K.S. Rhee

Fatty acid composition of goat diets vs intramuscular fat

Twenty Boer x Spanish goats, at the age range of 90-118 days, were assigned to two dietary treatments, with 10 animals fed a grain ration (G) and the other 10 grazed in rangeland. The grain ration contained sorghum grain (67.5%), cottonseed hulls, dehydrated alfalfa meal, cottonseed meal, soybean meal, molasses, and mineral and vitamin supplements. Animals were slaughtered at the age range of 206-234 days. Intramuscular fat (IF) and the diet specimens - representative samples of G and the parts of range plants (RPs) that goats were expected to have consumed - were analyzed for fatty acid composition. The percentage of 16:0 was higher in RPs than in G, but not different between IF from range goats and that from grain-fed goats. Total unsaturated fatty acid (UFA) percentage was higher in G than in RPs. The major UFAs were 18:2 and 18:3 in RPs, and 18:1 and 18:2 in G. In IF, 18:1 constituted more than two-thirds of UFAs, regardless of diet type.

Fatty acid profiles of the total lipids and lipid oxidation in pork muscles as affected by canola oil in the animal diet and muscle location

Twelve pigs at about 35 days of age were fed a control diet or test diets containing either 10% or 20% canola oil (CO) for 100 days. Four different muscles were excised from each carcass at 24 h post-mortem for analyses. Inclusion of 10% and 20% CO in the animal diet increased (P < 0·05) the relative amount (weight per cent) of unsaturated fatty acids in the total lipids (lipids extracted by 2:1 chloroform-methanol) by 6·7 and 15·8 percentage points, respectively, from 57·8% for the control and also increased (P < 0·05) that of polyunsaturated fatty acids by 5·5 and 9·7 percentage points, respectively, from 19·4% for the control. The 20% CO treatment increased (P < 0·05) the relative amount of monounsaturated fatty acids (primarily C18:1) by 6·1 percentage points from 38·4% for the control, while the 10% CO treatment had no significant effect. The 10% or 20% CO treatment had no significant effect on microsomal enzymic lipid peroxidation activity, heme pigment content, nonheme iron content and total lipid concentration. Overall lipid oxidation in ground muscle samples stored at 4°C tended to be higher for the 10% and 20% CO treatment groups than for the control. The tendency of increased lipid oxidation by the CO treatments apparently resulted from the increased percentages of polyunsaturated fatty acids, rather than from changes in catalytic constituents.

Antioxidant properties of selected Oriental non-culinary/nutraceutical herb extracts as evaluated in raw and cooked meat

Ethanol extracts of white peony (WP), red peony (RP), sappanwood (SW), Moutan peony (MP), rehmania (RE) or angelica (AN) were individually added to ground goat meat at 0.5-2.0% (g dry extract/100 g final meat sample), and raw and cooked samples were aerobically refrigerated for 0, 3 or 6 days. These extracts and rosemary extract (RO) were also individually added to salted or unsalted ground beef at 0.01-0.25% and refrigerated as raw or cooked patties. WP, RP, RE, SW and MP markedly reduced (P<0.05) lipid oxidation in cooked-stored goat meat. With 0.25% of WP, RP, SW, MP or RO in beef, lipid oxidation during storage was minimal in raw and cooked patties (plain or salted); raw patty redness values at day 6 were higher (P<0.05) for SW, WP, RP or MP than RO treatment or the control. At 0.01%, SW was more antioxidative (P<0.05) than the other extracts.

Effect of reduction and replacement of sodium chloride on rancidity development in raw and cooked ground pork

Ground pork (raw and cooked) was treated with NaCl, KCl or MgCl2 at ionic strengths of either 0.70 or 0.35, and stored at 4 or -20°C. Regardless of storage temperature, NaCl and MgCl2 increased rancidity of both raw and cooked samples, whereas KCl increased rancidity of raw samples only. In raw pork samples, NaCl increased rancidity the most. In cooked samples, MgCl2 increased rancidity more than NaCl when samples were stored at 4°C, but the opposite was true for samples stored at -20°C. Discoloration was most severe for raw, frozen samples treated with NaCl. Replacement of NaCl with KCl was most effective for decreasing rancidity in both raw and cooked samples.

Antioxidant Properties of Dried Plum Ingredients in Raw and Precooked Pork Sausage

Raw pork sausages with no antioxidant (control), 3% or 6% dried plum puree (DP), 3% or 6% dried plum and apple puree (DPA), or 0.02% butylated hydroxytoluene and butylated hydroxyanisole (BHA/BHT) were (1) stored raw in chubs at 4 degrees C (RR) and evaluated weekly over 28 d, (2) cooked as patties, vacuum packaged, and stored at 4 degrees C (PR) for weekly evaluation over 28 d, or (3) cooked, vacuum packaged, and stored at -20 degrees C (PF) and evaluated monthly over 90 d. DP at 3% or 6% levels was as effective as BHA/BHT for retarding lipid oxidation in PR sausage patties. Likewise, DP at 3% was equally as effective in PF patties, but DP at 6% was even more effective (lower TBARS values) than BHA/BHT for retarding oxidative rancidity. All treatments decreased the fat and increased moisture content of raw sausages but only 6% DP reduced cooking yields. Inclusion of 6% DP decreased internal redness while both 6% DP and DPA increased yellowness of raw sausage. Trained panel sensory evaluations indicated that DP enhanced sweet taste, decreased salt and bitter tastes, and masked cooked pork/brothy, cooked pork fat, spicy/peppery, and sage flavors. In general, warmed-over flavor notes were not affected by storage treatments. Overall, pork sausage with 3% DP or DPA was as acceptable to consumers as the control or those patties with BHA/BHT, but patties with 6% of either plum product were less desirable. Inclusion of 3% DP was effective as a natural antioxidant for suppressing lipid oxidation in precooked pork sausage patties.

Antioxidant properties of plum concentrates and powder in precooked roast beef to reduce lipid oxidation

Boneless beef roasts (Semimembranosus+Adductor) were injected (20%) with a brine containing (1) no plum ingredient (control), (2) 2.5 or 5% fresh plum juice concentrate (FP), (3) 2.5 or 5% dried plum juice concentrate (DP), or (4) 2.5 or 5% spray dried plum powder (PP). Whole roasts were cooked, vacuum-packaged and stored at <4.0°C for 10wk. At 2wk intervals, evaluations were performed on sliced product to determine vacuum-packaged purge, Allo-Kramer shear force, lipid oxidation (TBARS), color space values, and sensory attributes. All plum ingredients reduced TBARS values and had minimal effects on tenderness, sensory characteristics, color and appearance. Small changes in purge, color values, TBARS and some sensory properties were found during storage. These results indicate that 2.5% FP or DP could be incorporated into precooked beef roasts to reduce lipid oxidation and potentially, warmed-over flavor (WOF).

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.

Chloride salt type/ionic strength, muscle site and refrigeration effects on antioxidant enzymes and lipid oxidation in pork.

The effects of NaCl and KCl at varying ionic strengths on catalase and glutathione peroxidase (GSH-Px) activities and lipid oxidation in refrigerated ground pork muscles from different anatomical locations were studied. Catalase and GSH-Px activities were higher in boston butt (BB) than in longissimus dorsi (LD), whereas lipid oxidation measured by 2-thiobarbituric acid substances (TBARS) content was higher in LD. Catalase activity was stable in both BB and LD during 4-day storage; GSH-Px activity decreased in LD. GSH-Px activity decreased more with NaCl than KCl, whereas salt type had no consistent effect on catalase activity. TBARS content, however, increased more with NaCl than with KCl. NaCl at the highest ionic strength decreased GSH-Px activity by 19.2 and 18% in LD and BB, respectively, and increased TBARS content by 8- and 3.6-fold. Results indicated that pork samples with higher catalase and GSH-Px activities would undergo less lipid oxidation, and the accelerated lipid oxidation in salted pork may be partly related to a decrease in GSH-Px activity.

Characteristics of pork products from Swine Fed a high monounsaturated fat diet: Part 1-Whole muscle products.

Twelve percent of high-oleic sunflower oil (HOSO) was incorporated into a swine diet to replace substantial amounts of saturated fatty acids (S) in pork by monounsaturated fatty acids (M). Pork loin chops (longissimus dorsi), cooked to 74°C, and eye of round roasts (semitendinosus), cooked to 77°C, from animals on the HOSO diet were 49% and 66%, respectively, higher in the M S ratio as compared to their counterparts from animals on the control diet. Cooking had little effect on relative differences in the M S ratio between HOSO and control samples. Cooking loss and sensory properties were not adversely affected by the changes in fatty acid composition. However, cooked chops and roasts from the HOSO group had lower thiobarbituric acid values during storage at 4°C.

Influence of animal diet and muscle location on cholesterol content of beef and pork muscles

Muscles at three different anatomical locations from carcasses of 12 pigs and 12 steers that were fed diets with varying levels of oleic acid-pigs in the form of canola oil at levels of 0, 10 and 20% and steers in the form of canola rapeseed at levels of 0 and 20%-were analyzed for cholesterol concentrations. The cholesterol level of beef or pork muscles was not significantly affected by the animal diet modification. For each animal species, muscles at different anatomical locations were similar in cholesterol content. Beef and pork muscles were not significantly different in cholesterol content.