CHARACTERIZATION OF OLEOGELS OBTAINED BY ENRICHING WITH VARIOUS ESSENTIAL OILS AND THEIR USE IN FUNCTIONAL BISCUIT PRODUCTION

Project no. 31862 · Status: Kapanmış · 2023

Summary

<p>The&nbsp;aim&nbsp;of&nbsp;this&nbsp;thesis&nbsp;was&nbsp;to&nbsp;develop&nbsp;olive&nbsp;oil–based&nbsp;oleogels&nbsp;as&nbsp;healthier&nbsp;alternatives&nbsp;to&nbsp;saturated&nbsp;and&nbsp;trans&nbsp;fats&nbsp;by&nbsp;incorporating&nbsp;essential&nbsp;oils&nbsp;(orange,&nbsp;lemon,&nbsp;and&nbsp;cinnamon)&nbsp;and&nbsp;natural&nbsp;waxes&nbsp;(beeswax&nbsp;and&nbsp;carnauba&nbsp;wax),&nbsp;and&nbsp;to&nbsp;optimize&nbsp;their&nbsp;production&nbsp;parameters&nbsp;to&nbsp;obtain&nbsp;oleogels&nbsp;with&nbsp;maximum&nbsp;oil-binding&nbsp;capacity,&nbsp;maximum&nbsp;firmness&nbsp;and&nbsp;cohesiveness,&nbsp;and&nbsp;minimum&nbsp;peroxide&nbsp;values.&nbsp;These&nbsp;oleogels&nbsp;were&nbsp;further&nbsp;evaluated&nbsp;as&nbsp;potential&nbsp;fat&nbsp;replacers&nbsp;in&nbsp;biscuit&nbsp;formulations,&nbsp;with&nbsp;the&nbsp;objective&nbsp;of&nbsp;producing&nbsp;functional&nbsp;and&nbsp;health-promoting&nbsp;bakery&nbsp;products.</p><p>In&nbsp;the&nbsp;first&nbsp;stage&nbsp;of&nbsp;the&nbsp;study,&nbsp;the&nbsp;Response&nbsp;Surface&nbsp;Methodology&nbsp;(RSM)&nbsp;employing&nbsp;a&nbsp;Box–Behnken&nbsp;Design&nbsp;(BBD)&nbsp;was&nbsp;used.&nbsp;The&nbsp;optimized&nbsp;oleogels&nbsp;were&nbsp;characterized&nbsp;through&nbsp;physical,&nbsp;chemical,&nbsp;structural,&nbsp;thermal,&nbsp;textural,&nbsp;and&nbsp;rheological&nbsp;analyses,&nbsp;and&nbsp;their&nbsp;storage&nbsp;stability&nbsp;was&nbsp;monitored&nbsp;for&nbsp;three&nbsp;months&nbsp;at&nbsp;4&nbsp;°C.&nbsp;Rheological&nbsp;analysis&nbsp;revealed&nbsp;that&nbsp;all&nbsp;oleogels&nbsp;exhibited&nbsp;viscoelastic&nbsp;behavior&nbsp;with&nbsp;high&nbsp;storage&nbsp;modulus&nbsp;(G′)&nbsp;and&nbsp;low&nbsp;loss&nbsp;modulus&nbsp;(G″)&nbsp;values,&nbsp;indicating&nbsp;a&nbsp;pronounced&nbsp;gel-like&nbsp;structure.&nbsp;Firmness&nbsp;and&nbsp;cohesiveness&nbsp;increased&nbsp;during&nbsp;storage.&nbsp;Fourier&nbsp;Transform&nbsp;Infrared&nbsp;(FTIR)&nbsp;spectroscopy&nbsp;confirmed&nbsp;the&nbsp;structural&nbsp;features&nbsp;of&nbsp;both&nbsp;waxes&nbsp;and&nbsp;essential&nbsp;oils&nbsp;within&nbsp;the&nbsp;oleogel&nbsp;matrix.&nbsp;X-ray&nbsp;Diffraction&nbsp;(XRD)&nbsp;results&nbsp;showed&nbsp;diffraction&nbsp;peaks&nbsp;at&nbsp;around&nbsp;4.12&nbsp;Å&nbsp;and&nbsp;3.70&nbsp;Å,&nbsp;corresponding&nbsp;to&nbsp;the&nbsp;β′&nbsp;crystal&nbsp;form,&nbsp;which&nbsp;is&nbsp;associated&nbsp;with&nbsp;the&nbsp;desirable&nbsp;smooth&nbsp;and&nbsp;creamy&nbsp;texture&nbsp;of&nbsp;oleogels.&nbsp;Differential&nbsp;Scanning&nbsp;Calorimetry&nbsp;(DSC)&nbsp;demonstrated&nbsp;that&nbsp;the&nbsp;oleogels&nbsp;could&nbsp;regain&nbsp;their&nbsp;solid&nbsp;structure&nbsp;after&nbsp;heating,&nbsp;maintaining&nbsp;their&nbsp;thermal&nbsp;stability.&nbsp;Nuclear&nbsp;Magnetic&nbsp;Resonance&nbsp;(NMR)&nbsp;and&nbsp;oxidation&nbsp;analyses&nbsp;indicated&nbsp;that&nbsp;essential&nbsp;oil–enriched&nbsp;oleogels&nbsp;exhibited&nbsp;good&nbsp;oxidative&nbsp;stability&nbsp;throughout&nbsp;storage.&nbsp;During&nbsp;storage,&nbsp;limonene&nbsp;and&nbsp;cinnamaldehyde&nbsp;levels&nbsp;decreased&nbsp;by&nbsp;approximately&nbsp;9–11%.&nbsp;In&nbsp;olive&nbsp;oil,&nbsp;the&nbsp;α-tocopherol&nbsp;content&nbsp;decreased&nbsp;from&nbsp;140.77&nbsp;mg/kg&nbsp;at&nbsp;day&nbsp;0&nbsp;to&nbsp;81.32&nbsp;mg/kg&nbsp;at&nbsp;day&nbsp;90&nbsp;(≈&nbsp;42%&nbsp;loss),&nbsp;whereas&nbsp;the&nbsp;lowest&nbsp;reduction&nbsp;was&nbsp;observed&nbsp;in&nbsp;the&nbsp;orange&nbsp;essential&nbsp;oil–beeswax&nbsp;oleogel&nbsp;(PBO),&nbsp;decreasing&nbsp;from&nbsp;136.66&nbsp;mg/kg&nbsp;to&nbsp;106.81&nbsp;mg/kg&nbsp;(≈&nbsp;22%&nbsp;loss).&nbsp;The&nbsp;decrease&nbsp;observed&nbsp;in&nbsp;the&nbsp;other&nbsp;oleogels&nbsp;was&nbsp;also&nbsp;lower&nbsp;than&nbsp;that&nbsp;of&nbsp;pure&nbsp;olive&nbsp;oil.</p><p>In&nbsp;the&nbsp;second&nbsp;stage,&nbsp;the&nbsp;optimized&nbsp;oleogels&nbsp;were&nbsp;used&nbsp;in&nbsp;biscuit&nbsp;production,&nbsp;and&nbsp;the&nbsp;resulting&nbsp;samples&nbsp;were&nbsp;compared&nbsp;with&nbsp;control&nbsp;biscuits&nbsp;prepared&nbsp;with&nbsp;margarine.&nbsp;The&nbsp;biscuits&nbsp;were&nbsp;analyzed&nbsp;on&nbsp;days&nbsp;0,&nbsp;21,&nbsp;42,&nbsp;and&nbsp;63&nbsp;of&nbsp;storage&nbsp;for&nbsp;their&nbsp;physical,&nbsp;chemical,&nbsp;textural,&nbsp;sensory,&nbsp;and&nbsp;oxidative&nbsp;stability&nbsp;properties.&nbsp;Biscuits&nbsp;formulated&nbsp;with&nbsp;oleogels&nbsp;exhibited&nbsp;greater&nbsp;diameter&nbsp;(54.42–57.21&nbsp;mm),&nbsp;thickness&nbsp;(8.86–9.97&nbsp;mm),&nbsp;and&nbsp;spread&nbsp;ratio&nbsp;(5.55–6.15)&nbsp;compared&nbsp;with&nbsp;the&nbsp;control.&nbsp;They&nbsp;showed&nbsp;lower&nbsp;hardness&nbsp;and&nbsp;fracturability,&nbsp;indicating&nbsp;a&nbsp;soft&nbsp;yet&nbsp;crisp&nbsp;texture.&nbsp;Margarine-based&nbsp;biscuits&nbsp;contained&nbsp;significantly&nbsp;higher&nbsp;saturated&nbsp;and&nbsp;trans&nbsp;fatty&nbsp;acid&nbsp;contents.&nbsp;Sensory&nbsp;evaluation&nbsp;results&nbsp;revealed&nbsp;that&nbsp;biscuits&nbsp;containing&nbsp;orange&nbsp;and&nbsp;lemon&nbsp;essential&nbsp;oils&nbsp;received&nbsp;higher&nbsp;scores&nbsp;in&nbsp;taste,&nbsp;texture,&nbsp;and&nbsp;overall&nbsp;acceptability.</p><p>These&nbsp;findings&nbsp;demonstrate&nbsp;that&nbsp;essential&nbsp;oil–enriched&nbsp;oleogels&nbsp;represent&nbsp;promising&nbsp;structuring&nbsp;and&nbsp;fat-replacement&nbsp;systems,&nbsp;capable&nbsp;of&nbsp;improving&nbsp;the&nbsp;technological,&nbsp;oxidative,&nbsp;and&nbsp;sensory&nbsp;quality&nbsp;of&nbsp;bakery&nbsp;products&nbsp;while&nbsp;providing&nbsp;healthier&nbsp;lipid&nbsp;profiles&nbsp;compared&nbsp;with&nbsp;conventional&nbsp;margarine.</p><p>Keywords:&nbsp;Volatile&nbsp;compounds,&nbsp;antioxidant&nbsp;activity,&nbsp;thermal&nbsp;properties,&nbsp;total&nbsp;phenolic&nbsp;content,&nbsp;α-tocopherol,&nbsp;oxidative&nbsp;stability.</p>

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