Tag Archives: heat treatment

1434–1441 A. Põldvere, A. Tänavots, R. Saar, S. Sild and L. Lepasalu
Effect of heat treatment at constant 120 °C temperature on the rheological and technological properties of pork
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Effect of heat treatment at constant 120 °C temperature on the rheological and technological properties of pork

A. Põldvere¹⋅²⋅*, A. Tänavots², R. Saar¹, S. Sild¹ and L. Lepasalu¹

¹Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal
Sciences, Department of Food Science and Technology, F.R reutzwaldi 56/5,
EE51014 Tartu, Estonia
²Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal
Sciences, Department of Animal Genetics and Breeding, F.R. Kreutzwaldi 62,
EE51014 Tartu, Estonia
³Estonian Pig Breeding Association, Aretuse 2, EE61411 Märja, Tartumaa, Estonia
*Correspondence: aarne.poldvere@emu.ee

Abstract:

The aim of the study was to evaluate the influence of low-temperature heat treatment on the physical and technological properties of pork. The Longissimus thoracis muscles from four pigs were used to determine the quality indicators of pork at 24 hours after slaughtering. Meat samples were cooked at constant 120 °C in a cooking bag until the internal temperatures of 62, 67, 72, 77 and 82 °C. Raw meat was the darkest and differed considerably (P < 0.05) from the heat-treated meat. The colour values of the heat-treated meat differed slightly among internal temperature phases. The ultimate pH value of raw meat also differed significantly (P < 0.05) from that of cooked meat. The pH value of cooked meat varied only within the range of 0.05 units. The electrical conductivity of muscle decreased gradually as the temperature increased. In case of heat-treated meat, the cooking loss increased considerably (from 18.88% to 31.73%) along with the increase in the internal temperature. The Warner-Bratzler shear force value was the highest (38.50 N) in the meat cooked until 77 °C, and the lowest (28.51 N) in that cooked until 67 °C. Strong negative correlation (P < 0.001) between electrical conductivity and cooking loss was observed during the heating procedure. Heat treatment can significantly decrease the electrical conductivity and increase the cooking loss of meat. Meat was the toughest when the internal temperature was 77 °C. However, the best rheological properties were observed in the meat cooked until the internal temperature of 72 °C.

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629-638 R. Chotěborský and M. Linda
FEM based numerical simulation for heat treatment of the agricultural tools
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FEM based numerical simulation for heat treatment of the agricultural tools

R. Chotěborský¹ and M. Linda²⋅*

¹Czech University of Life Sciences in Prague, Faculty of Engineering, Department of Material Science and Manufacturing Technology, Kamýcka 129, CZ-16521 Praha – Suchdol, Czech Republic 2Czech University of Life Sciences in Prague, Faculty of Engineering, Department of Electrical Engineering and Automation, Kamýcka 129, CZ-16521 Praha – Suchdol, Czech Republic; *Correspondence: linda@tf.czu.cz

Abstract:

Quenching as a heat treatment method is commonly used to control the mechanical properties of steels. This article deals with the modelling and simulation of quenching of steel chisel using a multi–phase model. The process of the heat treatment is non stationary phase due to temperature variation with time. In this study, the problem of heat transfer in three dimensional phase was transformed into a two dimensional axisymmetric case. ElmerFem solver was used for the heat transfer through different cooling media such as water, oil and salt bath. The results from heat solver were used for austenite transformation modelling by applying Johnson–Mehl–Avrami–Kolmogorov equation in TTT diagram. The Scheill’s decomposition was used for anisothermal transformation of austenite. The hardness prediction was done according to simple mixture rule where total hardness of the steel was calculated based on volume of the phases and their Vickers hardness.

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807-812 A. Sats, H. Mootse, L. Lepasalu and V. Poikalainen
Use of Delvotest T for Quantitative Estimation of β-lactam Antibiotic Residues in Waste Milk and for Evaluation of Thermal Treatment Efficiency – a Methodical Pilot Study
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Use of Delvotest T for Quantitative Estimation of β-lactam Antibiotic Residues in Waste Milk and for Evaluation of Thermal Treatment Efficiency – a Methodical Pilot Study

A. Sats*, H. Mootse, L. Lepasalu and V. Poikalainen

Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, Department of Food Sciences, Kreutzwaldi ⁵⁶/⁵, EE⁵¹0¹⁴ Tartu, Estonia; *Correspondence: andres.sats@emu.ee

Abstract:

The aim of this work was to study possibilities of using microbiological broad-spectrum inhibitor test (Delvotest T) for express estimation of antibiotic residues in bovine milk. For quantitative estimation the waste-milk samples were stepwise diluted (dilution array) by antibiotic-free milk until negative test result was achieved. Another objective was to evaluate heat treatment efficiency of waste-milk in order to degrade antibiotic residues in it. Heat treatment (in water bath) at ⁹0°C was chosen according to references in literature. In order to study certain drug residue the waste-milk samples were collected at the next milking after medical treatment. Two different drugs were investigated: Carepen and Norocillin. Preliminary results indicated that the average concentration of antibiotic residue (active substance of drugs) exceeded European MRL (Maximum Residue Limit) ⁴,¹00 (± ²,⁴0⁸) and ¹³.0 (± ⁵.⁷) times respectively. The average heat treatment duration at ⁹0°C (until negative test result of Delvotest T) was ¹⁵.0 (± ⁵.0) and ⁷.⁸ (± ¹.⁵) hours respectively.

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815-826 M. Musto and M. L. Satriano
Fruit responses to postharvest heat treatment time: characterisation of heat-treated strawberry (Fragaria x ananassa) cv. ‘Candonga’ fruits
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Fruit responses to postharvest heat treatment time: characterisation of heat-treated strawberry (Fragaria x ananassa) cv. ‘Candonga’ fruits

M. Musto¹ and M. L. Satriano²

¹Metapontum Agrobios S.r.l., s.s. 106 Jonica Km 448.2, 75010 Metaponto (MT), Italy;
e-mail: mauro.musto@gmail.com
²Freelance researcher

Abstract:

Strawberries cv. ‘Candonga’ were heat-treated in an air oven (45°C) for 0.2 and 4 h,
and then stored at 0°C for 2 days. One-way ANOVA revealed significant differences in terms of
physical and chemical quality properties due to heat treatment time (P=0.000). In particular, as
treatment time increased, strawberries showed a significant decrease of weight, firmness,
redness (a*), yellowness (b*) and colour saturation (chroma). Additionally, the fruits were
darker (lower L* value) after 2 h of treatment and lighter after 4 h (higher L* value). Among
chemical quality properties, ph and soluble solids content (SSC) increased during treatments,
whereas vitamin C content (TAA) decreased. After 4 h of treatment, total anthocyanins and total
soluble phenolics (TSP) significantly decreased and increased, respectively. Principal
component analysis (PCA) was executed on the correlation matrix of significant variables. Two
principal components were extracted, explaining the 73.38% of the data variance. PC1 (60.15%
variance) was associated with most of the physical and chemical variables, whereas PC2
(13.23% variance) was associated with fruit lightness. PCA was found to be of value in
obtaining a visual representation of fruit samples based on heat treatment time.

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