Control of Listeriamonocytogenes on commercially-produced frankfurters prepared with and without potassium lactate and sodium diacetate and surface treated with lauric arginate using the Sprayed Lethality in Container (SLIC®) delivery method

Viability of Listeriamonocytogenes was monitored on frankfurters formulated with or without potassium lactate and sodium diacetate at a ratio of ca. 7:1 and treated with lauric arginate (LAE; 22 or 44 ppm) using the Sprayed Lethality in Container (SLIC®) delivery method. Without antimicrobials, pathogen numbers remained relatively constant at ca. 3.3 log CFU/package for ca. 30 d, but then increased to ca. 8.4 log CFU/package over 120 d. Regardless of whether or not lactate and diacetate were included, when treated with LAE, pathogen numbers decreased from ca. 3.3 log CFU/package to ca. 1.5 log CFU/package within 2 h, but then increased to 7.3 and 6.7 log CFU/package, respectively, after 120 d. When frankfurters were formulated with lactate and diacetate and treated with LAE, pathogen numbers decreased by ca. 2.0 log CFU/package within 2 h and remained relatively unchanged over the 120 d. These data confirm that LAE provides an initial lethality towards L. monocytogenes and when used in combination with reduced levels/ratio of lactate and diacetate as an ingredient for frankfurters provides inhibition throughout shelf life.     

Reduction of Listeria monocytogenes on frankfurters treated with lactic acid solutions of various temperatures

United States regulations require ready-to-eat meat and poultry processors to control Listeria monocytogenes using interventions which may include antimicrobials that reduce post-processing contamination by at least 1 log-cycle; if the treatment achieves ≥2 log reductions, the plant is subject to less frequent microbial testing. Lactic acid (LA) may be useful as a post-lethality intervention and its antimicrobial properties may increase with temperature of application. The aim of this study was to evaluate the effect of LA solution concentration and temperature on L. monocytogenes counts of inoculated frankfurters and to identify parameters (concentration, temperature, and time) that achieve 1 and 2 log-unit immediate reductions. Frankfurters were surface-inoculated with a 10-strain mixture of L. monocytogenes (4.4 ± 0.1 log CFU/cm²) and then immersed in distilled water or LA solutions (0–3%) of 4, 25, 40, or 55 °C for 0–120 s. A regression equation for L. monocytogenes reduction included significant (P < 0.05) effects by the terms of concentration, time, temperature, and the interaction of concentration and temperature; other tested parameters (other interactions, quadratic and cubic terms), within the experimental range examined, did not affect (P ≥ 0.05) the extent of reduction. Results indicated that the effectiveness of LA against L. monocytogenes, in addition to concentration, increased with solution temperature (in the range of 0.6–2.8 log CFU/cm²). The developed equation may allow processors to vary conditions of treatment with LA to achieve a 1 or 2 log-unit reduction of the pathogen and comply with United States regulations.     

Effectiveness of rosemary essential oil as an inhibitor of lipid and protein oxidation: Contradictory effects in different types of frankfurters

The effect of increasing levels (150, 300 and 600ppm) of rosemary essential oil on lipid and protein oxidation and the increase of non-heme iron (NHI) content during refrigeration (+4°C/60 days) of frankfurters produced with tissues from Iberian pigs (IF) or white pigs (WF), was studied. Frankfurters with no added essential oil were used as controls. Iberian pigs were free-range reared and fed on acorns and pasture whereas white pigs (Large-white×Landrance) were intensively reared and fed on a mixed diet. Large differences were detected between types of frankfurters (Iberian vs white) in terms of fatty acid composition and tocopherols content due to the different feeding background of the animals. The effect of the addition of rosemary essential oil on the oxidative stability of frankfurters depended on the level of added essential oil and the characteristic of the frankfurter. The rosemary essential oil successfully inhibited the development of lipid and protein oxidation in IF with that antioxidant effect being more intense at higher concentrations of essential oil. In WF, 150ppm rosemary essential oil showed an antioxidant effect, significantly reducing the generation of lipid and protein oxidation products. At higher levels (300 and 600ppm) the essential oil had, in general, no effect on lipid oxidation while significantly enhanced the oxidation of proteins and the release of iron from myoglobin. The presence of certain amounts of tocopherols in the frankfurters could have influenced the activity displayed by the added essential oil leading to antioxidant or prooxidants effects though the different fatty acid composition and oxidative status between frankfurters could also have had an effect.     

Extensively reared Iberian pigs versus intensively reared white pigs for the manufacture of frankfurters

Physico-chemical characteristics and different quality traits of the raw material (meat and adipose tissue) and the frankfurters elaborated from extensively reared Iberian pigs (IF) and intensively reared white pigs (WF) were evaluated. Hybrid frankfurters (HF) made with meat from white pigs and adipose tissue from Iberian pigs were also studied. The differences found between muscles and adipose tissues from Iberian and white pigs largely influenced the characteristics displayed by the frankfurters. Particularly remarkable are the higher amounts of substances with proven antioxidant activity such as tocopherols and phenolic compounds in tissues from Iberian pigs than in those from white pigs. No significant differences were found amongst frankfurters for their proximate composition though IF presented a higher iron content than WF and HF. IF exhibited a redder and darker colour than WF and HF. The latter were paler and showed higher hue values than IF. Concerning their fatty acid composition, IF had higher proportions of oleic acid and MUFA and smaller proportions of SFA and PUFA than WF. From a nutritional point of view, IF had a lower n-6/n-3 value than WF. The addition of adipose tissue from Iberian pigs to the HF modified its fatty acid composition compared to that of WF, significantly increasing the percentages of MUFA and reducing the proportions of PUFA, SFA and the n-6/n-3 value. Though no significant differences were found amongst frankfurters for their texture profile, a clear trend was detected, with the HF showing intermediate texture characteristics between IF and WF.     

Porcine plasma as polyphosphate and caseinate replacer in frankfurters

The aim was to replace polyphosphate and caseinate by porcine blood plasma as functional ingredients in frankfurters. Three trials, each consisting of one control, formulated with caseinate and tripolyphosphate, and one test, formulated with plasma, were carried out in a pilot plant. The frankfurters with plasma were compared to their respective controls by determining the composition, water holding capacity, cooking losses, internal colour, texture, microstructure, sensorial characteristics, and overall acceptance. No significant differences were found in proximate analysis, WHC, and cooking losses. Texture was not affected by the replacement, according to both sensorial and instrumental measurements. Nevertheless, the panellists detected the presence of animal taste and odour in plasma-containing sausages. Despite this, their overall acceptance was scored as 6.3 in a 10 maximum scale, so plasma could be considered as an interesting alternative to produce healthier and cheaper frankfurters.     

Physicochemical properties of low sodium frankfurter with added walnut: effect of transglutaminase combined with caseinate, KCl and dietary fibre as salt replacers

This study compares the effects of combinations of microbial transglutaminase (TGase) and various non-meat ingredients (caseinate, KCl and wheat fibre) used as salt replacers, with the effects of NaCl on the physicochemical properties (cooking loss, emulsion stability, texture and colour) of frankfurters with added walnuts. The combination of TGase with caseinate, KCl or fibre led to harder, springier and chewier (P < 0.05) frankfurters with better water- and fat-binding properties (emulsion stability and cooking loss) (P < 0.05) than those made with TGase only. Ranking of ingredient efficiency in combination with TGase showed that caseinate > KCl > fibre. Frankfurters with caseinate presented the highest lightness and the lowest redness values. Frankfurter with NaCl had a harder, springier and chewier gel/emulsion network with lower cooking loss than those NaCl free.     

Effect of tomato paste and nitrite level on processing and quality characteristics of frankfurters

Fourteen treatments of frankfurters (18% fat) were produced with two levels of sodium nitrite, 0 and 150mg/kg (0.015%), and seven levels (0%,2%,6%,8%,12% and 16%) of tomato paste with 12% soluble solids The higher the tomato paste level the higher the preference of consumers for frankfurters based on their colour. Frankfurters with 16% tomato paste had a sour taste while those with 12% tomato paste were the most acceptable. In a 2nd experiment three treatments of frankfurters (18% fat) were produced with 0, 50 and 100mg/kg of sodium nitrite and 12% tomato paste and a fourth (control) with only 150mg/kg sodium nitrite. Treatments with 12% tomato paste had lower (p<0.05) pH values and residual nitrite, and higher (p<0.05) thiobarbituric acid values, lightness and yellowness than control. Frankfurters with reduced levels of sodium nitrite (50 and 100mg/kg) and 12% tomato paste had the highest (p<0.05) redness. Storage time affected (p<0.05) all quality attributes. The nitrites added to frankfurters can be reduced from 150mg/kg to 100mg/kg in combination with 12% tomato paste without any negative effect on the quality of the product.     

Evaluation of the physico-chemical, rheological and sensory characteristics of commercially available Frankfurters in Spain and consumer preferences

The physico-chemical, rheological and sensory characteristics of different commercially available Frankfurters were studied. Samples presented values of A_w and pH from 0.954 to 0.972 and 5.88 to 6.43, respectively. Greater differences were observed in parameters such as fat and salt content, with values ranging from 10.83% to 21.92% and 1.85% to 3.01%, respectively. With regard to total nitrogen, all samples presented values close to 2%. Free-choice profiling and generalised procrustes analysis of the sensory data permitted differentiation between samples and provided information about the attributes responsible for the observed differences. All the frankfurters scored in the moderate range for overall acceptability. Consumers identified reasons for purchasing frankfurters when evaluating the product's packaging. The most important criterion for consumers when purchasing frankfurters was the appetising aspect of the product in the packaging's illustration.     

Reducing sodium levels in frankfurters using naturally brewed soy sauce

Sodium chloride (NaCl; salt) serves important functions in processed meats, contributing to desirable quality and food safety characteristics; however, renewed interest exists in reducing sodium in the human diet despite sodium being a required component of the diet for physiological regulation. This study investigated consumer sensory and quality impacts from replacement of normally added NaCl (flake salt) with naturally brewed soy sauce (SS). Varying levels of SS were used with NaCl and/or potassium chloride (KCl) to comprise treatments (TRT) which investigated flake salt replacement (Phase I) and sodium reduction (Phases II and III). Phase I identified a 50% replacement of NaCl with SS as the baseline for subsequent phases. Phase II indicated that the inclusion of SS could allow for a 20% NaCl reduction without adverse effects on quality or sensory attributes. Phase III results demonstrated that it was feasible to reduce NaCl by 35% via the inclusion of KCl in SS containing frankfurters without major quality or sensory changes.