master's thesis
Effect of extrusion parameters of corn grits on rheological properties of extrudates

Mariana Pavoković (2012)
Josip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Department of Food Technologies
Sub-department of Carbohydrates Technology
Metadata
TitleUtjecaj parametara ekstruzije kukuruzne krupice na reološka svojstva ekstrudata
AuthorMariana Pavoković
Mentor(s)Jurislav Babić (thesis advisor)
Abstract
Ekstruzija je suvremeni postupak obrade različitih vrsta sirovina i proizvodnje širokog spektra prehrambenih proizvoda, pri čemu se kao osnovna sirovina često koristi kukuruzna krupica. Cilj ovog rada bio je utvrditi utjecaj parametara ekstruzije kukuruzne krupice na reološka svojstva ekstrudata. Kukuruzna krupica vlažnosti 15 % i 20 % ekstrudirana je na laboratorijskom jednopužnom ekstruderu Brabender 19/20 DN pri temperaturnom profilu 135/170 °C, uz upotrebu puževa konfiguracije 4:1 i 1:1. Dobivenim ekstrudatima ispitana su fizikalna, termofizikalna i reološka svojstva te su rezultati uspoređeni sa kontrolnim neekstrudiranim uzorcima kukuruzne krupice. Istraživanjem je utvrđeno da je ekspanzijski omjer veći kod ekstruzije pužem 4:1 i pri nižem sadržaju vlage. Nasipna masa je veća kod ekstruzije s većim sadržajem vlage i upotrebom puža konfiguracije 1:1. Moć upijanja kukuruzne krupice povećala se nakon provedenog procesa ekstruzije kod svih uzoraka, a ekstruzija je imala značajan utjecaj i na reološka svojstva, pri čemu se viskoznost vrha smanjila kod svih uzoraka nakon provedenog procesa ekstruzije. Većina uzoraka je pokazala dobru stabilnost tijekom miješanja na visokoj temperaturi, što se može zaključiti iz niskih vrijednosti kidanja, dok „setback“ vrijednosti pokazuju da su neekstrudirani uzorci kukuruzne krupice najskloniji retrogradaciji.
Keywordsextrusion grits corn grits rheological properties
Parallel title (English)Effect of extrusion parameters of corn grits on rheological properties of extrudates
Committee MembersDrago Šubarić
Jurislav Babić
Đurđica Ačkar
Mirela Kopjar
GranterJosip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Lower level organizational unitsDepartment of Food Technologies
Sub-department of Carbohydrates Technology
PlaceOsijek
StateCroatia
Scientific field, discipline, subdisciplineBIOTECHNICAL SCIENCES
Food Technology
Engineering
Study programme typeuniversity
Study levelgraduate
Study programmeFood Engineering
Academic title abbreviationmag. ing. techn. aliment.
Genremaster's thesis
Language Croatian
Defense date2012-07-12
Parallel abstract (English)
Extrusion is a modern procedure for processing different types of raw materials and production a wide range of food products, where corn grits are often used as main raw materials. The aim of this study was to determine the effect of extrusion parameters of corn grits on the rheological properties of extrudates. Corn grits with 15% and 20% moisture content were extruded on a laboratory single screw extruder Brabender 19/20 DN, at temperature profile 135/170 °C, using screws with compression ratio 4:1 and 1:1. Physical, rheological and thermophysical properties of the obtained extrudates were determinated, and results were compared with control samples of nonextruded corn grits. The results showed that the expansion ratio is higher at extrusion with screw 4:1 and at a lower moisture content. Bulk density was higher in extrusion with higher moisture content and with use of screw 1:1. Water absorption index increased after extrusion for all samples, and extrusion had a significant effect on the rheological properties, where the peak viscosity decreased in all samples after extrusion. Majority of samples showed good stability during mixing at high temperature, what can be concluded from the low values of breakdown, while “setback” values indicate that the nonextruded corn grits most tends to retrogradation.
Parallel keywords (Croatian)ekstruzija krupica kukuruzna krupica reološka svojstva
Resource typetext
Access conditionAccess restricted to students and staff of home institution
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:109:973988
CommitterSanda Hasenay