Energy content, sensory properties, and microbiological shelf life of German bologna-type sausages produced with citrate or phosphate and with inulin as fat replacer

ABSTRACT:  The aim of this study was to determine the feasibility of reducing energy content (9% to 48%) in bologna-type sausages by replacing fat with inulin and to study the effects of substituting citrate for phosphate in the traditional sausage formula. German-type mortadella was produced, and fat was replaced with increasing amounts of inulin as a frozen gel to yield 3%, 6%, 9%, and 12% inulin in the final product. In another part of the study, citrate was substituted for the phosphate in the recipe. All sausages produced were sliced, packaged under a modified atmosphere (70% N₂, 30% CO₂), and stored for 23 d at +7 °C. Sausage quality was determined by chemical and instrumental texture profile analyses, color measurement, sensory evaluation, and microbiological testing. Replacing fat with inulin led to significant energy content reductions of up to 47.5% (with 12% inulin). However, the sensory properties of these sausages were also different from those of the control mortadella: fracturability fell, hardness and adhesiveness rose, and color became darker. In general, the substitution of citrate for phosphate significantly reduced the negative effects of inulin. There were no significant differences in microbiological stability between different inulin batches but there were significant differences between phosphate and citrate batches. Overall, the energy content of bologna-type sausages produced with citrate and with up to 6% inulin as a fat replacer was 22% lower than that of the control sausages. Furthermore, the sensory attributes (texture, color) of these 6% inulin–citrate sausages were comparable to the control sausages, and the sausages were microbiologically stable for 23 d of storage.     

Influence of soil moisture on sunflower oil extraction of polycyclic aromatic hydrocarbons from a manufactured gas plant soil

The influence of soil moisture on efficiency of sunflower oil extraction of polycyclic aromatic hydrocarbons (PAHs) from contaminated soil was investigated. The PAH-contaminated soil was collected from a manufactured gas plant (MGP) site in Berlin, Germany. Half of the soil was air-dried, and the other half was kept as field-moist soil. Batch experiments were performed using air-dried and field-moist soils, and sunflower oil was used as extractant at oil/soil ratios of 2:1 and 1:1 (v/m). The experimental data were fitted to a first-order empirical model to describe mass-transfer profiles of the PAHs. Column extraction experiments were also conducted. Field-moist and air-dried soils in the column were extracted using sunflower oil at an oil/soil ratio of 2:1. In the batch experiments, PAHs were more rapidly extracted from air-dried soil than from field-moist soil. Removal rate of total PAH increased 23% at oil/soil ratio of 1:1 and 15.5% at oil/soil ratio of 2:1 after the soil was air dried. The most favorable conditions for batch extraction were air-dried soil, with an oil/soil ratio of 2:1. In the column experiments, the removal rate of total PAH from air-dried soil was 30.7% higher than that from field-moist soil. For field-moist soil, extraction efficiencies of the batch extraction (67.2% and 81.5%) were better than that for column extraction (65.6%). However, this difference between the two methods became less significant for the air-dried soil, with a total removal rate of 96.3% for column extraction and 90.2% and 97% for batch extractions. A mass-balance test was carried out for analytical quality assurance. The results of both batch and column experiments indicated that drying the soil increased efficiency of extraction of PAHs from the MGP soil.     

3D deconvolution of spherically aberrated images using commercial software

Refractive index mismatch between the specimen and the objective immersion oil results in spherical aberration, which causes distortion and spreading of the point spread function, as well as incorrect readings of the axial coordinates. These effects have to be taken into account when performing three-dimensional restoration of wide-field fluorescence images. By using objects with well-defined geometry (fluorescently stained Escherichia coli or actin filaments) separated from a cover slip by a layer of oil with known refractive index, we investigated the accuracy of three-dimensional shape restoration by the commercial programs Huygens and Autoquant. Aberration correction available in the software dramatically reduced the axial blur compared to deconvolution that ignored the refractive index mismatch. At the same time, it failed to completely recover the cylindrical symmetry of bacteria or of actin fibres, which showed up to a three to five times larger width along the optical axis compared to the lateral plane. The quality of restoration was only moderately sensitive to the exact values of the specimen refractive index but in some cases improved significantly by assuming a reduced NA of the objective. Because image restoration depends on the knowledge of the vertical scale, we also performed detailed measurements of the axial scaling factor and concluded (in agreement with some previous authors) that scaling is adequately described by the simple paraxial formula, even when high-NA oil-immersion objectives are used.