Saran Film Research Articles

Changes in the specific migration characteristics of packaging–food simulant combinations caused by ionizing radiation: Effect of food simulant

The primary objective of the present study was to evaluate the extent to which the affinity of the surrounding medium for the migrant, as well as the packaging material, affects the specific migration characteristics of the latter. For this purpose, migration tests were conducted with vinylidene chloride copolymer (PVDC/PVC) in contact with the EU specified solvents simulating all food types: namely, distilled water, 3% w/v acetic acid, 10% v/v ethanol and isooctane. Migration testing was carried out at 40°C for 10 days for the aqueous simulants, and at 20°C for 2 days for the fatty food simulant (EC, 1997; EEC, 1993). In addition, food-grade saran film was subjected to ionizing radiation treatment with a [60Co] source at doses equal to 5, 15 and 25kGy. Acetyl tributyl citrate (ATBC) plasticizer levels were monitored as a function of time for untreated, as well as gamma-irradiated packaging material, with a secondary objective to investigate the effect of ionizing radiation on polymer/migrant/surrounding medium interactions. Depending on the food simulant, determination of the analyte was performed by either direct gas chromatographic analysis, or surfactant (Triton X-114) mediated extraction followed by gas chromatographic-flame ionization detection (GC-FID). ATBC concentrations determined in aqueous and fatty food simulants were 0.216−0.497 and 5.0−5.9mg/L, respectively. Therefore, the most efficient extracting medium of plasticizers in vinyl chloride copolymers is the non-polar isooctane. Moreover, an extremely high rate of ATBC migration into isooctane during the early stages of contact was observed. The above observation verifies the aggressiveness of isooctane towards plastic packaging materials. Amongst the aqueous food simulants tested, the 10% ethanol solution demonstrated the highest migration levels. Gamma-irradiation enhanced ATBC migration; specific migration levels increased with increasing contact time and radiation dose. This was expected, since ATBC did not undergo chemical decomposition upon irradiation up to 25kGy. Finally, specific migration decreased proportionally with increasing polarity of the food-simulating solvent.

SENSORY EVALUATION OF GROUND BEEF PATTIES IRRADIATED BY GAMMA RAYS VERSUS ELECTRON BEAM UNDER VARIOUS PACKAGING CONDITIONS

ABSTRACTGround beef patties were packaged in air with: nylon/polyethylene, Saran/polyester/polyethylene, or Saran film overwrap plus a styrofoam tray. Samples were irradiated at 2 kGy by either gamma rays or electron beam, and evaluated for 7 flavor, 3 mouthfeel, and 7 taste attributes by a trained sensory panel. The only difference observed between irradiated and unirradiated samples was that the latter had a more pronounced beef/brothy flavor than irradiated patties. No differences were detected according to packaging material used. Comparing the two sources of irradiation, patties irradiated by gamma rays had more intense cardboardy and soured flavors, and salty and sour tastes than patties irradiated by electron beam.

Transmittance of a thin Saran film in the 45–584-Å wavelength region

The transmittance of a free-standing Saran film, 4260 Å thick, has been measured by means of synchrotron radiation in the 45-584-Å wavelength region. The transmittance was calculated by means of the elemental composition of the film material as determined by x-ray photoelectron spectroscopy and the optical constants as derived from atomic-scattering factors. The calculated transmittance agreed with the measured transmittance in the 45-150-Å wavelength region. The calculated transmittance was significantly lower than that measured for the wavelength range 150-340 Å. This difference implies that molecular effects that are not accounted for by atomic-scattering factors become increasingly important at the longer wavelengths.

High-resolution light microscopy of living organs in situ

Most organs in anesthetized small laboratory animals can be studied in vivo by light microscopy of relatively thin (3-5mm), transilluminated areas of the organ. Thicker areas of the organs in these species, as well as thicker organs of larger animals can be examined only by epi-ilumination. However, the resolution obtainable with epi-ilumination usually is inferior to that realized with transillumination. This paper reviews these methods using the liver as an example of the organ of study. A standard compound trinocular microscope is used which is modified for in vivo microscopy and is equipped for both transillumination and epi-illumination. After the animal is anesthetized, the liver is gently exteriorized through a subcostal, abdominal incision and positioned over a window of optical grade mica or glass on a specially designed, heated microscope stage having provisions for draining irrigation fluids. The window overlies a long working distance condenser. The liver is covered by a piece of Saran or Mylar film which holds it in position and limits movements induced by respiration, the heart and the intestines.

Effects of plasticizer desorption, temperature, and pressure on the permeability of saran

AbstractWork has shown that (1) the permeability of saran film increases exponentially with increasing temperature due to activation energy, (2) permeability of saran film decreases slightly with increasing pressure–but to only a very slight extent, (3) microwave radiation does not affect permeability as long as the film is not heated during treatment, and (4) low amounts of liquid additives correlate with lower permeability. It is suggested that the barrier property of saran film can be improved without sacrificing the processing ability.

A new evaporation procedure for monitoring of iodine-125 in liquid waste

A simplified monitoring method of 125I in liquid waste was devised. The waste water of 200 cm3 was taken on a Saran (polyvinylidene chloride) film covering a stainless steel vat. A stable iodine (20 mg) and sodium hydroxide (1 mmol) was added. The water was evaporated using an infra-red lamp. After heating to dryness, the Saran film was folded and transferred into a polyethylene tube. The radioactivity of 125I was counted with a well type NaI(Tl) scintillation counter. When a multi-channel analyzer was available for counting, an absolute decay rate of 125I was calculated with single and sum photo-peak counts. The radioactivity of 125I counted by a single-channel counter must be corrected with the counting efficiency of about 55%, with a special emphasis of a self absorption of photons. The recovery of 125I for concentrations below the permissible level was more than 98%.

PENETRATION OF PACKAGING FILMS BY THE COWPEA WEEVIL (COLEOPTERA: BRUCHIDAE)1

Cowpeas infested with the cowpea weevil, Callosobruchus maculatus (F.), were sealed individually in small packets made of various packaging films. Also, other small packages of insect-free cowpeas were subjected to attack by C. maculatus adults placed inside and outside the packages. Packages made of polyurethane, polyester, polyethylene/ethylene vinyl acetate, saran, or permethrin-treated polypropylene resisted penetration. Thin saran film, polypropylene, paper/polyethylene, polyvinyl chloride, polyethylene, and cellophane films were penetrated.

Gas-Solid Chromatographic Determination of Vinylidene Chloride in Saran Film and Three Food-Simulating Solvents

Abstract Gas-solid chromatographic (GSC) procedures are described for the analysis of Saran films for vinylidene chloride (VdC) and for determining the level of VdC migration from Saran film into 3 food-simulating solvents. The films are dissolved in tetrahydrofuran and analyzed for VdC by direct injection of the polymer solutions. VdC migration from Saran film to corn oil, heptane, and water is measured by headspace GSC. With electron capture detection and confirmation by GSC-mass spectrometry fragmentography, about 1 ppm VdC can be quantitated in the polymer and 5–10 ppb in the food simulants. Data for VdC migration from 2 commercial Saran films into the food simulants are presented to demonstrate the utility of the method.

Determination of Vinylidene Chloride in Saran Films by Electron Capture Gas-Solid Chromatography and Confirmation by Mass Spectrometry

A method is presented for determining vinylidene chloride (VdC) in Saran food packaging films by using electron capture gas-solid chromatography. The VdC present was confirmed by combined gas-solid chromatography-mass spectrometry, employing selected ion recording. The method is capable of detecting larger than or equal to 5 ppm VdC in films. Production lots of Saran film were analyzed and found to contain 6-30 ppm VdC.

A bacteriological study of stored, sulphite treated peeled potatoes.

SUMMARYPeeled, sulphite treated potatoes were stored at 23° for 3 days or at 6° for 7 days in packs sealed with perforated or unperforated polythene or with Saran film. After storage, gas samples were withdrawn from the packs for analysis and viable counts made of micro organisms associated with the potatoes. There was a marked increase in the CO2 concentration and a corresponding decrease in O2 concentration in the unperforated packs; samples from these packs tended to have a lower bacterial count than samples from perforated packs. 180 bacterial isolates representing the spoilage flora were examined. At 23° the major groups of isolates were Gram negative bacteria attacking glucose fermentatively (Enterobacteriaceae) or oxidatively (fluorescent pseudomonads); isolates from storage at 6° were all pseudomonads most of which were fluorescent. Twentyeight % of the pseudomonads, but none of the fermentative isolates, were pectolytic.

Rindless, Swiss-Type Cheese. II. Prevention of Surface Mold Growth during Curing and Storage

Summary Methods of preventing mold growth on the surface of rindless Swiss-type cheese, cured in an unsealed film wrap, were investigated. Painting the cheese with a 15 to 20% aqueous solution of potassium sorbate, 1 oz/20-lb. block, resulted in very slight mold growth and small cleaning losses during curing periods up to 9.5 mo. Holding for longer periods allowed slightly more extensive mold growth and cleaning losses. The use of 10% solutions of this compound was less effective. A 1 or 2% solution of sorbic acid in propylene glycol failed to inhibit mold growth sufficiently to be acceptable. The use of oils or greases was unsatisfactory. Mold growth occurred on all blocks treated with Confecto grease, a candy-slab releasing agent. Mineral oil was inconsistent in its ability to protect the cheese surface against mold growth; at times its use resulted in extensive cleaning losses. The use of Saran film dusted with 2.0 mg. of sorbic acid per 100 sq. in. consistently failed to inhibit mold growth. Cryovac film was preferred slightly over Saran for wrapping the cheese because the former, after shrinking, maintained a closer contact with the cheese surface.