Utjecaj ultrazvuka visokog intenziteta na enzimsku aktivnost i tehnološka svojstva pšeničnih posija

master's thesis

• Title (english): The influence of high-intensity ultrasound treatment on enzyme activity and technological properties of wheat bran
• Author: Marija Gregov
• Mentor: Dubravka Novotni (mentor)
• Committee member: Tomislava Vukušić Pavičić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Food Technology and Biotechnology; (Department of Food Engineering); (Laboratory for Cereal Chemistry and Technology); Zagreb
• Defense date and country: 2020-02-28, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Food Technology

Abstract

Zbog visokog udjela prehrambenih vlakana i bioaktivnih tvari, pšenične posije predstavljaju koristan nusproizvod prehrambene industrije koji doprinosi boljem zdravlju čovjeka. Cilj ovog rada bio je istražiti utjecaj ultrazvuka visokog intenziteta (UVI) na enzimsku aktivnost i tehnološka svojstva pšeničnih posija. Utvrđeno je kako tretman posija UVI smanjuje aktivnost njihovih enzima (polifenol oksidaze, peroksidaze i lipaze) ovisno o udjelu posija u vodenoj suspenziji (15 g vs. 30 g u 100 mL vode). Ultrazvukom obrađene posije, dodane u pšenično brašno, manje narušavaju njegova tehnološka svojstva u odnosu na nativne posije, i to: sposobnost stvaranja glutenske mreže na Glutopeaku i želatinizirajuća svojstva (viskoznost) na mikroviskoamilografu. Posije tretirane UVI povećavaju tvrdoću, gumenost i rezilijenciju krušnog tijesta, dok elastičnost i kohezivnost ostaju nepromijenjeni. Odgođena fermentacija (48 h) smanjuje negativne promjene na tijestu izazvane tretmanom posija. Specifični volumen, oblik, čvrstoća sredine, svjetlina (L*) i intenzitet crvenila (a*) ne ovise o tretmanu, dok se intenzitet žute boje (b*) sredine kruha povećao. Ultrazvučna obrada posija doprinosi njihovoj stabilnosti uspješnom inaktivacijom enzima te poboljšava pojedina tehnološka svojstva čime bi se omogućila veća primjenjivost posija u pekarskoj industriji.

Abstract (english)

Due to the high content of dietary fiber and bioactive substances, wheat bran is a useful by-product of the food industry that contributes to human health. The aim of this study was to investigate the impact of high-intensity ultrasound (HIU) treatment on the enzymatic activity and technological properties of wheat bran. Ultrasound treatment was found to reduce the activity of bran's enzymes (polyphenol oxidases, peroxidases and lipases), depending on the content of the bran in aqueous suspension (15 g vs. 30 g in 100 mL of water). Ultrasound-treated bran in a mixture with wheat flour less impairs its technological properties, namely the ability to form a gluten network on Glutopeak and gelatinizing properties (viscosity) on a microviscoamylograph. Ultrasound treatment increases the hardness, gummyness and resilience of bread dough, while the springiness and cohesiveness remain unchanged. Delayed fermentation (48 h) reduces the negative changes in the dough caused by the treatment of bran. Specific volume, shape, strength of the bread crumb, brightness (L*) and intensity of red color (a*) do not depend on treatment, while the intensity of yellow color (b*) of the bread crumb increased. Ultrasonic processing of bran contributes to their stability for successful inactivation of enzymes and improves individual technological properties, which would allow greater applicability of bran in the bakery industry.

• Keywords: pšenične posije; ultrazvuk visokog intenziteta; tehnološka svojstva; aktivnost enzima
• Keywords (english): wheat bran; high-intensity ultrasound; processing properties; enzyme activity
• Language: croatian
• URN:NBN: urn:nbn:hr:159:677442
• Study programme: Title: Food Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka prehrambenog inženjerstva (magistar/magistra inženjer/inženjerka prehrambenog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-03-02 12:50:16