doctoral thesis
Determination and prediction of thermal properties of unleavened dough during processing

Sandra Budžaki (2009)
Josip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Department of Process Engineering
Sub-department of Thermodynamics and Reaction Engineering
Metadata
TitleOdređivanje i predviđanje toplinskih svojstava beskvasnih tijesta tijekom procesiranja
AuthorSandra Budžaki
Mentor(s)Bernarda Šeruga
Abstract
Istraživana su toplinska svojstava beskvasnih tijesta AACC (American Association of Cereal Chemists, standardno masno tijesto) i HS (Hard Sweet, standardno slatko tijesto) formulacije, tijesta za kroštule, tijesta za mlince, tijesta od pšeničnog brašna bez dodataka i krumpirovog tijesta tijekom procesiranja na temperaturama od 20 do 150 °C i to koeficijent toplinske vodljivosti, specifični toplinski kapacitet i temperaturna vodljivost, gustoća i temperaturni profil. Izrađen je uređaj za određivanje specifičnog toplinskog kapaciteta koji se temelji na modifikaciji standardne metode miješanja, izrađen je i uređaj za određivanje koeficijenta toplinske vodljivosti na temelju nestacionarnog prijenosa topline. Vrijednosti za prividnu gustoću opadaju s temperaturom unutar dva perioda (do 100 °C i nakon 100 °C). Najviša određena vrijednost prividne gustoće zabilježena je kod uzorka krumpirovog tijesta i iznosi 1,3291 ± 0,0088 g/cm3 na 78,5 °C, dok je najniža vrijednost zabilježena kod tijesta od pšenicnog brašna i iznosi 0,6585 ± 0,0098 g/cm3 na 102,3 °C. Najviša vrijednost za k, određenog s pravocrtnim izvorom topline, zabilježena je kod uzorka krumpirovog tijesta i iznosi 0,5308 W/mK, na 56,7 °C, dok je najniža vrijednost zabilježena kod tijesta standardne HS formulacije i iznosi 0,2675 W/mK na 112,9 °C. Najviša vrijednost za cp, određenog modificiranom metodom miješanja, zabilježena je kod uzorka krumpirovog tijesta i iznosi 4,0775 kJ/kgK, na 58,8 °C, dok je najniža vrijednost zabilježena kod tijesta za kroštule i iznosi 1,4929 kJ/kgK na 35,3 °C. Rezultati cp dobiveni diferencijalnom motridbenom kalorimetrijom predstavljaju ''prividni'' specifični toplinski kapacitet jer dobivene vrijednosti sadržavaju i toplinu koja je potrebna za fizikalno-kemijske i biokemijske promjene koje se događaju pod utjecajem topline. Sapphire metoda nije primjenjiva za određivanje stvarnog cp ispitivanih beskvasnih tijesta. Temperaturna vodljivost dobivena je računski i njene vrijednosti se nalaze unutar intervala od 0,075 do 0,125·10-7 m2/s. Za svako toplinsko svojstvo (k i cp) dane su pojedinačne jednadžbe za svaki tip beskvasnog tijesta, te po jedna jednadžba za predviđanje toplinskog svojstva koja obuhvaća sve ispitivane formulacije beskvasnih tijesta. Pogreška (P) za sve dane jednadžbe i za sva beskvasna tijesta kreće se od 0,008 % do9,28 %.
Keywordsdough thermal conductivity specific heat DSC
Parallel title (English)Determination and prediction of thermal properties of unleavened dough during processing
Committee MembersŽaneta Ugarčić (committee chairperson)
Bernarda Šeruga (committee member)
Srećko Švaić (committee member)
GranterJosip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Lower level organizational unitsDepartment of Process Engineering
Sub-department of Thermodynamics and Reaction Engineering
PlaceOsijek
StateCroatia
Scientific field, discipline, subdisciplineBIOTECHNICAL SCIENCES
Food Technology
Engineering
UDK664
APPLIED SCIENCES. MEDICINE. TECHNOLOGY
Production and preservation of solid foodstuffs
Study programme typeuniversity
Study levelpostgraduate
Study programmeFood Engineering
Academic title abbreviationdr. sc.
Genredoctoral thesis
Language Croatian
Defense date2009-02-06
Parallel abstract (English)
Thermal properties of the unleavened dough AACC (American Association of Cereal Chemists) i HS (Hard Sweet) formulation, dough for kroštule, dough for mlince, dough of wheat flour with no additions and potato dough during processing on temperature from 20 to 150 °C were investigated. The thermal conductivity, specific heat and thermal diffusivity, apparent density and temperature profile were determined. Apparatus for determination of specific heat based on modification of mixing method, and for determination of thermal conductivity based on transient method was specially constructed. The values for apparent density decreased with increasing temperature during two periods (before 100 °C and after 100 °C). The highest value, determined for potato dough, was 1.3291 ± 0.0088 g/cm3 at 78.5 °C, and the smallest value, for dough of wheat flour with no additions, was 0.6585 ± 0.0098 g/cm3 at 102.3 °C. The highest value for k, determined by transient method, was 0.5308 W/mK at 56.7 °C for potato dough and the smallest value was 0.2675 W/mK at 112.9 °C for standard HS dough. The highest value for cp, determined by mixing method, was 4.0775 kJ/kgK at 58.8 °C for potato dough and the smallest value was 1.4929 kJ/kgK at 35.3 °C for dough for kroštule. The values for cp determined by DSC (Differential Scanning Calorimetry) in the first run present the apparent specific heat which includes heat for temperature change and a heat for physical, chemical and biochemical changes. Due this, the sapphire method is not suitable for determination of true cp. Thermal diffusivity was determined by calculation method and ranged from 0.075 to 0.125·10-7 m2/s. Prediction equations for thermal properties were proposed for each dough and within few temperature intervals. Also, separate equations were proposed for each thermal property which refers to all dough’s formulation within few temperature intervals. Mean relative error (P) was for given prediction models for all unleavened dough range from 0.008 to 9.28%.
Parallel keywords (Croatian)tijesto koeficijent toplinske vodljivosti specifični toplinski kapacitet DSC
Extent145 str.; 30 cm
Versionaccepted version
Resource typetext
Access conditionAccess restricted to students and staff of home institution
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
Noteaccepted version
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:109:890920
CommitterIvana Šuvak