High‐pressure processing effects on the barrier properties of flexible packaging materials

Effect of ohmic heating on the structure and properties of flexible multilayer packaging

Food-packaging-processing interactions define packaging materials' performance properties and product quality. This study evaluated the effect of ohmic heating (OH) processing and different food simulants on the properties of four multilayer flexible packaging materials (PETmet/PE, PETmet/PP, PET/Al/PE, and PET/Al/PA/PP). OH treatment was applied to the sealed packages containing the food simulants using a voltage gradient of 3.7 V/cm at a frequency of 20 kHz, resulting in a thermal process of at 80 °C for 1 min. The structure and performance of the different packages were then evaluated. The materials did not show changes in chemical groups nor thermal properties. However, the simulant-packaging-processing interaction resulted in changes in crystallinity, morphology, mechanical and barrier properties (water and oxygen), especially for metallized films in contact with acidic food simulants. The results indicate that although OH resulted in changes in packaging materials, these materials can be used under the conditions applied in this study.

Moisture sorption isotherms characteristics for shelf-life prediction of peanuts (Arachis Hypogaea L.)

BACKGROUND

The spring grown peanut varieties J87 and TG37A are prone to quality deterioration as a result of high temperature and relative humidity during harvesting. Thus, the sorption isotherms of peanut varieties were evaluated at 25, 35 and 45 °C and the water activity (a_w ) range of 0.110-0.975 aiming to predict the suitable storage conditions, packaging material and shelf-life.

RESULTS

The equilibrium moisture content (EMC) increased with increased a_w and isotherms of type II were observed. The monolayer moisture content varied between 3.135% and 4.235% for J87 and between 3.906% and 5.640% for TG37A variety. The experimental data were fitted to seven mathematical models. The variations in correlation coefficients were in the range 0.879-0.992 and in root mean square were in the range 0.055-1.988. On the basis of statistical parameters, Guggenheim Anderson de Boer and Double Log Polynomial were considered to be best fitted models. At a_w of 0.6, critical moisture content (CMC) was 7.59%, 7.060% and 5.89% for J87 and 9.06%, 8.904% and 7.80% for TG37A at 25, 35 and 45 °C, respectively. The shelf-life prediction model provided that the aluminum packages had the maximum predicted shelf-life of around 1779 days for TG37A and 1077 days for J87 variety at 25 °C with an initial moisture content of 5.91% and 4.81%, respectively.

CONCLUSION

The EMC and CMC evaluated from sorption study provided the basis for determination of package properties and shelf life. Aluminum packages had the minimum water vapor transmission rate and permeability. Hence, peanuts packaged in these bags and stored at 25 °C and 75% relative humidity had the potential to attain the maximum storage life. © 2023 Society of Chemical Industry.

Food-Package-Processing relationships in emerging technologies: Ultrasound effects on polyamide multilayer packaging in contact with different food simulants

In this study, the effect of ultrasound processing on the properties of two packages widely used in food products was evaluated: polyamide (PA) and polyethylene (PE) multilayer packaging. Packages composed of PE/PA/PE (Film A) and PE/PA/PE/PA/PE (Film B) were filled with aqueous and fatty food simulants and treated in an ultrasound water bath (frequency 25 kHz, volumetric power of 9.74 W/L, temperature of 25 °C, and time of 30 and 60 min). Materials were evaluated in term of structure and performance properties. Ultrasound did not or induced small changes in chemical groups, crystallinity, melting temperature, and tensile strength of the films. Film A showed a reduction in heat sealing tensile strength of 25% in the machine direction and 22% in the transverse direction. Film B showed a 20% increase of water vapor transmission rate after ultrasound processing. Although ultrasound had little impact on the properties of the evaluated materials, these modifications do not compromise the use of these packages for applications in ultrasound-processed foods. Therefore, the results indicate that ultrasound can be used as a food processing technology in multilayer PA and PE packaging.

Effect of High-Pressure Processing on the Packaging Properties of Biopolymer-Based Films: A Review

Suitable packaging material in combination with high-pressure processing (HPP) can retain nutritional and organoleptic qualities besides extending the product’s shelf life of food products. However, the selection of appropriate packaging materials suitable for HPP is tremendously important because harsh environments like high pressure and high temperature during the processing can result in deviation in the visual and functional properties of the packaging materials. Traditionally, fossil-based plastic packaging is preferred for the HPP of food products, but these materials are of serious concern to the environment. Therefore, bio-based packaging systems are proposed to be a promising alternative to fossil-based plastic packaging. Some studies have scrutinized the impact of HPP on the functional properties of biopolymer-based packaging materials. This review summarizes the HPP application on biopolymer-based film-forming solutions and pre-formed biopolymer-based films. The impact of HPP on the key packaging properties such as structural, mechanical, thermal, and barrier properties in addition to the migration of additives from the packaging material into food products were systemically analyzed. HPP can be applied either to the film-forming solution or preformed packages. Structural, mechanical, hydrophobic, barrier, and thermal characteristics of the films are enhanced when the film-forming solution is exposed to HPP overcoming the shortcomings of the native biopolymers-based film. Also, biopolymer-based packaging mostly PLA based when exposed to HPP at low temperature showed no significant deviation in packaging properties indicating the suitability of their applications. HPP may induce the migration of packaging additives and thus should be thoroughly studied. Overall, HPP can be one way to enhance the properties of biopolymer-based films and can also be used for packaging food materials intended for HPP.

Benefits and effectiveness of high pressure processing on cheese: a ricotta case study

Today High Pressure Processing (HPP) is receiving interest thanks to its ability to stabilize foods preserving nutritional and sensorial characteristics. This work applies HPP on nutrient ricottas created in the Parmigiano Reggiano area and demonstrates not only its benefits, but also disadvantages, testing different pressures and packaging. Moreover, the ability of HPP to prolong the lag phase and reduce the maximum growth rate of bacteria is illustrated with a mathematical model. Results show the influence of HPP parameters on microbial growth, volatile organic compounds, syneresis, softness and colour, and demonstrate that not all packaging are suitable for the treatment. Obtained data highlight the effectiveness of HPP, which results the best stabilization method to sell safe and nutritive ricottas on the market with a long shelf life. Of course, the work can be a starting point for food companies who want to test an innovative and promising non-thermal technology.

Effect of low concentrations of SiO2 nanoparticles on the physical and chemical properties of sodium alginate-based films

This work investigated the effect of adding low concentrations of nano-SiO₂ (0.5, 1.0 and 1.5%) in the properties of films based on sodium alginate, to identify lower thresholds in the proportion of the reinforcing agent. It was found that, even in the smallest proportion, thermal stability of the nanocomposites improved significantly (with degradation onset increased by almost 15% compared with the control film). The surface morphology showed pronounced roughness at nano-SiO₂ concentrations greater than 1.0%, indicating agglomeration of part of the nanomaterial. Mechanical properties were reduced for the samples with concentrations equal to 1.0 and 1.5%, however, without significant differences between them. Conversely, water vapor and light barrier properties have not undergone significant changes in any formulation. Therefore, the use of 0.5% nano-SiO₂ in alginate films would be an easy and economically interesting way to improve thermal stability, without significantly reducing mechanical properties of the pure material.

Essential oils as additives in active starch-based food packaging films: A review

The production of sustainable food packaging from renewable sources represents a prominent alternative to the use of petrochemical-based plastics. For example, starch remains one of the more closely studied replacement options due to its broad availability, low cost and significant advances in improving properties. In this context, essential oils as additives fulfil a key role in the manufacture of renewable active packaging with superior performances. In this review, a comprehensive summary of the impact of adding essential oils to the starch-based films is provided. After a brief introduction to the fundamental concepts related to starch and essential oils, details on the most recent advances in obtaining active starch-based films are presented. Subsequently, the effects of essential oils addition on the structure-property relationships (from physicochemical to antimicrobial ones) are thoroughly addressed. Finally, applications and challenges to the widespread use of essential oils are critically discussed.