Partial replacement of pork fat by conjugated linoleic acid and/or olive oil in liver pâtés: Effect on physicochemical characteristics and oxidative stability

The effect of replacing pork fat in liver pâtés by an enriched conjugated linoleic acid oil (CLA-pâté), olive oil (OO-pâté), or the combination of both type of oils (CLA + OO-pâté) on the fatty acid profile, lipid oxidative stability, consistency and emulsion stability was studied and compared with a traditional liver pâté (C-pâté). Pâtés were analyzed at days 1, 6, 21 and 71 of refrigerated storage (4 °C). A enrichment in CLA was attained in CLA-pâté and CLA + OO-pâté. CLA-pâtés had the highest content in polyunsaturated fatty acids (PUFA) (p < 0.05) due to their content in CLA. A lower content in saturated fatty acids was achieved when using OO or CLA in pâtés (p < 0.05). OO-pâtés showed the highest levels of monounsaturated fatty acids (MUFA) (p < 0.05). No changes in the fatty acid profile and in lipid oxidation (mg malondialdehyde per kg of sample) throughout the storage of the products were found. Lower consistency and emulsion stability were obtained when using CLA or OO in the formulation. Consistency values (in N/cm²) tended to increase and emulsion stability to decrease throughout the storage in CLA or OO enriched pâtés.     

Quality of ham pâté containing bovine globin and plasma as fat replacers

The effect of the incorporation of globin (10%), plasma (10%) and both combined (5% each) as fat replacers on the quality of ham paté was investigated. The chemical composition, the sensorial analysis (color, flavor and consistency) and the instrumental analysis of the texture (hardness, adhesiveness, elasticity, cohesiveness and tackiness) were evaluated. The results showed an increase of moisture and protein contents after the fat replacement, while the fat reduction of 25-35% led to the preparation of light products. No change was observed for the aroma, taste and the consistency of fat replacing products, but an intensification of the cohesivity and a reduction of color, hardness and tackiness were detected in some samples.     

FIA evaluation of nitrite and nitrate contents of liver pâtés

A comparative study on the nitrite and nitrate contents of 15 liver pâté brands, in a total of 45 samples (three batches per brand) is presented. The study was conducted on two different kind of pâtés: pork liver pâtés and fowl liver pâtés. For the simultaneous determination of nitrite and nitrate, an automated flow injection system with spectrophotometric detection was used. The manifold was based on the splitting of the flow after injection and subsequent confluence of the flow before reaching the detector, allowing the reduction of nitrate to nitrite in part of the sample plug on an on-line copper cadmium reductor column. Spectrophotometric determination was made after a diazotization coupling reaction. The levels of nitrites and nitrates ranged from 1.07 mg NaNO₂ kg⁻¹ ± 0.43 to 15.9 mg NaNO₂ kg⁻¹ ± 5.2 and from 24.5 mg NaNO₃ kg⁻¹ ± 2.7 to 207 mg NaNO₃ kg⁻¹ ± 14, respectively. The levels of concentration of these constituents were below the allowable limits. A significant dispersion in the results was observed between different brands and within some of the brands.     

Potential antimicrobials to control Listeria monocytogenes in vacuum-packaged cold-smoked salmon pâté and fillets

In the wake of recent outbreaks associated with Listeria monocytogenes in ready-to-eat foods and an increasing desire for minimally processed foods, there has been a burgeoning interest in the use of natural antimicrobials by the food industry to control this pathogen. The minimum inhibitory concentrations (MICs) of nisin and salts of organic acids (sodium lactate (SL), sodium diacetate (SD), sodium benzoate (SB), and potassium sorbate (PS)) against twelve strains of L. monocytogenes in a TSBYE broth medium at 35 degrees C were determined. The MICs were strain-dependent and fell in the range of 0.00048-0.00190% for nisin, 4.60-5.60% for SL, 0.11-0.22% for SD, 0.25-0.50% for SB and 0.38-0.75% for PS, respectively. The two most antimicrobial-resistant strains were used as a cocktail in the following experiments to represent a worst case scenario. The five antimicrobials alone and in binary combinations were screened for their efficacy against the two-strain cocktail in TSBYE at sub-MIC and sub-legal levels at 35 degrees C. Seven effective antimicrobial treatments were then selected and evaluated for their long-term antilisterial effectiveness in cold-smoked salmon paté and fillets during refrigerated storage (4 degrees C) of 3 and 6 weeks, respectively. The two most effective antimicrobial formulations for smoked salmon paté, 0.25% SD and 2.4% SL/0.125% SD, were able to inhibit the growth of L. monocytogenes during the 3 weeks of storage. Surface application of 2.4% SL/0.125% SD was the most effective treatment for smoked salmon fillets which inhibited the growth of L. monocytogenes for 4 weeks. These antimicrobial treatments could be used by the smoked salmon industry in the U.S. and Europe in their efforts to control L. monocytogenes as they are effective against even the most antimicrobial-resistant strains tested in this study.     

Effect of natural and synthetic antioxidants on protein oxidation and colour and texture changes in refrigerated stored porcine liver pâté

The antioxidant effect of two plant essential oils (sage and rosemary) and one synthetic antioxidant (BHT) on refrigerated stored porcine liver paté (4°C/90 days) was evaluated. Patés with no added antioxidants were used as controls. Liver patés were analysed for protein oxidation, modification of heme (HI) and non-heme iron (NHI) concentrations, and colour and texture characteristics at days 0, 30, 60 and 90 of refrigerated storage. The amount of carbonyls from protein oxidation significantly (p<0.05) increased during refrigerated storage, and this increase was significantly higher in the control patés than in their treated counterparts. Antioxidants successfully protected heme molecules from degradation and significantly inhibited the increase of NHI in refrigerated stored liver patés. Colour changes seemed not to be directly related to oxidative processes since patés with added antioxidants suffered greater colour modifications than the controls. The addition of rosemary essential oil significantly reduced hardness of liver patés. Sage and rosemary essential oils exhibited similar antioxidant properties to BHT denoting their suitability as alternatives to synthetic antioxidants.     

Characterisation of a traditional Finnish liver sausage and different types of Spanish liver pâtés: A comparative study

The physico-chemical characteristics of a traditional Finnish liver sausage (FLS) and different types of Spanish porcine liver pâtés (commercial, home-made and experimental) were studied. The characteristic recipes and different protocols of manufacture influenced the chemical composition and oxidative stability of the liver products. FLS showed, amongst the liver products, the smallest percentage of monounsaturated fatty acids (MUFAs) and the highest of polyunsaturated fatty acids (PUFAs) acids, including long-chain PUFAs. From a nutritional point of view, the FLS showed the smallest n − 6/n − 3 value whereas the experimental liver pâté (ELP) presented the smallest ratio between hyper- (lauric, myristic and palmitic acids) and hypocholesterolemic fatty acids (oleic and linoleic acids). A large variety of volatile compounds were isolated from the liver products including lipid-derived volatiles, Strecker aldehydes and alcohols, sulphur and nitrogen containing compounds and volatile terpenes, providing information on their oxidative stability and aroma characteristics. The FLS presented a balanced profile between lipid-derived volatiles and volatile terpenes from spices. The presence of potent odorants from added flavourings in the commercial liver pâté (CLP) could mask undesirable aroma odours from a large variety of lipid-derived volatiles. The home-made liver pâté (HMLP) also presented large amounts of lipid-derived volatiles as a likely consequence of strong thermal treatment during cooking, the presence of high amounts of iron and the absence of sodium nitrites and ascorbate in its composition. The ELP showed the simplest profile due to its high oxidative stability and the absence of added spices.     

A healthier oil combination and konjac gel as functional ingredients in low-fat pork liver pâté

Healthier lipid patés were formulated by reducing the fat content and/or replacing the pork backfat by a healthier oil combination (olive, linseed and fish oils) and konjac gel (0-15%). The reformulation results were evaluated by composition (proximate analysis and fatty acid profile), technological properties (emulsion stability, colour, and texture), microbiological and sensory parameters of the patés. Patés with partial or total replacement of pork backfat had lower levels of saturated fatty acids (SFA) (27.4% and 21.3%) and monounsaturated fatty acids (MUFA) (49.8% and 42.5%), and higher levels of polyunsaturated fatty acids (PUFA) (22.4% and 35.6%) compared with control patés (32.2%, 58.2% and 9.04% respectively). The n-6/n-3 PUFA ratio was decreased from 6.78 (in control patés) to 0.79 and 0.48 when partial and total pork backfat respectively was replaced by a healthier oil combination. Although emulsion stability was affected by the formulation, in general all patés had good fat and water binding properties. The fat reduction produced a softer and more spreadable paté, although no effect on penetration parameters was observed after by pork fat replacement by a healthier oil combination. The addition of 15% of konjac gel produced stiffer structures (as compared with 0 and 7%) which are very close to those of the control samples. No microbiological limitations were produced by the reformulation process, obtaining patés with acceptable sensory characteristics, similar to the control sample.     

Lipid and protein oxidation, release of iron from heme molecule and colour deterioration during refrigerated storage of liver pâté

In the present work, lipid and protein oxidation, increase of non-heme iron (NHI) content and colour changes occurring during refrigerated storage (90 days/4 °C) of liver pâtés from Iberian and white pigs were studied. Iberian pigs were reared outdoors and fed on natural resources (grass, acorns) while white pigs were intensively reared and fed on a mixed diet. Lipid and protein oxidation were, respectively, measured by determining TBA reactive substances (TBARS) and protein carbonyl groups. Pâtés from Iberian pigs had better oxidative stability at all stages of storage, having lower amounts of TBARS and carbonyls compared to those from white pigs (p<0.05). NHI increased during refrigerated storage of liver pâtés, with those from white pigs having a higher amount of NHI at all stages of storage (p<0.05). During refrigerated storage, L^*-values tended to increase while the evolution of a^* and b^* depended on the group and did not seem to be related to the oxidative processes.     

Effect of rosemary extract dose on lipid oxidation, colour stability and antioxidant concentrations, in reduced nitrite liver pâtés

The oxidative stability of liver pâté was investigated in relation to different doses of rosemary extract (RE) and sodium nitrite. Colour stability, lipid oxidation (TBARS) and concentrations of ascorbic acid, α-tocopherol, carnosic acid and nitrite were measured on the batters before cooking and on the cooked liver pâté before and after exposure to light and air for 48 h at 4 °C. Results showed that the use of RE significantly reduced lipid oxidation, whereas it had no effect on colour stability. Ascorbic acid and nitrite concentrations were significantly higher and lower respectively when RE was added. RE dose-dependently increased the concentration of carnosic acid. Lower sodium nitrite doses resulted in significantly lower nitrite concentrations and slightly lower TBARS values. It was concluded that in liver pâté sodium nitrite levels may be lowered to 80 mg/kg without negatively affecting colour and lipid stability and that the use of RE may help in maintaining lipid stability.     

Effect of sodium ascorbate dose on the shelf life stability of reduced nitrite liver pâtés

The effect of sodium ascorbate (SA; 500, 750, 1000 mg/kg) and sodium nitrite (SN; 40, 80, 120 mg/kg) doses on the shelf-life stability of liver patés was investigated in a full factorial design. Clear dose-dependent responses of the added SN or SA were found for the concentrations of nitrite, ascorbic acid and dehydroascorbic acid in the raw batters and in the cooked patés before and after 48 h of chilled display. Decreasing the SN dose to 80 mg/kg had no negative impact on the colour stability (a* value) and lipid oxidation (TBARS), and no additional antioxidant effect of SA was noticed. Lowering SN to 40 mg/kg resulted in proper colour formation, but the colour stability was inferior and lipid oxidation increased. Yet, increasing the amount of SA, at this low SN dose, resulted in lower TBARS values. Decreasing the SN dose to 80 or 40 mg/kg had no distinct effect on protein oxidation, which was however only measured by carbonyl content.     

Extensively reared Iberian pigs versus intensively reared white pigs for the manufacture of liver pâté

Physico-chemical characteristics and quality traits of the raw ingredients (muscle cuadriceps femoris, liver and adipose tissue) and the patés made from extensively reared Iberian pigs and intensively reared white pigs, were evaluated. The differences found between muscles, livers and adipose tissues from Iberian and white pigs influenced the characteristics of the patés. Compared to patés from white pigs, patés from Iberian pigs had a higher content of heme iron (27.5 μg/g vs 11.5 μg/g; p<0.05) and lower content of non-heme iron (27.5 μg/g vs 33.7 μg/g; p<0.05). Patés from Iberian pigs exhibited a darker colour (L (?):18.6 vs 15.9, p<0.05) with less redness (a (?) values: 9.1 vs 11.3; p<0.05) and yellowness (b (?) values: 13.1 vs 14.8, p<0.05). Thus, patés from white pigs had higher values of chroma (18.6 vs 15.9, p<0.05) and smaller values of hue (52.5 vs 55.2, p<0.05) that those from Iberian pigs' patés. In fatty acid composition, patés from white pigs had higher proportions of SFA (37.9% vs 32.8%, p<0.05) and PUFA (14.4% vs 9.6%, p<0.05) than patés from Iberian pigs and lower percentages of oleic (53.4% vs 43.6%, p<0.05) and total of MUFA (57.5% vs 47.6%, p<0.05). Patés from Iberian pigs had a lower n-6/n-3 values (13.2 vs 17.2; p<0.05).     

Pasting,rheological, and dough mixing behavior of rice flour as affected by the addition of native and partially hydrolyzed β-glucan concentrate

This study was aimed at evaluating the potential of barley β-glucan concentrates (native and partially hydrolyzed) in modifying the techno-functionality of rice flour dough. β-Glucan concentrate was partially hydrolyzed to obtain a low molecular weight polymer and their influence on the pasting, rheological, and thermal properties of rice dough were assessed. Hydration, thermal, and pasting properties were significantly modified with the added β-glucans. The rice dough supplemented with β-glucan concentrates showed improved viscoelastic and creep behavior and the effectiveness of β-glucans in imparting strength to rice dough depended on its molecular weight. Hydrolyzed β-glucan concentrates having low molecular weight increased dough elasticity to the greater extent in comparison to native β-glucan concentrates. The micrographs of supplemented dough showed a strong and dense network indicating improved structure and strength.     

Furosine and Nε-carboxymethyl-lysine in cooked meat product (kavurma): Effects of salt and fat levels during storage

The aim of the study was to determine the effects of different salt (1%, 1.5% and 2%) and fat (10%, 15% and 20%) levels on the content of furosine and N^ε-carboxymethyl-lysine (CML) of kavurma (an uncured-cooked meat product) during the storage time (6 months at 4 °C under vacuum packaging). The increasing salt levels caused an increase in TBARS value. Kavurma with 10% fat showed the lowest mean value for TBARS. The furosine content increased with increasing storage time. At the end of storage, however, furosine content was not affected by the salt level. Kavurma with 20% fat had a higher mean furosine content than 10% fat level at 6th months. The salt level had no significant effect on CML in kavurma, while the interaction of fat level x storage time was significant. After 4 and 6 months of storage, CML content was not affected by the fat level.     

Addition effects of bovine blood globin and sodium caseinate on the quality characteristics of raw and cooked ham pâté

The incorporation of 3% globin bovine extracted by the acidified acetone (AG) and carboxymethylcellulose (CG) methods as replacer for sodium caseinate (CA) in ham paté was evaluated. The raw paté batter was evaluated for salt-soluble protein content (SSP), water holding capacity (WHC) and raw batter stability (RBS). The results of CG were similar to those of CA, having both improved two of the three paramaters studied, and AG was the most deleterious, having decreased SSP, WHC and RBS. Only the AG incorporation had unfavorable effects on the cooked ham paté, decreasing the pH and increasing the thiobarbituric acid reactive substances (TBARS) over the storage period (0-45 days). The results suggest CG as the best replacer for CA as the emulsifying agent for ham paté.     

Specific detection and quantification of Aspergillus flavus and Aspergillus parasiticus in wheat flour by SYBR® Green quantitative PCR

Aflatoxins are important mycotoxins that represent a serious risk for human and animal health. These mycotoxins are mainly produced by Aspergillus flavus and Aspergillus parasiticus, two closely related species with different array of aflatoxins. In this work, two specific quantitative PCR (qPCR) assays were developed to detect and quantify both species in wheat flour using primers based on the multicopy ITS2 rDNA target sequence. The species specificity of the assays was tested in a wide range of strains of these species and others colonizing the same commodities. The sensitivity of the assay was estimated in 2.5 pg/reaction in both species. Discrimination capacity for detection and relative quantification of A. flavus and A. parasiticus DNA were analyzed using samples with DNA mixtures containing also other fungal species at different ratios. Both qPCR assays could detect spore concentrations equal or higher than 10⁶ spores/g in flour samples without prior incubation. These assays are valuable tools to improve diagnosis at an early stage and in all critical control points of food chain integrated in HACCP strategies.     

Persimmon (Diospyros kaki Thunb.) coproducts as a new ingredient in pork liver pâté: influence on quality properties

Persimmon (Diospyros kaki Thunb.) coproducts are rich in fibre, sugar, minerals and bioactive compounds, make it a good candidate for use in the meat industry. The aim was to evaluate the effect of adding (3% and 6%) two different types of persimmon flour (from cultivars ‘Rojo Brillante’ and ‘Triumph’) on the chemical composition (proximate composition, haeme iron and nitrite residual level), physicochemical properties (pH, water activity and colour), lipid oxidation, emulsion stability, texture and sensory acceptance of pork liver pâté. The addition of persimmon flours decreased residual nitrite levels in pâté to an extent that depended on the concentration and type of flour. Lipid oxidation in pâtés was also reduced by persimmon flour addition, an effect made evident by the increase in pâté redness, which could allow its application as natural antioxidant. In a sensory analysis, all the pâtés with persimmon flour added were better accepted than the control.     

A by-product from virgin olive oil production (pâté) encapsulated by fluid bed coating: evaluation of the phenolic profile after shelf-life test and in vitro gastrointestinal digestion

Pâté is a by-product of virgin olive oil production presenting a high phenolic content and beneficial health effects. This research aims to evaluate the storage stability of phenolic compounds of pâté and a coated formulation, and to verify the bioaccessibility of the phenolic compounds. An accelerated shelf-life test at 40 °C/75% relative humidity was carried out for 75 days. Different combinations of degradative and hydrolytic reactions impacted the results. Indeed, at the end of the storage period, 84% of phenols was recovered in pâté with free tyrosol and hydroxytyrosol showing an increase due to secoiridoids hydrolysis. The total phenolic content of coated pâté did not significantly decrease, showing a higher increment of free tyrosol and hydroxytyrosol. Simulated digestion led to the liberation of 15% of phenols by both samples. In conclusion, the coating process improved the stability of pâté phenolic compounds without affecting their bioaccessibility.     

Low-fat pork liver pâtés enriched with n-3 PUFA/konjac gel: dynamic rheological properties and technological behaviour during chill storage

Low-fat pork liver patés enriched with n-3 PUFA/konjac gel were formulated by replacing (total or partially) pork backfat by a combination of healthier oils (olive, linseed and fish oils) and konjac gel. Dynamic rheological properties and technological behaviour of patés during chill storage (2 °C, 85 days) were analysed. Cooking yields were affected (P<0.05) by formulation, with percentages ranging between 88 and 98%. According to the frequency sweep test, patés presented a gel/emulsion-like pattern with a loosely-structured network and the consistency of a viscoelastic gel. Thermal processing caused the formation of a protein gel network with a considerable element of emulsion-like characteristics. Patés became lighter and less red (P<0.05) during chill storage. Purge losses of around 1% were observed at the end of the storage period, irrespective of formulation. Textural parameters of patés were affected by formulation and storage time. The results suggest that the replacement of pork back fat by oil-in-water emulsion and the incorporation of konjac gel could provide a mixture of ingredients that effectively mimics the normal animal fat content in patés.