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Proceeding of the 4 rd International Symposium“NEW RESEARCH IN BIOTECHNOLOGY” USAMV Bucharest, Romania, 2011SECTION V: FOOD SAFETYNEW PACKAGING MATERIALS AND THEIR EFFECT ON THESHELF-LIFE OF PACKAGED SALADIONESCU MARIANA 1 , MUSTATEA GABRIEL 1 , IONESCU VALENTIN 1 ,SMEU IRINA 1 , SPADARO GIUSEPPE 1 , VULUGA ZINA 21 INCD – IBA Bucharest, 6 Dinu Vintila Street, 2 Bucharest2 INCDCP - ICECHIM, 202 Splaiul Independentei, 6 BucharestAbstract. The quality of fresh products, minimally processed, such as salad, depends on preparationmethod, packaging material and storage conditions. Packaging material affect sensory properties ofsalad, because the intensity of respiration and color change of the product depend on the compositionof the used material.Depending on the product, process and storage conditions the microbiological shelf-life may bedetermined by either the growth of spoilage or pathogenic microorganisms. Traditional methods forthe determination of shelf-life include storage of the product at different temperatures anddetermining spoilage by sensory evaluation or microbial count. This will involve the natural flora ofthe product, which may vary between batches. For products where the shelf-life may be set by thegrowth of pathogenic microorganisms this may involve challenge testing the product with theorganism prior to storage and microbial analysis at intervals.In the experiments was used salad – chopped fresh leaves, packed in normal atmosphere, usingdifferent types of new packaging materials: nanocomposite-based LDPE/modified silicate monolayerfilms containing starch and hydrolyzed collagen and usually PP films. Bags containing salad werestored at 5 Celsius degrees.Packaging material effect on product was followed by microbiological and sensory analysis duringstorage up to 10 days under mentioned conditions. Sensory evaluation parameters included: color,browning, odor, degradation and overall quality. Microbiological and sensory analyses results werecorrelated with the permeability properties to O 2 , CO 2 and water vapor.The best option may be considered LDPE/silica-Amp for which can be estimate a shelf-life longerthan 7 days obtained with PP films currently used.Keywords: shelf-life, minimally processed food, packaging1. INTRODUCTIONLettuce is an important leafy vegetable and one of the main sources of dietarycarotenoids (Liu & al. [1], Moeller & al. [2]). The cut and packaged lettuce for food serviceand salad mixes are some increasingly important components of the produce industry.Increased demand for the convenient, pre-cut salads and lettuce has led the scientists tosearch for ways to select lettuce cultivars that stay fresh, colorful, and crisp. Shelf life andvisual quality of fresh-cut lettuce are affected by many things, including productionenvironment, vegetative maturity, and type of lettuce chosen. Although an increasing156
Proceeding of the 4 rd International Symposium“NEW RESEARCH IN BIOTECHNOLOGY” USAMV Bucharest, Romania, 2011variety of lettuce types are being grown, romaine and "crisp-head" (such as iceberg) are themost widely produced for salad-cut products.One of the major problems facing food manufacturers is responding rapidly to thedemands of the major retailers who supply a large proportion of the market.The salad leaves, as other leafy vegetables, damage themselves quite rapidlyduring the storage period, because of their increased respiration rate (Soliva & Martin [3]).The low shelf life of fresh-cut minimally processed lettuce leaves is one of the majorproblems that the producers are facing with (Brecht & al. [4], Saltveit [5]). As so, thequality of made up products depends on the method of their preparation, packing materialand storage conditions (Barry-Ryan [6]). Using efficient packaging materials is nownecessary for all types of fresh or processed foods. All the qualities and attributes of aproduct, that have been developed during production processes can be lost if it the productdoesn’t reach the consumer in good conditions.Packing materials influence sensory properties of products, because lettucerespiration intensity and product color changes depend on the composition of the usedmaterials (Del Nobile & al. [7]).One of the major problems facing food manufacturers is responding rapidly to thedemands of the major retailers who supply a large proportion of the market.MAP can be defined as an active packaging method that creates a new atmosphereinside the package, resulting in a delay of chemical damage and at the same time, inhibitgrowth of microorganisms perish. The main gases used are oxygen, carbon dioxide andnitrogen. Carbon monoxide has limited applications in MAP, but sulfur dioxide is usedmore frequently.2. MATERIALS AND METHODSSample preparationTwo types of lettuce were analyzed: Type A – imported “Endivia mix/Latino mix”(kindly provided by Eisberg Romania), known to be quite sensible at O 2 concentrations andtype B – lettuce from a local supplier. The samples were represented by lettuce leaves.After they were washed with cold tap water, the excess of water was manually removed.Samples containing 180 grams each from type A lettuce were packaged innanocomposite-based LDPE/modified silicate monolayer films and samples containing 50grams each from type B lettuce were packaged in BOPP films (with and withoutperforations).There were used bags with dimensions of about 30x20 cm. The bags werehermetically sealed and stored at 4-5°C. The samples were observed for 10 days.Films characterizationThe following films: nanocomposite-based LDPE/modified silicate monolayer filmscontaining starch (D20A-Amp) and hydrolyzed collagen (D20A-C08G), LDPE film, andusually BOPP films (with 5 mm perforations and without perforations) were tested in termsof barrier properties. The barrier properties to water vapor and gases expressed by thepermeability were determined by specific analysis: determining transmission rates of watervapor according to DIN EN ISO 15106-1: 2005 (method of moisture detection) anddetermining gas transmission rate through plastic films and foils according to DIN 53380-1157
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