Sara Limbo

Solid-phase micro-extraction (SPME-GC) and sensors as rapid methods for monitoring lipid oxidation in nuts

Dry foods with high fat content are susceptible to lipid oxidation, which involves a quality deterioration of the product, since this process is responsible for the generation of off-flavours. Hexanal is considered to be a good shelf-life indicator of such oxidation products. In addition, due to its high volatility, hexanal can be easily determined by fast headspace analytical techniques. For this reason an electronic nose comprising ten metal oxide semiconductors (MOS) and a solid-phase microextraction (SPME) coupled with gas chromatography and flame ionization detector (GC-FID) method were compared in order to determine hexanal formed in hazelnuts during storage under different conditions (room temperature, 40°C, ultraviolet light, with and without oxygen scavenger). The results obtained by the two methods showed a good correlation, confirming the possibility of using a multi-sensor system as a screening tool for the monitoring of shelf-life and oxidation state of nuts.

Evaluation of freshness decay of minced beef stored in high-oxygen modified atmosphere packaged at different temperatures using NIR and MIR spectroscopy

Meat freshness has been monitored by various microbiological, chemical and sensorial indices. However, these methods are slow and not suited to automation. Infrared spectroscopy is one of the most convenient analytical tools which could be used to monitor the evolution of food quality. The aim of this work was to investigate the ability of both NIR (Near Infrared) and MIR (Mid Infrared) spectroscopy to follow meat freshness decay. The minced beef was packaged in high-oxygen modified atmosphere (30% CO2 and 70% O2) and stored at three temperatures. Spectra were collected by Fourier-Transformation (FT)-NIR and FT-IR instruments. PCA, applied to the data, was able to discriminate samples on the basis of storage time and temperature. The modelling of PC scores versus time allowed the setting of the time of initial freshness decay for the samples (6-7 days at 4.3°C, 2-3 days at 8.1°C and less than 1 day at 15.5°C).

Shelf life of case-ready beef steaks (Semitendinosus muscle) stored in oxygen-depleted master bag system with oxygen scavengers and CO2/N2 modified atmosphere packaging

This study aims to evaluate the stability of beef from Semitendinosus muscle packaged in oxygen permeable wrapped-tray units and stored in a master bag system, with and without oxygen scavengers. Changes in the atmosphere composition, microbiological indexes, myoglobin forms and color parameters were monitored during the storage in master bag, blooming and display life. The presence of scavengers reduced rapidly the oxygen concentration and maintained it at values not detectable instrumentally. Within few days of storage in master bags, the resolution of the transient discoloration was completed and the meat quality was maintained over the anoxic storage. After the removal from master bags meat bloomed completely reaching OxyMb level and Chroma values higher than those on fresh meat at t(0). During 48 h of display life at 4 °C, quality attributes had a decay slower than samples stored traditionally in air. Without scavengers the oxygen caused the irreversible discoloration within 7 days, due to the formation of metmyoglobin on the surface.

Bio-based coatings as potential barriers to chemical contaminants from recycled paper and board for food packaging

Partition and diffusion experiments were carried out with paper and board samples coated with different biopolymers. The aim was to evaluate the physicochemical behaviour and barrier properties of bio-coatings against migration of typical contaminants from recycled paper packaging. Focus was directed towards water-based, renewable biopolymers, such as modified starches (cationic starch and cationic waxy starch), plant and animal proteins (gluten and gelatine), poured onto paper with an automatic applicator. Additionally, a comparison with polyethylene-laminated paper was performed. Microstructural observations of the bio-coated paper allowed the characterisation of samples. From the partitioning studies, considerable differences in the adsorption behaviour of the selected contaminants between bio-coated or uncoated paper and air were highlighted. For both the polar and non-polar compounds considered (benzophenone and diisobutyl phthalate, respectively), the lowest values of partition coefficients were found when paper was bio-coated, making it evident that biopolymers acted as chemical/physical barriers towards these contaminants. These findings are discussed considering the characteristics of the tested biopolymers. Diffusion studies into the solid food simulant poly 2,6-diphenyl-p-phenylene oxide, also known as Tenax®, confirmed that all the tested biopolymers slowed down migration. The Weibull kinetic model was fitted to the experimental data to compare migration from paper and bio-coated paper. Values found for β, an index determining the pattern of curvature, ranged from 1.1 to 1.7 for uncoated and polyethylene paper, whereas for bio-coated papers they ranged from 2.2 to 4.9, corresponding to the presence of an evident lag phase due to barrier properties of the tested bio-coatings.

Plastic Packaging Materials

Words ‘plastics’ and ‘polymers’ are used quite often, particularly in the packaging sector, as synonymous even if they do not have the same meaning. These macromolecules are composed of many repeated subunits, i.e. definitely polymers. Actually, plastic packaging materials are predominately constituted of polymers (70–99 %) containing always various amounts of additives, such as plasticisers, antioxidants, pigments, antistatic, fillers and many other compounds. These chemicals are essential to provide the expected functionality; for this reason, final products are not definitely polymers. When speaking of food packaging applications, all starting substances, as well as finished plastics materials must have regulatory approvals, based on their specific chemical and toxicological features. Hereafter, the chemistry and general information about food packaging polymers are discussed here regarding two arbitrary categories: synthetic-oil derived polymers—polypropylene, polystyrene, polyvinyl chloride, etc.—on the one hand, and oil-derived and biodegradable bioplastics on the other side.

Food Packaging Materials

1 Introduction to Food Packaging Materials 2 Ceramic Packaging Materials 3 Metal Packaging Materials 4 Cellulosic Packaging Materials 5 Plastic Packaging Materials 6 Materials Combinations 7 Chemical Features of Food Packaging Materials

HPLC study of migration of terephthalic acid and isophthalic acid from PET bottles into edible oils

BACKGROUND Polyethylene terephthalate (PET) containers for food oil packaging were evaluated with a newly established determination method for terephthalic acid (TPA) and isophthalic acid (IPA). The analysis of monomers, TPA and IPA that migrate from PET bottles into oils was performed using high-pressure liquid chromatography with a diode array detector. Three types of commercial oils (sunflower oil, canola oil and blended oil which included sunflower oil, soy bean oil and cottonseed oil) were bottled in PET containers. These samples were incubated for 10 days at 49 °C as accelerated test condition. RESULTS The means of recovery for this method varied from 70% to 72% and from 101% to 111% for TPA and IPA, respectively. The results showed that the amounts of specific migration of TPA and IPA into the samples conform to European Union legislation that identifies specific migration limits. More important, the results highlighted a different behavior of migration as a function of the fatty acid profile. CONCLUSION Previous investigations have been performed with food simulants such as HB307 or 20% ethanol but our study used real food samples and determined trace amounts of the migrated compounds. Further investigation will be needed to better explain the influence of fatty acid conformation on migration of PET monomers.

Influence of temperature and sakacin A concentration on survival ofListeria innocua cultures

The antimicrobial activity of sakacin A, a bacteriocin produced byLactobacillus sakei, was investigated at 30, 10 and 4°C againstListeria innocua in stationary and lag phases of growth. When sakacin was added toListeria innocua cells in stationary phase, two death kinetics were observed. Populations ofListeria innocua were reduced up to threelog cycles when sakacin A was increased from 0 (control) to 1600 AU ml−1. When sakacin A was added toListeria innocua cells in lag phase, lag time, inhibition time and rate were proportionally extended, and maximum population decreased when employing higher bacteriocin levels. Sakacin A was found to influenceListeria innocua growth, a microorganism able to grow at 4 °C. At refrigerated temperatures, the addition of sakacin A was found to inhibitListeria innocua cell growth. Sakacin A may be considered a promising molecule to be used as antimicrobial agent to preserve the shelf life of refrigerated foods.

Shelf life extension of whole-wheat breadsticks: Formulation and packaging strategies

The aim of this study was the shelf life extension of whole-wheat breadsticks through the addition of a rosemary extract and packaging under nitrogen. Shelf life was studied at four temperatures (20, 27, 35, 48°C) for up to 200 storage days. The minimal changes observed in moisture, water activity and texture of the samples, coupled with the high peroxide values (13-539meqO2/kgfat) measured at the end of storage, and the exponential increase of hexanal concentrations (up to 13-34mg/kg) confirmed that quality decay of whole-wheat breadsticks is mainly associated to lipid oxidation. The kinetic study of oxidation development and the consumer sensory acceptance determined by the survival analysis demonstrated that the rosemary extract addition yields a 42% shelf life extension, higher than that observed using nitrogen in the package (24-29%). The combination of the formulation and packaging strategies gave the best result (83% shelf life extension at 25°C).

Active packaging of foods and its combination with electron beam processing

Abstract The principal aim of an active packaging solution is to control the package headspace composition during food storage. Controlled release packaging (CRP) is a new generation of packaging materials that can release active compounds at different controlled rates to enhance the quality and safety of a wide range of foods during storage. Different active substances with different mechanisms of action have been investigated and discussed in this chapter. The ultimate goal of an active packaging system should be the reduction of food loss and waste, extending product shelf life and reducing waste by clarifying the suitability of a product for consumption.