Influence of carnauba wax concentration on the ......Influence of carnauba wax concentration on the...
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Influence of carnauba wax concentration on the physicochemical properties of olive oil organogels 1. CEB - Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal 2. INL - International Iberian Nanotechnology Laboratory,Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal Email: [email protected] Silva, P. 1 , Fasolin. L. 1 , Martins, A. 1,2 , Vicente, A. A. 1 University of Minho School of Engineering Abstract Methods Conclusions Introduction Edible oils have potential health benefits when compared to saturated and/or trans fats typically used in food products. In order to widen their use as spreadable products, structuring these oils is a requirement. Thus, the aim of this work consisted in the development of an olive-oil organogel, foreseeing its application in the food industry. Olive-oil was used for the production of the organogels, with carnauba wax (CW) as organogelator (1% to 6% (w/w)), solubilized under magnetic stirring (90 °C) and cooled to room temperature. Systems were evaluated regarding oxidation (PV), textural, rheological (flow curves; non-isothermal oscillatory sweeps) and thermal properties. Olive-oil and commercial butter were used as controls. An increase in CW concentration increased the textural parameters. Compared to values of commercial butter, organogels values were lower, indicating a less structured organogel (highest values: firmness of 3.79 N and 10.29 N for organogel and butter respectively; spreadability of 3.17 N/sec and 10.15 N/sec for organogel and butter respectively). Thixotropy, initial viscosity, onset temperature, enthalpy, also showed an increase with increasingly higher CW concentrations. Melting point of organogels was determined and compared with calorimetric analysis. Similar trends were found: an increase in concentration increased the melting point; Regarding oxidative stability (63 days of storage, room temperature, exposed to light), results showed that, while an increase exists, it is within expected values (maximum PV, 1.10 meqO2/kg at 63 days), and all organogel samples were below the PV of olive oil (maximum PV of 1.47 meqO2/kg, at 63 days). Results show that varying gelator concentration, physicochemical properties can be easily changed and tailored, possibly creating a wide range of products. Thus, an industrial application can be easily projected, since olive oil is a healthier alternative to other spreadable products. Results Natural vegetable oils are known to have several benefits in comparison to saturated and/or trans fats. However, these saturated and/or trans fats are generally used in food products as texture modifiers due to their physical properties while healthier edible oils are generally found in a liquid state, therefore limiting its applicability; Therefore, modulating the physicochemical properties by conferring structure to edible oils without changing lipid profile and chemical composition could overcome this lack of structure and allow a greater range of applications The aim of this work was to develop an olive oil organogel, observing how different concentrations of organogelator impacted its characteristics. In order to do so organogels were characterized regarding morphology, physicochemical, thermal, textural and rheological properties. This work can be seen as a possible step in developing an olive oil organogel, foreseeing its application in the food industry. Sample Preparation Physical assessments Phase contrast microscopy Transmittance Spectrum; Transform to CIELAB data TTC Spreadability Rig (HDP/SR) probe; Test speed: 3 mm/s; Post-Test speed: 10 mm/s Flow curves at 25 °C (0.1 to 300 s -1 ), up-down-up step program; Cooling and heating ramps between 90 °C and 5 °C at 10 °C/min, 1 Hz Solubilize carnauba wax (1 % up to 6 % (w/w)) in virgin olive oil at 90 °C during 30 min to ensure full solubilization Heating and cooling ramps from 5 to 90 °C with a 10 °C/min rate; Under nitrogen atmosphere Thermal Analysis Oxidative Stability This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Morphology Color Assessment Rheology Analysis Mechanical properties • Peroxide values were well below both the values of the control samples and the legal limits; • Comparing DSC results and non-isothermal rheology it was possible to see a clear tendency between melting and crystallization peaks; It is clearly seen that an increase in gelator concentration increases initial viscosity and thixotropy and thus creates a stronger 3D network in the organogel. This data and conclusions are supported by the textural results. • These results show that by varying the gelator concentration it is possible to modulate organogels characteristics to target a specific application in the food industry, as a possible replacement or healthier alternative for currently used spreadable products. aA bA cA dA bA eA fA aB bB cB bB dB eB fB 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1% 2% 3% 4% 5% 6% Control meq O 2 /kg T0 T1 Figure 2. Peroxide values of carnauba-virgin olive oil organogels. Different small letters indicate statistical differences between different concentration, while different capital letters indicate statistical differences between different time assessments (p<0.05); T0=0; T1=63 days. 1% 2% 3% 4% 5% 6% Figure 1. Phase contrast micrographs for all carnauba wax-virgin olive oil organogel samples, after organogelation Sample ∆E*ab (T1-T0) 1% 4.058 2% 2.630 3% 4.785 4% 5.057 5% 4.903 6% 5.155 Control 53.964 Sample T0 T1 ∆E*ab (2%-1%) 11.775 9.399 ∆E*ab (3%-2%) 3.172 4.481 ∆E*ab (4%-3%) 4.912 5.874 ∆E*ab (5%-4%) 1.955 1.492 ∆E*ab (6%-5%) 3.239 4.197 Table 1. Color differences between final and initial assessments Table 2. Color differences between sequential concentrations for the initial (T0) and final (T1) assessments Melting Crystallization Sample Peak (T m °C) ΔH m (J/g) Onset (T m °C) Peak (T c °C) ΔH c (J/g) Onset (T c °C) 1% 70.77 0.97 65.24 42.06 -1.07 44.65 2% 72.09 0.98 66.17 42.63 -1.08 46.03 3% 73.64 2.31 67.92 47.58 -2.72 50.18 4% 74.73 4.79 68.95 50.32 -4.83 53.92 5% 75.28 9.87 69.12 53.05 -8.54 58.78 6% 76.72 8.96 68.63 54.38 -8.43 58.52 Control 85.39 144.70 82.25 75.74 -136.27 78.89 Table 3. Thermal properties of the carnauba wax-virgin olive oil organogels. Different small letters for the same property represent significant differences 0 10 20 30 40 50 60 70 80 90 0 50 100 150 200 250 300 350 Stress (Pa) Shear Rate (1/s) 1% 2% 3% 4% 5% 6% 0.01 0.1 1 10 100 1000 0.001 0.01 0.1 1 10 100 1000 Viscosity (Pa.s) Shear Stress (1/s) 1% 2% 3% 4% 5% 6% Figure 4. Viscosity (bottom) and stress (top) results for all carnauba wax-virgin olive oil organogel samples . Sample Melting Point (°C) Crystallization point (°C) 1% N.D. N.D. 2% 30.328 11.171 3% 62.373 27.436 4% 73.617 42.935 5% 76.729 48.671 6% 78.153 50.757 Sample Thixotropy (Pa/s) Initial Viscosity (1/s) 1% 427.51 12.78 2% 1263.72 132.20 3% 2324.33 345.07 4% 3443.54 1095.64 5% 6237.67 2510.25 6% 12219.23 4328.86 Table 4. Melting and crystallization points obtained from non-isothermal oscillation rheology of all carnauba wax- virgin olive oil organogel samples. Different small letters represent significant differences Table 5. Thixotropy and Initial Viscosity (0.05 s -1 ) of all carnauba wax- virgin olive oil organogel samples. Different small letters represent significant differences a a a a a b c a a a a ab b c a a a a a a b 0 5 10 15 20 1% 2% 3% 4% 5% 6% Control Butter Firmness Spreadability Adhesiveness Figure 3. Mechanical properties of candelilla-virgin olive oil organogels. Different small letters for the same property represent significant differences. Firmness (N); Spreadability (N.s); Adhesiveness (N.s) (in modulus). 5 mins 500 nm C 8 H 18 and C 3 H 8 O (3:2 v/v) CHCl 3 and CH 3 OH (7:3 v/v) Add NH 4 SCN Add Iron (II) solution
Transcript of Influence of carnauba wax concentration on the ......Influence of carnauba wax concentration on the...
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Influence of carnauba wax concentration on thephysicochemical properties of olive oil organogels1. CEB - Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal2. INL - International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga, PortugalEmail: [email protected]
Silva, P.1, Fasolin. L.1, Martins, A.1,2, Vicente, A. A.1University of MinhoSchool of Engineering
Abstract
Methods
Conclusions
IntroductionEdible oils have potential health benefits when compared to saturated and/or trans fats typically used in foodproducts. In order to widen their use as spreadable products, structuring these oils is a requirement. Thus, theaim of this work consisted in the development of an olive-oil organogel, foreseeing its application in the foodindustry. Olive-oil was used for the production of the organogels, with carnauba wax (CW) as organogelator (1%to 6% (w/w)), solubilized under magnetic stirring (90 °C) and cooled to room temperature. Systems wereevaluated regarding oxidation (PV), textural, rheological (flow curves; non-isothermal oscillatory sweeps) andthermal properties. Olive-oil and commercial butter were used as controls. An increase in CW concentrationincreased the textural parameters. Compared to values of commercial butter, organogels values were lower,indicating a less structured organogel (highest values: firmness of 3.79 N and 10.29 N for organogel and butterrespectively; spreadability of 3.17 N/sec and 10.15 N/sec for organogel and butter respectively). Thixotropy, initialviscosity, onset temperature, enthalpy, also showed an increase with increasingly higher CW concentrations.Melting point of organogels was determined and compared with calorimetric analysis. Similar trends were found:an increase in concentration increased the melting point; Regarding oxidative stability (63 days of storage, roomtemperature, exposed to light), results showed that, while an increase exists, it is within expected values(maximum PV, 1.10 meqO2/kg at 63 days), and all organogel samples were below the PV of olive oil (maximumPV of 1.47 meqO2/kg, at 63 days). Results show that varying gelator concentration, physicochemical propertiescan be easily changed and tailored, possibly creating a wide range of products. Thus, an industrial application canbe easily projected, since olive oil is a healthier alternative to other spreadable products.
Results
Natural vegetable oils are known to have several benefits in comparison to saturated and/or transfats. However, these saturated and/or trans fats are generally used in food products as texturemodifiers due to their physical properties while healthier edible oils are generally found in a liquidstate, therefore limiting its applicability; Therefore, modulating the physicochemical properties byconferring structure to edible oils without changing lipid profile and chemical composition couldovercome this lack of structure and allow a greater range of applicationsThe aim of this work was to develop an olive oil organogel, observing how different concentrations oforganogelator impacted its characteristics. In order to do so organogels were characterized regardingmorphology, physicochemical, thermal, textural and rheological properties. This work can be seen as apossible step in developing an olive oil organogel, foreseeing its application in the food industry.
Sample Preparation Physical assessments
Phase contrast microscopy Transmittance Spectrum;Transform to CIELAB data
TTC Spreadability Rig(HDP/SR) probe;Test speed: 3 mm/s;Post-Test speed: 10 mm/s
Flow curves at 25 °C (0.1to 300 s-1), up-down-upstep program;Cooling and heatingramps between 90 °C and5 °C at 10 °C/min, 1 Hz
Solubilize carnauba wax (1 % up to 6 % (w/w)) invirgin olive oil at 90 °C during 30 min to ensure fullsolubilization
Heating and cooling ramps from 5 to 90 °C with a 10°C/min rate; Under nitrogen atmosphere
Thermal Analysis
Oxidative Stability
This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorteoperation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.
Morphology Color Assessment
Rheology AnalysisMechanical properties
• Peroxide values were well below both the values of the control samples and the legal limits;• Comparing DSC results and non-isothermal rheology it was possible to see a clear tendency
between melting and crystallization peaks; It is clearly seen that an increase in gelatorconcentration increases initial viscosity and thixotropy and thus creates a stronger 3D network inthe organogel. This data and conclusions are supported by the textural results.
• These results show that by varying the gelator concentration it is possible to modulate organogelscharacteristics to target a specific application in the food industry, as a possible replacement orhealthier alternative for currently used spreadable products.
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Figure 2. Peroxide values of carnauba-virgin olive oil organogels. Different smallletters indicate statistical differences between different concentration, whiledifferent capital letters indicate statistical differences between different timeassessments (p
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