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Journal of food physicsVol. 28-29. (2016.)


  • A. S. Szabo ,
    P. Laszlo :

    Abstract: The development and modification of the science, forming and establishment of new fields is a normal process, carried out in general by 2 ways: differentiation and integration. This trend of development is typical for the segments of natural science, as well, including e.g. physics, chemistry, biology. Analysing some special fields of natural science the paper tries to find true answers to the following questions: - what are the dominant parts of food science and applied physics? - is food physics a bridge between applied physics and food science? - what are the factors, influencing the development of food physics? - is food physics an interdisciplinary sub science? - what are the development trends of food physics (Quo Vadis Cibus Physicorum)?

    Keywords: applied physics, food physics a bridge, development of food physics, interdisciplinary food physics,

  • Omer Faruk Gamlih ,
    Tülin Eker ,
    Özge Süfer :
    Convective drying kinetics and phenolic contents of olive leaves14-20en [250.60 kB - PDF]EPA-02408-00009-0040

    Abstract: Olive leaves have considerable amount of “oleuropein” which is a kind of polyphenol. This compound could lower blood pressure, cancer risk and oxidative damage of cells. Because of the health benefits of this excellent antioxidant material, olive leaves are the subject of this study. Results of the research will contribute to information about drying behaviour of and drying impact on olive leaves. Leaves were collected from Olea europaea trees from the garden located in Osmaniye Korkut Ata University, Turkey. After collection, they were washed, waited in room temperature to evaporate residual water and pulverized in a commercial blender. Leaf powders were dried in a conventional oven at 50, 60 and 70°C and the weight changes of samples were recorded manually in every 10 minutes for 50 and 60°C and 5 minutes for 70°C. Moisture ratio values were fitted into 13 different thin layer drying models and Parabolic and Cubic models were the best and had the highest R2 value. On the other hand, total phenolic contents of dried powders were determined with Folin-Ciocalteu method and the highest phenolic amount (633.85 mg / kg gallic acid equivalent) belonged to the 60°C. Colour is accepted as one of the major quality characteristic of leaves and L*, a* and b* values of leaf powders were determined. Temperature had an important effect on a* and b* values of samples (P 0.05).

    Keywords: Olive leave, Drying, Mathematical modelling, Phenolich compound, Color

  • P. Sipos :
    Rheological parameters of cereals21-25en [187.83 kB - PDF]EPA-02408-00009-0050

    Abstract: Rheology is a widely used tool in the qualification of cereals and cereal products. Maybe the most specific rheological analytical equipments were developed and used in the analysis of the dough made from flour and water. It is not a surprise as the dough is a very specific material. The moistened gluten proteins forms a three dimensional network in the dough what is a complex chemical system, and the chemical knowledge of this netwotk is hard to analyse and also hard to translate for the prediction of technological behaviour. On the other hand, the high starch content with the fiber content of the flour and the mechanical properties of the flour modify the usability of dough. The rheological analysis of this complex system is a rapid and practically useful way of qualification. The Farinograph, Alveograph, Extensigraph, Mixograph and Amylograph are specific complex equipments for the quality prediction and this paper will summarize the principles of these methods and their use in the qualification.

    Keywords: cereals, rheology, qualification, wheat flour

  • E. Vozáry ,
    Gy. Csima ,
    L. Csapó ,
    F. Mohos :
    Application of fractional calculus in food rheology26-32en [235.38 kB - PDF]EPA-02408-00009-0060

    Abstract: In fractional calculus the order (β) of differentiation or integration is not an integer number, generally β is a fractional number between 0 and 1. The root of fractional calculus goes back to the 18th century, and this calculus is intensively developing nowadays, too. Application of fractional calculus can be found in rheology, in electrical impedance spectroscopy, in physiological description. It is interesting, that the description of viscoelastic properties of biological material is much more accurate with fractional calculus than with ordinary differentiation and integration. In this work the creeping and recovery curves of a simple sweet, - gum candy –and bread slice, were approached with ordinary and fractional calculus. The rheological parameters of gum candy were determined. The fractional calculus gave better fit on the measured creep recovery curve points, than classical rheology models containing discrete elastic and viscous elements.

    Keywords: fractional calculus, viscoelastic, food, creep, recovery

  • Adnan Bozdoĝan ,
    Kurban Yşar :
    To increase the nutritional value of sahlep33-39en [213.08 kB - PDF]EPA-02408-00009-0070

    Abstract: Innovations on technology and changing consumer expectations forced the development of dairy industry for producing novel products possessing different properties. In recent years, nutritionally enriched functional products have been prepared by the addition of highly valued nutritional compounds to milk. Sahlep, is a milk beverage, not only used as a drinking purpose to keep body the warm but also used for having the benefits of nutritional constituents and alleviating various diseases in Turkey for a long time. Whey proteins, contain, amino acids and various nutritionally high components. In addition, antioxidant, anticarcinogenic and hypocholesterotemic effects are the known some bioactivities. In this study, sahlep milk beverage was supplemented with whey protein concentrate (WPC 35) (1%, 2% and 3%). The pH, viscosity and sensory characteristics were analyzed. When sahlep milk beverage was supplemented with WPC 35 showed no effect on the pH value; however, viscosity was increased. According to sensory evaluations, supplemented with WPC 35 affected on colour, structure, taste and smell properties of sahlep milk beverage. The panelists gave the highest score to sahlep milk beverage supplemented with WPC 35 (3%), which is close to the control. It could be concluded that sahlep supplemented with WPC 35 (3%) could be prepared and suggested as a novel and nutritionally high product.

    Keywords: Sahlep, milk beverage, whey protein concentrate, nutrition, sensory, viscosity

  • A. S. Szabo ,
    M. Izsak :
    Physics experiments in secondary grammar schools40-46en [249.72 kB - PDF]EPA-02408-00009-0080

    Abstract: Teaching of physics (and other branches of natural science, like chemistry, biology) in the schools the experiments are of primary importance (Sprott, 2015).The pupils are satisfied if the investigated materials are food samples, wellknown for them. The paper deals with 3 simple experiments of physical type. The following foodstuffs were investigated: sugar, salt, apple, potato, lemon, egg. For teaching the following experiments were prepared and carried out (Szabo et al., 2015), (Bozi et al., 2016), (Szabo, Izsak, 2016): boiling point measurement in case of sugar and salt (NaCl) solutions for determination of the concentrations creation of galvanic battery using agricultural products, like lemon, potato or apple differentiation between raw (crude) fresh egg and boiled (cooked) egg without cracking (breaking) the egg shell

    Keywords: teaching of physics investigated food materials, boiling point galvanic battery fresh egg and boiled (cooked) egg

  • L. Kubík :
    Statical compressive properties of cultivar golden delicious fruits47-56en [668.07 kB - PDF]EPA-02408-00009-0090

    Abstract: The study is aimed on the experimental evaluation of the apple cultivar Golden Delicious (Malus domestica L.) fruits at statical compressive loading in lateral direction. Mechanical properties such as rupture force and deformation as well as modulus of elasticity can be used to evaluate the behaviour of the fruits mechanically under the static loading. Apparent moduli of elasticity were determined on the base of elastic Hook theory and Hertz theory (ASAE, 2004). A testing machine Andilog Stentor 1000 (Andilog Technologies, Vitrolles, France) was employed for compression tests. The behaviour of the hemisphere of fruit was studied between two parallel plates and the indentation with the flat – faced cylindrical intender of diameter 8 mm and cone intender of diameter 6.4 mm and angle 60 degree was also studied.

    Keywords: apple, compression, modulus of elasticity, rupture point

  • Burcu Bektas ,
    Gülşah Çalışkan ,
    S. Nur Dirim :

    Abstract: Centrifugal freeze concentration is a new technique to obtain the concentrated solution from liquid foods in food industry, which is a method for recovering a food solute from a solution based on the separation of pure ice crystals from a freeze concentrated aqueous phase. The aim of this study was to investigate the concentration of mulberry molasses by the centrifugation freeze concentration method. For this purpose, the mulberry molasses (73.2 oBx) was diluted to different total soluble dry matter contents (20, 25, 30, 35, 40, and 45 oBx) and the method of freeze concentration assisted by centrifugation was applied. The concentrated solution which was obtained after the removal of formed ice by filtration was frozen again at same conditions and same processes were repeated (cycle). The percentage of concentrate, efficiency of concentration and recovered solute values were calculated for each cycle. According to the results of the successive three cycles, the amount of remaining solutions after the removal of ice content decreased and in contrary to increase in total soluble solid content, the concentration efficiency decreased. The percentage of concentrate changed between 79.4% and 94.8% and the recovered solute values reached to 0.80 and 0.93 kg/kg.

    Keywords: Freezing, Freeze Concentration, Centrifuge, Mulberry Molasses

  • Z. Goranova ,
    M. Baeva ,
    S. Stankov ,
    G. Zsivanovits :

    Abstract: Sensory and textural characteristics of sponge cake prepared with different functional ingredients (einkorn wholemeal flour, Jerusalem artichoke powder, cocoa husk powder) in replacement of the part of the wheat flour were investigated during 6 days storage (on the 1st, the 3rd and the 6th day). Descriptive sensory analysis was used to compare the new and the control sponge cakes. The functional ingredients did not produce significant changes in the sensory characteristics of the sponge cakes, except of crumb’s texture. The texture changes are characterised by elastic modulus, hardness and cutting force. These parameters of sponge cakes changed differently during the storage period. During the 6 days storage period the samples with functional ingredients preserved in better way the elastic modulus in comparison with the control sample, because they are more reach in fibre. The sponge cake, containing 20% Jerusalem artichoke powder, keeps their freshness longer time.

    Keywords: sponge cake, functional ingredients, textural characteristics, storage, sensory analysis

  • Tuğçe Türkoğlu ,
    Gülşah Çalışkan ,
    S. Nur Dirim :

    Abstract: In this study, it was intended to determine the soaking behaviour of soybeans. Soybeans are legumes, which, as a family are rich in proteins, carbohydrates, dietary fiber, vitamins, and minerals. In order to obtain the edible form of legumes, they are processed through pretreatments such as soaking, grinding and cooking. The soaking process, which is one of the most important pretreatments, results in gaining water, easiness of the cooking, and reduction of the cooking time. In this study, the effects of different soybean:water ratios (1:2.5, 1:5, 1:10, and 1:20 (weight:weight) (w:w)) and the salt concentrations (1, 2, and 5%) and temperatures of the soaking medium (4, 25, and 80°C) on the total soluble solid content of soaking medium and colour values of the soybeans were examined with their effects on the weight gain of soybeans. According to the results of the analyses, a higher rate of weight gain values was observed for the experiments performed at 80°C. In general, the total soluble solid contents of the soaking medium, which indicates the loss of solids, were found to be inversely proportional to the amount of water both for the experiments in water and brine.

    Keywords: Pre-treatment, soaking, soybeans, weight gain, solid loss

  • S. Stankov ,
    M. Baeva ,
    Z. Goranova ,
    M. Marudova :

    Abstract: The present research investigated the effect of three types of emulsifiers on the starch gelatinization in sponge cake batter. The method of differential scanning calorimetry (DSC) was applied to determine the changes in the gelatinization temperature and the endothermic transition enthalpy during the baking of sponge cake batters. The following 4 samples were examined – control sponge cake, prepared by traditional recipe, sponge cakes with added 1% of one of the following emulsifierspolyglycerol monostearate ester (E475), sucrose stearate ester (E473) and modified inulin palmitate ester (HP-25). It was found that the presence of emulsifier affected both the gelatinization temperature and the phase transition enthalpy. The starch gelatinization in the control was carried out in the lowest temperature range and was characterized with the lowest transition energy (enthalpy of the endothermic transition) - 1.78 J/g. The addition of emulsifiers let to narrowing the temperature range where the gelatinization is observed and to increasing the gelatinization temperature and the transition energy. The most pronounced effect was observed for the samples, which were with the sucrose stearate ester. The transition energy in this case was 2.68 J/g. The results obtained confirmed the emulsifiers retard the starch gelatinization in sponge cake batter.

    Keywords: sponge cake batter, emulsifiers, starch gelatinization, DSC thermograms

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