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.     

Characteristics of pork products from swine fed a high monounsaturated fat diet: Part 3-A high-fat cured product

Fresh pork bellies from animals fed a control sorghum-soybean diet and a similar diet containing 12% high-oleic sunflower oil (HOSO) were cured and processed in a smokehouse to an internal temperature of 55·6°C. Cooking losses were not significantly different (p < 0·05) between bacon strips from animals on the control diet and those from animals on the HOSO diet. The ratio of monounsaturated fatty acids to saturated fatty acids for the cooked rasher from the HOSO group was 1·84 times that for the cooked rasher from the control group (2·48 versus 1·35). The cooked rasher had a slightly lower (p < 0·05) percentage of total monosaturates that uncooked bacon strips within each diet group. When considering stearic acid as a fatty acid that does not raise the plasma cholesterol level in the human, along with all unsaturated fatty acids, only 16·83% and 12·26% of total fatty acids in the cooked rasher and the drip, respectively, from the HOSO group were fatty acids (C14:0 and C16:0) which may raise the plasma cholesterol level. The residual nitrite level in the raw and cooked bacon was higher (P < 0·05) for samples from the HOSO group than for those from the control group, probably due to binding of nitrite to the double bonds in unsaturated fatty acids that were higher for samples from the HOSO group. The extent of the accumulation of thiobarbituric acid-reactive substances during frozen storage was not affected (P > 0·05) by the inclusion of 12% HOSO in the animal diet, regardless of the packaging method.     

Effect of dietary high-oleic sunflower oil on pork carcass traits and fatty acid profiles of raw tissues

Ten gilts were randomly assigned to either a control sorghum-soybean diet or a similar diet containing 12% high-oleic sunflower oil (HOSO). No significant differences between the two groups were found in feedlot performance, carcass muscling and marbling score, but animals fed the HOSO diet had softer carcass fat and oilier carcasses than those fed the control diet. The ratio of monounsaturated fatty acids to saturated fatty acids (M/S) for subcutaneous fat increased from 1·58 in the control group to 3·76 in the HOSO group (138% increase); the M/S ratio for muscles (longissimus dorsi, semimembranosus and semitendinosus) increased from 0·96–1·19 to 1·84–1·88 (73% increase on an average). The percentage of polyunsaturated fatty acids in both adipose or muscle tissue was generally similar between the two diet treatments.     

Microbiological characteristics of pork chops and ground pork from swine fed a high monosaturated fat diet

Twelve percent high-oleic acid sunflower oil (HOSO) was included in a swine diet to increase the ratio of monounsaturated fatty acids to saturated fatty acids in pork chops and ground pork patties. Aerobic plate counts (APCs) of pork chops prepared from animals on control and HOSO diets did not differ (P >0·05) and no specific pattern of differences in the microflora of pork chops or ground pork patties could be attributed to diet. However, after 4 days of refrigerated storage, APCs of ground pork patties from animals fed the HOSO diet were lower (P<0·05) than those of comparable patties prepared from animals fed the control diet.     

Processing characteristics of beef roasts made from high and normal pH bull inside rounds

The processing characteristics of roasts manufactured from either high or normal pH bull inside rounds (semimembranosus and adductor muscles), which had been stored chilled or frozen, were investigated. Roasts were injected with a salt/phosphate brine and cooked to an internal temperature of 63 °C in a 70 °C water bath. High-pH meat that had been frozen had less purge than normal pH meat. However, pH did not affect purge from chilled meat. Meat pH and storage conditions did not affect retention of pumped brine. Cook yields were significantly (P<0.05) higher for roasts made from high pH meat (103.8 vs 98.8%). Raw and cooked meat colour was affected by meat pH but not storage condition. Cooking reduced the effect of pH on meat colour but cooked roasts manufactured from high pH meat were redder than roasts manufactured from normal pH meat.     

Fatty acid content and composition of english beef, lamb and pork at retail

We have determined the fatty acid content and composition of retail samples of meat and assessed them with respect to UK dietary recommendations. Fifty beef sirloin steaks, pork chops and lamb chops were purchased from four supermarkets on separate occasions. The percentage of muscle (boneless basis) in the samples was 84.4 ± 4.3, 69.8 ± 7.7 and 78.9 ± 7.1 for beef, lamb and pork, respectively, with fatty acid contents of 3.84 ± 1.3, 4.73 ± 1.66 and 2.26 ± 0.7 g per 100 g muscle, respectively. Adipose tissue fatty acid contents were 70.0 ± 8.2, 70.6 ± 8.6 and 65.3 ± 9.4 g per 100 g tissue. A range of C20 and C22 polyunsaturated fatty acids (PUFA) was present in the muscle of all three species and pork adipose tissue but their concentrations in lamb and beef adipose tissue were too low to measure. The mean P:S ratios for beef, lamb and pork muscle were (adipose tissue values in parentheses): 0.11 (0.05); 0.15 (0.09) and 0.58 (0.61), and the n−6:n−3 ratios were 2.1 (2.3), 1.3 (1.4) and 7.2 (7.6). We conclude that the muscles of red meat species are a valuable source of PUFA, particularly the C20 and C22 n−3 fatty acids, in the human diet and that, considered as part of a varied diet, the low P:S ratio of the ruminant muscle, the high n−6:n−3 ratio of pork and the total fatty acid contents do not detract significantly from the nutritional value of lean meat.     

Vacuum-Packaged Precooked Pork from Hogs Fed Supplemental Vitamin E: Chemical, Shelf-Life and Sensory Properties

Precooked longissimus chops and semimembranosus/adductor roasts from pigs (n = 30) given no supplemental vitamin E (CON) or supplemented with 100 mg vitamin E/kg diet (VITE) were evaluated for lipid oxidation, microbial growth, sensory characteristics, cooking/storage losses and reheating losses. Chops and roasts were vacuum packaged, precooked to 60°C and stored at 2°C for 0, 7, 14, 28, or 56 days. Lipid oxidation was lower in VITE chops and roasts than in CON chops and roasts. Off-flavor intensity scores were more acceptable and storage/ cooking losses were lower for VITE roasts than for CON roasts. Supplementation of vitamin E in a swine diet provided added protection against lipid oxidation and precooking pork under vacuum provided a palatable product with a shelf-life of 56 days.     

Fatty acid and proximate composition of raw and cooked retail cuts of beef trimmed to different external fat levels

Beef steaks and roasts from US Choice, US Select and US Standard quality grades were used to determine the effect of 0·64 cm external fat trim and zero (no external fat) trim on the proximate and fatty acid composition of cooked cuts of beef. Total fat percentage of the cooked lean was affected by external fat trim, quality grade, cooking and degree of doneness. Fat retention percentages were higher in tenderloin and clod samples when cooked with external fat attached than when cooked with no external fat. No consistent effect of fat trim level or degree of doneness on the percentage of specific fatty acids was observed.     

Effect of carbon monoxide in modified atmosphere packaging, storage time and endpoint cooking temperature on the internal color of enhanced pork

The objective of this research was to evaluate the effects of gas atmosphere, refrigerated storage time, and endpoint temperature on internal cooked color of injection-enhanced pork chops. Enhanced chops were packaged in 0.36% CO/20.34% CO₂ (CO-MAP), 80% O₂/20% CO₂ (HO-MAP), or PVC-overwrapped (PVC-OW; controls), stored at 4 °C for 0, 12, 19 or 26 days, displayed for 2 days then cooked to six endpoint temperatures (54, 60, 63, 71, 77, and 82 °C). L^*, a^*, and b^* values, hue angle and chroma were determined on the internal cut surface of cooked chops. Chops packaged in CO-MAP had the highest a^* values; a^* value began increasing on day 14. The lowest hue angles occurred in chops cooked to lower endpoint temperatures. Chops in CO-MAP had lower hue angles and higher chroma than those in HO-MAP and PVC-OW. Above 71 °C, hue angle and chroma increased. Overall, CO-MAP packaged chops stored for longer time periods then cooked to lower endpoint temperatures appeared reddest. HO-MAP packaged chops were less red, did not change over time, and appeared more well done at lower endpoint temperatures than those in other gas atmospheres. CO-MAP packaged chops retained redness even after cooking at 82 °C.     

Cooking method and endpoint temperature effects on sensory and color characteristics of pumped pork loin chops

The objective of this study was to evaluate the effects of pumping, cooking method and endpoint temperature on quality of fresh pork chops. The longissimus was removed from 30 paired pork sides. One side was pumped to 110% of original weight (0.4% phosphate, 0.4% salt+added water). Chops were cut (2.5 cm thick) then fried or grilled to 70 or 80 °C. As endpoint temperature increased from 70 to 80 °C, pork flavor increased (P<0.05) from 95 to 104 (on a 150 point scale) for pumped samples but remained constant in unpumped samples. Juiciness decreased when unpumped samples cooked to 80 °C (62) rather than 70 °C (78). Warner–Bratzler shear values were lower (P<0.05) in pumped chops than in unpumped controls. Pork flavor was higher and off-flavor was lower in fried chops. Pumping loins appears to enhance sensory attributes of chops even when cooked to abusive endpoint temperatures with limited detrimental effects on physical characteristics.     

Tenderness and collagen composition of beef semitendinosus roasts cooked by conventional convective cooking and modeled, multi-stage, convective cooking

Beef semitendinosus roasts were cooked in a forced-air convection oven using conventional or modeled, multi-stage cooking. Conventional cooking was defined as cooking at 163°C to a core endpoint of 65°C. The model method was developed using a finite difference heat and mass transfer model optimized for a three-stage cooking process that included preheating, holding, and finishing. Model cooking resulted in lower (P<0.05) Warner–Bratlzer peak shear force values than conventional cooking (3.3 vs 4.7 kg). Collagen total unaltered fraction was lower (44 vs 55%, P=0.05) and enzyme labile fraction was higher (56 vs 45%, P<0.05) in the model-cooked samples than in conventionally cooked samples. The three-stage cooking process results in a more tender product without adversely affecting product yield.     

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.     

Changes in fatty acids and microbial populations of pork inoculated with two biopreservative strains

Meat surface fermentation has been reported as an efficient method to reduce undesirable microbial population of this food commodity in tropical areas with high ambient temperatures and humidity. However, in order to efficiently apply this method, growth of biopreservative strains and changes in the meat substrate should be studied. Changes in long-chain fatty acids as well as pH and microbial growth (lactic acid bacteria and enterobacteria) were studied in pork inoculated with two biopreservative strains (Lactobacillus alimentarius and Staphylococcus carnosus) and stored at 4 and 20 °C. Both tested strains produced more than 6 mg lactic acid/g tissue, however, S. carnosus was more efficient in reducing enterobacteria populations at 20 °C. No significant increase in long-chain fatty acid concentration in samples stored at 4 °C was observed but there was a rapid increase of free fatty acids when stored at 20 °C.     

ANCM bibliography

Changes in fatty acid profiles of pork loin chops fried in different culinary fats (olive oil, sunflower oil, butter and pig lard) during 10 days of refrigerated storage were studied. Olive oil-fried loin chops (OOLC) were significantly highest in monounsaturated fatty acids (MUFA) and C18:1. Sunflower oil-fried loin chops (SOLC) showed the highest polyunsaturated fatty acid (PUFA) proportions, mainly due to C18:2 contents. Butter-fried loin chops (BTLC) were significantly richer in saturated fatty acids (SFA), such as C12:0, C14:0 and C16:0, while pig lard-fried loin chops (PLLC) contained moderate proportions of SFA, MUFA and PUFA. Fatty acid profiles of neutral lipids (NL), free fatty acids (FFA) and polar lipids (PL) were slightly changed after refrigerated storage. After 10 days of refrigerated storage, differences among samples fried in different culinary fats were maintained or increased. NL from OOLC had the significantly largest percentages of C18:1 and MUFA, while SOLC had the significantly largest percentages of C18:2 and PUFA. The highest percentages of C12:0, C14:0, C16:0 and SFA were characteristic for pork loin chops fried in butter at the end of the storage period. Refrigerated pork loin chops fried in pig lard showed intermediate percentages of SFA, MUFA and PUFA. OOLC had a more desirable nutritional value than other fried pork loin chops after and before the refrigerated storage.     

Processing and sensory characteristics of cooked roast beef: effect of breed, age, gender and storage conditions

Two separate experiments investigated the effect of breed (Bos indicus, Bos indicus×and Bos taurus), gender/age and chilled and frozen storage on the processing characteristics of roasts made from inside rounds (semimembranosus, adductor and gracilis muscles). Roasts were injected with a salt/phosphate brine and cooked to an internal temperature of 63 °C. Freezing the meat increased purge lost from the raw meat. Country of origin had no significant effect on cook yield. Sensory evaluations with a US consumer panel indicated only slight sensory differences due to country of origin and breed but a significant effect from storage regime. Tenderness comparisons between breeds were confounded by country of origin and indicated that roast beef from inside rounds from Brahman cattle had lower WBS values than roast beef made from inside rounds from British cattle. Although breed and age/gender often significantly affected processing characteristics of the roasts, differences were small and would have little practical or economic importance for selecting the type of meat for this market sector.     

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.     

The influence of porcine growth hormone on muscle fibre characteristics, metabolic potential and meat quality

Treatment of lean female pigs with porcine growth hormone (placebo or 80 μg pGH per kg body weight per day) for 6 weeks from 50 kg to 86 kg body weight did not change the frequency and the percentage area of muscle fibre types (ST, FTa and FTb fibres) and muscle capillarity of M. longissimus dorsi, M. gluteus medius and M. psoas major. The mean fibre cross-sectional area increased 5·3%, albeit nonsignificantly, corresponding to a 6·6% increase in carcass meat. The muscles contained slightly less dry matter and protein, and the lipid content of M. longissimus dorsi decreased 19% after pGH treatment. In the backfat the fatty acid composition changed towards a higher ratio of polyunsaturated to saturated fatty acids. The pH_u of M. longissimus dorsi was unaltered, while the pH₄₅ was reduced by pGH. The muscle glycogen level and the activity of lactate dehydrogenase (LDH), citrate synthetase (CS), and 3-OH-acyl-CoA-dehydrogenase (HAD) of M. longissimus dorsi were unchanged by pGH. The haem pigment, shear force, sarcomere length and eating quality of loin chops, were unaffected by pGH treatment. The results show that pGH treatment did not change the muscle characteristics in a way that affects the meat quality of M. longissimus dorsi in lean female pigs.     

Intramuscular fatty acid composition of lambs given a tanniniferous diet with or without polyethylene glycol supplementation

The aim of this trial was to investigate the effects that dietary tannins have on lamb intramuscular fatty acids. Twenty-seven lambs were divided into three homogeneous groups: control group, receiving commercial concentrate based on maize; tannin group, fed a diet based on carob pulp (45% as fed basis); PEG group, receiving the same diet as the latter with addition of 42 g/kg of polyethylene glycol (PEG, a binding agent that eliminates the effects of condensed tannins). The duration of the trial was 45 d. Intramuscular fatty acids were measured in the longissimus dorsi muscle. The isomer cis-9 trans-11 of linoleic acid (conjugated linoleic acid or CLA) and linolenic acid were higher in the longissimus muscle fat from animals fed the control diet compared to the other groups (P < 0.0005); these fatty acids were higher in the fat from animals fed the carob diet supplemented with PEG compared to those fed the same diet without PEG (P < 0.05). trans-Vaccenic acid (C18:1 trans-11) was found at higher concentration in fat from control and PEG lambs compared to tannin lambs (P < 0.01); the CLA/C18:1 trans-11 ratio was lower in lambs fed control and PEG diets than in tannin-fed animals (P < 0.05).     

Water-Soluble Flavor and Odor Precursors of Meat. 4. Influence of Cooking on Nucleosides and Bases of Beef Steaks and Roasts and Their Relationship to Flavor, Aroma and Juiciness

SUMMARY: Cooking resulted in significant increases in adenylic acid, total purine nucleosides and bases of 80 beef roasts of eight different cuts. It decreased the contents of inosinic acid, guanylic acid and sum of individual nucleotides (adenylic, cytidylic, uridylic, inosinic and guanylic acids) in these samples. Significant differences were also found between the various constituents of raw and cooked samples of the beef cuts.