Flavour formation in pork semimembranosus: Combination of pan-temperature and raw meat quality

Flavour development and overall eating quality of pork semimembranosus were investigated with regard to different raw meat qualities (feeding/fasting strategy; control/low glycogen level, gender; castrate/female, slaughter live-weight; 84 kg/110 kg) combined with frying temperature (150 °C/240 °C). It was further investigated whether the precursor levels of glycogen, IMP, inosine, and hypoxanthine in the raw meat were correlated to the raw meat quality and fried/grilled attributes. Pork schnitzels were fried on a pan (155 °C) or grill–pan (240–250 °C) to a core temperature of 70 °C. Frying temperature was the one factor with greatest influence on the sensory attributes, and pan-grilled schnitzels had significantly higher scores in fried/grilled attributes regardless of meat quality compared to pan-fried schnitzels. Texture was not appreciably influenced by any treatment. There was no correlation between precursor levels and raw meat qualities or fried sensory attributes. Gender and slaughter live-weight had no pronounced influence on flavour and overall eating quality.     

Sensory quality of short- and long-term frozen stored pork products. Influence of diets varying in polyunsaturated fatty acid (PUFA) content and iodine value

Predicting aspects of pork quality is becoming increasingly important from a nutritional as well as a technological point of view. Here, the influence of increasing PUFA and iodine values (IV) in feed and pigs on sensory qualities of short- and long-term frozen stored products was investigated. Entire male and female grower-finisher pigs were fed diets with iodine value products of 48 (LowIVP), 77 (MedIVP) or 99 (HighIVP) according to a restricted feeding scale. Ribs, chops and meat balls were short- (0-3 months) and long-term (6-9 months) frozen stored before sensory profiling. C18:2n−6 increased linearly in backfat with increased dietary inclusion. No negative effect on sensory quality was found in short-term stored products. After long-term storage the lean chops was the product most affected. Increasing the dietary IVP led to an increased rancid and total odour and flavour intensity, and to reduced meat and sour odour and flavour.     

Significance of fat supplemented diets on pork quality - Connections between specific fatty acids and sensory attributes of pork

The influence of two diets with different fatty acid compositions has been studied with regard to overall pork quality and significance of specific fatty acids on sensory attributes in fried chops and oven roasts. Twenty castrates and 20 females were in a balanced experimental set-up fed with a standard diet supplemented with α-tocopherol (200mg/kg feed) where the fat source was either 3% of palm oil or 3% rapeseed oil. After slaughter, despite differences in lipid composition and sensory attributes, no significant difference in overall meat quality parameters and flavour precursors was found. Comparison of the two diets showed that supplementation with rapeseed oil resulted in a significantly higher content of C18:3n-3 (polar lipid (PL), neutral lipid (NL)), C18:2n-6c (NL) and C20:2 (NL) in LD and C18:1n-9c, C18:2n-6c, C18:3n-3, C20:3n-3, C22:5n-3 in backfat, while supplementation with palm oil resulted in a higher content of C16:0 (NL), C16:1 (PL), C18:1n-9t (NL) in LD and C16:0, C17:0, C18:0, C16:1, C20:4n-6 in backfat. A positive and significant correlation between the contents of C18:2n-6c, C20:3n-6 in the PL fraction and the sensory attributes fried meat odour and sweet odour were found in fried pork chops from female pigs. Likewise, positive correlations were seen between the content of C18:1n-9c in the PL fraction and sensory attributes such as sourish odour, piggy odour and piggy flavour in whole oven roasts. These data substantiate the view that specific fatty acids in the PL fraction influences flavour attributes in pork.     

Spermine and spermidine concentrations in pork loin as affected by storage, curing and thermal processing

Spermine and spermidine concentrations in pork loin as affected by three factors used in food processing [immersion-curing (10% brine: NaNO₂ and NaCl content of 0.6 and 99.4 g/l, respectively, and 20% brine: NaNO₂ and NaCl content of 0.6 and 199.4 g/l, respectively), boiling and grilling (70 °C core temperature) and storage of raw loin chops (“non-stored” versus storage at 4 °C for 5 days)] were studied. Spermidine and spermine concentrations of the “non-stored” raw loin chops were 2.7±0.7 and 19.8±1.5 mg/kg (fresh weight), respectively. Storage effects were negligible. Curing in 20% brine resulted in statistically significant spermidine decreases as compared to non-cured meat (p=0.04). Statistically significant decreases of spermine were observed for curing in 20% brine as compared with 10% brine (p=0.08), and boiling of meat in an equal amount of water compared to raw meat and grilled meat (p=0.03). Combined curing in 20% brine and cooking in an equal amount of water resulted in 2.0±1.0 mg/kg spermidine and 14.4±2.6 mg/kg spermine. Combined common food processing techniques resulted in a decrease of spermine and spermidine concentrations in pork loin of maximum 26% only. The latter should be considered as relevant for consumers for which the dietary polyamine uptake is critical.     

Shelf life and quality of pork and pork products with raised n-3 PUFA

Pork chops, liver, bacon and sausages from 80 pigs fed on a control or a linseed-rich test diet were assessed for their sensory qualities and oxidative stability after conditioning and storage, either frozen or under simulated retail display. There was no significant effect of diet on lipid oxidation as assessed by the TBA test (P>0.05) for pork, liver and sausages, values being less than 0.2 throughout the display period, lower than the threshold of 0.5 mg MDA/kg at which consumers may detect rancidity. Nor was there any significant effect of diet on colour changes of pork chops, sausages and bacon under simulated retail display conditions. Grilled loin chops, bacon and sausages from male pigs received significantly higher abnormal flavour scores than those from females but panellists were unable to discern any major differences between control and test diets, even though they could detect this relatively small sex effect. The test diet resulted in higher α-linolenic acid (18:3) levels, with major increases in total n-3 PUFA content, but the concentrations were generally lower than reported values that have resulted in stability problems. The n-6 PUFA content was also reduced by the test diet. The results demonstrate that the nutritional value of pigmeat can be improved by using an 18:3-enriched diet without adversely affecting normal eating quality parameters.     

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 9days. Moreover, olive leaves and α-tocopheryl acetate supplemented at 10g/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.     

Oxidative stability and dietary treatment with vitamin E, oleic acid and copper of fresh and cooked pork chops

Research has been conducted on the effects of feed supplementation with vitamin E, oleic acid (sunflower oil) and copper on some quality characteristics of pork chops. The study was based on the measurement of pH 45' and 24 hr post mortem, proximate composition, colour both objective and sensory, colour stability after packing in oxygen permeable film and protective atmosphere, copper and iron contents, vitamin E content in fresh and cooked chops, peroxide and TBARS value in raw and cooked meat, total cholesterol, cholesterol oxides and aldehydes in cooked meat, sensory evaluation of the eating quality of cooked chops and iodine number of subcutaneous fat. Vitamin E content was significantly higher with oil and vitamin supplementation. No variation has been observed in copper and iron contents. A higher stability of the colour of meat packed under modified atmosphere has been observed with increasing vitamin E content, but the same did not apply with meat packed in oxygen permeable film. No differences have been observed on fatty acid oxidative stability of fresh m. longissimus dorsi and cooked chops (peroxide and TBARS values), on cholesterol oxidation and aldehydes production of cooked chops with increasing vitamin E content. Iodine number in supplemented animals reached levels normally considered at risk for fat firmness.     

Muscle traits for long matured dried meats

The distinctive flavour of aged pork products is a complex mix of taste, smell and even touch. To meet increasing consumer's preference for ethnic foods or foods addressing linkage with specified geographic origin or complying with traditional manufacturing and breeding guidelines, efforts should be made to encourage selection of processing techniques and raw materials targeting desired end product qualities. Thanks to research carried out with sensory analysis and chemical and physical characterisation of raw and matured pork, as well as breeding and genetics, improved knowledge is now available relating dried meat properties to raw matter or manufacturing. The achievement of the distinctive taste and texture properties of aged products through genetics (animal selection for the enhancement or the removal of some muscle traits), breeding (effect of diet and slaughtering age on pork properties) with reference to current findings about this type of products is discussed.     

A comparison of organic and conventionally-produced lamb purchased from three major UK supermarkets: Price, eating quality and fatty acid composition

Organic and conventional lamb loin chops, labelled as British lamb, were bought from three major UK supermarket chains (designated A, B and C) in the Bristol area on 10 occasions over a six week period. Samples (n=360) were from unknown production systems but representative of what is available to UK consumers. The nutritional quality of muscle was assessed in terms of its fatty acid composition and eating quality was assessed by a trained sensory panel. Lamb prices varied between ￡9 and ￡12.50 per kg, with a relatively modest price differential between organic and conventional lamb chops of ￡1.10, ￡1.88 and ￡1.16 ￡/kg for supermarkets A, B and C, respectively. On average, organic chops were 20g heavier than conventional chops. Chops were relatively lean, having just 14% of subcutaneous fat, approximately half that of a similar survey 10 years ago. Organic lamb had a better eating quality than conventional lamb in terms of juiciness (p<0.05), flavour (p<0.05) and overall liking (p<0.05) thus providing some evidence for the perception among consumers that organic products 'taste better'. Differences in juiciness were attributed to the higher intramuscular fat content of organic meat whilst differences in flavour were attributed to differences in fatty acid composition, in particular, the higher level of linolenic acid (18:3) and total n-3 PUFA in organic chops. Conventional chops had a higher percentage of linoleic acid (18:2). Chops from both productions systems had a favourable n-6:n-3 ratio. The most important difference between the three supermarkets was that lamb flavour was significantly lower in chops from supermarket A, probably due to differences in their 'display until' dates. Chops from supermarket A were also the cheapest.     

Effects of Dietary Rape Seed Oil, Copper(II) Sulphate and Vitamin E on Drip Loss, Colour and Lipid Oxidation of Chilled Pork Chops Packed in Atmospheric Air or in a High Oxygen Atmosphere

The effect of addition of rapeseed oil (canola), CuSO(4) and vitamin E (all-rac-α-tocopheryl acetate) to pig diets on pork meat quality (lipid oxidation, colour and drip loss) was studied. Pigs were reared on ten different diets, either a control diet (no supplementation of rapeseed oil, CuSO(4) or vitamin E) or 6% rapeseed oil diets supplemented with CuSO(4) (0, 35 or 175mg/kg) and vitamin E (0, 100 or 200mg all-rac-α-tocopheryl acetate/kg). The natural content of vitamin E originating from feed ingredients amounted to 9-23mg vitamin E (α-tocopherol) per kg feed. Muscle vitamin E levels reflected the dietary intake and pigs fed the control diet had significantly lower levels than pigs fed rapeseed oil diets. The quality of fresh pork chops packed in air or in 80% O(2):20% CO(2) was followed during chill storage for 8 and 13 days, respectively. Colour, as measured by tristimulus colorimetry of pork chops packed in 80% oxygen atmosphere, was significantly improved with respect to redness when compared to chops packed in air, regardless of dietary treatment. The low vitamin E content in pigs fed the control feed significantly decreased a values and the oxidative stability of pork chops during chill storage compared to the other feeding groups. Packing of chops in a high-oxygen atmosphere increased lipid oxidation, especially in chops with low levels of vitamin E. Supplementation of rapeseed oil diets with 100 or 200mg vitamin E significantly decreased lipid oxidation of chill stored chops. Supplementation with CuSO(4) did not influence meat quality attributes (drip loss, colour stability and lipid oxidation) for any of the storage conditions.     

Sensory and functional meat quality characteristics of pork derived from three halothane genotypes

The effect of the halothane gene in pigs on the meat and sensory qualities thereof were determined. Meat derived from 60 Landrace×Large White pigs of three halothane genotypes was used. The sensory qualities, cooking loss, colour, shear value and proximate analysis of the cooked pork loin roasts were determined. The three genotypes did not differ significantly (P>0.05) with regard to the colour of the cooked meat, percentage cooking loss and percentage moisture. There were significant differences (P<0.05) between the genotypes in the percentage protein, ash and fat. Meat from the three genotypes also differed significantly (P<0.05) in juiciness, an analytical sensory panel scored the juiciness of meat from the NN-genotype the highest with a value of 71.3 when using a structured line scale. Meat from the nn-genotype had the lowest score for juiciness (62.8). Meat from the three genotypes did not differ significantly (P>0.05) with regard to tenderness, pork flavour and no mealiness. Correlation values showed a positive correlation (r=0.46, P<0.05) between juiciness and tenderness. These results indicate that the inclusion of the halothane gene in pig production programmes results in meat with an inferior quality and it can be recommended to exclude the halothane positive genotype from any pig production system where fresh pork quality is considered a primary goal.     

The effects of method of castration,rearing condition and diet on sensory quality of pork assessed by a trained panel

Beside surgical castration possible alternatives helping to reduce the incidence of boar taint in cooked pork are rearing conditions, immunocastration and feeding strategies for entire males known to lower the skatole levels. The goal of this study was to assess the effects of these alternatives on the sensory acceptability of pork. In experiment 1, carcasses from barrows, entire males (EM) and entire males fed raw potato starch (EM+) 7 d before slaughter were selected based on the androstenone (≤ 2 µg/g) and skatole (≤ 0.32 µg/g) levels. In experiment 2, carcasses from barrows, immunocastrates (IC), entire males either group-penned (EMG) or individually penned (EMP) were selected based on the aforementioned criteria. Boar odour and boar flavour intensities of longissimus dorsi (LD) and neck chops were evaluated by trained panellists. Boar odour and flavour scores were higher (P < 0.01) in neck than LD chops. Although skatole tissue levels in barrows and EM+ were similar (P > 0.05), boar odour and flavour scores were greater (P < 0.05) in EM+ than barrows. In experiment 2, scores for boar odour and flavour were lower (P < 0.05) in pork from barrows and IC than EMP, with intermediate values for EMG. In conclusion, we observed a discrepancy between the known boar taint compounds androstenone and skatole and sensory acceptability, which indicates that other factors influenced the perception of boar taint. Thus, surgical castration with or without anesthesia or immunocastration are still the safest methods to avoid boar taint.     

Physicochemical and Sensory Qualities of Fresh Pork Chops as Affected by Phosphate, Ascorbate or Sorbate Dipping Prior to Irradiation

Fresh pork chops were dipped for a target absorption of 0.5% sodium tripolyphosphate (STPP), 550 ppm sodium ascorbate (SA), or 0.1% potassium sorbate (PS) prior to irradiation (1.0 kGy). Untreated pork chops, both irradiated and unirradiated, were used as controls. Dipping with STPP decreased drip loss and improved color and lipid stability of irradiated chops and resulted in better tenderness and juiciness scores than undipped, irradiated samples. Also, STPP treated chops had similar or better physicochemical and sensory properties than untreated (no irradiation, no dipping) controls. Dipping with SA or PS had little effect compared with STPP, but improved some sensory qualities.     

原料肉中磷酸盐本底含量状况调查与分析

运用比色法,先后对5类1353个生肉样品、5类121个副产品样品,共计1474个原料肉样品进行了磷酸盐本底含量的测定。结果表明,原料肉中磷酸盐本底含量范围为1.49～16.5g/kg,多数处于低端水平;不同种类的生肉中磷酸盐含量存在显著差异(P<0.05),其中生猪肉中磷酸盐含量最高,其次为鸭肉,生羊肉中磷酸盐含量最低;不同种类的副产物中磷酸盐含量存在显著差异(P<0.05),其中生猪肝中磷酸盐含量最高,其次为生牛肝,生猪肠、肺中磷酸盐含量最低。     

Characteristics of pork products from swine fed a high monounsaturated fat diet: Part 2-Uncured processed products

The effects of incorporation of 12% high-oleic sunflower (HOSO; >85% in oleic acid) into a swine diet on properties of uncured, processed pork products were determined. Restructured pork chops (with an initial total-fat level of <5%) and ground pork patties (with targeted initial total-fat levels of 15% and 30%) processed from animals fed the HOSO diet, when compared to the corresponding products from animals fed the control diet without HOSO, were 28% and 38%, respectively, lower (0·72 and 0·62 fold, respectively) in the proportion of total saturated fatty acids; 25% higher (1·25 fold) in the proportion of total monounsaturated fatty acids for both products; and 73% and 105%, respectively, higher in the ratio of monounsaturated to saturated fatty acids (M/S). The M/S ratio differences were not significantly changed by cooking. Cooking loss for either restructured chops or ground pork patties was similar between the product from animals on the control diet and that from animals on the HOSO diet. When restructured chops were evaluated for sensory properties, HOSO and control samples were similar in all sensory attributes evaluated for broiled chops while HOSO samples were juicier for precooked-reheated chops. Thiobarbituric acid (TBA) values were not significantly different between HOSO and control samples for stored, restructured chops; for pork patties, differences between the diet treatment groups were dependent on whether patties were stored raw or cooked.     

MECHANICAL MEASUREMENTS OF MEAT TENDERNESS USING THE NIP TENDEROMETER

Abstract. A series of evaluations to compare the sensory panel ratings for tenderness with the Warner-Bratzler shear force and the Nip Tenderometer values was conducted using 150 pork chops, 239 lamb chops and 674 beef steaks. The Warner-Bratzler shear force values were more highly correlated with panel tenderness ratings than were the Nip Tenderometer readings for samples of pork, lamb and beef tested after cooling to room temperature (23 °C). Nip Tenderometer determinations on hot samples of beef (75 °C) were more closely related to panel tenderness ratings ( r =— 0.80) than were Nip Tenderometer readings ( r =— 0.58) or shear force values ( r =— 0.63) obtained on cold samples (23 °C). The combined advantages of ease and speed of application, correlation with sensory panel ratings and the demonstrated accuracy in identifying 'tough' vs 'tender' steaks suggest that the Nip Tenderometer has potential as an objective means for evaluating meat tenderness.     

Determination of cholesterol oxidation products in raw and processed beef and pork preparations

The effect of pan-frying on the formation of cholesterol oxidation products (COPs) in different processed meat samples (beef patties, braised meat, and fillets of pork) was studied. Samples were pan-fried with or without addition of oil. Different unsaturated oils (olive oil, corn oil or partly hydrogenated plant oil) were used throughout the study. After extraction, seven toxicologically relevant COPs were analyzed using LC–MS. Prior to heat processing up to 6.7 mg COPs/kg extracted fat could be detected in the raw material. Neither the cholestanetriol nor 25-hydroxycholesterol, which are the most cytotoxic COPs in vitro, were detectable in any sample. Differences in the COPs contents were observed between beef (up to 16.5 mg/kg extracted fat) and pork (up to 22.2 mg/kg extracted fat) samples. In prepared samples higher COPs content was noted compared with raw samples. Generally, a certain order of COPs increase dependent on the plant oil used could be recognized: corn oil < partially hydrogenated plant oil < olive oil. It appears that short heating time, mild heating conditions, and the use of fresh and shortly stored raw materials keep COPs levels low.     

Einflüsse von Braten und Grillen auf Fettqualität,Zartheit und Zusammensetzung von Schweinekoteletts aus verschiedenen Markenfleischprogrammen

Differences in fat quality, tenderness and composition of raw, roasted and grilled pork loin chops obtained from different meat brands Three loin chops obtained from each of a total of 180 pigs within one slaughter house either were left raw or were roasted at 120 °C for 12 min or simultaneously grilled on both sides at 180 °C for 6 min, respectively. Four different groups of 45 animals each were employed: pigs of conventional origin, pigs from a meat brand basing on animal welfare principles (Neuland) and pigs from two sub-systems of another commercial meat brand (Pigour) among others using higher contents of medium chain fatty acids in the feed. With the less intensive roasting, lower cooking losses and shear forces were observed as compared to grilling. The final intramuscular fat content was almost twice as high as the initial value of 1.3% with both cooking procedures. In subcutaneous back fat, cooking resulted in a highly significant reduction of the proportion of the polyenic acids which, however, was of only low numerical extent. The induction period till fat oxidation was significantly increased by 25% with roasting and by 8% with grilling. The clear differences in the quality of the raw chops obtained from the different origins could be almost completely recovered in the cooked chops.