Sensory and chemical assessment of pork supplemented with iron and vitamin E

Pork muscle samples (M. longissimus dorsi and M. psoas major) were obtained from pigs given one of four dietary treatments, (1) control diet, (2) supplemental iron (7g iron (II) sulphate/kg feed), (3) supplemental vitamin E (200 mg dl-α-tocopheryl acetate/kg of feed) and (4) supplemental vitamin E+supplemental iron. Vitamin C was supplemented to all dietary treatments to facilitate iron uptake. Vitamin E and iron tissue levels were determined for each treatment. Warmed-over flavour (WOF) was evaluated by a trained sensory panel (n=8) for the four treatments which were cooked and refrigerated at 4?°C for up to 5 days. Thawing loss, driploss and thiobarbituric acid reactive substances (TBARS) were also determined. Vitamin E muscle tissue levels were greatest in the Iron/vitamin E-treated group followed by the vitamin E group, control and iron treated groups, respectively for M. longissimus dorsi. Whereas, for M. psoas major vitamin E tissue levels were in order of magnitude, vitamin E>iron/vitamin E>iron>control group. Iron tissue levels were in the order vitamin E>iron/vitamin E>control>iron for M. longissimus dorsi and iron>vitamin E>control>iron/vitamin E for M. psoas major. Thus, vitamin E and vitamin C promoted non-supplemental iron absorption in the vitamin E-treated group for M. longissimus dorsi and to a lesser extent for M. psoas major. M. psoas major was more susceptible to warmed-over flavour development than M. longissimus dorsi for all treatments as determined by sensory profiling, due to higher tissue iron levels. From sensory profiling, WOF development in M. longissimus dorsi and M. psoas major was highest in the iron-supplemented groups followed by the control and vitamin E-supplemented groups.     

Lipid stability and meat colour of beef from pasture- and grain-fed cattle with or without vitamin E supplement

Meat from pasture-fed cattle can have high contents of α-tocopherol and other anti-oxidants originating from naturally occurring compounds present in grasses. However, meat from pasture-fed cattle may have an increased demand for endogenous anti-oxidants because of its high content of polyunsaturated fatty acids, which in turn, may affect its colour and lipid stability. In the work described, we evaluated the effects of pasture-feeding alone and with vitamin E supplementation and compared the findings with those obtained for grain-fed cattle (predominantly sorghum) with and without supplementation. Within each nutritional background, vitamin E supplementation did not alter meat colour or colour stability of fresh or 47-day aged muscle during 7-day aerobic storage. However, both control and supplemented grain-fed product had better meat colour (more redness) compared with meat from grass-fed cattle. These differences in redness between pasture- and grain-fed fresh beef were not apparent after ageing. The treatments did not affect the lipid stability of fresh meat during aerobic storage; however, supplementation reduced (P<0.01) lipid oxidation in grain-fed aged beef compared with pasture-fed aged beef, despite both having similar α-tocopherol contents. Pasture-fed beef had more linolenic acid, less linoleic acid and, overall, was more polyunsaturated than grain-fed beef (P<0.05). In summary, vitamin E supplementation of pasture-fed cattle did not alter muscle tocopherol contents but pasture-fed beef (both control and supplemented) was more susceptible to lipid oxidation following ageing than vitamin E supplemented grain-fed beef.     

Variation in haem pigment concentration and colour in meat from British pigs

Variation in chemically determined total haem pigment concentration and instrumentally determined colour was examined in 223 samples of M. longissimus dorsi (LD) representative of the majority of slaughter pigs currently produced in the UK. Whether pigs were sired by White (Large White or Landrace) or Meat-line boars did not affect any measured characteristic but source breeding company influenced total haem pigment concentration (P < 0·01). Haem pigment concentration was higher in muscles from gilts, compared with castrates, boars being intermediate. Gilts also had darker muscles, based on EEL Reflectance values (P < 0·05), and lower hue values (P < 0·05). When compared with animals fed ad-libitum, restricted-fed pigs had higher concentrations of muscle haem pigment (P < 0·001) and this resulted in meat that was slightly darker (P < 0·05), despite having lower ultimate pH (pHu) (P < 0·05), and had a lower hue value (P < 0·001). Measurements of reflectance, total soluble protein and pHu indicated that differences in the incidence of potentially pale, soft, exudative or dark, firm, dry muscle were unlikely to be important contributors to variation in the colour of the meat in this study.     

Sensory characterization of meat from pigs vaccinated against gonadotropin releasing factor compared to meat from surgically castrated,entire male and female pigs

Boar taint is a sensory defect mainly due to androstenone and skatole. The most common method to control boar taint is surgical castration at an early age. Vaccination against gonadotropin releasing factor (also known as immunocastration) is an alternative to surgical castration to reduce androstenone content. In this experiment, loins from 24 female (FE), 24 entire male (EM), 24 vaccinated males (IM) and 23 surgically castrated males (CM) were evaluated by eight trained panellists in 24 sessions. Loins were cooked in an oven at 180 °C for 10 min. Furthermore loins were evaluated by consumers and its androstenone and skatole content were also chemically determined. Meat from EM had higher androstenone and skatole odour and flavour than meat from FE, IM and CM and lower sweetness odour scores. High correlations were found between androstenone and skatole levels assessed by trained panelists, chemical analysis and consumers’ acceptability. Moreover meat from EM is mainly related to androstenone and skatole attributes.     

Physicochemical assessment of fresh chilled dairy dessert supplemented with wheat germ

Wheat germ is an available and economical source of protein, vitamins and antioxidants with an increasing application in food products. The main aim of this study was to investigate the effects of different levels (0.0, 2.5, 5.0, 7.5 and 10.0%) and particle sizes (120, 210 and 354 μm) of wheat germ on physicochemical properties of fresh chilled dairy dessert. With increasing wheat germ level, dry matter of the dessert increased while the pH decreased. Particle size had no significant effect on these parameters. Increasing the wheat germ content and particle size enhanced darkness, hardness, cohesiveness and gumminess of the desserts while decreasing springiness and water release of the samples. Wheat germ level had greater effects on different quality aspects of the desserts than its particle size. The most acceptable dessert was produced with no more than 5.0% wheat germ with either of the particle sizes used in this study.     

Effect of dietary vitamin E supplementation on the colour and lipid stability of fresh, frozen and vacuum-packaged beef

The effects of dietary vitamin E supplementation on tissue α-tocopherol (α-Toc) levels and on the susceptibility of fresh, frozen and vacuum-packaged beef to lipid oxidation and colour deterioration were investigated. Friesian cattle were fed diets containing 20 (basal, n=5) or 2000 (supplemented, n=5) IU (α-tocopheryl acetate/kg feed/day for approximately 50 days prior to slaughter. α-Toc levels were higher (p<0.05) in muscles from supplemented animals than from those on a basal diet. Significant differences in α-Toc levels were also observed between muscles from different treatment groups, the order of the supplemented group was: M. psoas major (PM)>M. longissimus dorsi (LD)>M. gluteus medius (GM) (p<0.05), and in the basal group the order was: PM>GM>LD (p<0.05). Supplemented fresh, frozen and vacuum packed beef showed greater colour and lipid oxidative stability than meat from the basal group after 7 days retail display at 4°C (p<0.05). Thus, dietary (α-Toc supplementation appeared to retard metmyoglobin and TBARS formation in LD, GM and PM and increased the colour shelf life of these muscles.     

Bacterial populations associated with bulk packaged beef supplemented with dietary vitamin E

Five Simmentaler type calves were fed diets supplemented with 500 mg vitamin E per day and five fed control diets, Rump steaks from each carcass were PVC-overwrapped and bulk packaged in 100% CO2 or 20% CO2:80% O2. Bulk packs were stored up to 42 days at 4 degrees C and PVC-overwrapped samples subsequently displayed up to 7 days at 4 degrees C. After display the Aerobic Plate Count (APC) of steaks was determined and four colonies were randomly selected from the highest dilution APC plates showing growth. A total of 627 colonies were obtained. Gram-reaction, catalase, oxidase, morphology and motility of the isolates were determined. The gram-negative and gram-positive isolates were then identified using a dichotomous identification key. Enterobacteriaceae, Pseudomonas spp. and Acinetobacter spp. predominated on rump steaks from both feeding treatments and in packaging treatments. After 42 days bulk storage Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria and Acinetobacter spp. predominated in 20% CO2:80% O2 and 100% CO2 bulk packaging. Enterobacteriaceae, Pseudomonas spp. and Acinetobacter spp. predominated on rump steaks, from both feeding and packaging treatments, during the aerobic display period of 7 days.     

维生素E在肉类加工中的应用

维生素是调节人体新陈代谢,维持机体生命和健康必不可缺少的元素。它不能在人体内合成,需从外界摄入,以满足人体的需要。本文将就维生素E对人体的功能及其在肉食加工中的应用作简单介绍。     

Microbiological shelf life of bulk-packaged Musculus gluteus medius supplemented with dietary vitamin E

Five Simmentaler type calves were fed diets supplemented with 500 mg vitamin E per day and five fed control diets. Rump steaks from each carcass were PVC-overwrapped and bulk packaged in 100% CO, or 20% CO(2):80% O(2). Bulk packs were stored up to 42 days at 4°C and steaks displayed up to 7 days at 4°C. Bacterial counts of rump steaks from either packaging treatment were not significantly influenced during bulk storage or retail display by supplementation with dietary vitamin E. Both packaging treatments delayed bacterial growth during bulk storage. Aerobic plate counts of rump steaks stored in 100% CO(2) were lower than those of rump steaks stored in 20% CO(2): 80%: O(2). This study showed that rump steaks supplemented with dietary vitamin E can be bulk packaged in 20% CO(2): 80% O(2) or 100% CO(2) and stored for up to 42 days with shelf life of 4-7 days.     

Effect of dietary fat and vitamin E on colour stability and on lipid and protein oxidation in Turkey meat during storage

The objectives of the study were to investigate the effects of dietary fat (6% soya oil or rapeseed oil or tallow), together with tocopheryl acetate at either a basal (30 ppm) or a supplemented (400 ppm) level for 16 weeks on lipid and protein oxidation, including myoglobin, during refrigerated storage of turkey muscles. When turkeys were fed tallow in particular, vitamin E supplementation improved the vitamin E status of the muscles. Vitamin E supplementation significantly delayed lipid oxidation measured by TBARS, whatever the dietary fat. TBARS were highest in meat from animals fed soya oil. Vitamin E supplementation had no positive effect on colour stability of meat during refrigerated storage. Feeding soya oil induced significantly higher oxidation of proteins (carbonyl content) than rapeseed oil or tallow and vitamin E supplementation induced a slight decrease in carbonyl content at day 9 of storage for M. sartorius. SH content was significantly higher in vitamin E supplemented M. sartorius and M. pectoralis than in controls.     

Concentrations of oxysterols in meat and meat products from pigs fed diets differing in the type of fat (palm oil or soybean oil) and vitamin E concentrations

The aim of this study was to find out whether concentrations of oxysterols in pig meat are affected by dietary polyunsaturated fatty acids and vitamin E. 48 growth-finishing pigs were fed diets with either palm oil or soybean oil and vitamin E concentrations of 15, 40 or 200 mg/kg. Concentrations of oxysterols were analyzed in fresh and heat-processed (180 °C, 20 min) meat (M. longissimus dorsi) and in boiled sausage prepared from meat and back fat of the animals. Concentrations of oxysterols in fresh muscle were below 5 nmol/g dry matter; they were independent of the dietary fat type and vitamin E concentration. Heating caused a large increase of oxysterol concentration (up to 55 nmol/g dry matter). This effect was reduced by increasing dietary vitamin E concentration but was independent of the dietary fat. Sausage from pigs fed soybean oil had higher concentrations of oxysterols than sausage from pigs fed palm oil; vitamin E reduced concentrations of oxysterols in sausage from pigs fed soybean oil, but not in sausage from pigs fed palm oil.     

The relationship between oxidative damage and vitamin E concentration in blood, milk, and liver tissue from vitamin E supplemented and nonsupplemented periparturient heifers

This study investigated the relationship between oxidative damage and the effect of vitamin E supplementation in blood, milk, and liver tissue in 16 periparturient heifers. The question is whether measurements of oxidative and vitamin E status in blood of a periparturient cow are representative of the total body, given that blood concentrations of both vitamin E and oxidative stress products change around this period. The daily vitamin E intake of the vitamin E-supplemented Holstein-Friesian heifers (n = 8) was 3,000 international units and was started 2 mo before calving; the control heifers (n = 8) were not supplemented. Oxidative damage was determined on the basis of malondialdehyde (MDA) concentrations. Blood was sampled 9 times before calving, on calving day, and twice after calving. Liver biopsies were taken at wk −5, −1, and 2 relative to calving day. Milk was obtained from all heifers immediately after calving, the first 2 milkings and on d 3, 7, and 14 at 0600 h. Serum and liver tissue were analyzed for vitamin E, cholesterol, and MDA; and milk samples were analyzed for vitamin E, MDA, fat, protein, and somatic cell count. The results showed that vitamin E supplements increased both absolute vitamin E concentrations and the ratio of vitamin E to cholesterol in blood and liver tissue. Absolute vitamin E concentration in milk tended to be greater in supplemented cows. Based on the increased MDA blood concentrations at calving, it seems that dairy heifers experience oxidative stress. The effect of vitamin E on MDA differs between the blood, liver, and mammary gland. Vitamin E supplementation could not prevent the increase in blood MDA at calving, but the significantly lower MDA blood concentrations of supplemented cows in the 2 wk after calving suggest that vitamin E has a role in recovery from parturition-related oxidative stress. Vitamin E supplementation reduced oxidative damage in liver, whereas no obvious effect was found on milk MDA concentrations. A strong relationship was found between blood and liver vitamin E and the ratio of vitamin E to cholesterol. Concentrations of MDA in blood and milk were also strongly related. The results show that the relationship between oxidative damage and vitamin E differs within blood, liver tissue, and milk. This implies that oxidative and vitamin E status calculated on the basis of blood values alone should be interpreted with caution and cannot be extrapolated to the whole animal.     

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 dietary vitamin E supplementation on beef colour stability

The effect of dietary vitamin E upon colour, waterholding capacity, bacterial growth and lipid oxidation of beef longissimus thoracis (LT) and psoas major (PM) muscle were examined during aerobic display of fresh muscle and after aging in vacuum for 26 days. Forty crossbred beef bulls received a whole crop corn silage, supplemented with concentrate. Twenty bulls were each supplemented with 2025 mg vit E per day (added to the concentrate) for 136 day prior to slaughter and compared with non-supplemented control animals (n=20). In fresh LT muscle drip loss did not differ between treatment groups, while in PM muscle drip loss was significantly higher for the supplemented group. The treatment did not affect bacterial growth in fresh and aged muscles. Lipid oxidation during 12 day storage of fresh muscle was significantly lower for the supplemented group, as indicated by the lower TBA-values. No effect of the vitamin E treatment was observed on a (?)-values of both fresh and aged LT muscle during display for 8 and 5 days, respectively. In PM muscle, supplemented beef had lower a (?)-values in fresh (at day 1) and aged (at days 1 and 2) muscle, due to a lower oxygenation. The reason for this lower oxygenation is unclear. After aging, colour stability was decreased and more variable than in fresh muscle. Similar results were obtained when the difference in reflection values at 630 and 580 nm (R630-580), instead of the a (?) value, was used as a parameter for colour stability. The absence of an effect of vit. E on the rate of discoloration, might possibly be explained from the observation that α-tocopherol levels in control muscle were relatively high (LT: 2.1 and PM: 3.2 μg/g muscle), compared with data from literature. Analysis of the feed for vit. E suggests that this was due to a relatively high natural vit. E uptake from the feed, which was calculated to be approx. 330 mg vit. E per animal per day for the control group.     

Sensory quality of meat from lambs fed garlic

The objective of this study was to determine whether the inclusion of garlic in a ration would have a negative impact on the flavour of lamb. The study used meat from 31 Merino wether lambs fed diets with varying levels of garlic (0%, 1.8% and 3.6%) for 10 weeks. Cooked samples of meat from the lambs were assessed for flavour and acceptability as lamb by an untrained consumer panel. There was no difference (P>0.05) between the treatments in flavour score, but the 3.6% garlic treatment group scored significantly higher in terms of acceptability as lamb (P<0.05) and was commented on positively by the panellists more frequently than the meat from any other treatment (P<0.05). These results suggest that the inclusion of garlic into the animals' feed did not have a negative impact on the flavour of the lamb and, at the high rate (3.6%), made the meat more acceptable to the panellists.     

DNA tests based on coat colour genes for authentication of the raw material of meat products from Iberian pigs

Traceability in the meat supply chain depends on systems based on electronic identification, but DNA tests would be suitable to audit the genetic origin of some labelled meat products. Differentiated labelling is required for highly prized meat products from purebred Iberian pigs and from animals crossbred with the Duroc breed. A panel of breed specific markers based on polymorphisms found in two coat colour genes was investigated in the present study. The genotyping of the G/C or A/G polymorphisms at nucleotide positions ?160 and 727 bp of the melanocortin receptor 1 (MC1R) gene can be indistinctly used to discriminate the Duroc specific allele (MC1R*4) from all the alleles (MC1R*3, MC1R*6 and MC1R*7) found in the Iberian breed. It allows one to differentiate unambiguously samples from purebred Iberian and Duroc crossbred genotypes. The additional genotyping of the A/G polymorphism at position 2462 of the pink‐eyed dilution (OCA2) gene, four microsatellites (SW24, SW413, SW874 and SW1057) and nine amplified fragment length polymorphism (AFLP) markers would allow one to detect Duroc crossbred genotypes with a probability of exclusion of the pure Iberian origin greater than 0.968. The validation of batches of marketed products may be achieved with more single tests on pooled DNA samples. Copyright © 2004 Society of Chemical Industry