Author(s):
1. Grujić Radoslav, Republic of Srpska, Bosnia and Herzegovina
2. Danica Savanovic, UNIBL, Republic of Srpska, Bosnia and Herzegovina
3. Sladjana Rakita, Institute of Food Technology, University of Novi Sad, Serbia
4. Mirko Dobrnjac, Mašinski fakultet Univerziteta u Banjoj Luci, Republic of Srpska, Bosnia and Herzegovina

Abstract:
Sažetak: Tokom smrzavanja i skladištenja hrane u smrznutom stanju dešavaju se različite promjene. Vrsta i intenzitet promjena zavise od različitih faktora. Diferencijalna skenirajuća kalorimetrija (DSC) omogućava brzo određivanje termo-fizičkih svojstava koja opisuju promjenu stanja prehrambenih proizvoda tokom smrzavanja i odmrzavanja. Cilj ovog rada je bio da se korištenjem diferencijalne skenirajuće kalorimetrije ispita uticaj brzine skeniranja na toplotna svojstva voća i povrća (jabuka, krompir i mrkva). Pri brzini skeniranja od 10 °C/min ustanovljene su statistički značajne razlike (p<0,05) između vrijednosti toplotnih svojstava ispitivanih uzoraka voća i povrća. Temperatura staklastog prelaza (Tg), pri brzini 10 °C/min, je iznosila -9,20 ºC za jabuku, -5,67 ºC za krompir i -8,23 ºC za mrkvu. Kod uzorka svježeg krompira povećanjem brzine hlađenja ustanovljena je značajna promjena (p<0,05) entalpije kristalizacije (ΔHc) od -195,77 J/g (brzina 5°C/min) do -234,07 J/g (brzina 15°C/min). Tokom fazne promjene topljenja u uzorcima svježeg krompira sa povećanjem brzine zagrijavanja od 5 do 15°C/min ustanovljeno je značajno povećanje vrijednosti entalpije topljenja (ΔHm), i to od 192,90 J/g do 238,27 J/g. Kod istog uzorka promjenom brzine zagrijavanja od 5 do 15°C/min došlo je do statistički značajanog povećanja (p<0,05) temperature pika krive topljenja (Tm), kao i do povećanja temperature završetka fazne promjene topljenja (Tmend). Abstract: During the freezing and storage of food in frozen state, different changes occur. The type and intensity of changes depend on different factors. Differential Scanning Calorimetry (DSC) enables rapid determination of thermo-physical properties that describe state changes of food products during freezing and thawing. The aim of this study was to test the influence of scanning rate on the thermal properties of fruits and vegetables (apple, potato and carrot), using the differential scanning calorimetry method. For the scanning rate 10 °C/min, statistically significant differences (p<0.05) were found between the values of thermal properties of the tested fruits and vegetables samples. The glass transition temperature (Tg) for the rate 10 °C/min was -9.20 ºC for apple, -5.67 ºC for potato and -8.23 ºC for carrot. In the fresh potato sample by increasing the cooling rate, a significant change (p<0.05) of the crystallization enthalpy (ΔHc) from -195.77 J/g (rate 5 °C/min) to -234.07 J/g (rate 15 °C/min) was established. During the melting phase change in fresh potato samples, with increasing the heating rate from 5 to 15 °C/min a significant increase of the melting enthalpy (ΔHm) was observed, from 192.90 J/g to 238.27 J/g. In the same sample, the change in the heating rate from 5 to 15 °C/min resulted in a statistically significant increase (p<0.05) of the peak melting temperature (Tm), as well as the increase of the end melting temperature (Tmend).

Key words:
Voće i povrće,Toplotna svojstva,Staklasto stanje,DSC / Fruits and Vegetables,Thermal properties,glass transition,DSC

Thematic field:
SYMPOSIUM B - Biomaterials and nanomedicine

Date of abstract submission:
03.06.2018.

Conference:
Contemporary Materials 2018 - Savremeni Materijali

Applied paper from author Final paper