Effect of varying the gas headspace to meat ratio on the quality and shelf-life of beef steaks packaged in high oxygen modified atmosphere packs.

Beef steaks (M. longissimus dorsi) were stored in modified atmosphere packs (MAP) (80% O2:20% CO2) with gas headspace to meat ratios of 2:1, 1:1 and 0.5:1 for 14 days at 4 °C. The pH, surface colour, texture and microbiology of beef steaks were unaffected (P>0.05) by varying the gas headspace to meat ratio. APLSR (ANOVA-partial least squares regression) and jack-knife uncertainty testing indicated that lipid oxidation (TBARS) was significantly positively correlated with days 10 (P<0.05) and 14 (P<0.001) of storage. Chemical and sensory detection of lipid oxidation in beef steaks were in agreement on day 14 of storage. The sensory quality and acceptability of beef steaks were similar in gas headspace to meat ratios of 2:1 or 1:1 and unacceptable in 0.5:1. Results indicate that pack size and gas volume can be reduced without negatively affecting fresh beef quality and shelf-life.

Assessment of the ability of seaweed extracts to protect against hydrogen peroxide and tert-butyl hydroperoxide induced cellular damage in Caco-2 cells.

The ability of brown seaweed extracts, Ascophyllum nodosum, Laminaria hyperborea, Pelvetia canaliculata, Fucus vesiculosus and Fucus serratus to protect against tert-butyl hydroperoxide (tert-BOOH) induced stress in Caco-2 cells was investigated. Oxidative stress was determined by measuring alteration in the enzymatic activity of catalase (CAT) and superoxide dismutases (SOD) and cellular levels of glutathione (GSH). L. hyperborea, P. canaliculata and F. serratus significantly protected against tert-BOOH induced SOD reduction but did not protect against the reduction in CAT activity or the increased cellular levels of GSH. The ability of F. serratus and F. vesiculosus to protect against H(2)O(2) and tert-BOOH induced DNA damage was also assessed. The DNA protective effects of the two seaweed extracts was compared to those of three metal chelators; deferoxamine mesylate (DFO), 1,10-phenanthroline (o-phen) and 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis (BAPTA-AM). F. serratus and F. vesiculosus significantly protected (P<0.05) against H(2)O(2) (50 µM) induced DNA damage but not tert-BOOH induced damage.

Lipid and colour stability of M. longissimus muscle from lambs fed camelina or linseed as oil or seeds.

Colour and lipid stability of M. longissimus dorsi (LD) from sheep fed diets containing different lipid sources (Megalac (MG), camelina oil (CO), linseed oil (LO), NaOH-treated camelina seed (CS), NaOH-treated linseed (LS) or CO treated with ethanolamine (CA)) were examined. After 100 days on-feed, samples of LD were collected, fatty acid profile determined and colour and lipid oxidation (2-thiobarbituric acid reactive substances; TBARS) measured during retail display in high oxygen packaging. The LS ration was most effective in increasing the 18:3n-3 and conjugated linoleic acid (CLA) concentration in muscle. Within camelina, CA resulted in the highest 18:3n-3 and lowest CLA concentration in muscle. There was no difference in colour stability. Oil (seed) supplementation increased TBARS compared to MG in the early part of display while linseed-based rations tended to cause higher TBARS than camelina-based rations. Higher muscle 18:3n-3 concentration was associated with higher oxidation during early retail display but this was not reflected in a loss of colour stability.

The effect of hot-boning and reduced added phosphate on the processing and sensory properties of cured beef prepared from two forequarter muscles.

The functionality of pre-rigor beef was investigated in terms of the effects of phosphate reduction and curing of hot-boned meat on the processing and sensory properties of relatively low-value muscles, M. infraspinatus (IS) and M. pectoralis profundus (PP), from the forequarter. Muscles were excised within 90 min post-mortem (HB) or, from chilled carcasses, 24 h post-mortem (CB), and were injected to 115% of green weight with brine containing phosphate and were vacuum tumbled continuously for 2 h. Hot-boning gave lower total yield of cooked meat for both muscles. Hot-boned PP joints had slightly higher (P<0.05) cook loss than cold-boned. Reduction of added phosphate (from sodium tri-polyphosphate) from 0.3% to 0.15% of cured meat had detrimental effects on colour; joints containing the conventional 0.3% were lighter (P<0.001) and redder for both muscles. Hot-boning gave PP joints which were rated less tender by sensory panels, corresponding with higher (P<0.001) hardness TPA values, higher (P<0.05) Warner-Bratzler shear force (WBSF) values and shorter (P<0.05) sarcomere lengths. Effects of phosphate level and boning method were less in IS joints. In these, hot-boning gave products that were rated by sensory panel as slightly more tender but there was no effect on TPA or WBSF values. Furthermore, total yields from hot-boned products did not reflect the expected increase in functionality and reducing added phosphate during processing had a detrimental effect in binding and forming of joints.

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 200mg/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 (200mg/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.

Influence of different gas compositions on the short-term storage stability of mother-packaged retail-ready lamb packs.

Longissmus dorsi muscles were removed from Suffolk cross-breed lambs (aged 4-9 months) and cut into steaks. Lamb steaks were over-wrapped on trays and placed in vacuum pack bags. Bags were divided into 3 groups and flushed with gas mixtures containing 100:0, 90:10 or 80:20/CO(2):N(2). Mother packed lamb bags were stored for 4 days (T2) and 7 days (T3), respectively, in darkness at 4 °C, prior to retail display. The effect of aerobic packaging alone on lamb meat quality was used as the control (T1). Under retail display, all over-wrapped trays were held under refrigerated conditions (4 °C, 616 lx) for up to 8 days. Steaks were assessed for microbial growth, oxidative and colour stability as well as pH every 2 days. Mother-packing in 100:0/CO(2):N(2) was the most effective way of extending the storage life of retail ready lamb prior to display, particularly over longer storage periods. TVCs for T3 lamb meat using all gas compositions remained below 2.0×10(6) CFUs/g meat up until day 6 compared to day 4 in both T1 and T2 lamb. Lipid oxidation in lamb mother-packed for 7 days occurred at a faster comparative rate than discolouration and microbial growth and was the major determinant of shelf-life. However, under simulated retail display in aerobic packages, TBARS values did not increase significantly. There was no significant difference between Hunter 'a' values for T3 lamb meat and the control, but T3 meat mother-packed in 100:0/CO(2):N(2) had higher 'a' values than those of the control and T3 meat packed in other gas compositions. Lamb steaks in T3 previously mother-packed in 100:0/CO(2):N(2) were also significantly (p<0.05) higher than those of T2 on day 0. T3 meat also maintained initial colour values over those of the control.

Assessment of the antioxidant potential of natural food and plant extracts in fresh and previously frozen pork patties.

Antioxidant activities of aloe vera, fenugreek, ginseng, mustard, rosemary, sage, soya protein, tea catechins and whey protein concentrate (35% protein) were evaluated in pork patties prepared from both fresh and previously frozen (-20°C) pork. Chemical analysis showed test ingredients to be more effective in reducing lipid oxidation in patties made from previously frozen pork. Tea catechins, rosemary and sage were identified as being the most effective antioxidants with potency decreasing in the following order: tea catechins>rosemary>sage. Optimum addition rates of these ingredients suggested levels of 0.25, 0.10, 0.05% for tea catechins, rosemary and sage, respectively. Soya protein (0.10%) increased meat redness in fresh pork patties producing significantly (P<0.05) higher Hunter 'a' values over the controls on days 0, 3 and 6. However, fenugreek (0.01%) was more effective in increasing Hunter 'a' values in patties manufactured from previously frozen pork. No significant (P>0.05) differences in Hunter 'L' and 'b' values were found between test and control samples on storage. The pH values of tea catechins, sage and soya protein fluctuated over time. Fresh pork patties with mustard and ginseng caused an initial decrease followed by a subsequent increase in pH values. Fenugreek caused an initial increase in pH values followed by a decrease from day 3 onwards.

Evaluation of the antioxidant potential of natural food/plant extracts as compared with synthetic antioxidants and vitamin E in raw and cooked pork patties.

Antioxidant potential for previously identified optimum levels of aloe vera (AV), fenugreek (FGK), ginseng (G), mustard (M), rosemary (R), sage (S), soya protein (SPI), tea catechins (TC) and whey protein concentrate (WPC) were evaluated in raw and cooked patties manufactured from frozen pork. The optimum levels determined were: AV (0.25%), FGK (0.01%), G (0.25%), M (0.10%), R (0.10%), S (0.05%), SPI (0.10%), TC (0.25%) and WPC (4%). Test ingredients were evaluated against synthetic antioxidants butylated hydroxyanisole/butylated hydroxytoluene (BHA/BHT) (0.01%) and a supplemented meat containing natural antioxidant, α-tocopherol (1000 mg α-tocopheryl acetate/kg feed). Ranking the decreasing antioxidant effectiveness of added ingredients in raw patties on day 9 showed that: Control>G>SPI>FGK>AV>M>WPC>S>α-tocopherol>R>TC>BHA/BHT. Cooking resulted in a four-fold increase in TBARS values over raw patties with TC being the most effective antioxidant having significantly (P<0.001) lower TBARS values than the cooked control on days 3, 6 and 9. Ranking of decreasing antioxidant effectiveness of added ingredients showed that: M>SPI>G>FGK>α-tocopherol>AV>control>S>BHA/BHT>R>WPC>TC. BHA/BHT had the most beneficial effect on cooked meat redness with Hunter 'a' values being significantly (P<0.05) higher than the control on days 3, 6 and 9. Ranking of Hunter 'a' values for added test ingredients showed that FGK>WPC>control>R>BHA/BHT>α-tocopherol>TC>AV>SPI>M>G>S on day 9. Hunter 'L' and 'b' values showed no significant trend over the storage period in either raw or cooked patties. The pH values of both raw and cooked pork control patties and products containing added test antioxidants were variable and while a number of trends were observed, no significant differences were recorded between samples.

Dietary tea catechins and iron-induced lipid oxidation in chicken meat, liver and heart.

The effects of dietary tea catechins (TC) supplementation at levels of 50 (TC 50), 100 (TC 100), 200 (TC 200), and 300 (TC 300) mg kg(-1) feed on susceptibility of chicken breast meat, thigh meat, liver and heart to iron-induced lipid oxidation were investigated. Day old chicks (n=200) were randomly divided into six groups. Chicks were fed diets containing either basal (C), or α-tocopheryl acetate supplementation at a level of 200 mg kg(-1) feed (VE 200), or TC supplementation for 6 weeks prior to slaughter. Lipid oxidation was assessed by monitoring malondialdehyde formation with 2-thiobarbituric acid (TBA) assay. TC supplementation at all levels exerted antioxidative effects for all tissues with the exception of 50 mg kg(-1) feed for breast meat. TC supplementation at levels of 200 and 300 mg kg(-1) feed were found to be significantly (P<0.05) more effective in retarding lipid oxidation in all tissues, compared to the control. TC supplementation at a level of 300 mg kg(-1) feed was also found to be significantly (P<0.05) superior to vitamin E supplementation at a level of 200 mg kg(-1) feed (VE 200) for oxidative stability in chicken thigh meat, but it was inferior to VE 200 in chicken liver and heart. TC supplementation at a level of 50 mg kg(-1) feed was found to be pro-oxidative in breast meat, but this did not occur in chicken thigh meat, liver and heart. The variation of TC antioxidative properties in different tissues may be explained by the uneven distribution of lipid, iron and TC accumulation in tissues.