Aktivacija ksilanaze v moki

magistrsko delo

Tina Mihelčič (Author), Maja Leitgeb (Mentor), Gordana Hojnik Podrepšek (Co-mentor)

Abstract

Moka je osnovno živilo, ki se uporablja pri peki in kuhanju, zato ima širok spekter uporabe. Polnozrnata ržena moka je mleto zrno rži, ki vsebuje endosperm, kalček in zunanje ovoje. Vsebuje veliko proteinov, arabinoksilana in naravno prisotne encime, vsebuje pa manj škroba in glutena, zato je priprava testa težja kot s pšenično moko. V pekarnah pogosto dodajajo encime v testo, da bi zagotovili kakovost in okus izdelkov. Z namenom, da bi zmanjšali porabo encimov kot dodatek k moki za izboljšanje lastnosti testa, smo želeli s tretiranjem moke s superkritičnim ogljikovim dioksidom (scCO2) povišati aktivnost naravno prisotnega encima ksilanaze. Ksilanaza hidrolizira arabinoksilan in poskrbi za večji volumen testa. Zanimalo nas je, katera vrsta moke vsebuje najvišjo aktivnost ksilanaze. V 6 vrstah moke smo izmerili koncentracijo proteinov z metodo po Bradfordu in določili aktivnost ksilanaze. Dalje smo pri različnih pogojih v visokotlačnem reaktorju izpostavili polnozrnato rženo moko scCO2. Nato smo z metodo po Bradfordu določili koncentracijo proteinov in z aktivnostnim testom določili aktivnost ksilanaze. Tekom raziskav smo ugotovili, da je polnozrnata ržena moka vsebovala najvišjo aktivnost encima ksilanaza. Po tretiranju smo ugotovili, da so optimalni pogoji, pri katerih smo dosegli najvišjo aktivnost ksilanaze (120 %), 400 bar in 1 h. Želeli smo ugotoviti vpliv povišane aktivnosti na fizikalno-kemijske lastnosti polnozrnate ržene moke, zato smo ji določili še vsebnost vlage in vsebnost maščob. Vsebnost vlage se je znižala z 12,00 % MC na 11,67 % MC. Tudi vsebnost maščob se je znižala s 3,68 % na 3,43 %. Iz netretirane in s scCO2 tretirane moke smo spekli kruh in mu določili specifični volumen. Ta pa se je zvišal z 1,50 cm3/g na 1,56 cm3/g, kar pomeni, da je višja aktivnost ksilanaze vplivala na večji volumen kruha. Ksilanazo smo uspešno aktivirali, znižala se je vsebnost vlage in vsebnost maščob. Znižanje vsebnosti vlage in maščob pomembno vpliva na mikrobiološko in oksidativno stabilnost, s tem se podaljša tudi rok uporabe moke. Tretiranje moke s ccCO2 je zato dober način povišanja aktivnosti ksilanaze, hkrati pa vplivamo na kakovost moke in kakovost kruha kot končnega izdelka.

Keywords

polnozrnata ržena moka;superkritični CO2;ksilanaza;encimi;arabinoksilani;magistrske naloge;

Data

Language:	Slovenian
Year of publishing:	2022
Typology:	2.09 - Master's Thesis
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
Publisher:	[T. Mihelčič]
UDC:	604.4:577.15:664.641.14(043.2)
COBISS:	130731011
Views:	59
Downloads:	14
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Activation of xylanase in flour
Secondary abstract:	Flour is a basic ingredient in baking and cooking, therefore it has a wide range of uses. Whole grain rye flour is milled rye which contains the endosperm, germ, and bran. It contains a lot of protein, arabinoxylan, and naturally occurring enzymes, but it contains less starch and gluten, which makes it more difficult to prepare the dough as opposed to making a dough with wheat flour. Bakeries often use enzymes when preparing the dough to ensure the right technological properties of the mix together with the quality and taste of the final product. To avoid adding enzymes to the flour, we wanted to increase the activity of the naturally occurring xylanase enzyme. Xylanase hydrolyzes arabinoxylan and provides a greater dough volume. We wanted to establish which type of flour possesses the highest xylanase activity. The protein concentration was measured in 6 types of flour, according to the Bradford method and xylanase activity was determined. Next, whole grain rye flour was exposed to supercritical CO2. We then measured the protein concentration using the Bradford method and determined the xylanase activity using the enzyme activity test. During the research, we found that whole grain rye flour contained the highest activity of the xylanase. After treatment, we found that the optimal conditions under which we achieved the highest xylanase activity (120 %) were 400 bar and 1 h. We wanted to find out the influence of higher enzyme activity on the physicochemical properties of whole grain rye flour, so we also determined its moisture and fat content. The moisture content decreased from 12,00 %MC to 11,67 %MC. The fat content also decreased from 3,68 % to 3,43 %. We baked bread from untreated and scCO2-treated flour and its specific volume was determined. The specific volume increased from 1,50 cm3/g to 1,56 cm3/g, which means that the higher xylanase activity affected the larger volume of the bread. We then baked bread from untreated and scCO2-treated rye flour and measured its specific volume. Xylanase enzyme was successfully activated, and moisture and fat content decreased. Reducing the moisture and fat content significantly affects on the microbiological and oxidative stability, thereby extending the shelf life of the flour. Treating flour with scCO2 is therefore a good way to increase xylanase activity, while at the same time affecting the quality of flour and the quality of bread as a final product.
Secondary keywords:	whole rye flour;supercritical CO2;xylanase;enzymes;arabinoxylans;
Type (COBISS):	Master's thesis/paper
Thesis comment:	Univ. v Mariboru, Fak. za kemijo in kemijsko tehnologijo
Pages:	1 spletni vir (1 datoteka PDF (VIII, 35 f.))
ID:	16265982