Oil-Structuring Characterization of Natural Waxes in Canola Oil Oleogels: Rheological, Thermal, and Oxidative Properties
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Appl Biol Chem (2017) 60(1):17–22 Online ISSN 2468-0842 DOI 10.1007/s13765-016-0243-y Print ISSN 2468-0834 ARTICLE Oil-structuring characterization of natural waxes in canola oil oleogels: rheological, thermal, and oxidative properties Jeongtaek Lim1 . Hong-Sik Hwang2 . Suyong Lee1 Received: 25 October 2016 / Accepted: 2 December 2016 / Published online: 20 December 2016 Ó The Korean Society for Applied Biological Chemistry 2016 Abstract Natural waxes (candelilla, carnauba, and bees- Keywords Natural wax Á Oleogel Á Organogelator Á wax) were utilized as canola oil structurants to produce Texture Á Thermo-rheology oleogels. Physicochemical properties of the oleogels were evaluated from textural, thermo-rheological, and oxidative points of view. The oleogels with candelilla wax exhibited the highest hardness, followed by carnauba and beeswax Introduction oleogels, while the most adhesive and cohesive properties were observed in the beeswax oleogel. The flow behaviors Edible vegetable oils are well-recognized to contain a of the oleogels over temperature exhibited greater sensi- variety of health-functional components, such as unsatu- tivity of carnauba wax oleogels to temperature. The storage rated fatty acids, compared to solid fats of animal origin. moduli of the oleogels were more temperature-dependent, However, the edible oils that are generally in a liquid state causing the crossover of the storage and loss moduli during at room temperature lack the physical functionalities suit- the temperature change. Highly linear correlations able for the texture and stability of food products. Liquid (R2 [ 0.96) were observed in the log plots of solid fat oils are chemically or enzymatically converted into semi- content and rheological property. In addition, the lowest solid or plastic fats to produce shortening and margarine peroxide values were observed in the candelilla wax (Ghosh 1996). However, there still exist health-related oleogels, followed by the carnauba and beeswax oleogels, concerns such as the increased amount of saturated fatty demonstrating that oleogels with a harder texture exhibited acids and generation of trans fatty acids. greater resistance to oxidation during storage. As a novel structuring method for edible oil, organogela- tion has recently received much attention in the food and pharmaceutical industry. Through this organogelation, edible oils are entrapped within a thermo-reversible and three-di- Mention of trade names or commercial products in this article is solely for the purpose of providing scientific information and does not mensional network derived from organogelators. Thereby, imply recommendation or endorsement by the U.S. Department of the liquid oils are physically solidified without changing their Agriculture. USDA is an equal opportunity provider and employer. chemical compositions, producing oleogels also called organogels (Vintiloiu and Leroux 2008). These oleogels have & Suyong Lee been shown to have great potential as alternatives to solid fats [email protected] in specific food applications such as baked goods (Jang et al. 1 Department of Food Science & Technology and 2015;Yılmaz and O¨ g˘u¨tcu¨ 2015) and ice cream (Zulim Carbohydrate Bioproduct Research Center, Sejong Botega et al. 2013). However, it is a challenge to explore University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747, suitable oleogels that can provide a similar level of perfor- Republic of Korea mance without organoleptic changes. 2 United States Department of Agriculture, Agricultural Since oleogels are biphasic systems consisting of Research Service, National Center for Agricultural Utilization Research, Functional Foods Research, Peoria, IL, organogelators and edible oil, the physical characteristics of USA the oleogels vary depending on the type and concentration 123 18 Appl Biol Chem (2017) 60(1):17–22 of the organogelators used. Out of various organogelators, Textural measurement waxes that are a mixture of more or less hydrophobic organic substances of medium chain length (Endlein and In order to investigate the textural properties of the oleogel Peleikis 2011) exist in form of natural substances and are re- samples, texture profile analysis was conducted using a texture obtained in a sustainable cycle. Furthermore, natural waxes analyzer (TMS-Pro; Food Technology Co., Sterling, VA, can be considered as promising candidates for food appli- USA) with a 100 N load cell. For doing so, the cylindrical- cations because they are FDA-approved as food additives shaped oleogel samples were prepared with a mold (25 mm (FDA 2015). In preceding studies, several natural waxes diameter, 10 mm height). The oleogels were placed on the were combined with vegetable edible oils to produce oleo- platform of the texture analyzer and then compressed two gels. Candelilla and carnauba waxes were applied to saf- times to 30% of the original height by using a cylindrical probe flower and virgin olive oils, respectively (Toro-Vazquez (5 cm diameter) at a speed of 10 mm/min. Textural parame- et al. 2007;O¨ gˇu¨tcu¨ and Yılmaz 2014). Soybean oil oleogels ters (hardness, adhesiveness, cohesiveness, gumminess) were were prepared with sugarcane, candelilla, and sunflower measured from the force versus time curves obtained. waxes and their thermal and optical properties were char- acterized (Rocha et al. 2013; Hwang et al. 2015). In addi- Rheological measurements tion, sunflower oil-rice bran wax oleogels were prepared to replace solid fat in ice cream (Zulim Botega et al. 2013) and The rheological properties of oleogels (shear viscosity and rapeseed oil was structured with shellac wax for several dynamic viscoelasticity) were investigated as a function of food applications such as spreads, chocolate pastes, and temperature by using a controlled-stress rheometer cakes (Patel et al. 2014). However, the physicochemical (AR1500ex, TA Instruments, New Castle, DE, USA) with properties of oleogels have not been extensively compared, a 40-mm parallel plate. The melted oleogels were placed depending on the types of natural wax and vegetable oil. on the peltier plate of the rheometer and their viscosities Furthermore, research focuses have not been placed on the were measured at a shear rate of 100/s by increasing correlation between the textural/rheological properties of temperature from 50 to 90 °C at a heating rate of 2 °C/min. oleogels and their oxidative stability that is a critical attri- In the case of the dynamic viscoelasticity, dynamic tem- bute of oil-based food products with regard to quality perature ramp tests from 25 to 80 °Cat2°C/min were attributes. carried out at a frequency of 1 Hz and a 0.01% strain, Canola oil is known to be higher in unsaturated fatty which was within the linear viscoelastic limit. acids than other vegetable oils (Kim et al. 2010). There- fore, the oleogels prepared with canola oil have a high level Determination of solid fat content of unsaturated fatty acids while they may be more vul- nerable to oxidation during storage. Thus, in this study, The solid fat content (SFC) of oleogels was measured in canola oil oleogels were prepared with three different the temperature range from 10 to 85 °C using an Mq-one natural waxes—candelilla, carnauba, and beeswax. Their SFC Analyzer (Bruker, Ettlingen, Germany). The oleogels physicochemical characteristics were then evaluated in were melted at 90 °C for 30 min, poured into NMR glass terms of textural, thermo-rheological, and oxidative tubes, and placed at 0 °C for 60 min. They were then held properties. at each measuring temperature for 30 min prior to SFC measurement. Thermal analysis Materials and methods Differential scanning calorimetry (DSC 200 F3 Maia, Preparation of oleogels NETZSCH, Bavaria, Germany) was used to investigate the thermal properties of oleogels. The oleogels (10–15 mg) Candelilla wax (Kahl GmbH & Co. KG, Trittau, Germany), were weighed into stainless steel pans that were hermeti- carnauba wax (Starlight Co., Fortaleza, Brazil), and bees- cally sealed. The sample was heated from 25 to 90 °C, and wax (Hooper pharm GmbH Co., Hamburg, Germany) were then cooled to -20 °C, and heated again to 100 °C at a rate obtained from commercial sources and canola oil was of 10 °C/min and the empty pan was used as reference. provided from CJ Co. (Seoul, Korea). In order to prepare oleogels, canola oil was heated and each wax was slowly Peroxide value measurement added (10% w/w) with continuous agitation until com- pletely dissolved, followed by cooling at room temperature The effect of natural waxes on the oxidative stability of overnight. oleogels was investigated by measuring their peroxide 123 Appl Biol Chem (2017) 60(1):17–22 19 values during 18-day storage under the accelerated condi- with rice bran, carnauba, and candellila waxes (Das- tions (60 °C). Based on the method of Cho and Lee (2015), sanayake et al. 2009). In addition, the beeswax oleogels the peroxide values of the oleogel samples were periodi- were the most adhesive and cohesive, while the lowest cally measured and expressed as miliequivalents of active values were observed in the candelilla wax samples. In the oxygen per kilogram of oil (meqO2/kg). case of gumminess (hardness 9 cohesiveness), the can- delilla wax oleogels exhibited greater gumminess than the Statistical analysis other samples due to their hard texture. Thus, canola oil seemed to pack more tightly within the gel network derived All measurements were made in triplicate and the SAS from candelilla wax, producing oleogels with a harder program