magistrsko delo
Nina Berglez (Author), Nataša Šegatin (Reviewer), Lea Demšar (Mentor)

Abstract

Cvrtje je eden najstarejših, najhitrejših in najpreprostejših načinov toplotne obdelave hrane, katerega problem je hitro poslabšanje kakovosti in povečanje stopnje oksidacije olj med cvrtjem pri 160 °C. Namen naloge je bil določiti primernost alternativnih olj (arašidovo, konopljino, laneno in sezamovo olje ter sončničnega kot kontrole) v povezavi z njihovo senzorično kakovostjo in maščobnokislinsko sestavo po večkratnem, trikratnem zaporednem cvrtju kroglic v modelnem sistemu. Izmerili smo sestavo hranilnih snovi v svežih govejih mesnih kroglicah (NIR) in izgubo mase po vsakem cvrtju. Na oljih in mesnih kroglicah smo določili točko dimljenja, maščobnokislinsko sestavo (GC) in število tiobarbiturne kisline (TBK, spektrofotometrično) ter senzorično analizirali olja (opisna analiza) po treh zaporednih cvrtjih. Stabilnost uporabljenih olj je odvisna od točke dimljenja (sezamovo 164 °C, konopljino 171 °C, laneno 175 °C in arašidovo olje 184 °C) in števila TBK, ki se po zaporednem cvrtju v oljih (arašidovo in sezamovo < sončnično < laneno in konopljino olje) in mesnih kroglicah poviša, ter je v povezavi z maščobnokislinsko sestavo olj (na splošno višji delež večkrat nenasičenih maščobnih kislin pomeni višjo stopnjo oksidacije med cvrtjem). Z zaporednim cvrtjem se spremeni maščobnokislinska sestava olj in mesnih kroglic, po prvem cvrtju se v oljih za cvrtje poviša delež enkrat nenasičenih in zniža delež večkrat nenasičenih maščobnih kislin, pri nadaljnjih cvrtjih se maščobnokislinska sestava ne spreminja pomembneje, vrsta olja vpliva na maščobnokislinsko sestavo mesnih kroglic po prvem cvrtju. Po zaporednem cvrtju se poslabšajo senzorične lastnosti uporabljenih olj. Vse vrste hladno stiskanih olj niso enako primerne za cvrtje, po primernosti si sledijo sezamovo > arašidovo > sončnično olje > konopljino > laneno olje. S prehranskega in zdravstvenega stališča ugotavljamo, da sta za uživanje najbolj primerna laneno in konopljino olje, če se uporabita hladna in ne v ostrih postopkih toplotne obdelave.

Keywords

cvrtje;olja;mesne kroglice;maščobe;rastlinska olja;večkratno cvrtje;maščobnokislinska sestava;senzorične lastnosti;točka dimljenja;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL BF - Biotechnical Faculty
Publisher: [N. Berglez]
UDC: 641.522.2:664.35
COBISS: 74042371 Link will open in a new window
Views: 372
Downloads: 81
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Other data

Secondary language: English
Secondary title: Suitability of alternative oils for frying foods
Secondary abstract: Deep frying is one of the oldest, quickest and easiest ways of heat treating food, the problem of which is the rapid deterioration of the quality and stability of the oils during deep frying. The aim of this work was to determine the suitability of alternative oils (peanut, hemp, flaxseed and sesame oils, sunflower as control) in terms of their sensory quality and fatty acid composition after multiple, three consecutive deep-frying of meatballs in the model system. The nutrient composition in fresh beef meatballs (NIR) and weight loss after each frying were measured. Smoke point of used oils, as well as fatty acid composition (GC) and thiobarbituric acid number (TBA, spectrophotometric) were determined on oils and meatballs after three consecutive frying, additionally oils were also sensory analysed (descriptive analysis). The stability of the used oils depended on the smoke point of the oil (sesame 164 °C, hemp 171 °C, flaxseed 175 °C and peanut oil 184 °C) and the TBA number, which increased after consecutive frying in oils and meatballs (peanut and sesame < sunflower < flaxseed and hemp oil). The TBA number was related to the fatty acid composition of used oils (in general, a higher proportion of polyunsaturated fatty acids means poorer stability during frying). Consecutive deep frying changes the fatty acid composition of oils and meatballs. After the first frying the proportion of monounsaturated fatty acid in frying oils increases and the proportion of polyunsaturated fatty acid decreases. After successive frying, the sensory properties of the used oils deteriorate. Not all types of cold-pressed oils are equally suitable for deep-frying; regarding suitability, the oils follow each other in the following order: sesame > peanut > sunflower oil > hemp > flaxseed oil. From a nutritional and health point of view, flaxseed and hemp oil are the most suitable for consumption, of course if used cold and not in harsh heat treatment processes.
Secondary keywords: frying;oils;meatballs;fat;vegetable oils;repeated frying;fatty acid composition;sensory properties;smoke point;
Type (COBISS): Master's thesis/paper
Study programme: 0
Thesis comment: Univ. v Ljubljani, Biotehniška fak., Oddelek za živilstvo
Pages: XII, 59 f., [13] f. pril.
ID: 13285831