and contamination. In addition to basic postharvest technologies of temperature management, an array of others have been developed including various physical (heat, irradiation and edible coatings), chemical (antimicrobials, antioxidants and anti-browning) and gaseous treatments. This article examines the current status on postharvest treatments of fresh produce and emerging technologies, such as plasma and ozone, that can be used to maintain quality, reduce losses and waste of fresh produce. It also highlights further research needed to increase our understanding of the dynamic response of fresh produce to various postharvest treatments.

Design and development of modified atmosphere packaging system for guava (cv. Baruipur)

Modified atmosphere packaging (MAP) is a dynamic system during which respiration and permeation occur simultaneously. Hence factors affecting both respiration and permeation were considered for designing a package. In the design of MA packages for guava (cv. Baruipur) a total of 13 variables were considered. The independent variables includes: weight of fruits, surface area of packaging film, free volume of the package, thickness of the film and permeabilities of film to O2 and CO2 gas. The fixed variables considered were: the surrounding gas composition and temperature, the respiration rates for O2 consumption and CO2 evolution, and the equilibrium gas compositions to be attained in the package so that the fruit's shelf-life is extended. Two types of MA packages, having package size of 19 cm × 19 cm for a fill weight of 1,000 ± 100 g were developed. Packages were designed to accommodate a fill weight range of 0.90-1.10 kg. Various package parameters were optimized to facilitate establishment of dynamic equilibrium at target levels of O2 and CO2 concentration in the package. The storage study of MA packages was performed at 10, 15, 20 and 25 °C temperatures. The performance of film packages was evaluated for their ability to establish equilibrium at target levels and to extend the shelf life of the packaged fruit. The MA packaging system increased the shelf life of guava by 128-200 % compared to the unpacked fruits at various storage temperatures with a quality comparable with the freshly harvested commodity.

Modified Atmosphere Packaging Technology of Fresh and Fresh-cut Produce and the Microbial Consequences-A Review

Modified atmosphere packaging (MAP) technology offers the possibility to retard the respiration rate and extend the shelf life of fresh produce, and is increasingly used globally as value adding in the fresh and fresh-cut food industry. However, the outbreaks of foodborne diseases and emergence of resistant foodborne pathogens in MAP have heightened public interest on the effects of MAP technology on the survival and growth of pathogenic organisms. This paper critically reviews the effects of MAP on the microbiological safety of fresh or fresh-cut produce, including the role of innovative tools such as the use of pressurised inert/noble gases, predictive microbiology and intelligent packaging in the advancement of MAP safety. The integration of Hazard Analysis and Critical Control Points-based programs to ensure fresh food quality and microbial safety in packaging technology is highlighted.

Novel wireless sensor system for monitoring oxygen, temperature and respiration rate of horticultural crops post harvest

In order to design optimal packages, it is of pivotal importance to determine the rate at which harvested fresh fruits and vegetables consume oxygen. The respiration rate of oxygen (RRO₂) is determined by measuring the consumed oxygen per hour per kg plant material, and the rate is highly influenced by temperature and gas composition. Traditionally, RRO₂ has been determined at discrete time intervals. In this study, wireless sensor networks (WSNs) were used to determine RRO₂ continuously in plant material (fresh cut broccoli florets) at 5 °C, 10 °C and 20 °C and at modified gas compositions (decreasing oxygen and increasing carbon dioxide levels). Furthermore, the WSN enabled concomitant determination of oxygen and temperature in the very close vicinity of the plant material. This information proved a very close relationship between changes in temperature and respiration rate. The applied WSNs were unable to determine oxygen levels lower than 5% and carbon dioxide was not determined. Despite these drawbacks in relation to respiration analysis, the WSNs offer a new possibility to do continuous measurement of RRO₂ in post harvest research, thereby investigating the close relation between temperature and RRO₂. The conclusions are that WSNs have the potential to be used as a monitor of RRO₂ of plant material after harvest, during storage and packaging, thereby leading to optimized consumer products.