Effects of feeding elevated concentrations of monounsaturated fatty acids and vitamin E to swine on characteristics of dry cured hams

Thirty Large White×Great York gilts were fed six experimental diets containing three levels of poly and monounsaturated fatty acids. Within each dietary fat treatment, one group was fed a basal level of vitamin E (20 mg α-tocopheryl acetate/kg diet) and the other group received a supplemented level (200 mg α-tocopheryl acetate/kg diet). Concentration of α-tocopherol was significantly higher in hams from pigs fed supplemented dietary levels of vitamin E (P<0.0001), but no significant effect of dietary fat was observed. Dietary vitamin E supplementation reduced the concentration of thiobarbituric acid reactive substances after 9 days storage of sliced samples (P<0.0001), while dietary fat source showed no significant effect. Significantly lower oxidation was observed in ham homogenates from pigs fed higher concentrations of monounsaturated fatty acids after 120 min of incubation under pro-oxidant conditions (P=0.013). No effect of dietary treatment was observed in ham volatile aldehyde profile. No significant effect of dietary vitamin E was observed on surface redness during storage, but a significant effect was observed for luminosity after 7 days of storage (P=0.033). Hams from pigs fed diets enriched in monounsaturated fatty acid showed higher ‘a’ values (P=0.040) in stored sliced samples. Sensory evaluation revealed a significant effect of dietary vitamin E on redness of ham slices (P<0.001). Dietary supplementation with vitamin E also produced a significantly higher odour and flavour intensity (P=0.006 and P=0.01 respectively). Dry cured ham samples from pigs fed higher amounts of monounsaturated fatty acids showed a significantly higher consistency fat than those from pigs fed polyunsaturated fatty acids.     

The influence of carrageenan on the properties of low-fat frankfurters

Research was undertaken to study the technological properties of six carrageenan fractions and their usefulness as fat substitutes in frankfurter type sausages. In the first stage of the experiment hardness of gels made of 3% solutions of carrageenan preparations with different pH (5.5, 6.0 and 6.5) was evaluated. The highest F_max. values were noted in gels obtained from G-WG carrageenan (kappa I fraction). In the second stage of the study frankfurter type sausages were produced, containing 20% and 10% of fat in meat batter with or without (control) kappa I carrageenan (G-WG). Carrageenan as a fat substitute caused a reduction in cooking and storage weight losses, increased hardness, gumminess and chewiness. All frankfurters produced with carrageenan, irrespective of fat content, were characterized by significantly higher sensory evaluation scores for texture, color and taste in comparison to control sausages.     

水油乳化剂替代猪背脂法兰克福香肠的品质及感官研究

将橄榄油、葵花籽油和芥花油混合,用不同的非肉蛋白体系(酪蛋白酸钠、大豆分离蛋白和微生物转谷氨酰胺酶)乳化后,将该水油乳化剂替代猪背脂改良法兰克福香肠的品质。以脂肪酸组成、色泽、质构和感官评定为评价指标,研究其与含猪背脂的法兰克福香肠的脂肪酸组成和品质。结果表明:改良后的法兰克福香肠,饱和脂肪酸含量降低(19.3%),单不饱和脂肪酸变化很小,而多不饱和脂肪酸含量增加较显著(P<0.05),香肠的硬度、弹性和咀嚼性得到增加,产品的感官评定值达到了5.6,在消费者可接受范围内。可见添加健康植物油及蛋白体系可以提高香肠的质构、抗氧化性以及营养价值。     

Texture of low-fat Iranian White cheese as influenced by gum tragacanth as a fat replacer

The effect of different concentrations of gum tragacanth on the textural characteristics of low-fat Iranian White cheese was studied during ripening. A batch of full-fat and 5 batches of low-fat Iranian White cheeses with different gum tragacanth concentrations (without gum or with 0.25, 0.5, 0.75, or 1 g of gum/kg of milk) were produced to study the effects of fat content reduction and gum concentration on the textural and functional properties of the product during ripening. Cheese samples were analyzed with respect to chemical, color, and sensory characteristics, rheological parameters (uniaxial compression and small-amplitude oscillatory shear), and microstructure. Reducing the fat content had an adverse effect on cheese yield, sensory characteristics, and the texture of Iranian White cheese, and it increased the instrumental hardness parameters (i.e., fracture stress, elastic modulus, storage modulus, and complex modulus). However, increasing the gum tragacanth concentration reduced the values of instrumental hardness parameters and increased the whiteness of cheese. Although when the gum concentration was increased, the low-fat cheese somewhat resembled its full-fat counterpart, the interaction of the gum concentration with ripening time caused visible undesirable effects on cheese characteristics by the sixth week of ripening. Cheeses with a high gum tragacanth concentration became very soft and their solid texture declined somewhat.     

Acceptability of Bacon as influenced by the Feeding of Elevated Levels of Monounsaturated Fats to Growing-finishing Swine

The acceptibility of bacon produced from swine fed diets containing elevated levels of oleic acid was evaluated. Slicing yields and sensory scores for overall palatability and flavor quality were lower for bacon produced from swine fed canola oil (P < 0.05). A higher percentage of panelists detected off-flavors in canola oil bacon than in bacon produced from swine fed safflower oil, sunflower oil, animal fat or a typical corn-soybean meal diet (P < 0.05).     

Technological and sensory characteristics of reduced/low-fat,low-salt frankfurters as affected by the addition of konjac and seaweed

This paper reports the effect of an edible seaweed, Sea Spaghetti (Himanthalia elongata), on the physicochemical (emulsion stability, cooking loss, colour, texture, residual nitrite and microstructure) and sensory characteristics of reduced- and low-fat, low-salt (NaCl) frankfurters prepared with konjac gel as a fat substitute. The effects on emulsion stability of substituting konjac gel for pork backfat were conditioned by the proportion of the substitution. Incorporation of a combination of Sea Spaghetti/konjac gel (accompanied by reduction in salt) increased (P < 0.05) cooking loss and reduced (P < 0.05) emulsion stability in the gel/emulsion systems. Incorporation of Sea Spaghetti/konjac gel produced a decrease (P < 0.05) of lightness (L∗) and redness (a∗) values and an increase (P < 0.05) of yellowness (b∗) as compared to the other samples. The effect of adding seaweed on the texture parameters of low-salt frankfurters varied depending on the proportion of konjac gel used in the formulation. Morphological differences in frankfurter microstructure were observed as fat content was reduced and konjac gel increased. Incorporation of a combination of Sea Spaghetti/konjac gel caused the formation of a more heterogeneous structure, in which the seaweed was integrated in the meat protein matrix.     

The relationship between the composition and texture of conventional and low-fat frankfurters

The chemical composition, instrumental texture and sensory properties of eighteen conventional and three low-fat commercially produced frankfurters were analysed. The most important factors in defining the texture of the product were hardness and juiciness, these being related respectively to the percentage of protein and the fat/protein ratio in the frankfurter. Subsequently, using a basic formulation of soya protein and starch, different levels of fat (10 and 15%) and hydrocolloids [carrageenan, carboxymethylcellulose (CMC) and apple pectin] were tested. According to results from these trials, three low-fat formulations were chosen. The three low-fat sausages were a sausage with 15% fat and carrageenan (0.5%), a sausage with 10% fat and a combination of carrageenan (0.5%) and pectin (0.4%) and a sausage with 10% fat and a combination of carrageenan (0.5%) and CMC (0.1%). The sensory and instrumental texture attributes of the three low-fat and the standard sausages were investigated. Results indicated that low-fat (10%) frankfurters with a texture profile similar to standard frankfurters could be manufactured through the addition of mixtures of proteins and hydrocolloids. The combination of carrageenan with CMC or apple pectin is more efficient than the use of carrageenan alone as both combinations allow a higher reduction of fat, at the same time achieving a final texture well liked by consumers.     

Effects of feeding diets containing different fat supplements to swine on the visual properties and storage stability of low-fat sausage

Sixty barrows and gilts were assigned to one of five dietary treatments consisting of a control diet of corn and soybean meal and four similar test diets that contained a 10% replacement of either animal fat, safflower oil, sunflower oil or canola oil, to determine the effects of high levels of oleic acid in the diet of swine on the storage stability of fresh pork sausage. Pork trim from each treatment was used to formulate sausage that contained two fat levels (25% and 35%), and two levels of added water (3% and 11%). Thiobarbituric acid values did not differ between the control, safflower oil or sunflower oil treatments and all treatments were acceptable after 10 weeks of storage. Microbial numbers increased with the level of added water and during time in storage (up to 3 weeks). Visual evaluation showed that the control was the most red and least discolored, while the canola oil treatment was the least red and the most discolored. Results from the present study suggest that a 105 replacement of a typical corn/soybean meal diet to swine with safflower or sunflower oil did not alter the storage-stability of fresh pork sausage.     

Rheological,microstructural and sensory characterization of low-fat and whole milk set yoghurt as influenced by inulin addition

The effect of inulin addition (0–4%) upon texture and microstructure of set yoghurt with different levels of fat (0.2%–3.5%) was investigated. A two-factor experimental design with four treatments was used for data analysis. Skimmed milk with various inulin and cream concentrations was standardized to 4% protein content, homogenized, heated to 92 °C and fermented at 42 °C until a pH of 4.6 was reached. The chemical composition, pH, consistency and microstructure properties of the yoghurts were analysed after 6 days of storage at 5 °C. The statistical analysis showed that inulin and fat significantly affected the rheological and sensory results. Higher yield stress, “firmness” and “creaminess” values were observed in yoghurt produced with higher inulin additions, whereas the pH value was not affected. A significant correlation was found between yield stress and sensory determined firmness (r = 0.91). The microstructure examined by confocal laser scanning microscopy (CLSM) was only slightly affected by the concentrations of inulin in the range studied, possibly due to weak protein interactions between the inulin and the milk protein network.     

Thermal,microscopic, and quality properties of low-fat frankfurters and emulsions produced by addition of different hydrocolloids

This study involves investigation of the effects of addition of different hydrocolloids on the thermal, microscopic, and quality properties of low-fat meat emulsions and frankfurters. The emulsion stability of the samples containing 0.5% κ-carrageenan, λ-carrageenan or chitosan, and the 1% chitosan containing sample were lower than that of the control group. Thermal analyses showed three denaturation peaks for minced meat at 57.42 °C, 64.21 °C and 78.58 °C. While the denaturation temperature of myosin for the sample produced with 0.5% of κ-carrageenan was significantly lower, samples containing 1% κ-carrageenan and 0.5% λ-carrageenan were not significantly different than that of the control group. The thermal denaturation temperature of myosin for samples containing 1% λ-carrageenan, and for 0.5% and 1% guar gum, xanthan gum and chitosan was significantly higher than that of the control. The denaturation temperature of sarcoplasmic proteins and actin for samples with 1% κ- and λ-carrageenan and 0.5% chitosan, was higher than for the control, while for other samples it was not significantly different. The scanning electron microscopy images of the control group and samples produced with 0.5% and 1% λ-carrageenan, 0.5% and 1% guar gum, and 1% κ-carrageenan showed gel-like structures, whereas other samples did not. Sensory evaluations showed that addition of hydrocolloids and reduced fat content lowered acceptance of frankfurters. Results showed that both κ- and λ-carrageenan, especially at 0.5% were the most suitable hydrocolloids for production of low-fat frankfurters and xanthan gum was the least suitable since it did not form proper structure.     

Acrylamide formation and colour development in low-fat baked potato products as influenced by baking conditions and oil type

The objective of this study was to investigate the effect of oil type and oxidation status on acrylamide (AA) formation and colour development in potato products under domestic baking conditions. Sunflower, soybean and olive oil were used; the first one was thermally oxidized to obtain different oxidation status. A potato dough containing 10 % oil, potato powder, flour and water was shaped into thin discs and baked at 180 °C for different heating times. AA concentration, moisture content and surface colour were determined. Results obtained showed that neither the nature of lipids present, in terms of content of unsaturated fatty acids, nor the degree of fat oxidation influenced AA formation in low-fat baked potato products. Browning ratio higher than 45 % and moisture content lower than 17 % resulted in dark brown, almost burnt, products. Moreover, in those cases, no correlation could be found between those variables and AA content, since formation and degradation simultaneously occur. When the browning ratio ranged between 0 and 45 %, a good linear correlation with AA formation was observed, suggesting that the browning ratio may be considered as a reliable indicator of AA concentration. Finally, AA less than 1000 μg/kg, which is an indicative value that has been recently set for potato crisps by the European Commission, corresponds to a browning ratio of less than 8 % and moisture content more than 23.5 %.     

Effect of adding smoke-flavouring to frankfurters on nitrite and nitrate levels

Different concentrations of sodium nitrite, potassium nitrate or both together were used to prepare four standard solutions and four frankfurter formulations. These were elaborated with and without the addition of 2 g/kg of a commercial solid smoke-flavouring preparation. Monitoring of nitrite and nitrate residual levels in standard solutions stored at 3 °C showed that smoke-flavouring addition results in a depletion of nitrite levels and/or reduction of nitrate to nitrite. In a much more complex system such as meat products, nitrite and nitrate, incorporated in the formulation separately or combined, were also rapidly depleted when smoke-flavouring was added.     

Forestomach and whole tract digestibility for lactating dairy cows as influenced by feeding frequency

Three lactating Holstein cows, averaging 510 kg and fitted with T-type duodenal cannulae in the proximal duodenum, were in a 3 X 3 Latin-square experiment to measure digestion in forestomachs and whole tract of feed nitrogen and neutral detergent fiber components as influenced by frequency of feeding. Cows were fed one diet containing 65% chopped grass legume hay, 26% cracked corn, and 8% soybean meal. Mixed ration was fed either once daily, four times daily, or the concentrate portion of the diet was fed once daily and the forage portion four times. Ytterbium, as ytterbium chloride, was included with diets to allow calculation of flow rates of duodenal and fecal dry matter. Assayed ratios of nitrogen to diaminopimelic acid in ruminal bacteria and duodenal digesta or fecal bacteria and feces were used to calculate duodenal and fecal bacterial nitrogen flows respectively. Ratios of nitrogen to diaminopimelic acid in ruminal and fecal bacteria averaged 4.15 and 2.38 g/mmol. Apparent digestibility of organic matter in the forestomachs and whole tract averaged 43.7 and 66.4%. Forestomach and whole tract digestibility of cellulose, hemicellulose, and lignin averaged 56.1, 52.0, 14.7, and 58.7, 58.5, and 16.8. Bacterial nitrogen flows averaged 255 and 91 g/day at the duodenum and in the feces. Bacterial nitrogen yield in the rumen averaged 36.6 g/kg organic matter apparently digested in the forestomachs. Frequency of feeding had no effect on almost all measures and components of rumen and whole tract metabolism and digestion. For these intakes, frequency of feeding had little effect on feed intake and nutrient utilization.     

Characteristics of meat emulsion systems as influenced by different levels of lemon albedo

The effect of the addition of lemon albedo on the functional properties of emulsions was studied by using a model system. Oil/water (O/W) model emulsion systems were prepared by the addition of two types of lemon albedo (raw and dehydrated) at five concentrations (0.0%, 2.5%, 5.0%, 7.5% and 10%) to mechanically deboned chicken meat. The emulsion capacity, stability, viscosity and flow properties of the prepared model emulsions were analyzed. In addition, the colour parameters of cooked emulsion gel were determined. The addition of lemon albedo increased the emulsion capacity (EC) and the highest EC value was reached with 5% of albedo added. However, further increase in the albedo concentration caused an inverse trend in the EC values. A similar trend was observed in the emulsion stability (ES) values. Dehydrated albedo (DA) addition caused higher EC and ES values than did raw albedo (RA). DA increased the L^∗, a^∗ and b^∗ values of the cooked emulsion gels. Emulsion viscosity (EV) values were positively correlated with an increase in albedo concentration and the highest EV value was obtained from the emulsions with 10% albedo. Albedo addition did not change the flow properties of the emulsions and, in addition, increased the pseudoplasticity. As a consequence, the use of lemon albedo might be a potential dietary fiber source to enhance the functional and technological properties for frankfurter-type meat products.     

Optimization of salt, olive oil and pectin level for low-fat frankfurters produced by replacing pork backfat with olive oil

Response surface methodology was used to determine the optimum salt level (1.3-2.1%) and pectin level (0.25-1.0%) when olive oil replaced pork backfat (0-100%) for the production of highly acceptable low-fat frankfurters (9% fat, 13% protein). The test ingredients significantly affected (P<0.05) jelly separation of the batter, skin strength, hardness, saltiness, odour and taste and the overall acceptability of the low-fat frankfurters. Batters with high pectin levels recorded the highest (P<0.05) jelly separation. Low-fat frankfurters with high salt levels tended to have very hard skins and increased (P<0.05) saltiness while those with a high pectin level were very soft, tasted like cream and had the lowest (P<0.05) score for odour and taste. The low-fat frankfurters with 1.8-2.1% salt, 0-35% olive oil and 0.25-0.45% pectin had the highest overall acceptability. However, low-fat frankfurters produced with 1.3% salt, 0.25-0.30% pectin and 80-100% olive oil were also acceptable. Such low-fat frankfurters, compared to commercial products, have a 48% lower salt content (from 2.5 to 1.3%) and 66.6% lower fat content (from 30 to 10%), in which 80-100% of the added fat is olive oil. Further research is needed to improve the acceptability of these frankfurters.     

Textural and functional changes in low-fat Mozzarella cheeses in relation to proteolysis and microstructure as influenced by the use of fat replacers,pre-acidification and EPS starter

The influence of exopolysaccharides (EPS), pre-acidification and use of two fat replacers, FR1 and FR2, on the textural and functional characteristics of Mozzarella cheeses were studied. Control cheeses made with EPS producing Streptococcus thermophilus 285 had the lowest moisture (52.84%) and yield while hardness and melt properties of these cheeses improved with storage. Addition of FR1 or FR2 and pre-acidification of milk increased the moisture content in cheeses. All cheeses were softer than the control. Cheeses made with FR1 exhibited the greatest stretch and melt; those made with FR2 showed poor stretch and melt. Each cheese showed a unique microstructure prior to, and after the hydration of the protein matrix. The rate of α- and β-casein proteolysis was greater in cheeses made with pre-acidified milk and those having higher moisture content. Pizza bake performance was improved with FR1, but FR2 cheeses had the least favourable bake characteristics. Coating cheese shreds with oil was necessary for adequate browning, melt and flow.     

Composition of subcutaneous fat from dry‐cured Iberian hams as influenced by pig feeding

The triacylglycerol and free fatty acid composition and volatile profile of subcutaneous fat of three batches of dry‐cured lberian hams from pigs fed in an extensive system based on acorn and pasture (‘montanera’: MONT) or in confinement with a control diet (FEED) or a 100 mg α‐tocopheryl acetate kg^?1 enriched diet (VITE) were investigated. Triacylglycerol of subcutaneous fat of hams from pigs fed on acorn and pasture (MONT) was more unsaturated, with larger percentages of monounsaturated and polyunsaturated fatty acids, than triacylglycerol of subcutaneous fat of hams from pigs fed on concentrate feeds (FEED and VITE). However, the trend of oxidative processes was quite similar in the groups that contained antioxidants (‘montanera’ and α‐tocopherol supplementation); namely, the highest volatile contents were found in subcutaneous fat of hams from pigs fed on acorn and pasture, while α‐tocopherol supplementation gave rise to a different profile of volatile compounds in comparison with the control diet. Therefore antioxidant presence could contribute to a high intensity and quality of aroma of these hams. © 2001 Society of Chemical Industry     

Optimum levels of zinc in the diets of pigs in the tropics as influenced by the addition of graded levels of lard

Two feeding trials were carried out, the first to establish the optimum level of zinc in the diets of growing pigs reared in the tropical environment using essentially the locally-produced feeding stuffs, and the second to investigate the effects of adding graded levels of lard to these diets on the performance characteristics of pigs and on the incidence of parakeratosis. The parameters investigated include daily gains, feed consumption, efficiency of feed utilisation and the appearance of parakeratotic lesions on the skin. Diets in trial 1 were supplemented with 0, 100, 200, 400 and 500 parts/million of zinc, while those in trial 2 were supplemented with four levels of zinc 0, 100, 200 and 300 parts/million and three levels of lard, 0, 2.5 and 5% in a 4 × 3 factorial experiment. The optimum level of zinc as established by trial 1 was 100 parts/million, the 300–500 parts/million zinc levels being detrimental, while with the addition of graded levels of lard in trial 2 these higher levels of zinc gave better performances as the lard levels increased. A direct relationship between lard level and zinc content of the diets was therefore established, the higher the level of lard in the diet, the greater was the level of zinc supplementation for optimum growth response and feed utilisation efficiency of young pigs.     

Yield,nitrate levels and sensory properties of spinach as influenced by organic and mineral nitrogen fertiliser levels

Spinach was fertilised at two levels of nitrogen, 140 kg/ha (x) and 420 kg/ha (3x), using split applications of ammonium sulphate and dried blood as nitrogen sources. A single application of ammonium sulphate (x) 19 days prior to harvest was also tested. A no-nitrogen control was also employed. The x rate of mineral nitrogen produced statistically the same yield as the 3x organic source but at a lower tissue nitrate level. The 3x mineral fertiliser produced both the highest yield and nitrate concentration. Excluding late fertiliser application, nitrate levels were closely related to yield and dependent upon rate of nitrogen availability from each of the two sources. Late application of mineral nitrogen did not increase yield over a no-nitrogen application control, but resulted in an eight-fold increase in tissue nitrate. Triangle taste panels demonstrated significant differences in raw, cooked, and frozen samples when comparing the no-nitrogen application against both the 3x organic and mineral nitrogen applications and the late mineral application. No significant sensory differences resulted between organic and mineral fertilisers at either application level. Colour measurements revealed that higher nitrogen application darkened colour. Organic sources gave darker colours than corresponding mineral fertiliser levels. Late application of mineral nitrogen resulted in the darkest colour. Gas–liquid chromatography headspace scans demonstrated that increasing nitrogen rates from x to 3x approximately doubled total peak area. No qualitative differences were noted. Late application of mineral fertiliser resulted in a headspace scan similar to those obtained at the 3x nitrogen rates.