Luciano Piergiovanni

Food Packaging Science and Technology

Overview of Food Packaging Systems Introduction Science and Technology of Food Packaging Socioeconomic Needs Packaging Functions Packaging Environments Food Packaging Systems Tables for Analyzing Food Packaging Systems Food Package Development Chemical Structures and Properties of Packaging Materials Chemical Constituents Chemical Bonding Intermolecular Forces Spatial Arrangements Chemical Reactivity and Susceptibility of Packaging Physical Properties of Packaging Materials Introduction Thermal Properties Electromagnetic Properties Mechanical Properties Permeation of Gas and Vapor Introduction Basic Concepts of Permeation Theoretical Analysis Terminology and Units for Permeation Permeability Coefficients of Food Packaging Polymers Factors Governing Permeation Measurements for Permeation Properties Migration and Flavor Scalping Introduction Phenomenal Description of Migration Process Migration Issues in Food Packaging Flavor Scalping and Sorption Migration Testing Predictive Migration Models Regulatory Considerations Food Packaging Polymers Basic Concepts of Polymers Polymerization Reactions Plastics versus Polymers Composition/Processing/Morphology/Properties Relationships Characteristics of Packaging Polymers Food Packaging Polymers Polymer Processing Glass Packaging Introduction Chemical Structure Glass Properties Glass Containers Manufacturing Glass Container Strengthening Treatments Use of Glass Containers in Food Packaging Other Ceramic Containers Metal Packaging Introduction Aluminum Coated Steels Stainless Steel Metal Corrosion Metal Container Manufacturing Protective Lacquers Cellulosic Packaging Introduction Cellulose Fiber-Morphology Cellulose Fiber-Chemistry Paper and Paperboard Production Paper Bags & Wrappings Corrugated Board and Boxes Folding Cartons and Set-up Boxes Composite Cans and Fiber Drums Cartons for Liquids Molded Cellulose Cellophane Other Quasi Cellulosic Materials End-of-Line Operations Introduction Printing Label and Labeling Coding Sealing of Plastic Surfaces Case Study: Finding Sealing Conditions for a LLDPE Film Food Packaging Operations and Technology Food Packaging Line Filling of Liquid and Wet Food Products Filling of Dry Solid Foods Closure and Closing Operation Methods of Wrapping and Bagging Form/Fill/Seal Various Forms of Contact and Contour Packaging Case Studies Thermally Preserved Food Packaging: Retortable and Aseptic Introduction Thermal Destruction of Microorganisms and Food Quality Basics of Thermal Processing Design Hot Filling In-container Pasteurization and Sterilization Aseptic Packaging Case Study: Design of a Thermal-Processed Tray-Set Containing High- and Low-Acid Foods Vacuum/Modified Atmosphere Packaging Basic Principles Non-respiring Products Respiring Products Case study: Design of Modified Atmosphere Package for Blueberries Microwavable Packaging Microwaves and Microwave Oven Microwave/Food/Packaging Interactions Challenges in Microwave Heating of Foods Microwavable Packaging Materials Interactive Microwave Food Packages Case Study: Effect of Metal Shielding on Microwave Heating Uniformity Active and Intelligent Packaging Introduction Active Packaging - Absorbing System Active Packaging - Releasing System Active Packaging - Other System Intelligent Packaging Framework Smart Packaging Devices Legislative and Human Behavior Issues Case Study: Intelligent Microwave Oven with Barcode Reader Shelf Life of Packaged Food Products Introduction Food Distribution Channel Criteria Determining Shelf Life Kinetics Measurements and Prediction Case Study: Shelf Life of a Potato Chip Product with Two Interacting Quality Deterioration Mechanisms Elements of Packaging, Distribution and Shelf Life of Each Category Foods Introduction Cereals and Bakery Products Meat and Fish Products Dairy Products Confectionery Products Fats and Oils Drinks Fresh Fruits and Vegetables Frozen Foods Sustainable Food Packaging Sustainable Packaging Packaging Related Environmental Issues Management of Packaging Wastes Recycling of Packaging Materials Biodegradable Materials Degradable Packaging Life Cycle Assessment Sociological and Legislative Considerations Introduction Tamper Evident Packaging Product Liability Labeling Information

Wetting of biopolymer coatings: contact angle kinetics and image analysis investigation

The surface wetting of five biopolymers, used as coating materials for a plastic film, was monitored over a span of 8 min by means of the optical contact angle technique. Because most of the total variation was observed to occur during the first 60 s, we decided to focus on this curtailed temporal window. Initial contact angle values (θ(0)) ranged from ∼91° for chitosan to ∼30° for pullulan. However, the water drop profile began to change immediately following drop deposition for all biocoatings, confirming that the concept of water contact angle equilibrium is not applicable to most biopolymers. First, a three-parameter decay equation [θ(t) = θ(0) exp(kt(n))] was fit to the experimental contact angle data to describe the kinetics of the contact angle change for each biocoating. Interestingly, the k constant correlated well with the contact angle evolution rate and the n exponent seemed to be somehow linked to the physicochemical phenomena underlying the overall kinetics process. Second, to achieve a reliable description of droplet evolution, the contact angle (CA) analysis was coupled with image analysis (IA) through a combined geometric/trigonometric approach. Absorption and spreading were the key factors governing the overall mechanism of surface wetting during the 60 s analysis, although the individual quantification of both phenomena demonstrated that spreading provided the largest contribution for all biopolymers, with the only exception of gelatin, which showed two quasi-equivalent and counterbalancing effects. The possible correlation between these two phenomena and the topography of the biopolymer surfaces are then discussed on the basis of atomic force microscopy analyses.

Tunable green oxygen barrier through layer-by-layer self-assembly of chitosan and cellulose nanocrystals

We address the oxygen-barrier properties of a nanocomposite created by layer-by-layer assembly of two biopolymers, chitosan (CS) and cellulose, in nanocrystals form (CNs), on an amorphous PET substrate. We systematically investigated the oxygen permeability, morphology, and thickness of the nanocomposite grown under two different pH combinations and with different number of deposition cycles, up to 30 bilayers. Noticeably, the thickness of each deposited bilayer can be largely tuned by the pH value of the solution, from ~7 up to ~26 nm in the tested conditions. By our analysis, it is reliably concluded that such CS/CNs nanocomposite holds promises for gas barrier applications in food and drug packaging as a clear coating on plastic films and tridimensional objects, improving performance and sustainability of the final packages.

Self-assembled pullulan-silica oxygen barrier hybrid coatings for food packaging applications.

The scope of this study encompassed the evaluation of pullulan as a suitable biopolymer for the development of oxygen barrier coatings to be applied on poly(ethylene terephthalate) (PET), especially for food packaging applications. To enhance the oxygen barrier properties of the organic phase (pullulan) even at high relative humidity values, an inorganic phase (silica), obtained through in situ polymerization, was also utilized to obtain hybrid coatings via the sol-gel technique. Transmission electron microscopy (TEM) images and Fourier transform infrared (FT-IR) spectra showed that mixing the two phases yielded a three-dimensional hybrid network formed by self-assembly and mediated by the occurrence of new hydrogen-bond interactions at the intermolecular level, although the formation of new covalent bonds could not be excluded. The deposition of the hybrid coatings decreased the oxygen transmission rate (OTR) of the plastic substrate by up to 2 orders of magnitude under dry conditions. The best performance throughout the scanned humidity range (0%-80% relative humidity) was obtained for the formulation with the lowest amount of silica (that is, an organic/inorganic ratio equal to 3).

Encapsulation of volatiles in nanofibrous polysaccharide membranes for humidity-triggered release

A single-step electrospinning process will be applied to a blend of edible carbohydrate polymers (pullulan and β-cyclodextrin) to encapsulate bioactive aroma compounds and allow a humidity-triggered release. The encapsulation is rapid and efficient and the final product is an active nanofibrous membrane that can be directly used for food or active packaging applications. The membrane hosts small and homogeneously dispersed crystals of cyclodextrin-aroma complexes which are formed during the electrospinning. With this type of structure, the release of aroma compound is negligible at ambient conditions (23 °C and 55% UR) even at high temperature (up to 230 °C), and it occurs beyond a given relative humidity threshold (90%), useful for food packaging applications. The mass fraction of free aroma released is directly related to the water activity of the system, namely, φ=aW(n)/(aW(n)+Kapp) explaining the observed key role played by the relative humidity on the release of the aroma compounds.

Ultrasound-Assisted Pullulan/Montmorillonite Bionanocomposite Coating with High Oxygen Barrier Properties

In this paper, the preparation and characterization of oxygen barrier pullulan sodium montmorillonite (Na(+)-MMT) nanocomposite coatings are presented for the first time. Full exfoliation of platelets during preparation of the coating water dispersions was mediated by ultrasonic treatment, which turned out to be a pivotal factor in the oxygen barrier performance of the final material even at high relative humidity (RH) conditions [oxygen permeability coefficients ~1.43 ± 0.39 and 258.05 ± 13.78 mL·μm·m(-2)·(24 h)(-1)·atm(-1) at 23 °C and 0% RH and 70% RH, respectively]. At the micro- and nanoscale, the reasons are discussed. The final morphology of the coatings revealed that clay lamellae were stacked on top of one another, probably due to the forced confinement of the platelets within the coating thickness after solvent evaporation. This was also confirmed by modeling the experimental oxygen permeability data with the well-known Nielsen and Cussler permeation theoretical models, which suggested a reasonable aspect ratio (α) of ~100. Electron microscopic analyses also disclosed a peculiar cell-like arrangement of the platelets. The stacking of the clay lamellae and the cell-like arrangement create the excellent oxygen barrier properties. Finally, we demonstrated that the slight haze increase in the bionanocomposite coating materials arising from the addition of the clays depends on the clay concentration but not so much on the sonication time, due to the balance of opposite effects after sonication (an increase in the number of scattering centers but a reduction in their size).

Water transport properties of cellophane flexible films intended for food packaging applications

Abstract In the present paper, a mathematical model able to predict the water barrier properties of cellophane film as a function of the water activity at the upstream and downstream side of the film is presented. To validate the model water sorption, and permeation tests were performed at 30 °C and at several water vapor activities. Despite the approximations involved in deriving the model, its ability to predict the water permeability of the investigated film is quite satisfactory. The proposed model was then applied to hypothetical measuring conditions in which the water activity at one side of the film was set equal to zero (like in a permeation test) or equal to 0.6 (like in the real working conditions), while the water activity of the other side changes between 0 and 0.6. A substantial difference has been observed between the two examined cases, showing the need for a more accurate analysis of the transport phenomena in the case of water sensitive packaging films like cellophane.

Polysaccharide-assisted rapid exfoliation of graphite platelets into high quality water-dispersible graphene sheets

Ultrasound exfoliation of graphite with the assistance of three polysaccharides (nonionic pullulan, cationic chitosan, and anionic alginate) was investigated in this work. The effects of polymer type, initial concentration of graphite, and ultrasonication period on the graphene yield and quality were compared. Under a sonotrode-type ultrasonication treatment for 30 min, graphene aqueous dispersions with concentrations of up to 2.3 mg ml−1 in pullulan solutions and 5.5 mg ml−1 in chitosan solutions were achieved. The obtained graphene nanosheets were characterized as low-defect mono-layer, bi-layer, and few-layer (<5), and formed stable dispersions in water for up to 6 months. The adsorption of pullulan and chitosan biopolymers on the graphene surface as determined by TGA technique was approximately 2.5 wt% and 8.5 wt%, respectively, which accounts for the dispersibility and stability of the graphene sheets in water. Findings arising from this work suggest that pullulan and chitosan are more effective in exfoliating graphite into graphene than alginate due to the different surface free energy and thermodynamic affinity. The polysaccharide-assisted aqueous-exfoliation approach enables the production of water-dispersible graphene with high quality and large quantity, thus providing an industrially scalable route for new potential applications of graphene-based nanocomposites, e.g. in the food packaging industry.

Comparison of cellulose nanocrystals obtained by sulfuric acid hydrolysis and ammonium persulfate, to be used as coating on flexible food-packaging materials

Cellulose nanocrystals (CNCs), extracted from trees, plants, or similar cellulose-containing materials, can be used in combination with other materials to improve their performance or introduce new applications. The main purpose of this study was to compare and understand the potentialities, as coatings for Poly(ethylene terephthalate) films, of CNCs obtained starting from the same cotton linters by two different processes: sulfuric acid hydrolysis and a less common treatment with ammonium persulfate (APS), able to provide also a cellulose oxidation. The results showed that CNCs produced through the APS treatment showed higher charge densities, due to the carboxylic groups formed during the process, higher crystallinity, higher clarity of the solution and, as a consequence, higher transparency of the coating. These characteristics provide a higher oxygen barrier with respect to the CNCs produced by the H2SO4 treatment, together with the availability of active sites for potential surface modification or chemical grafting. Both CNC coatings showed oxygen permeability coefficients that were lower than synthetic resins commonly used in flexible packaging. Furthermore, they did not significantly affect the optical properties of the substrate, while revealing good friction coefficients. Due though to the moisture sensitivity of the coating and its non-sealable nature, similar to EVOH or PVOH oxygen barrier synthetic resins, CNCs developed using APS will need to be laminated with another plastic layer such as a polyolefin. They could then be used to enhance the final properties of packaging solutions as an alternative to conventional food-packaging materials for perishable food products, while reducing their environmental impact with a thin layer of a bio-based polymer.

Revealing Differences in Metabolic Flux Distributions between a Mutant Strain and Its Parent Strain Gluconacetobacter xylinus CGMCC 2955

A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955) using DEC (diethyl sulfate) and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct) concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA) cycle was obtained in mutant strain (57.0%) compared with parent strain (17.0%). It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP) and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH), which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53–6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain.