Oxygen Permeable Film Research Articles

Enhancement of the nutritional status and quality of fresh pork sausages following the addition of linseed oil, fish oil and natural antioxidants

Fresh pork sausages (pork shoulder, pork back fat, water, rusk and seasoning) were manufactured where 15% of the pork back fat was substituted with linseed oil (LO) or fish oil (FO). Green tea catechins (GTC) and green coffee antioxidant (GCA) were added to both LO (LGTC 200 and LGCA 200) and FO (FGTC 200 and FGCA 200) substituted sausages at a level of 200 mg/kg. Raw and cooked pork sausages were either over-wrapped with oxygen permeable film (aerobic storage) or stored in modified atmosphere packages (MAP) containing 80% O 2:20% CO 2 or 70% N 2:30% CO 2, respectively for 7 days at 4 °C. Effects on fatty acid profiles, lipid oxidation, colour and sensorial properties were investigated. α-Linolenic acid increased from 1.34% (control) to 8.91% (LO) and up to 11.2% (LGTC 200 and LGCA 200). Addition of fish oil increased levels of EPA from 0.05% (control) to 2.83% (FO), 3.02% (FGTC 200) and 2.87% (FGCA 200) and DHA levels increased from 0.04% (control) to a maximum of 1.93% (FGTC 200). Lipid oxidation was low in raw and cooked linseed oil containing sausages. GTC (200 mg/kg) significantly ( P < 0.05) reduced lipid oxidation in raw fish oil containing sausages after 7 days of storage. Colour parameters in raw pork sausages were unaffected by the packaging atmosphere. L ∗ lightness values were lower ( P < 0.05) in LGTC 200 and a ∗ redness values lower ( P < 0.05) in LGTC 200 and FGTC 200 after 7 days of storage. Sensory scores of cooked pork sausages were unaffected by linseed oil addition. Flavour and overall acceptability scores in cooked fish oil containing sausages were improved by GTC addition. Results obtained demonstrate potential for the production of nutritionally enhanced fresh pork sausages.

Preparation of Oxygen Permeable Thin Films on YSZ Porous Substrates

Mixed oxide-ion and electronic conductive thin films with the composition of (Ce0.85Sm0.15)O2−δ-15 vol%MnFe2O4 (CSO-MFO) were prepared on porous yttria stabrized zirconia substrates by a spin coating process, and their oxygen permeation flux densities were measured. The porous substrates were prepared from ZrO2-3 mol%Y2O3 (3YSZ)-33 vol%carbon and NiFe2O4. 3YSZ porous substrates were obtained from 3YSZ-33 vol%carbon by sintering at 1350°C under Ar for 5 h and following oxidation at 800°C under air for 2 h. For 3YSZ-33 vol%NiFe2O4, the optimum condition was sintering at 1400°C under air for 5 h and following reduction at 800°C under H2 for 2 h. A CSO-MFO film was prepared by a spin coating process on the substrate. The thickness of the CSO-MFO was approximately 150 nm. Oxygen flux density of the CSO-MFO sample was found to be 8.9×10−8 mol·cm−2·s−1.

Use of Carbon Monoxide Combined with Carbon Dioxide for Modified Atmosphere Packaging of Pre- and Postrigor Fresh Pork Sausage To Improve Shelf Life

Fresh pre- and postrigor pork sausage patties were manufactured in the Iowa State University Meat Laboratory and packaged either in modified atmosphere (MAP) with 0.4% carbon monoxide (CO) and 99.6% carbon dioxide (CO2) or on foam trays overwrapped with oxygen-permeable film (OW). Packages were stored at 2 to 4°C under fluorescent lights for up to 31 days. Aerobic, anaerobic, and psychrotrophic plate counts, raw and cooked color, purge, and lipid oxidation were measured during storage. Results indicated that both pork sausage products in MAP had lower aerobic and psychrotrophic counts and less lipid oxidation throughout storage (P < 0.05). Raw color of both products in MAP was redder than the OW patties (P < 0.05), but the prerigor pork sausage in MAP benefited more from the CO atmosphere in terms of raw color than the postrigor pork sausage in MAP. Cooked color of the prerigor pork sausage in MAP was significantly redder than cooked color of the postrigor pork sausage. Both pork sausage products in MAP were also lighter (L* value) than the OW patties for raw and cooked color. Therefore, the combination of CO and CO2 in MAP was beneficial in extending the shelf life of preand postrigor fresh pork sausage by reducing aerobic and psychrotrophic microbial growth and improving oxidative stability and color, compared to conventional OW packaging. However, increased purge, increased anaerobic growth, and changes in cooking behavior were also observed for the products in MAP during storage (P < 0.05).

Preventive method of color deterioration of yellowtail dark muscle during frozen storage and post thawing

: The aim of this study was to develop a practical preventive method for color deterioration of sliced or filleted yellowtail muscle, especially of dark muscle, during frozen storage and post thawing. When the sliced meats were packaged in a vacuum with low oxygen permeable flexible films and then stored frozen below −40°C, no significant discoloration or browning of dark muscle was observed for 9 months or more. For higher temperature storage at −20°C or −30°C, nitrogen gas substituted packaging was a useful practical method for storing sliced meats for 6 weeks. In order to prevent color deterioration of sliced meats after thawing and subsequent storage at 0°C, the efficacy of materials of packaging was investigated. The most desirable result was obtained by using a film with oxygen permeability of 50–90 cm3/m2 per 24 h.

SHELF‐LIFE OF RETAIL BEEF MUSCLES FOLLOWING STORAGE IN A LOW OXYGEN ENVIRONMENT

ABSTRACT The effect of low oxygen storage followed by three aerobic display treatments on color, visual lean color acceptability, microbiological counts and sensory attributes of four beef muscles (M. longissimus thorasic et lumborum (LTL), M. semimembranosus (Sm), M. psoas major (PM) and M. gluteus medius (GM)) was investigated. Low oxygen, gas flushed steaks and vacuum‐packed primals were stored for 3 weeks. At display, packs were either perforating or the steaks were wrapped in an oxygen permeable film. The LTL steaks bloomed at display resulting in a 3 day display life compared to 2 days for the control. The Sm, GM and PM steaks failed to bloom due to oxidation of myoglobin to metmyoglobin during storage. Microbiological and sensory parameters were satisfactory for all muscles and all treatments. Thus, lean color was the limiting factor in the success of this system, which was successful for long term storage of the LTL steaks only.

Effect of erythorbate, storage and high-oxygen packaging on premature browning in ground beef

Premature browning (PMB) was investigated in ground beef patties with (0.04%, w/w) and without erythorbate. In Experiment 1, patties were stored at 4 °C for 48 h; at −18 °C for 21 days; or at −18 °C for 21 days, thawed at 4 °C for 24 h; and cooked. Bulk ground beef was stored at −18 °C for 24 days, thawed for 24 h at 4 °C, and patties prepared and cooked immediately. In Experiment 2, fresh patties were overwrapped with oxygen-permeable film or packaged in 80% O 2/20% N 2 (MAP), and stored for 48 h at 4 °C, or at −18 °C for 21 days, and cooked. Total reducing activity and color ( L*, a* and b* values) were measured immediately prior to cooking. Patties were cooked to internal temperatures of 60, 66, 71 and 77 °C and internal cooked color was measured. Total reducing activity was higher for the erythorbate treatment than controls for all storage conditions ( P < 0.05). a* Values of cooked patties were higher for erythorbate than control treatments under all storage and packaging conditions at 60 and 66 °C ( P < 0.05). The presence of erythorbate in ground beef patties appeared to maintain red color at cooked internal temperatures of 60 and 66 °C. Frozen bulk storage appeared to increase the susceptibility of ground beef to PMB when compared to fresh and frozen patties. Patties cooked directly from frozen state appeared less susceptible to PMB than frozen-thawed and bulk storage. Ground beef appeared predisposed to PMB when stored in high-oxygen MAP at 4 °C for 48 h.

Influence of a commercial warm chlorinated water treatment and packaging on the shelf-life of ready-to-use lettuce

Ready-to-use (RTU) lettuce washed in 100 ppm chlorine at 4 °C and packaged in oxygen-permeable film has a limited shelf-life due to continued respiration and enzymatic activity within the lettuce tissue. Preliminary laboratory work has revealed that washing in 100 ppm chlorine at 47 °C has the potential to extend the shelf-life of RTU lettuce; however, this has not been demonstrated in a commercial processing setting. A flume was constructed which allowed the continuous treatment of chopped lettuce at 48 °C for 30 s, with rapid cooling to below 20 °C. Lettuce processed by either warm or cold water treatment was packaged at 340, 680 or 1134 g in 28 × 30 cm bags made from two different films with oxygen transmission rate of 981 and 550 mL m −2 h −1, and stored for up to 18 days at 4 °C. Loss of quality was assessed by a sensory panel, and residual O 2 and CO 2 concentrations in the bags were determined at various intervals. Quality of cold washed lettuce was retained over 18 days in packages containing 1134 g of lettuce. The warm water treatment had a significantly beneficial effect on the visual quality of lettuce packaged in 340 or 680 g amounts between days 8 and 14 of storage at 4 °C. CO 2 levels were lower in packages with 340 or 680 g of lettuce; however, the O 2 levels reached 0.1% with all treatments after 4 days of storage. Treatments in which the CO 2 reached an equilibrium concentration of 15–20% gave the least deterioration of quality. Equilibrium gas concentrations predicted from respiration experiments were higher (>0.5% O 2) or lower (<5.75% CO 2) than experimental values. Microbiological analysis showed that increased counts of psychrotrophs and Pseudomonas spp. correlated with loss of quality. The results suggest that warm water washing of lettuce may have some benefit if the product is stored for intermediate times; however, further improvements will require a more standardized and automated washing procedure.

Preliminary observations on the colour variability of breast meat ('magrets') in force-fed ducks

Fifty-eight force-fed mule ducks were used to evaluate the variability of 'magret'(breast meat) colour. Trichromatic coordinates in the CIELAB system (L*, a*, b*) were measured at 4 and 24 h post mortem and after 6 days of storage at +4 o C under an oxygen-permeable film. At 24 h post mortem, the colour of breast meat was visually assessed and the 'magrets' were assigned to one of three colour groups (normal, intermediate, pale). At 24 h post mortem, 22% of the magrets were clas- sified as very pale, and showed higher L* and b* than those classified as normal. These differences were maintained over the 5 days storage but their magnitude was not increased. The L* and b* values were significantly and positively correlated with the content of intramuscular fat (r = 0.50, P < 0.01 and r = 0.29, P < 0.05, respectively). The different measurements could not clearly demonstrate that the abnormal colour was due to myoglobin and lipid oxidation and/or colour defects such as those en- countered in PSE (Pale, Soft, Exudative) meat. These preliminary observations showed a high vari- ability of breast meat colour in force-fed ducks. Further research is needed to elucidate the underlying mechanisms.

Probes and Polymers for Optical Sensing of Oxygen

Oxygen detection techniques are used in various fields, such as chemical or clinical analysis and environmental monitoring. Recently, a variety of devices and sensors based on photo-luminescent or photoexcited state quenching of organic dyes have been developed to measure oxygen partial pressure on the solid surface. Many optical oxygen sensors are composed of organic dyes, such as polycyclic aromatic hydrocarbons (pyrene, pyrene derivative etc.), transition metal complexes (Ru2+, Os2+, Ir3+ etc.), metalloporphyrins (Pt2+, Pd2+, Zn2+ etc.) and fullerene (C60 and C70) immobilized in oxygen permeable polymer films. In this review, the properties of various oxygen permeable polymers for matrix of optical oxygen sensor and various dye probes for oxygen sensing are described.

EFFECTS OF DIETARY POULTRY LITTER SUPPLEMENTATION ON BEEF STEAK RETAIL COLOR AND APPEARANCE1

ABSTRACTTen Holstein steers were fed conventional back grounding and finishing diets and 10 comparable steers were supplemented with poultry litter. At the end of the finishing period, all animals were harvested. After 144 h at 2C, the boneless M. longissimus thoracis et lumborum muscles were removed, cut into steaks (1.9 cm), vacuum packaged, and frozen. A steak adjacent to the thirteenth thoracic vertebra of alternate carcass sides was removed and thawed (4C for 24 h). All steaks were then over wrapped in oxygen permeable film, displayed for four days, and evaluated for retail properties and performance. Changes in visual properties and meat pigments during display clearly demonstrated samples from treated animals had an additional day of color stability over their untreated counterparts, resulting in an additional day of retail case‐life based upon visual properties.

Survival and Growth of Listeria monocytogenes and Escherichia coli O157:H7 in Ready-to-Eat Iceberg Lettuce Washed in Warm Chlorinated Water

Cut iceberg lettuce inoculated with Escherichia coli O157:H7 and Listeria monocytogenes before and after washing for 3 min in cold (4°C) and warm (47°C) water containing 100 mg/liter total chlorine was stored at 1 and 10°C in oxygen-permeable film packages (6,000 to 8,000 cc/m2/24 h). Cold chlorinated water was detrimental to the survival of E. coli O157: H7 and L. monocytogenes at both storage temperatures. In contrast, washing in warm chlorinated water favored the growth of both pathogens in lettuce stored at 10°C. There was no evidence of a relationship between the magnitude of spoilage microflora and the fate of either bacterium.

Foodborne pathogenic bacteria in prepackaged fresh retail portions of farmed rainbow trout and salmon stored at 3 °C

Twelve lots of fresh unskinned fillets of rainbow trout ( Oncorhynchus mykiss) and 10 lots of fresh sliced salmon ( Salmo salar) prepacked in trays wrapped with an oxygen-permeable film were obtained immediately after packing from two supermarkets having in-plant facilities for packaging wet fish. During storage at 3 °C, Listeria innocua was detected in eight lots of trout fillets after 4 days storage. L. monocytogenes was recovered from a single lot also contaminated with L. innocua. Initial numbers of aeromonads were significantly ( p<0.05) lower in trout fillets (3.35±0.62 log cfu g −1) than in salmon slices (4.20±0.89 log cfu g −1). In both fish products, these bacteria significantly ( p<0.05) increased up until spoilage. Most Aeromonas spp. isolates from trout fillets were assigned to A. veronii biovar sobria HG8 (hybridisation group 8), A. caviae HG4, A. eucrenophila HG6, A. hydrophila HG1 and A. veronii biovar veronii HG10. Strains of HG12 ( A. schubertii), HG4 and HG8 formed the majority of aeromonads recovered from salmon slices.

Detailed analysis of α,ω-bis(4-hydroxybutyl) poly(dimethylsiloxane) using GPC-MALDI TOF mass spectrometry

In this study the prepolymer α,ω-bis(4-hydroxybutyl) poly(dimethylsiloxane), used in the formulation of oxygen permeable films, is evaluated by gel permeation chromatography (GPC) combined with matrix assisted laser desorption ionization (MALDI) time of flight (TOF) mass spectrometry (MS). Two unexpected mass distributions are observed in the mass spectra. Reaction schemes for the formation of these distributions are proposed. A solution phase trimethylsilane end group modification was performed on the prepolymer to determine whether the unexpected mass distributions occur as impurities from synthesis or as artifacts from the MS process. Evaluation of the TMS modified prepolymer indicates the unexpected mass distributions indeed occur as impurities from the synthetic procedure. Average molecular weight values are determined by traditional GPC, direct MALDI-TOF MS, and GPC-MALDI-TOF MS methods and the results are compared.

Adult rat hepatocytes cultured on an oxygen-permeable film increases the activity of albumin secretion.

Primary culture of rat hepatocyte was performed in an oxygen-permeable film dish (F-dish), which would be expected to give an oxygen-rich culture condition. In the conventional culture dish in which the depth of medium was 2 mm, the oxygen tension (pO(2)) in the medium decreased from 19% (144 mmHg) to 0.3% (2.3 mmHg) within 2 hr, while the pO(2) in the F-dish maintained 8.5% (64.6 mmHg) even after 2 hr. The adverse effect of the oxygen-deficiency appeared in the albumin secretion activity of the hepatocytes and it was more remarkable in the early period of culture. The average rate of albumin secretion for the initial 48 hr was 2.0 mug ml(-1) hr(-1) or 96 mug 10(6) cells(-1) day(-1) in the F-dish. The average rate of albumin secretion for the initial 12 hr was only 0.36 mug ml(-1) hr(-1) in the conventional culture dish. The activity of ammonia elimination in the F-dish was 20-50% higher than the conventional culture dish. Three-dimensional aggregate was formed only in the F-dish. The advantage of three-dimensional aggregate for albumin secretion was not clear compared with two-dimensional monolayer.

Effect of erythorbic acid on cooked color in ground beef

Consumers often use the color of cooked ground beef as an indicator of doneness. For safety reasons, it is recommended that the center of ground beef products be heated to 71°C. In some instances beef may appear done before reaching 71°C, a condition termed premature browning (PMB). Ground beef (15% fat), with added erythorbic acid (ERY) at 0.04 and 0.06% was formed into patties, wrapped in oxygen permeable film, and stored in the dark at 4°C. Patties were stored for either 10 h or 58 h and then cooked to internal end point temperatures of 60, 66, 71 or 77°C. Internal cooked color L ∗, a ∗ and b ∗ values were measured. For beef patties stored 10 h, there was no effect of ERY on internal cooked color. After 58 h storage, ground beef with 0.04 and 0.06% ERY had higher a ∗ values than controls at 60°C ( P<0.05). Beef with 0.04% ERY cooked to an internal temperature of 66°C had higher a ∗ values than 0.06% ERY and controls ( P<0.05). There was no effect of ERY on color of beef patties cooked to 71 or 77°C. The presence of 0.04% ERY in ground beef patties stored 58 h appeared to maintain red color at internal temperatures of 60 and 66°C.

Reduced nitrite levels and dietary α-tocopheryl acetate supplementation: effects on the colour and oxidative stability of cooked hams

The objective of the present study was to determine the effects of dietary vitamin E supplementation and reduced nitrite levels on the colour stability of cooked hams. Large white × Landrace pigs (male n=6, female n=6) were each subdivided into two groups ( n=3) and fed an α-tocopheryl acetate supplemented diet (1000 mg/kg feed) and a basal diet (10 mg/kg feed) for a period of 10 weeks . M. semitendinosus were removed from each pig, divided into light and dark pigmented fractions, vacuum packed and stored at 4°C for 24 h. Muscles were cured with input nitrite levels of 25 and 100 mg/kg meat and were tumbled and massaged for 17 h. Samples were cooked, sliced and overwrapped in a high oxygen permeable film for a storage period of 10 days. Surface colour of hams was measured and expressed as Hunter ‘ a’ values. Concentrations of α-tocopherol were significantly ( P<0.001) greater in supplemented muscles compared to basal muscles for both male and female pigs. Hams manufactured from male and female supplemented pigs resulted in significantly ( P<0.001) higher Hunter ‘ a’ values than hams manufactured from male and female pigs receiving the basal diet. Muscles cured with 100 mg nitrite/kg meat formed products with significantly ( P<0.001) higher ‘ a’ values than those cured with the lower (25 mg/kg meat) nitrite level. Hams manufactured from supplemented muscles, treated with 25 mg nitrite/kg meat showed significantly ( P<0.05) higher Hunter ‘ a’ values than hams manufactured from basal muscles, treated with 100 mg nitrite/kg meat. Hams manufactured from female porcine muscles had significantly ( P<0.001) higher ‘ a’ values than hams from male muscles during the 10 days of simulated retail display. No such gender differences were observed for TBARS values.

Colour stability and vitamin E content of fresh and processed pork

The effect of increasing muscular content of vitamin E on colour intensity and stability of pork (both fresh and processed) was studied by feeding manipulation. Fresh pork was represented by loin chops and processed pork was represented by a dry cured fermented sausage (salame Milano) and raw cured ham (Parma ham). Dietary vitamin E was increased by feeding the animals with sunflower oil and α-tocopheryl acetate at 100 and 200 ppm. Chops were packed in oxygen-permeable film and in a protective atmosphere (80% O2 and 20% CO2) whereas salame Milano and Parma ham were packed under vacuum and in a protective atmosphere (85% N2 and 15% CO2). No differences in colour intensity or type were observed in relation to vitamin E content. Colour stability tests suggested, on the other hand, that higher vitamin E contents could be associated with slower myoglobin oxidation rates in fresh chops packed in a protective atmosphere. No effect of vitamin E on colour stability was observed in salame, probably because of the soft fat induced by sunflower oil. Significant differences among dietary groups were also not observed in Parma ham.

Effect of gelatin dip on the oxidative and colour stability of cooked ham and bacon pieces during frozen storage

Summary Samples of cooked ham and bacon were dipped in water or 2, 4 or 6% gelatin solutions. Samples were then packed in oxygen permeable or vacuum packaging film and stored at −18 °C for seven months. Lipid oxidation (TBARS) and colour stability (Hunter a* values) were assessed monthly. The gelatin coating exerted beneficial effects on oxidative and colour stability.

Effects of alpha -tocopheryl acetate supplementation and salt addition on the oxidative stability (TBARS) and warmed-over flavour (WOF) of cooked turkey meat

1. Day-old turkey poults (n = 14) were randomly divided into 2 groups (n = 7) and fed diets containing 20 (E20) and 600 (E600) mg all-rac -alpha-tocopheryl acetate/kg food for 21 weeks prior to slaughter. Following slaughter, breast and leg meat was removed and 4 batches of patties were produced from each. Two of the batches were formed from E20 meat (E20) and E20 plus 1% salt (E20S). Two similar batches were formed from E600 meat (E600) and E600 plus 1% salt (E600S). 2. Patties were fried, cooled and overwrapped with high oxygen-permeable film. Overwrapped patties were displayed in a 4degreeC cabinet under fluorescent light (616 lux). Lipid oxidation (TBARS numbers) was determined on d 0, 2, 4, 6, 8 and 10, while taste panels to assess warmed-over flavour (WOF) were carried out on d 0, 2 and 4 of refrigerated (4degreeC) display. 3. In the case of both leg and breast meat, E600 patties were the least susceptible of the 4 treatment batches to lipid oxidation. Salt had the effect of promoting lipid oxidation, with E20S and E600S patties having higher TBARS numbers than the corresponding patty batches where salt was absent. 4. Taste panel results showed that leg and breast patties formed from the meat of turkeys given alpha-tocopheryl acetate enriched diets developed significantly (P < 0.05) less WOF than those formed from control turkey meat on d 2 and 4 of refrigerated (4degreeC) display . Patties containing 1% salt generally exhibited a greater degree of WOF than patties without salt. 5. A linear relationship was observed between TBARS numbers and WOF percentages for all batches of leg and breast patties.

Application of the bacteriocinogenicLactobacillus sakeiCTC494 to prevent growth of Listeria in fresh and cooked meat products packed with different atmospheres

The production of sakacin K byLactobacillus sakeiCTC494 at different temperatures and pH was evaluated before its application as a bioprotective culture againstListeriain different meat-based food packaging systems, that is, oxygen-permeable film, under vacuum and under a modified atmosphere (20% CO2: 80% O2) and stored at 7°C. TheLactobacillusculture produced the bacteriocin at a range of temperatures from 4°C to 30°C and at initial pH from 5·5 to 6·5.Listeriainhibition in raw minced pork, poultry breasts and modelized cooked pork could not be achieved by the sole application of vacuum or a modified atmosphere. Inoculation ofLb. sakeiCTC494 or sakacin K inhibited the growth ofListeriato different extents in all the products studied in each system; the greatest inhibition being observed in the vacuum packaged samples of poultry breasts and cooked pork, and in the modified atmosphere packaged samples of raw minced pork. Addition of sakacin K resulted in immediate bactericidal action againstListeriain every product and atmosphere studied.