Enriching breakfast sausages by feeding pigs with CLA supplemented diets

Approaches for improving the profile of functional unsaturated fatty acids in pork products include dietary supplementation of pigs with functional oils. Little information is available to indicate the benefit of this approach in a processed and cooked pork product such as breakfast sausages. Therefore, the aim of the present study is to examine the fatty acid profile and oxidation level in cooked pork sausages, produced following dietary supplementation with CLA compared to sunflower oil (SFO). Fat and moisture percentages, total fatty acid profiles and TBARS were analysed. Fatty acid profiles were altered in the sausages following all treatments. While a stronger effect was seen for CLA treatments, addition of SFO in the diet also resulted in linear increases of CLA in the sausages. CLA supplementation resulted in increased saturated fatty acid content; however, all treatments were within the recommended polyunsaturated/saturated fatty acid ratio of above 0.4. Improved oxidative stability was observed in sausages from CLA supplemented diets.     

Effects of dietary α-linolenic acid on the fatty acid composition, storage stability and sensory characteristics of pork loin

Effects of dietary α-linolenic acid on the fatty acid composition, storage stability and sensory characteristics of cooked pork were studied. Dietary α-linolenic acid (LNA) significantly (p < 0.05) increased the proportion of n−3 fatty acids and the degree of unsaturation in the neutral lipids and phospholipids. The increases in n−3 fatty acids were observed in the total lipids, triglycerides, phosphatidylethanolamine and phosphatidylcholine, and mainly consisted of C18:3n3, C20:5n3 and/or C22:5n3.The thiobarbituric acid reactive substances (TBARS) values (mg malondialdehyde per kg meat) of cooked vacuum packaged loins remained below 1.5, but in loose packaged loins TBARS values increased more than 3 times those of 0 time values during 2-day storage at 4 °C. The TBARS values of loins after LNA-enrichment were significantly higher than those of the control in both vacuum and loose packaging, and the increase of unsaturation in fatty acids had a strong prooxidant effect. The increase in dietary LNA enrichment increased oxidation (TBARS values) and had a detrimental effect on the acceptability of cooked pork loins held for 2 days in loose packaging.     

Lipid oxidation, color changes and volatiles production in irradiated pork sausage with different fat content and packaging during storage

Effects of irradiation on lipid oxidation, color and volatiles production in pork sausages with different fat content and packaging were determined. Sausages (with 4.7, 10.5 and 15.8% fat content) were sliced and vacuum-packaged either in oxygen-permeable or impermeable bags, irradiated (0 or 4.5 kGy) and stored at 4°C for 7 days. Lipid oxidation, color and volatiles productions were analyzed at 0, 3 and 7 days of storage. TBARS (2-thiobarbituric acid reactive substances) values of cooked pork sausages increased with the increase of fat content regardless of storage, irradiation or packaging types. Irradiated samples had higher TBARS than nonirradiated at 0 day but the difference disappeared during storage in both packaging types. Lightness of sausages (Hunter L-value) increased with the increase of fat content and storage time but was not affected by irradiation. In aerobic packaging, irradiation reduced Hunter a-values of pork sausages at 0 day but irradiation effect on a-value disappeared during storage. In vacuum packaging, however, irradiated samples had higher Hunter a-values than nonirradiated samples. Irradiation increased 1-heptene and total volatiles, but the amount of 1-heptene was not associated well with TBARS values of pork sausages. In both irradiated and nonirradiated pork sausages, aerobic packaging produced more volatiles than vacuum packaging during storage. It was concluded that irradiation and fat content had significant effects on lipid oxidation, color and volatiles production of cooked pork sausages during storage but that oxygen availability had a stronger effect than irradiation and fat content.     

Effects of pork meat cut and packaging type on lipid oxidation and oxidative products during refrigerated storage (8 degrees C)

ABSTRACT:  Lipid oxidation and oxidative products as affected by pork meat cut, packaging method, and storage time were evaluated during refrigerated storage. Pork belly had higher pH and thiobarbituric acid reactive substance (TBARS) values than pork loin, and aerobic-packaged belly had higher TBARS than vacuum-packaged counterparts. Loin had higher free fatty acid (FFA) values than belly, and increased FFA values were observed with increased storage time. Peroxide values increased up to 7 d and decreased thereafter. Volatile compounds such as alkanes, aldehydes, ketones, and alcohols with high volatility in belly were higher than those in loin. Nonanoic acid, ethyl ester in belly, and hexadecanoic acid in loin might be considered as indices of lipid oxidation. Overall, vacuum packaging was better than aerobic packaging to retard lipid oxidation and production of oxidative products, and loin was more sensitive to lipid oxidation than belly.     

中式香肠加工及贮藏中脂肪氧化对其品质特性的影响

通过对中式香肠加工贮藏过程中包装、温度、光照以及抗氧化剂的不同处理,建立中式香肠的氧化模型,并对脂肪氧化的相关性进行分析。结果表明：以酸价(AV)、过氧化值(POV)、硫代巴比氨酸反应物(TBARS)为氧化指标,经过不同方式处理的3组中式香肠氧化程度不同;贮藏过程中脂肪中磷脂和游离脂肪酸的变化显著,且与氧化程度显著相关。     

Lipid and colour stability of Milano-type sausages: effect of packing conditions

Lipid and colour oxidative changes in Milano-type fermented sausages were studied in relation to packing conditions and extended storage under fluorescent light. Matured sausages were sliced and packed under vacuum or in protective atmosphere (100% N(2)) and exposed in a display cabinet to mimic commercial conditions of light and temperature for 2 months. Lipid oxidation was measured by the determination of thiobarbituric acid reactive substances (TBARS) and cholesterol oxidation products (COP), whereas the oxidation of nitrosylmyoglobin was evaluated by a trained sensory panel. Lipid oxidation and discolouration were positively related in vacuum-packed sausages: TBARS and COP values increased significantly concurrently with increasing brown scores. Protective atmosphere came out to be more efficient than vacuum in controlling fatty acid oxidation and, to a lesser extent, cholesterol and pigment degradation: TBARS values remained constant during the whole storage period whereas cholesterol oxides and brown colour scores gradually increased but remained lower than those of vacuum-packed sausages. Higher residual oxygen in vacuum packing could be responsible for the observed differences in oxidative stability.     

Stability of linseed oil and antioxidants containing dry fermented sausages: A study of the lipid fraction during different storage conditions

Different packaging conditions (aerobic, vacuum and modified atmosphere) were evaluated in order to study the stability of the lipid fraction of dry fermented sausages manufactured with a partial substitution of pork backfat by linseed oil and antioxidants. After 5 months of storage, α-linolenic acid was better preserved by vacuum and MAP (7.32 and 7.74g/100g fatty acids, respectively) than in aerobic conditions (6.15g/100g fatty acids), without significant differences to values obtained after 2 months of storage for this acid. At the end of the storage, (n-6)/(n-3) fraction in sausages with linseed oil was in all cases lower than 3, in contrast to values obtained for control products that were all higher than 15. Better PUFA/SFA ratios were also observed in modified sausages (0.6-0.7g/100g fatty acids) than control ones (0.3-0.4g/100g fatty acids). No signs of lipid oxidation measured by TBARs and peroxides were detected for modified sausages regardless the packaging system used (TBARs values lower than 0.25ppm and peroxides lower than 4meq O(2)/kg), pointing at a high effectiveness of the antioxidants. Furthermore, vacuum and MAP prevented 2,4-decadienal formation. Nutritional benefits of linseed oil and antioxidants containing products were maintained after 5 months of storage.     

Effect of Antioxidants and Cooking on Stability of n-3 Fatty Acids in Fortified Meat Products

ABSTRACT: This study was carried out to determine the effect of processing and cooking on n-3 polyunsaturated fatty acid (PUFA) stability and to determine the efficacy of antioxidants (ANTI) to minimize lipid oxidation in cooked n-3 PUFA-fortified meat products. An emulsion of n-3 PUFAs (25% algal oil) was incorporated into ground turkey, pork sausages, or restructured hams (500 mg n-3 PUFA/110 g meat) with or without an "antioxidant cocktail" containing citrate (0.5% w/w), erythorbate (1 g/kg product), and rosemary (0.2% w/w). Ground turkey and pork sausages were frozen 2 d, then cooked to 71°C, and stored at 4°C for 2 d. Cooked, restructured hams were sliced, vacuum packaged, and stored at 4°C, or frozen and thawed with subsequent storage at 4°C. Treatments were CON (control), n-3 (n-3 PUFAs), CON + ANTI and n-3 + ANTI. Products were analyzed for color, lipid oxidation (TBARS and peroxide values), and n-3 PUFA profile. TBARS of n-3 PUFA-fortified treatments in ground turkey and pork sausages increased with storage ( P < 0.05); there were no changes in TBARS for CON + ANTI and n-3 + ANTI groups ( P > 0.05). For restructured hams nitrite curing appeared to delay lipid oxidation such that antioxidant treatment effects were unobservable ( P > 0.05). Overall recovery of n-3 PUFAs after heat processing was 69% to 85%, and there was no effect of storage on n-3 PUFA concentration in raw or cooked products ( P > 0.05). Sensory scores for n-3 treated restructured hams were lower than controls ( P < 0.05). Results suggested that cooking resulted in some losses of n-3 PUFAs in fortified meat products and that an "antioxidant cocktail" protected against lipid oxidation during subsequent storage in non-cured meat products.     

Cholesterol and Lipid Oxidation Products in Cooked Meat as Affected by Raw-Meat Packaging and Irradiation and by Cooked-Meat Packaging and Storage Time

Aerobic packaging significantly increased cholesterol oxidation products (COPs) and thiobarbituric acid reactive substances (TBARS) in cooked turkey, pork, and beef patties after 7‐d storage, but vacuum packaging was very effective in preventing cholesterol and lipid oxidation. Packaging of meat after cooking had a much stronger effect on COPs formation than before cooking, and irradiation had only a minor effect. The amount of total COPs correlated well with TBARS in cooked meat. Turkey had the highest rates of COPs and TBARS formation and beef had the lowest rates after 7‐d storage, which were closely related to the fatty acid composition of meats. 7a‐hydroxycholesterol, 7p‐hydroxycholesterol, and 7‐ketocholesterol were the major COPs detected in all 3 cooked meat patties.     

Effect of the packaging method and the storage time on lipid oxidation and colour stability on dry fermented sausage salchichón manufactured with raw material with a high level of mono and polyunsaturated fatty acids

The effects of fatty acid composition, two packaging methods (vacuum and 20% CO₂/80% N₂) and storage under refrigeration for 210 days were evaluated on a dry fermented sausage (salchichón), manufactured with raw material enriched in monounsaturated or polyunsaturated fatty acids. Fatty acid composition was determined on sausage mixtures and on ripened sausages and lipid oxidation and colour stability was determined on ripened sausage at different times during storage. The modification of fatty acid composition of the sausages raised the nutritional quality, slightly affecting the colour properties. Dry fermented sausages enriched in polyunsaturated and monounsaturated fatty acids presented higher lipid oxidation values than the control ones. Both packaging methods (vacuum and 20% CO₂/80% N₂) during 210 days of chilled storage had minor effects on the colour and the lipid oxidation stability.     

Changes in fatty acid composition and improved sensory quality of backfat and meat of pigs fed bacterial protein meal

A total of 48 pigs (11.4 and 107.2 kg initial and final weight) were used to evaluate increasing dietary levels of bacterial protein meal (BPM) produced on natural gas (0, 50, 100, or 150 g kg⁻¹) on fatty acid composition, sensory properties, and susceptibility of pork to lipid oxidation. Increasing levels of BPM to diets increased the content of C16:1 fatty acids in backfat and muscle and total monounsaturated fatty acids in muscle, but decreased the content of polyunsaturated fatty acids and iodine value in backfat and muscle. Pigs fed diets containing BPM had reduced thiobarbituric acid reactive substances (TBARS) value in backfat and muscle, reduced intensity of odor and rancid odor and taste in pork after short-time storage, and reduced off-odor and off-taste after intermediate-time storage. To conclude, adding BPM to diets for pigs changed the fatty acid profile, improved the oxidative stability, and sensory quality of pork.     

Effects of fat replacement with a mixture of collagen and dietary fibre on small calibre fermented sausages

Effects of fat replacement on physicochemical, microbial and sensory properties of fermented sausages were determined after drying process and 4 weeks of storage. Fermented sausages were formulated with 20% pork back fat (control), and three reduced‐fat treatments were prepared by replacing 25%, 50%, and 75% of fat with a mixture of collagen, dietary fibre and ice (1:1:8). TBARS values of reduced‐fat treatments were significantly lower compared with control after drying (P ≤ 0.05). As fat replacing ratio increased, fat content decreased significantly (P ≤ 0.05), whereas moisture, protein and ash content increased significantly (P ≤ 0.05). There was no marked difference between the treatments in terms of microbial analysis, sensory colour, flavour, off‐flavour or overall acceptability (P > 0.05) during refrigerated storage. Therefore, replacing pork back fat with a mixture of collagen and dietary fibre in fermented sausages may contribute to reduce lipid oxidation and maintain sensory properties during storage.     

Study of the shelf life of a dry fermented sausage "salchichon" made from raw material enriched in monounsaturated and polyunsaturated fatty acids and stored under modified atmospheres

The microbiological, physico-chemical and sensory properties of salchichon with high unsaturated fat content, packed under vacuum and 20/80% CO(2)/N(2) modified atmosphere, were evaluated to determine its quality changes during storage under refrigeration. These sausages were manufactured with pork meat and pork backfat obtained from pigs fed with three different diets (control diet-CO, high oleic diet-HO and high linoleic diet-HL). In general, few significant differences were found in counts of different groups of microorganism between the three types of sausages and no difference between the packaging methods. A reduction in pH values was observed during storage and no great differences were determined by storage period on water activity (a(w)). Both parameters (pH and a(w)) presented similar results to those found in different Spanish sausages and other European dry fermented products. The sensory results denoted that sensory quality gradually decreased during storage under both packaging conditions (vacuum and 20/80% CO(2)/N(2)), so it is not advisable to store longer than 150days. On the other hand, fermented sausages with high content of unsaturated fatty acids had similar sensory properties to those of conventional sausages, and even a comparable sensory stability. In conclusion, the results showed healthier salchichons (HO and HL) similar to the traditional (CO) one could be manufactured and stored under refrigeration after slicing for a reasonable period, but the advantage of the gas mixture packaging (20/80% CO(2)/N(2)) versus vacuum packaging was not clear.     

Effects of dietary soybean oil on lipid and protein oxidation in pork patties during chill storage

The effect of dietary soybean oil on lipid and protein oxidation in low and high fat pork patties made from quadriceps femoris during chill storage in a high oxygen atmosphere packaging (80% O(2)/20% CO(2)) in the dark for 7 days was investigated. Pigs were fed either a standard diet or a diet added 2% soybean oil. After slaughter high fat pork patties were prepared for both feeding regimes by addition of back fat from pigs fed the same diet whereas low fat pork patties were prepared without addition of back fat. The 2% soybean diet increased the amount of unsaturated fat in the pork. Secondary lipid oxidation products determined as thiobarbituric acid reactive substances (TBARS) were found to increase in the pork patties with increased unsaturated fat. Increased unsaturated fat in the pork patties had no effect on protein oxidation determined as free protein thiol content and protein carbonyl content. A small, but significant increase in protein oxidation was found in the high fat pork patties independent on dietary fat. In conclusion, protein oxidation is unaffected by dietary fat in pork patties during chill storage for periods normally used in retail trade, and lipid and protein oxidation are not coupled under these conditions.     

Effect of high pressure treatment on colour, microbial and chemical characteristics of dry cured loin

The effect of high pressure on sliced and vacuum packaged commercial dry-cured pork loin was determined by analysing the induced colour changes, the residual enzymatic activities of cathepsins, aminopeptidases and dipeptidilpeptidases and the changes in the content of free amino acids and also its effect on lipid oxidation, as TBARS (Thiobarbituric reactives substances) and volatile flavour compounds. High pressure treatments above 300 MPa affected the colour of dry cured pork loins producing an increase in lightness and decreased redness and these differences were detected during all vacuum storage. High pressure produced a reduction in the activity of aminopeptidases and dipeptidylpeptidases. The untreated samples showed an increase in free amino acid content during vacuum storage while the pressurised samples showed no significant increases probably due to the reduction in aminopeptidase activity. The oxidative stability of the pressurised dry-cured loins was not affected as observed by the absence of differences in TBARS values and in the abundance of volatile compounds from the lipid oxidation. However, the pressurised treatment produced a reduction of several flavour compounds, particularly those derived from Maillard reactions, although they are regenerated during vacuum storage. In summary, high pressure treatment after the ripening of dry-cured loin affects its quality but the differences can be minimised by vacuum storage.     

Effect of storage and packaging on fatty acid composition and oxidation in dry fermented sausages made with added olive oil and antioxidants

Dry fermented sausages produced by a partial substitution of pork backfat with pre-emulsified olive oil were manufactured and stored (2 and 5 months) using different packaging conditions (aerobic/vacuum piece/vacuum slices) in order to evaluate the intensity of the oxidation process. Also the effect of the addition of butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA) to one of the modified batches was studied. Addition of olive oil, especially with antioxidants, was more effective than using vacuum storing methods in avoiding lipid oxidation during storage. After 5 months of storage at 4 °C, the combination of the increase in oleic acid and the preservation of PUFA by the antioxidant activity of the olive oil emulsion and antioxidants (when added), lead to better MUFA+PUFA/SFA ratios in olive oil containing sausages (1.90-1.98 g/100 g fatty acids) and particularly in antioxidants containing sausages (2.02-2.16 g/100 g) than in control ones (1.72 g/100 g). Vacuum packaging of the piece was the best method to minimise formation of lipid oxidation volatile compounds.     

Measurement of lipid oxidation and porphyrins in high oxygen modified atmosphere and vacuum-packed minced turkey and pork meat by fluorescence spectra and images

This paper illustrates that fluorescence spectroscopy and imaging can be used to measure the extent and distribution of lipid oxidation in meat. Minced turkey thighs and pork semimembranosus muscles were stored for 7 and 12 days at 4°C in high oxygen (O(2)) modified atmosphere packages and vacuum. Turkey meat packed in high O(2) atmosphere was oxidised already after 7 days of storage. The sensory rancid odour score was 4.7 (on a scale from 1 to 9) and the TBARS value was 1.86mg MDA/kg. There was also an increase in fluorescence emission intensity in the 410-550nm region, which arises from lipid oxidation products. The combination of unsaturated fatty acids and access to O(2) resulted in lipid oxidation gradients in the turkey meat samples, and these gradients were clearly visualised by fluorescence images. In comparison, pork meat was more stable against lipid oxidation, with TBARS values <0.2mg MDA/kg and no development of fluorescent lipid oxidation products was detected. The fluorescence spectra measured in the present experiment suggest that turkey thighs and pork semimembranosus muscle in addition to protoporphyrin also have a natural content of Zn protoporphyrin. The porphyrin content was higher in pork meat than in turkey meat. It increased during storage time when the meat was packed in vacuum, and it decreased with O(2) availability. The distribution of porphyrins in the meat was visualised by fluorescence imaging.     

Lipid and cholesterol oxidation in Chinese-style sausage using vacuum and modified atmosphere packaging

The oxidation of lipid and cholesterol in Chinese-style sausage in vacuum packaging (VP) and modified atmosphere packaging (MAP) stored at 4°C and 15°C, respectively, for 5 months was investigated. The 2-thiobarbitaric acid reactive substance (TBARS) and peroxide value (POV) of sausage were variable with packaging treatments during storage. TBARS and POV in sausage stored at 15°C were significantly greater (p < 0·05) than at 4°C, and the MAP treatment was more stable than the VP treatment. In addition, the polyunsaturated fatty acids (PUFA) in sausage decreased with storage for both treatments. The content of cholesterol decreased significantly after 3 months of storage. 7-β-hydroxycholesterol, 7-ketocholesterol and 22-ketocholesterol were the major cholesterol oxidation products (COPs), but there was no detectable (< 1 μg/100 g) 25-hydroxycholesterol or cholestanetriol with either treatment.     

Effect of tocopherol concentration on rancidity development during frozen storage of a cured and an uncured processed pork product

This research evaluated the effect of addition during processing of various concentrations of tocopherol (0-1000 mg/kg) on the subsequent lipid oxidation and rancidity development during frozen storage of two pork products-a coarsely ground cured sausage and an uncured restructured pork roast. The results indicated that tocopherol had little effect on lipid oxidation, as measured by TBARS values and sensory evaluation during frozen storage at -18?°C for 37 weeks for either product. However, lipid oxidation only occurred to a limited extent even in products without tocopherol and was insufficient to cause rancid flavour development. It was, therefore, not possible to determine if tocopherol added during processing was effective as an antioxidant in preventing lipid oxidation in processed pork products during frozen storage.     

Effect of antioxidants on stabilization of meat products fortified with n-3 fatty acids

The effects of an n-3 oil emulsion, with and without added antioxidants, on lipid oxidation in n-3 polyunsaturated fatty acid (PUFA)-fortified meat products were studied. An emulsion of n-3 PUFAs was prepared (25% algal oil, 2.5% whey protein isolates, 10mM sodium citrate, 0.2% potassium sorbate, 500ppm of 70% mixed tocopherols, 100μM EDTA, pH 3, pasteurized at 75°C for 30min) and incorporated into fresh ground turkey, and fresh pork sausage (20% fat) to achieve a concentration of 500mg n-3 PUFA/110g meat. An antioxidant combination containing rosemary (0.2% w/w; radical quencher), citrate (0.5% w/w; sequestrant) and erythorbate (1g/kg product; reductant) was prepared and incorporated into ground turkey patties (5cm dia, 1.5cm thick) or fresh pork sausages (5cm dia, 1.5cm thick). Meat products were stored at 4°C or -18°C and analyzed for color (L*, a*, b* values), lipid oxidation (TBARS and lipid hydroperoxides) and n-3 PUFA profile. a* Values of refrigerated ground turkey patties decreased with storage, and an antioxidant combination effect was observed after 4 days (P<0.05). For fresh pork sausages at 4°C, control+antioxidant (CON+ANTI), and n-3+antioxidant (n-3+ANTI) groups showed greater a* values than controls (CON) indicating that the antioxidant combination stabilized meat color. TBARS and lipid hydroperoxides of both n-3 PUFA-enhanced meat products increased with storage (P<0.05); there were no significant changes in TBARS or lipid hydroperoxides for treatments containing the antioxidant combination (P<0.05). The actual level of n-3 PUFA incorporation in both meat products was greater than 87%; n-3 PUFA concentrations did not change within any treatment during storage (P>0.05). These results provide support for including antioxidant protection in n-3 PUFA fortified meat products.