Biodegradable high oxygen barrier membrane for chilled meat packaging

“Chilled” meat is more nutritional, healthy and hygienic than the meat kept at ambient temperature. “Poly(propylene carbonate) (PPC) and poly(vinly alcohol) (PVA) were used to prepare biodegradable three‐layer PPC/PVA/PPC films with high barrier and tensile properties. The potential benefits of the developed films were also evaluated on the shelf life of chilled meat products. Compared to PPC film, using 20 wt % PVA as an intermediate layer in PPC/PVA/PPC film remarkably enhanced oxygen barrier performance at 0 and 50 RH % by about 500 times, tensile strength by about 8 times, and Young's modulus by nine times, but no beneficial effect on water vapor barrier performance has been observed. A new “sandwich” type of completely biodegradable material with high barrier was obtained. The application of PPC/PVA20/PPC film as the packaging material of chilled meat was effectively kept the total viable count (TVC) and total volatile basic nitrogen (TVB‐N) to acceptable levels in chilled meats until 19th day of storage at 4°C, however, the spoilage occurred within 11th and 14th days of refrigerated storage in term of TVC and TVB‐N, respectively, in the chilled meats packed with only PPC. Herein, we report that PPC/PVA/PPC three‐layer film can be a promising well‐defined biodegradable material with excellent potential in chilled meat packaging. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41871.     

Rancidity development during the chilled storage of farmed Coho salmon (Oncorhynchus kisutch)

Coho salmon (Oncorhynchus kisutch) is a fatty fish species whose farming production has greatly increased in recent years. Lipid damage produced during Coho salmon chilled storage was studied for up to 24 d. Lipid hydrolysis (free fatty acids, FFA) and oxidation (conjugated dienes; peroxide value, PV; thiobarbituric acid index, TBA‐i; fluorescent compounds formation, FR; browning development) were determined and compared to lipid composition (polyene index, PI; astaxanthin, AX) changes and sensory assessment (rancid odour development) results. Most lipid damage indices developed slowly during storage; thus, values obtained for FFA, PV, TBA‐i and FR were in all cases under 1.5 g/100 g, 4.0 meq oxygen/kg lipid, 0.40 mg malondialdehyde/kg muscle and 0.40, respectively. Odour assessment showed a significant (p <0.05) rancidity development at day 10, when compared to starting fish material; then, non‐acceptable values were obtained at days 19 and 24. The PI analysis showed not many differences during the storage time, with the lowest mean value at day 19. AX analysis indicated a relatively high content in the white muscle, which was maintained till the end of the experiment. A low oxidation development is concluded for Coho salmon lipids when compared to other fatty fish species under the same chilling conditions. AX was found to contribute to the oxidation stability of Coho salmon lipids, due to its free radical scavenger properties.     

Damage detection in horse mackerel (Trachurus trachurus) during chilled storage

Sensory and chemical analyses were performed during the chilled storage of whole and filleted horse mackerel (Trachurus trachurus), an underutilized medium-fat fish species. For both kinds of fish products, satisfactory correlations with the storage time were obtained for amine formation (total volatile basenitrogen and trimethylamine-nitrogen), lipid damage (free fatty acid formation), and formation of interaction compounds (fluorescence detection in the aqueous phase). Sensory analyses showed a gradual lower grading with time, with a shelf life of 14 d for whole-fish samples and 12 d for fillet samples. Correlation and multivariate analyses between the sensory attributes and the chemical indices showed that trimethylamine-nitrogen detection was the most accurate chemical method for damage assessment during the chilled storage of whole and filleted horse mackerel.     

Effect of high‐pressure treatment on microbial activity and lipid oxidation in chilled coho salmon

This work studies the effect of a previous hydrostatic high‐pressure (HHP) treatment on chilled farmed coho salmon (Oncorhynchus kisutch). Three different HHP conditions were applied (135 MPa‐30 s, 170 MPa‐30 s, and 200 MPa‐30 s for treatments T‐1, T‐2, and T‐3, respectively) and compared to untreated (control) fish throughout a 20‐day chilled storage. Microbial activity and lipid oxidation development were analyzed. Assessment of aerobe, psychrotroph, Shewanella spp. and Pseudomonas spp. counts and trimethylamine formation showed a marked inhibitory effect (p <0.05) of HHP treatment on microbial activity, with this effect increasing with the pressure value employed. Related to lipid oxidation development, higher peroxide mean values (day 10–20 period) were found in control samples and fish treated under T‐1 condition when compared to their counterparts corresponding to T‐2 and T‐3 treatments. On the contrary, quantification of thiobarbituric acid‐reactive substances and fluorescent interaction compounds showed higher levels (p <0.05) in fish samples corresponding to T‐2 and T‐3 treatments. In spite of the lipid oxidation development found, polyene index and tocopherol isomer (α and γ) content did not provide differences (p >0.05) as a result of previous HHP treatment.     

Effect of advanced chilling methods on lipid damage during sardine (Sardina pilchardus) storage

Slurry ice is a biphasic system consisting of small spherical ice crystals surrounded by seawater at subzero temperature. Its effect on lipid damage (hydrolysis and oxidation) was evaluated during the chilled storage of a fatty fish species, sardine (Sardina pilchardus). Slurry ice treatment was checked alone and in combination with ozone and compared to traditional flake icing during a 22‐day storage. Different lipid damage indices (free fatty acids, FFA; peroxide value, PV; thiobarbituric acid index, TBA‐i; fluorescent compounds, FR) were checked and compared to sensory assessment and nucleotide degradation (K value). According to lipid hydrolysis (FFA) and oxidation (PV and FR) developments, slurry ice showed an inhibitory effect (p <0.05) on lipid damage during storage, as well as an inhibition of nucleotide autolytic degradation. Ozonised slurry ice did not provide differences (p >0.05) from slurry ice alone when considering lipid hydrolysis, nucleotide degradation and some lipid oxidation indices (PV and FR), although a higher (p <0.05) TBA‐i was observed at day 22 of storage when compared to flake ice and slurry ice treatments. However, a lower (p <0.05) fluorescence development was observed for fish treated under ozonised slurry ice when compared to traditionally iced fish. Sensory assessment showed a higher shelf life for fish samples treated under ozonised slurry ice than for their counterparts under slurry ice (15 d versus 12 d), while flake icing led to a far shorter shelf life (5 d). According to sensory and biochemical (lipid matter and nucleotide) analysis, slurry ice has proved to be a promising technology for damage inhibition and quality retention in a fatty fish species such as sardine. Ozonised slurry ice was also shown to be useful, since a longer shelf life was obtained in the present experiment and a pro‐oxidant effect of ozone on sardine lipids was not proved.     

Enhancing Lipid Oxidative Stability of Cooked‐Chilled Lamb Meat through Dietary Rosemary Diterpenes

A dietary rosemary extract (DRE) containing carnosic acid and carnosol at 1:1 (w/w) for enhancing the lipid oxidative stability in cooked‐chilled lamb meat, is evaluated. Three diets for fattening lambs are tested: i) a cereal‐based concentrate (C‐diet); ii) the C‐diet plus 600 mg vitamin E per kg feed (E‐diet); and iii) the C‐diet plus 600 mg rosemary diterpenes per kg feed (R‐diet). Griddled‐chilled lamb patties are kept at 4 °C and lighting for 2 days, simulating catering conditions. Diterpenes have a lower deposition rate than vitamin E in lamb muscle and are completely degraded during cooking. DRE is thus less effective than dietary vitamin E in enhancing the oxidative stability of the patties. After 2‐day storage, the R‐diet shows lower (p < 0.01) peroxide values and thiobarbituric acid reactive substances than the C‐diet, while, in contrast to the E‐diet, it does not inhibit (p > 0.05) the formation of cholesterol oxidation products. The R‐diet increases (p < 0.05) the proportion of polyunsaturated fatty acids and decreases (p < 0.05) the n‐6/n‐3 ratio. These findings suggest antioxidant protection by dietary bioactive compounds beyond the direct radical scavenging activity that is able to stabilize lipids during the meat shelf‐life. Practical Applications: Cooked‐chilled meat lipids strongly oxidize in ready‐to‐eat dishes kept in retailing conditions, which may negatively affect their levels of polyunsaturated fatty acids (PUFA), cholesterol oxidation products (COP), and other lipid oxidation products. Dietary rosemary diterpenes can be used as a clean alternative to feed additives to enhance the oxidative stability of cooked‐chilled meat. Improved health and antioxidant status of the animal might be able to reduce oxidative spoilage during meat shelf‐life. Diterpenes provide lesser antioxidant protection than dietary vitamin E but may improve the PUFA content, with positive implications for the nutritional quality of lamb fat. The use of dietary antioxidants with different properties may contribute to improving the efficacy of animal feeds to improve meat quality.     

Fluorescent image analysis of lipid hydroperoxides in fish muscle with 3-perylene diphenylphosphine

A fluorescent image analysis method was developed to evaluate lipid hydroperoxide formation in fish muscle. The lipid hydroperoxides generated in white and dark fish muscles during storage at 5–6°C oxidized 3-perylene diphenylphosphine located in the tissue to yield the fluorescent derivative, 3-perylene diphenylphosphine oxide (3-PeDPPO). 3-PeDPPO thus obtained was determined by digital fluorescent image analysis. The 3-PeDPPO fluorescence intensity of white and dark muscle increased during low-temperature storage (0–24 h) and was clearly correlated with total lipid hydroperoxide levels in muscle extracts, which were determined by using HPLC based on a triphenylphosphine oxidation method (R ²=0.954). These results suggest that 3-PeDPPO fluorescence, coupled with fluorescent image analysis, is a novel tool for direct determination of lipid hydroperoxides in fish muscle without a need for extraction of lipid.     

Lipid and mineral distribution in different zones of farmed and wild blackspot seabream (Pagellus bogaraveo)

Lipid composition was studied in different white muscle zones (ventral, dorsal and tail) of wild and farmed blackspot seabream (Pagellus bogaraveo). The study was complemented by moisture, trimethylamine oxide (TMAO) and trace mineral determinations. Farmed fish muscle showed higher lipid and triacylglycerol contents, but lower values for moisture, TMAO and α‐tocopherol than its wild fish counterpart; no differences could be observed between both kinds of fish for the phospholipid, sterol and free fatty acid contents. When compared to wild fish, a higher saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acid (PUFA) content was obtained in farmed fish, while lower values could be observed for the n‐3/n‐6 and 22:6n‐3/20:5n‐3 fatty acid ratios. Most minerals analysed (Cu, Fe, Mn, Se and Zn) showed higher mean values in farmed fish muscle, except for Ca and Mg which provided higher mean contents in wild fish. Concerning the muscle site comparison, greater SFA, MUFA and PUFA contents could be detected in the dorsal zone than in the two other locations both for farmed and wild fish, in accordance with a higher mean lipid content found at this site. Finally, the tail zone showed higher TMAO values than the two other locations.     

Formation of fluorescent substances from degradation products of methyl linoleate hydroperoxides with amino compound

The degradation products formed from methyl linoleate hydroperoxides by reaction with heme were fractionated by Sephadex LH-20 column chromatography and by reverse-phase high performance liquid chromatography, and the ability of each compound to form fluorescent substances through reaction with amino compound was compared. Maximum formation of fluorescent substances was obtained from monomeric degradation products with amino compound, but low molecular weight aldehydes such as hexanal, 2-hexenal and 2,4-decadienal, formed only a small amount of fluorescent substances. However, the major monomeric degradation products described previously, the hydroxy-, keto- and epoxy-derivatives, do not significantly contribute to the formation of fluorescent substances through reaction with amino compound. It was suggested that formation of fluorescent substances from lipid peroxides with amino compound may originate from a precursor present in monomeric degradation products formed from hydroperoxide of methyl linoleate during lipid peroxidation, and that low molecular weight aliphatic aldehydes are not involved in fluorescent substance formation. Moreover, the majority of TBA-reactive substances in secondary oxidation products prepared from autoxidized methyl linoleate are also unrelated to the formation of fluorescent substances through reaction with amino compound.     

Studies on rancidity inhibition in frozen horse mackerel (Trachurus trachurus) by citric and ascorbic acids

This study is aimed to investigate the effect of aqueous solutions of citric acid (CA) and ascorbic acid (AA) on the lipid stability of horse mackerel (Trachurus trachurus) fillets and whole fish during frozen storage (up to 6 and 9 months, respectively) by means of a soaking pretreatment. Best oxidation inhibition results on fish fillets were obtained when employing a 0.5% CA solution. Lower (p <0.05) peroxide (month 3), thiobarbituric acid‐reactive substance (months 1 and 3) and fluorescent compound formation (month 6) values were obtained from CA‐treated fish fillets than from the untreated (blank control) and water‐treated (water control) fish fillets. In the case of whole fish, soaking pretreatment with a mixture consisting of 0.5% CA and 0.5% AA showed the best results in inhibiting oxidation, as lower (p <0.05) peroxide formation was observed at 6 and 9 months of frozen storage compared to the untreated or water‐soaked counterparts. Advantages of both acids (CA and AA) are discussed, and further studies based on the positive role of a CA‐AA mixture will be carried out to extend the shelf life of medium‐ and high‐fat content fish species during frozen storage.     

Effects of ionizing radiations on fats. II. Accumulation of peroxides and other chemical changes

The accumulation of peroxides, carbonyl com-pounds and reducing substances during irradia-tion and post-irradiation storage of pure fatty acid methyl esters has been studied. Irradiation and storage of irradiated methyl myristate under vacuum results in formation of small quantities of these compounds. Irradiation under oxygen gives peroxides and carbonyl com-pounds in yields indicating that every ionization results in the formation of one molecule of each group, and antioxidants have no effect on the formation of these compounds during irradiation. Irradiation of methyl linoleate under vacuum results in destruction of pre-formed hydroperox-ides. During irradiation in oxygen, approximately one-eighth of the peroxides formed arises from the direct reaction of irradiation-induced free radi-cals with oxygen, while the rest is formed through a chain mechanism with an average chain length of 7. Peroxides continue to accumulate in irradiated methyl linoleate stored under oxygen at a rate increasing with initial irradiation dose. Antioxidants have some effect in retarding the formation of peroxides during irradiation of methyl linoleate and during post-irradiation stor-age, but the effect is small compared to their antioxygenic activity toward simple autoxidation. The effect varies with the nature of the antioxi-dant and with irradiation dose. Propyl gallate is much less effective than butylated hydroxy-anisole and appears to be easily destroyed during irradiation. For paper I of this series, see Ind. Eng. Chem.49. 1713 (1957). Presented at the AOCS Meeting in Minneapolis, 1963.     

Effects of lipid oxidation on fish lipids — amylopectin interactions

The results of studies on fish lipid oxidation effects on lipid‐amylopectin starch interactions are presented. Particular attention is paid to fish lipid availability (extractability from the system) and fatty acid contributions to individual lipid groups after mixing‐provoked interaction and after a 30‐day storage at —18 °C. The study involved model systems containing fish lipids at different levels of oxidation, lipids containing an antioxidant (BHA), and gelatinised amylopectin starch in a 10% aqueous solution. The lipid to starch ratio was 1:1. The test systems were subjected to selective extraction. The extracts were assayed for lipid content, peroxide value, anisidine value, fluorescence, and fatty acid composition. Compared to fresh fish lipids, those lipids, which were oxidised to a higher extent were shown to be more amenable to complexing with amylopectin, but they were also more readily released during frozen storage. On the other hand, addition of BHA stabilised the lipid‐amylopectin starch interaction during storage at —18 °C. In the entire systems tested, polyunsaturated fatty acids, eicosapentaenoic and docosahexaenoic acids in particular, proved to be most susceptible to binding, up to 90% of the latter being complexed.     

Relative FFA formation and lipid oxidation of commercially milled unseparated,head, and broken rice

This study was conducted to determine the relative rate of FFA formation and lipid oxidation of unseparated (head and broken), head, and broken rice and the effect of water washing on the lipid quality of broken rice. A regression model was developed with surface FFA or conjugated diene (CD) content vs. incubation time to determine the rates of FFA formation and lipid oxidation. The surface lipid contents of unseparated, head, and broken rice were 0.40, 0.38, and 0.50% of rice, respectively. FFA formation during storage showed three phases: an initial rapid formation, followed by a period of very little or no formation, and finally a phase of gradual formation. In contrast, CD formation initially showed a slow increase but later increased gradually with storage time. The relative rates of FFA and CD formation of unseparated, head, and broken rice were 0.0028, 0.0027, and 0.0036 and 0.192, 0.188, and 0.377, respectively. Water washing reduced the rates of FFA formation and lipid oxidation of broken rice to 0.0015 and 0.2192 from initial values of 0.0031 and 0.369, respectively. Water washing appears to be a simple and practical means of lowering the rates of FFA formation and lipid oxidation in broken rice.     

Electron spin resonance spectroscopy for evaluation of early oxidative events in semisolid palm oil

Electron spin resonance (ESR) spectroscopy was applied to study early oxidative events in semisolid palm oil in bulk. Oil was stored at mildly accelerated conditions of 50°C for 7 days and the free radical formation was followed with the addition of spin trap N‐tert‐butyl‐α‐phenyl‐nitrone. Dissolution of the oil samples in isooctane prior to ESR measurements stabilized the ESR signal allowing the changes in relative free radical concentrations during oil storage to be monitored. Formation of lipid hydroperoxides as primary lipid oxidation products was found to correlate with the tendency for the formation of free radicals in the oil during the storage and accordingly, ESR spectroscopy may be used to detect the early events in lipid oxidation in palm oil. However, the interference of added rosemary extract (RE) in ESR analyses was seen as an increased ESR signal while the efficiency of RE as antioxidant in palm oil was confirmed by isothermal DSC. Practical applications : ESR spectroscopy may be used to evaluate early events of oxidation in semisolid oils such as palm fat, which is widely used in food industry.     

Cellulose graft copolymers. III. Effects of oxygen on graft copolymerization of ethyl acrylate with γ-irradiated cellulose

The effects of oxygen on graft copolymerization of ethyl acrylate from methanol–water systems with γ-irradiated fibrous cotton cellulose were investigated by electron spin resonance spectroscopy and by the formation of cellulose–poly(ethyl acrylate) copolymer. The concentrations of free radicals in cellulose irradiated dry in an atmosphere of nitrogen at 25°C decreased during postirradiation storage in nitrogen or oxygen. The concentration of free radicals in the irradiated cellulose, moisture regain of the irradiated cellulose, and formation of cellulose–poly(ethyl acrylate) copolymer decreased with increase in temperature and time of postirradiation storage and to a greater extent when stored in oxygen rather than in nitrogen. From the decrease in moisture regain of irradiated cellulose during postirradiation storage, it was concluded that increased intermolecular bonding occurred in irradiated cellulose during storage in both nitrogen and oxygen atmospheres. When irradiated celluloses which had been stored in either oxygen or nitrogen were copolymerized with ethyl acrylate at 60°C, less formation of copolymer was observed than when the copolymerization reactions were conducted at 25°C. It was concluded that there was no evidence for the formation or decomposition of cellulose peroxides during these reactions and that formation of graft copolymer depended primarily on the concentration of free radicals in the irradiated cellulose at the time of copolymerization.     

Influence of heating time and oxygen availability on lipid oxidation in meat emulsions

The aim of the present study was to investigate the effect of heating time and oxygen availability on lipid oxidation during chill storage, using different step indicators, in a meat emulsion model. Lipid oxidation was measured by conjugated dienes, hydroperoxides and 2‐thiobarbituric acid reactive substances formation on raw and cooked meat emulsion at 80 °C in different oxygen availability bags, at 0 °C during 35 d. The results obtained showed that heat treatment and oxygen availability affected conjugated dienes, hydroperoxides and 2‐thiobarbituric acid reactive substances formation during chill storage. Besides cooked meat emulsion did not have a similar behaviour to that of raw samples. Thus, is very important to follow primary and secondary products of oxidative deterioration to understand the effect of heat treatment and oxygen availability overall lipid oxidation process in meat emulsion.     

High Density Lipoprotein Level is Negatively Associated With the Increase of Oxidized Low Density Lipoprotein Lipids After a Fatty Meal

Recent reports show that a fatty meal can substantially increase the concentration of oxidized lipids in low density lipoprotein (LDL). Knowing the LDL‐specific antioxidant effects of high density lipoprotein (HDL), we aimed to investigate whether HDL can modify the postprandial oxidative stress after a fatty meal. Subjects of the study (n = 71) consumed a test meal (a standard hamburger meal) rich in lipid peroxides, and blood samples were taken before, 120, 240, and 360 min after the meal. The study subjects were divided into four subgroups according to the pre‐meal HDL cholesterol value (HDL subgroup 1, 0.66–0.91; subgroup 2, 0.93–1.13; subgroup 3, 1.16–1.35; subgroup 4, 1.40–2.65 mmol/L). The test meal induced a marked postprandial increase in the concentration of oxidized LDL lipids in all four subgroups. The pre‐meal HDL level was associated with the extent of the postprandial rise in oxidized LDL lipids. From baseline to 6 h after the meal, the concentration of ox‐LDL increased by 48, 31, 24, and 16 % in the HDL subgroup 1, 2, 3, and 4, respectively, and the increase was higher in subgroup 1 compared to subgroup 3 (p = 0.028) and subgroup 4 (p = 0.0081), respectively. The pre‐meal HDL correlated with both the amount and the rate of increase of oxidized LDL lipids. Results of the present study show that HDL is associated with the postprandial appearance of lipid peroxides in LDL. It is therefore likely that the sequestration and transport of atherogenic lipid peroxides is another significant mechanism contributing to cardioprotection by HDL.     

Influence of Temperature Stress on Lipid Stability of Atlantic Herring (<Emphasis Type="Italic">Clupea harengus</Emphasis>) Muscle During Frozen Storage

Unstable conditions are commonly encountered during industrial storage and transportation of frozen fish. Temperature stress and fluctuations may increase the amount of unfrozen water in the muscle and enzymatic activity and lipid oxidation can thus still take place during frozen storage. The aim of this study was to investigate the changes of characteristics of different muscle types of herring at unstable modelled conditions during storage and transportation. Compositional changes, lipid oxidation and lipid hydrolysis were monitored in light and dark muscle of Atlantic herring (Clupea harengus), during frozen storage, as affected by temperature stress (samples were stored at ? 25 °C for 2 months, then stressed at ? 12 °C for 1 month, followed by storage at a stable ? 25 °C for the remaining storage duration), and compared to samples stored at a stable ? 25 °C for 14 months. The dark muscle was more sensitive to lipid oxidation than the light muscle, leading to faster degradation. Increased lipid oxidation and lipid hydrolysis were observed in temperature‐stressed samples of both muscle types. The study demonstrated the importance of avoiding temperature stress during industrial frozen storage and transportation to improve the quality and shelf life of frozen herring products. Removal of dark muscle by deep skinning could benefit both processors and customers regarding the shelf life and nutritional value of the light herring muscle.     

Lipid damage in farmed rainbow trout (Oncorhynchus mykiss) after slaughtering and chilled storage

The flow ice system including ozone (OFI condition) was tested for slaughtering and storage (up to 16 days) of farmed rainbow trout (Oncorhynchus mykiss). Lipid damage analyses were carried out and compared to sensory acceptance and instrumental colour changes. Comparison to individuals processed with the flow ice system in the absence of ozone (FI condition) was undertaken. Rainbow trout slaughtered and chilled under FI and OFI conditions showed a low lipid damage development, according to lipid oxidation and hydrolysis events and lipid composition (polyunsaturated fatty acids, phospholipids and endogenous antioxidants) changes. Additionally, both icing conditions led to largely good quality and shelf life times and to the absence of changes in colour properties. It is concluded that flow ice as such, or including the presence of ozone, can be considered as ideal strategy to be employed as slaughtering and storage system during the commercialisation of the actual farmed species. The ozone presence has shown some profitable effects as leading to an extended shelf life time by quality retention of several sensory parameters; in contrast, some negligible negative effects could be observed on the secondary and tertiary lipid oxidation development. However, the oxidation values reached by individuals kept under OFI conditions cannot be considered as particularly high.