Effect of modified atmosphere packaging on physicochemical and microbiological characteristics of Graviera Agraphon cheese during refrigerated storage.

The aim of this work was to examine the effect of modified atmosphere packaging on the physicochemical and microbiological changes of Graviera Agraphon cheese during refrigerated storage. Blocks of Graviera Agraphon cheese weighing around 200 g were packaged under natural (control) or modified atmosphere packaging (MAP) conditions (50% N2 - 50% CO2) and stored at 4 °C or 10 °C for up to 85 d. Prior to packaging, groups of cheese blocks were inoculated with one each of the following foodborne pathogens at around 104 log cfu/g: Listeria monocytogenes, Salmonella Typhimurium, Escherichia coli O157:H7 or Staphylococcus aureus, whilst further groups of cheese blocks were not inoculated. The protein, fat, moisture and salt contents as well as the pH of control and MAP cheese samples did not change significantly (P > 0.05) throughout 4 °C storage, while the pH values of control and MAP cheese samples were significantly (P < 0.05) reduced at 10 °C storage. At 10 °C storage, yeasts and molds, psychrotrophs and lactic acid bacteria (LAB) were significantly higher (P < 0.05) for the normal atmosphere than the MAP cheese samples after the 4th, 8th and 4th days, respectively. At 4 °C storage, the yeasts and molds or psychrotrophs were significantly higher (P < 0.05) than those of control after the 6th and 15th days, respectively at 4 °C storage. All foodborne pathogens showed a higher decrease (P < 0.05) at 10 °C than 4 °C storage. S. aureus proved more sensitive in inactivation in the MAP conditions than atmospheric conditions. L. monocytogenes and S. aureus presented a higher decrease than that of E. coli O157:H7 and S. Typhimurium. In conclusion, MAP proved efficient in retarding the growth of yeasts, molds, psychrotrophs and E. coli O157:H7, L. monocytogenes, S. Typhimurium and S. aureus in Graviera Agraphon cheese during refrigerated storage at 4 and 10 °C.

Effect of olive leaf (Olea europea L.) extracts on protein and lipid oxidation of long-term frozen n-3 fatty acids-enriched pork patties.

Our previous study has demonstrated the protective effects of olive leaf extracts on the oxidation of pork patties from n-3 fatty acid-enriched meat during refrigerated storage. The target of the present study was to examine these effects during frozen storage. Results showed that frozen storage accelerated (P=0.05) both lipid and protein oxidation in pork patties, but an addition of olive leaf extract at 200mg gallic acid equivalent/kg improved sensory attributes by delaying oxidation of lipids (reduction (P=0.05) of conjugated dienes, hydroperoxides and malondialdehyde), and of proteins (reduction (P=0.05) of protein carbonyls and inhibition (P=0.05) of the decrease of protein sulfhydryls).

Effect of olive leaf (Olea europea L.) extracts on protein and lipid oxidation in cooked pork meat patties enriched with n-3 fatty acids.

BACKGROUND: The effect of olive leaf extracts on lipid and protein oxidation of cooked pork patties refrigerated stored for 9 days was evaluated. Patties were prepared from longissimus dorsi muscle of pigs, and dietary supplemented with linseed oil. RESULTS: Results showed that dietary linseed oil modified the fatty acid composition of pork patties by increasing (P ≤ 0.05) n-3 (α-linolenic acid) and decreasing (P ≤ 0.05) n-6 (linoleic acid) fatty acids. Olive leaf extracts at supplementation levels of 200 and, especially, of 300 mg gallic acid equivalents kg⁻¹ meat, delayed lipid oxidation by reducing (P ≤ 0.05) both primary (conjugated dienes and hydroperoxides) and secondary (malondialdehyde) oxidation products. They also inhibited protein oxidation in a concentration-dependent manner by reducing (P ≤ 0.05) protein carbonyls and increasing (P ≤ 0.05) protein sulfhydryls. In addition, they improved sensory attributes of the n-3 enriched patties. CONCLUSION: Results suggested that olive leaf extracts might be useful to the meat industry as an efficient alternative to synthetic antioxidants.

Olive leaves (Olea europaea L.) versus α-tocopheryl acetate as dietary supplements for enhancing the oxidative stability of eggs enriched with very-long-chain n-3 fatty acids.

BACKGROUND: Ninety-six brown Lohmann laying hens were equally assigned into four groups with six replicates. Hens within the control group were given a corn/soybean-based diet supplemented with 30 g kg(-1) fish oil. Two other groups were given the same diet further supplemented with olive leaves at 5 (OL5) and 10 (OL10) g kg(-1) respectively, while the diet of the fourth group was supplemented with α-tocopheryl acetate (TOC) at 200 mg kg(-1). Eggs were analysed for lipid hydroperoxide and malondialdehyde (MDA) contents, fatty acid profile, α-tocopherol content and susceptibility to iron-induced lipid oxidation. RESULTS: Neither OL nor TOC supplementation affected (P>0.05) the fatty acid composition. Dietary supplementation with OL10 or TOC reduced (P≤0.05) the lipid hydroperoxide content but exerted no (P>0.05) effect on the MDA content of fresh eggs compared with controls. Eggs submitted to iron-induced lipid oxidation from the OL5 group presented higher (P≤0.05) MDA levels than the control but lower (P≤0.05) than the OL10 group. Eggs from the TOC group presented lower (P≤0.05) MDA levels compared with all groups at all incubation time points. CONCLUSION: The results of this study suggested that dietary supplementation with both OL10 and TOC could protect n-3 fatty acids in eggs from deterioration.

Lipid and protein oxidation of α-linolenic acid-enriched pork during refrigerated storage as influenced by diet supplementation with olive leaves (Olea europea L.) or α-tocopheryl acetate.

The objective of this study was to evaluate the effect of diet supplementation with olive leaves or α-tocopheryl acetate on lipid and protein oxidation of raw and cooked n-3 enriched-pork during refrigerated storage. Enrichment of pork with α-linolenic acid through diet supplementation with linseed oil enhanced (p≤0.05) lipid oxidation in both raw and cooked chops but had no effect (p>0.05) on protein oxidation during refrigerated storage while decreasing (p≤0.05) the sensory attributes of cooked pork. Diet supplementation with olive leaves or α-tocopheryl acetate had no effect (p>0.05) on the fatty acid composition of pork but decreased (p≤0.05) lipid oxidation while exerting no effect (p>0.05) on protein oxidation in both raw and cooked α-linolenic acid-enriched chops stored and chilled for 9 days. Moreover, olive leaves and α-tocopheryl acetate supplemented at 10 g/kg and 200mg/kg diet, respectively, exerted (p≤0.05) a beneficial effect on the sensory attributes of cooked α-linolenic acid-enriched pork chops.

The protective effect of alpha-tocopherol and GdCl3 against hepatic ischemia/reperfusion injury.

PURPOSE: To evaluate the combined effect of alpha-tocopherol and gadolinium chloride (GdCl3) in reducing lipid peroxidation after severe hepatic ischemia/reperfusion (IR) injury. METHODS: Sixty male Wistar rats, 200-250 g, were randomly divided into six equal groups. There were two sham operation (SHAM) groups, two untreated IR groups, and two IR groups treated with GdCl3 and alpha-tocopherol (IRGT). After 60 min of total hepatic ischemia and 120 min reperfusion, one of each group was killed, liver samples were taken for malondialdehyde (MDA) and myeloperoxidase (MPO) analysis and light microscopy examination, and blood samples were analyzed for aspartate (AST) and alanine (ALT) transaminase, lactate dehydrogenase (LDH), and alpha-tocopherol content. The remaining groups were monitored for survival rate determination. RESULTS: The mean MDA and MPO values in the SHAM, IR, and IRGT groups, respectively, were 1.117, 1.476, and 0.978 nmol/g wet tissue and 1.49, 6.26, and 1.78 (U/g). The mean alpha-tocopherol values in the SHAM, IR, and IRGT groups, respectively, were 10.4, 1.9, and 12 micromol/l. The mean serum AST, ALT, and LDH values were significantly higher in the IR group than in the SHAM group (P < 0.001), and significantly lower in the IRGT group than in the IR group (P < 0.001). Light microscopy examination revealed more severe congestion and vacuolization in the IR group than in the SHAM group, and minimal congestion and vacuolization in the IRGT group. Survival was significantly higher in the IRGT group than in the IR group. CONCLUSION: The administration of GdCl3 and alpha-tocopherol is likely to protect the liver against lipid peroxidation by suppressing Kupffer cell and polymorphonuclear leukocyte activation and enhancing endogenous antioxidant activity.

Attenuation of intestinal ischemia/reperfusion induced liver and lung injury by intraperitoneal administration of (-)-epigallocatechin-3-gallate.

The aim of this study was to evaluate the effect of ( - )-epigallocatechin-3-gallate (EGCG), a natural antioxidant, on liver and lungs after warm intestinal ischemia/reperfusion (I/R). Thirty male Wistar rats were equally divided into a sham-operation group, an intestinal I/R group and an intestinal I/R group pretreated with EGCG intraperitoneally. Intestinal ischemia was induced by occlusion of the superior mesenteric artery for 60 min followed by reperfusion for 120 min. Immediately after reperfusion, liver, lung and blood samples were collected and analyzed. Results showed that intestinal I/R increased the levels of aspartate (AST) and alanine (ALT) transaminase in serum to 987 and 752 IU/l, respectively. Malondialdehyde (MDA) increased in liver to 1.524 nmol/g in the group subjected to intestinal I/R compared to 0.995 nmol/g in the sham operation group. MDA was also increased in lungs to 1.581 nmol/g compared to 0.896 nmol/g in the sham operation group. Myeloperoxidase (MPO) increased in liver, after intestinal I/R, to 5.16 U/g compared to 1.59 U/g in the sham operation group. MPO was also increased in lungs to 3.89 U/g compared to 1.65 U/g in the sham operation group. Pretreatment with EGCG decreased serum levels of AST and ALT to 236 and 178 IU/l, respectively. It also decreased mean MDA levels in liver and lungs to 1.061 and 1.008 nmol/g, respectively, and mean MPO levels in liver and lungs to 1.88 and 1.71 U/g, respectively. Light microscopy and transmission electron microscopy examinations showed significant alteration in liver and lungs and protection of liver and lung parenchyma in the animals treated with EGCG.

Antioxidant activity of dietary oregano essential oil and alpha-tocopheryl acetate supplementation in long-term frozen stored turkey meat.

The effects of dietary oregano essential oil and alpha-tocopheryl acetate supplementation on the oxidative stability of long-term frozen stored turkey meat were investigated. Thirty 12-week-old turkeys, randomly divided into five groups, were given a basal diet or a basal diet supplemented with 200 mg of alpha-tocopheryl acetate kg(-1), or 100 or 200 mg of oregano oil kg(-1), or 100 mg of oregano oil plus 100 mg of alpha-tocopheryl acetate kg(-1) for 4 weeks prior to slaughter. Lipid oxidation in breast and thigh meat was assessed after 1, 3, 6, and 9 months of frozen storage at -20 degrees C prior to or following 7 days of refrigerated storage at 4 degrees C. Results showed that oregano oil increased the oxidative stability of breast and thigh meat during the frozen storage. Dietary oregano oil at the inclusion level of 200 mg kg(-1) feed was significantly (p < 0.05) more effective in delaying lipid oxidation compared to the level of 100 mg kg(-1), but equivalent to dietary alpha-tocopheryl acetate supplementation at 200 mg kg(-1), which in turn was inferior to dietary supplementation of 100 mg kg(-1) oregano essential oil plus 100 mg kg(-1) alpha-tocopheryl acetate that was significantly (p < 0.05) superior to all other treatments. Thigh meat was more susceptible to oxidation than breast meat, although the former contained alpha-tocopherol at markedly higher levels. Mean alpha-tocopherol levels in breast and thigh meat from all treatments decreased during the frozen storage, the decrease being sharper between 1 and 3 months of frozen storage for breast and between 3 and 6 months for thigh meat. Oregano oil supplementation increased (p < 0.05) the retention of alpha-tocopherol in meat, the increase being positively correlated with the supplementation level. However, the retention of alpha-tocopherol in meat could only partly elucidate the antioxidant activity exhibited by dietary oregano oil supplementation.