Abstract Flexible packaging has many advantages in the food industry, arising from low weight, formability, multilayer complexity and cost. Heat sealing is a very efficient technique to close flexible food packaging. Currently, many thermoplastic materials are used in seal layers. A seal can be formed when these materials are heated and brought into contact; thereafter, polymer chains diffuse across the seal interface and entangle. Hydrogen bonds, polar and ionic interactions are molecular forces that can come into play, depending on the thermoplastic materials that are used in the seal layer. Bonds between identical polymers, referred to as autohesion, are formed in pouch applications (e.g., horizontal and vertical form‐fill‐seal packages). In lidding applications, the flexible film is sealed to a rigid cup, tray or bottle, whereby bonds can be formed between non‐identical polymers because the materials are often provided by different suppliers. All heat seal technologies imply heating of seal layers but differ in the heating principle. In the food industry and in most scientific seal studies, the seals of mono‐ and multilayered packaging are mainly formed by conductive heating. Recently, the use of emerging technologies, such as ultrasonic and laser heating, is increasingly described in recent papers. Applied seals are characterized by strength after a specified cooling time. Immediately after heating, this strength is referred to as hot tack. A good seal performance is crucial to guarantee food safety and quality. Besides strength, tightness is important to prevent food degradation, caused by microorganisms and external gases, and to keep aromatic gases inside the package. This review aims to give a literature overview that can support stakeholders in the food industry to improve and optimize the material selection in flexible packaging, in order to obtain seals with desired tightness and strength. Heat seal studies on materials and seal technology of flexible food packaging, such as pouches and lidding films, are considered. Scientific data are categorized from a materials' perspective, based on chemical structure, which is revealed by chemical and thermal analysis. A majority of the seal studies is categorized in a first section on polyolefins as seal layers. The following sections describe the seal functionality of (i) ethylene copolymers, such as ionomers; and (ii) polyesters, such as poly (ethylene terephthalate), pol (lactic acid) and poly (butylene succinate). The role of plasticizers, fillers and other additives in the seal performance is also described. Finally, material properties, such as chain length and melting temperature (Tm), as underlying causes of seal performance, are summarized.

Abstract The aim of this study was to measure the vibration levels in one of the types of truck most used in Spain for the shipment of packaged goods, formed by tractor unit and air‐suspension semi‐trailer with 26 tonnes (26 000 kg) payload capacity, considering the most representative routes of the main Spanish road network. The data presented in this study will enable the development of new specific vibration tests and will help product and package engineers to reduce damage in transit. In this study, 30 transport routes recording nearly 10 000 km of the Spanish main road network have been selected and analysed, and power spectral density (PSD) profiles are provided to simulate truck transport in Spain using random vibration test methods. The resulting PSD profiles were established by generating two grms levels (0.21 and 0.15) obtaining the highest intensity from the calculation of the upper one‐sided normal tolerance limit (NTL) (30,95,50) and an average intensity profile at −6 dB with respect to the calculated NTL curve, which represents 70% of the lowest grms values of the study. This study uses NTL analysis to explore the vibration characteristics of a typical heavy goods transport vehicle type for various routes along main highways in Spain and propose new transport simulation test protocols dedicated to the Spanish main road distribution environment.

No abstract is available for this article.

Abstract The unintentional bacterial contamination in food seriously harms food quality and human health, so it is necessary to establish a real‐time bacterial detection method. Here, a colour indicator film was designed to detect bacterial by incorporating bromothymol blue (BTB) into degradable poly‐L‐lactic acid (PLLA) and polyvinylpyrrolidone (PVP). The colour indicator film was prepared into fibres by electrospinning technology. The colour indicator film showed colour responsiveness from yellow to green at different pH. The colour indicator film showed good colour stability at different temperature and humidity conditions. The colour indicator film was used for the detection of bacteria, and it was found that the colour indicator film could make a colour response visible to the naked eye according to different concentrations of bacteria, which showed the great potential of the colour indicator film in detecting bacteria.

Abstract An intelligent pH‐sensing indicator containing Roselle (Hibiscus sabdariffa L.) (ROS) anthocyanin and alizarin (ALZ) was developed and characterized as on‐package indicator tags to check the shrimp freshness during the storing at 4°C. Fourier transform infrared (FT‐IR) analysis showed that ROS and ALZ were successfully immobilized in the gelatin–glycerol film‐forming substrate. The addition of various natural dyes enhanced the thickness and antioxidant action of the colourimetric film. To assess the response to changes in the pH, the colourimetric film was immersed in different buffers. Based on volatile amines secreted by shrimp, a test application of a colourimetric film containing natural dyes at a ratio of ROS:ALZ = 4:1 (v/v) was conducted in shrimp at 4°C. The findings indicated that the designed colourimetric film could produce various colours, which are thought to indicate the freshness and spoilage of packaged shrimp. Therefore, the target film can be utilized as a promising smart packaging material for monitoring the freshness of shrimp and aquatic products in real time.

Abstract Dwell time is one of the main parameters influencing heat seal quality and process efficiency in flexible packaging. In this study, the rheological behaviour of polypropylene (PP)/low‐density polyethylene (PE‐LD)‐based compound films containing different ratios of talc was examined. The minimum dwell time required to supply a sufficient sealing was estimated based on heat conduction time and reptation time. Reptation is a rheological concept used to described the behaviour of a polymer melt, and the reptation time is the time required for a molecule to escape from its surrounded entangled structure. The results showed that increased levels of talc are associated with elevated complex viscosities, storage and loss modulus as well as an increased seal strength. The estimated minimum required dwell time at the seal initiation temperature (SIT) dropped sharply with the initial introduction of 10 wt% talc. However, increasing the talc ratio to 30 wt% did not create any major change in the estimated time value. Also, observed T‐peel strength values for 0.1 and 0.5 s dwell time at SIT confirmed the predicted minimum required dwell time values. On the other hand, when the seal temperature is increased to the higher end of the operation window, time estimations did not match with the observed seal strengths. Here, the melting already starts and the molecules diffuse up to a certain distance before the interface temperature reaches the desired level. Recalculation of the average diffusion distance by including this pre‐melting situation can present a better approach for the temperatures above SIT. When the molecules diffused around halfway along the sealant thickness observed, seal strengths reached a sufficient level (2.5 N/25 mm) for both SIT and the highest end of the operation window. In conclusion, it has been revealed that knowing the reptation time and the required time for the heat conduction during the sealing process can help to predict the minimum required dwell time to achieve quality sealing, especially at low sealing temperatures. Additional surface characterizations also helped to elaborate on the influence of changing insoluble filler ratio on the seal initiation properties. It has been showed that the added talc increases the surface free energy and supplies easier wetting at the seal interface. Therefore, adding talc or a similar insoluble filler can help to make the heat sealing process more efficient.

Ripeness of fruits is one of the factors causing food losses in the supply chain. Food loss increases the environmental burden through additional production undertaken to compensate for the losses. Packaging decreases the losses and consequently, the environmental burden, but itself causes additional environmental burden. This study models the relationship between food loss reduction via packaging for ripened peaches and the environmental burden across their life cycle. The results reveal that the slope of the straight line approximating the relationship increases with transportation distance. Relationship between the slope and transportation distance shows that for transportation up to 100 km, packaging with lower environmental burden is sufficient while above 300 km, packaging that provides a high level of protection for peaches—with the consequent reduction in food loss contributing to the reduction of the environmental burden—is appropriate. We propose packaging with superior environmental‐friendly qualities, based on the transportation distance, for ripened peaches.

Fresh beef is a typically perishable food because of its high water and protein content; thus, it requires proper packaging condition and storage temperature to ensure its quality. In this study, the beef steaks were stored at 4°C under HiO2 modified atmosphere packaging (MAP) (78.8% O2 + 18.8% CO2 + 2.4% N2) and HiCO2 MAP (60.0% CO2 + 40.0% N2). The traditional air packaging (AP) and vacuum packaging (VP) were used as the controls. The total viable count (TVC), colour, water holding capacity (WHC), myofibrillar protein (MP) oxidation and lipid oxidation of beef meat were investigated. The moisture distribution and migration were also analysed using the low‐field nuclear magnetic resonance (LF‐NMR). The association amongst all parameters was analysed by correlation analysis and principal component analysis (PCA). The results showed that the TVC values in the HiCO2 MAP (5.6 log CFU/g) steaks were lower than those of VP (5.9 log CFU/g), AP (7.0 log CFU/g) and HiO2 MAP (6.3 log CFU/g) steaks because of the sufficient CO2 after 15 days of chilled storage. The bright red colour and the higher WHC were maintained in the HiO2 MAP steaks than in the AP group during storage. However, higher levels of protein and lipid oxidation also occurred. The beef steaks stored under HiCO2 MAP had the lowest protein and lipid oxidation and highest value of immobile water content and WHC, however, similar to the VP group, the bright red colour was not shown. The moisture attributes (drip loss, cooking loss and P23), protein oxidation (protein solubility and carbonyl content) and lipid oxidation (TBARS value) have shown a close correlation by correlation analysis and PCA. Overall, two different packaging methods of MAP can prolong microbial‐shelf life and maintain higher WHC of beef steaks compared to AP and VP steaks, but higher oxidation level in HiO2 MAP and unattractive colour in HiCO2 MAP are concerns that need to be addressed.

In this study, the purpose is to present the steps and mathematical methods of improving the transport packaging process, which is an integral operation of outbound logistics. Case studies involving tertiary packaging have been conducted, as it is a traditional form of transport packaging. The research is supported by multicriteria decision-making (MDCM) and linear programming (LP) methods.

The present study investigates torsional and compressive loading of a paperboard package. Finite element (FE) analyses simulating the tests were performed to improve understanding of the stresses and deformations in the paperboard during loading. A simple experimental characterization of the necessary material properties could be performed to represent the multi‐ply paperboard as a single‐ply structure. The results from the single‐ply model were compared with a laminate model, and the differences between the models were small. Comparing experimental and FE simulations of box compression and torsion showed that the FE models could accurately predict the response curves. However, in the simulations, there was an overprediction of the maximum compressive force and maximum torque, which was expected since geometrical imperfections and the heterogeneous internal structure of the material were not accounted for in the material model or the FE model. Local yield lines formed at the onset of non‐linearities in the package load–displacement curves. Therefore, the strength of the paperboard affects the maximum compressive strength and maximum torque, and the bending stiffness of the paperboard only had a minor effect. When a first local maximum was reached, the number of FE that reached the failure stress increased exponentially. The simulations also showed that box compression was not an effect of package height, but higher packages had a lower maximum torque.