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The fat content (fat distribution) of the pork and beef raw material is one of their most important quality characteristics. Image processing methods were applied to provide with quantitative parameters related to these properties. Different hardware tools were tested to select the appropriate imaging alternative. Statistical analysis of the RGB data was performed in order to find appropriate classification function for segmentation. Discriminant analysis of the RGB data of selected image regions (fat-meat-background) resulted in a good segmentation of the fat regions. Classification function was applied on the RGB images of the samples, to identify and measure the regions in question. The fat-meat ratio and textural parameters (entropy, contrast, etc.) were determined. Comparison of the image parameters with the sensory evaluation results showed an encouraging correlation.

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Acta Alimentaria
Authors: L. Darnay, A. Dankovics, B. Molnár, L. Friedrich, Gy. Kenesei, and Cs. Balla

Several scientific papers suggest that microbial transglutaminase (mTG) is capable of reducing the salt content of cured and/or heat-treated meat products (ham, frankfurters, meat ball). These scientific results are not widely known in Hungary, and as a result of this, only little experience was gathered in our meat industry. According to this lack of knowledge, our aim was to lower the curing salt to a still microbiological safe level using mTG by frankfurters, one of the most well-known heat treated meat products in Hungary. The observed technofunctional properties suggest to use mTG enzyme preparation at 0.5% concentration. This enzyme dosage can reduce the average 1.8% salt content to 1.6% and it also may contribute to extended shelf life of popular frankfurters. Our sensorial analysis revealed that the panellists have not found a loss in quality between 1.4% and 1.6% salt.

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Water content of dry sausages may decrease due to improper ripening and storage as well. As a consequence, an outer crust appears on the surface of the products. The aim of the industry is either to eliminate the presence of outer crust, or decrease its occurrence. The thickness of outer crust can be estimated by non-destructive ultrasound technique. As the propagation time and attenuation of ultrasonic waves vary in the materials with different water content, the thickness of outer crust and the normal texture, respectively, can be estimated on the basis of these characteristics. The propagation and attenuation values are typical for the given layers. Thus, by measuring total attenuation and total width of the product, the thickness of outer crust can be calculated by means of the velocity and attenuation coefficients of ultrasonic waves. Results of this non-destructive measurement may support the proper adjustment of ripening and storage parameters such as temperature and humidity.

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The aim of the present study was to evaluate the effect of high hydrostatic pressure (HHP) processing (at 450 or 600 MPa for 300 s) on microbial quality as well as on organoleptic properties of fish salad with mayonnaise during 26 days of storage at 5 and 10 °C. The salad contained diced smoked trout fish, mayonnaise, and different kinds of spices. These freshly made salads usually have only a couple of days of shelf life. The HHP treatment basically did not affect the physical and organoleptic characteristics of the fish salad with mayonnaise. At both storage temperatures, the HHP treated samples showed enhanced safety and increased shelf-life up to 3 weeks.

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Acta Alimentaria
Authors: K.N. Hussein, L. Friedrich, R. Pinter, Cs. Németh, G. Kiskó, and I. Dalmadi

This study was conducted to evaluate the effect of bioactive compounds (BACs): linalool (LIN) and piperine (PIP) on chicken meat characteristics. The meat was treated with 500, 1000 ppm of BACs, vacuum packaged and stored at 4 °C for 8 days. Physicochemical characteristics, lipid oxidation (thiobarbituric acid reactive substances, TBARS), microbiological status, and sensorial (electronic-nose based) properties were investigated. Both BACs significantly increased the redness (a*) and chroma (C*) values in meat compared to increased lightness (L*) and higher TBARS in control. Although both BACs showed overlapping aroma profile, the E-nose was able to distinguish between the different meat groups. LIN with various dilution ratios, particularly 1:10 (v:v), showed in vitro growth inhibition against Escherichia coli, Staphylococcus aureus, Salmonella Typhimurium, and Bacillus cereus, concomitantly Listeria monocytogenes required 1:80 (v:v) to be inhibited, and no inhibition was detected for Pseudomonas lundensis. In contrast, PIP at different dilutions did not exhibit inhibitory activity. Regarding aerobic mesophilic counts (AMC), less than 7 log CFU g−1 were recorded except for control showing higher log. Both BACs have potential to improve quality characteristics and increase the shelf life of meat and meat products.

Open access
Acta Alimentaria
Authors: L. Darnay, A. Tóth, B. Salamon, K. Papik, G. Oros, G. Jónás, K. Horti, K. Koncz, and L. Friedrich

The aim of this study was to show how microbial transglutaminase (mTG) can be used as an effective texture-modifier for two popular Hungarian products: Trappist cheese and frankfurter. In both cases we investigated how components of these products, milkfat in cheese and phosphate in frankfurter, can be substituted by mTG. Therefore, Trappist cheese samples were produced from cow milk of 2.8%, 3.5%, and 5% milk fat. The effect of ripening was evaluated with Texture Profile Analysis (TPA) and sensory evaluation (scoring test, 10 trained panellists). Springiness and cohesiveness values were significantly higher by enzyme-treated semi-hard cheese samples at lower milk fat levels. Sensory evaluation showed that the enzyme-treatment led to higher scores by cheese samples made from cow milk of 3.5% and 5% milk fat. Frankfurter was made with 0.1%, 0.3%, 0.5%, and 0.7% tetrasodium pyrophosphate, and partly enzyme-treated with 0.2% commercial mTG enzyme preparation. Our results showed that mTG is able to significantly improve hardness and crunchiness by frankfurters made with 0.1% phosphate addition. Our sensory evaluation suggests that mTG and phosphate should be applied in combination in order to have a final product with recognisably more homogeneous texture.

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Acta Alimentaria
Authors: B. Csehi, E. Szerdahelyi, K. Pásztor-Huszár, B. Salamon, A. Tóth, I. Zeke, G. Jónás, and L. Friedrich

In the experiments pork loin and beef sirloin were treated by pressures of 100 to 600 MPa by 100 MPa steps for 5 min. Colour changes of samples and the changes of proteins were investigated. The latter were examined with isoelectric focusing and SDS polyacrylamide gel electrophoresis. We found that myoglobin behaved completely differently in case of the two different species. Myoglobin has mostly lost its native state at 300 MPa pressure in case of pork, but the beef myoglobin could remain native even up to 500 MPa. The treatment at 300 MPa or higher pressure values caused almost complete aggregation and denaturation in case of pork and beef proteins. The results of SDS-PAGE and the colour measurement confirmed this finding.

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Acta Alimentaria
Authors: B. Csehi, B. Salamon, T. Csurka, E. Szerdahelyi, L. Friedrich, and K. Pásztor-Huszár

Abstract

Bovine blood samples were treated with high hydrostatic pressure (HHP) to examine the changes that may occur in the blood related to its colour, microbiological characteristics, protein denaturation, and dynamic viscosity. Pressure treatments were carried out from 100 to 600 MPa in 100 MPa scale up, with 5 min holding time. The blood samples were treated with anticoagulant (EDTA) to eliminate the possible measurement distorting effects. We found that 2 log reduction in the microbial load could be achieved with a pressure treatment above 400 MPa. According to the protein denaturation measurements (DSC), blood proteins were resistant to pressure treatment, even at 300–400 MPa a substantial part of proteins remained in native state. The colour of the samples got darker with the rising pressure, however, visible colour change was observed only above 400 MPa. It can be established, that the HHP treatment was suitable to increase the microbiological stability of blood, without significantly changing its techno-functional properties.

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