Összes szerző

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Vozáry Eszter

az alábbi absztraktok szerzői között szerepel:

Homolya Szabolcs
Preliminary Experiments for the Rheological Study of Oleogels

Aug 29 - kedd

15:30 – 17:00

I. Poszterszekció

P13

Preliminary Experiments for the Rheological Study of Oleogels

Szabolcs Homolya¹, Katalin Badakné Kerti¹, Eszter Vozáry², Tímea Kaszab² and Anikó Lambertné Meretei¹

^1,2 Hungarian University of Agriculture and Life Science, Institute of Food Science and Technology

¹Department of Grain and Industrial Crops

²Department of Food Industrial measurements and Control

Due to deforestation to expand oil palm plantations and the many negative health effects of palm oil, the food industry needs other alternative sources of fats to replace palm oil. In our research, we investigated blends of fully hydrogenated rapeseed oil and non-hydrogenated high oleic sunflower oil, as well as beeswax and high oleic sunflower oil as possible oleogel alternatives. Oleogels are gelled forms of vegetable oils. Gelling agents can be waxes or proteins. The rheological properties of these oleogels were compared with the rheological properties of palm oil and a commercially available confectionery fat.

The rheological measurements were performed on the following materials: Unfractionated palm oil, Chocofill confectionery fat, Blends of fully hydrogenated rapeseed oil and non-hydrogenated high oleic sunflower oil: 25 m/m% rapeseed oil + 75 m/m% sunflower oil; 30 m/m% rapeseed oil + 70 m/m% sunflower oil; 35 m/m% rapeseed oil + 65 m/m% sunflower oil and Beeswax and high oleic sunflower oil mixture: 85 m/m% sunflower oil + 15 m/m% beeswax.

The flow curve in the shear rate range 0,1 to 100 1/s, as well storage (G’) and loss (G”) modules of oleogels, palm oil and confectionery fat were determined with an Anton-Paar MCR302 oscillatory rheometer. The flow curves were approximated with the Hershel-Bulkley and Casson model using the Excel Solver program. The linear viscoelastic limit was determined from the curves obtained by amplitude sweeping.

The confectionary fat showed rheological similarity with palm oil, however, this type of sample was the furthest from the rapeseed-sunflower and beeswax-sunflower blends in rheological properties. Based on the data analyses and the characteristics of the substitute blends, the sample containing 35% fully hydrogenated rapeseed oil and beeswax oleogel might be suitable as palm oil substitutes, but further studies are needed to determine this statement.

Somogyi Tamás
Variation of Electrical Impedance Parameters of Dry Crops during Soaking

Aug 29 - kedd

15:30 – 17:00

I. Poszterszekció

P25

Variation of Electrical Impedance Parameters of Dry Crops during Soaking

Tamás Somogyi, Eszter Vozáry and Viktória Zsomné Muha

Hungarian University of Agriculture and Life Science, Institute of Food Science and Technology

Department of Food Industrial Measurements and Control

When processing nutritionally important dry pulses such as beans, soaking is one of the most important preparatory steps. As this process is relatively time-consuming. However, this long soaking time can be reduced by ultrasound.

The experiments were performed on red kidney beans (Phaseolus vulgaris cv. Rampart). Prior to the actual sample preparation, beans were manually sorted into four groups according to their size (S - small ≤ 13 mm; M - medium = 13 - 15 mm; L – large = 15 - 17 mm; X - extra-large ≥ 17 mm).

For the ultrasound treatments we used an ultrasonic bath (HBM Machines, The Netherlands). The treatments applied were performed at 40 kHz 300 W at 20 °C.

The magnitude and phase angle of the impedance of the beans were measured in the frequency range of 30 Hz - 30 MHz with an HP4284A and HP4285A precision LCR meters at a measuring voltage of 1 V in an HP16451 B test fixture. To achieve a good electrical contact, an ECG electrically conductive gel was placed between the bean shell and the electrode.

As the soaking time increased, the magnitude of the impedance decreased, which may indicate that the increased water content reduced the viscosity and thus increased the mobility of the charges, resulting in a decrease in resistance and impedance.

This reduction is also clearly visible in the ultrasonic treatments compared to the control samples.

The phase angle spectrum shifted towards lower frequencies, which in turn may be a result of the destructive effect of ultrasound. The effect of the treatments shifts the minimum point around 31 kHz towards lower frequencies. The longer the soaking time, the lower the impedance value and the more the ultrasound-induced structure damage was well detected. These suggest that it may be possible to qualify the structural condition of the soaked dry structures.

Vozáry Eszter
Effect of Weight Loss on the Electrical Impedance Parameters of Lettuce and Iceberg Lettuce Stored at Room Temperature

Aug 30 - szerda

15:30 – 17:00

II. Poszterszekció

P34

Effect of Weight Loss on the Electrical Impedance Parameters of Lettuce and Iceberg Lettuce Stored at Room Temperature

Eszter Vozáry, Bíborka Gillay

Hungarian University of Agriculture and Life Science, Institute of Food Science and Technology

Department of Food Industrial Measurements and Control

We bought the lettuce and iceberg lettuce at the local market. The leaves were stored at room temperature. The weight loss of the leaves was measured with a scale. The electrical impedance spectra were determined with HP4284A and 4285A precision LCR meters in the frequency range of 30 Hz to 30 MHz. At a measuring voltage of 1 V, the magnitude and phase angle of the electrical impedance were measured. The measured spectra were corrected with the stray inductance and capacitance values. A homemade needle electrode and ECG electrodes were used for the measurement. The initial moisture content of the leaves was determined from samples dried to constant weight in an oven at 110°C. Both the impedance measurement and the weight measurement were performed at room temperature for each leaf for 10 minutes over 4-5 hours until the leaf completely withered. The measured impedance spectra were approximated with three distributed elements connected in series. We determined the resistance and capacity of the elements of the model circuit, as well as the relaxation time. The change in the obtained parameters followed well the weight loss, i.e. the change in the water content of the leaf.