Food Engineering
Mohammad Khalilian-Movahhed; Mohebbat Mohebbi; Charlotte Sinding
Abstract
IntroductionEfforts have always been made to protect valuable compounds of medicine, food and aromatics materials that are highly sensitive to environmental conditions by the encapsulation method. encapsulation of flavors, in addition to its protection, allows the aromatic substance to be released in ...
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IntroductionEfforts have always been made to protect valuable compounds of medicine, food and aromatics materials that are highly sensitive to environmental conditions by the encapsulation method. encapsulation of flavors, in addition to its protection, allows the aromatic substance to be released in a long time, and the time and place of its release can be controlled. To design these protection systems requires detailed information on encapsulation and release methods, the nature of walls and aromatic materials (Gunning et al.,1999). For encapsulation of sensitive compounds such as lipophilic materials, it is necessary to produce an emulsion of the desired substance in wall materials such as proteins, polysaccharides or a mixture of them. The important factors in encapsulation are the molecular weight, chemical properties and polarity of the core materials, the properties of the materials of the walls, and finally, the methods used to produce microcapsules. (Jafari et al., 2008).The aim of this study was to produce and evaluate the properties of two and six layer multilayer microcapsules containing limonene using soy protein isolate and starch modified by spray drying. The release of encapsulated limonene was investigated under artificial oral conditions under different stress conditions. The results of this study can be used to predict the release rate of the encapsulated flavors and their release conditions.Materials and MethodsSolution preparation: The solution of SPI (0-3%) was prepared by methods of Huang et al. (2012). The OSA starch stock solution (0-2%) was prepared by methods of Nilsson and Bergens (2007).Emulsion’s preparation: the primary emulsion of the optimum SPI and secondary emulsion of optimum OSA starch concentration prepared by the method of Noshad et al (2015).Microcapsule production: To prepare the Microcapsules, a laboratory spray dryer was used. 180±5 ᵒC, inlet air temperature, 25 (ml/min) feed rate, and 90±10 ᵒC outlet air temperature were used. Six layer microcapsules was also prepared in the same conditions (Ansarifar et al., 2017)The micro structure, morphology and release of limonene were evaluated and finally by Zero order, First order, Higuchi, and Korsemeyer- peppas models were used to the fitting of experimental data.Limonene release: To investigate the release of the encapsulated limonene, the release of these microcapsules (two and six layer) at 37 ° C and pH = 6.8, as well as frequent chewing (0, 50 and 100 rpm) were examined. For the apply of shear stress, an oral simulator was designed and developed by the Department of Food Science and Technology of Ferdowsi University of Mashhad was used. Results and DiscusionThe results of particle size changes of the initial emulsion formed with different levels of soy protein isolate showed that the particle size decreased with increasing the concentration of this protein to 1.5% and then it was increased. The results of zeta potential showed that with increasing the concentration of soy protein isolate to 1.5%, the zeta potential of the samples increased and with more than 1.5%, it did not have much effect on the zeta potential of the samples, which indicates that concentrate of 1.5% soy protein isolate has a good ability to cover surface of limonene particles. Similarly, 1.2% of OSA starch was determined for the secondary layer.SEM images of the microcapsules showed that in the two-layer wall microcapsules have cavities, cracks and shrinkage. In the starting of drying, the rate of moisture lost is high and on the other hand, the wall is not strong enough to withstand the stresses caused by the exit of moisture from the walls, so the microcapsule has cavities. In six-layer microcapsules, a smooth, non-cracked surface was observed, which can be attributed to the wall strength due to the increase in the number of layers. Fourier transform infrared spectroscopic (FTIR) test showed that the outer surface of the microcapsules was covered by OSA starch in two and six layer microcapsules.The release profile of encapsulated limonene showed that the release rate in two layer samples was faster than six layer samples. Also, with increasing shear rate, the amount of release increased. The results of experimental models fitting showed that the first-order model had the best description for releasing limonene from two- and six-layer samples in different conditions. Calculation of diffusion coefficient showed that six-layer microcapsules have a lower diffusion coefficient than two-layer microcapsules, which leads to a decrease in the release rate of limonene.Conclusion The results of this study showed that the layer-by-layer method could be used to produce limonene microcapsules. Soy protein isolate and modified starch can cover limonene droplets well. SEM images showed that the structure of six-layer microcapsules is free of cracks and cavities and has a more uniform surface than two-layer microcapsules. To investigate the mechanism of limonene release from two- and six-layer microcapsules, different kinetic models were used to fit the experimental release data. The results showed that the release of these microcapsules occurred based on the diffusion mechanism and Fick's law, which is the main mechanism of mass transfer in the release process. Also, the results showed that the six-layer microcapsules had a lower diffusion coefficient than the two-layer microcapsules and the release rate was lower in the two-layer microcapsule; This is due to the repetitive coating of soy protein isolate and modified starch around the microcapsules and the increase in wall thickness.
Mohammad Ganjeh; Seyed Mahdi Jafari; Mehrdad Niakosari; Ali-Mohammad Tamaddon; Yahya Maghsoudlou
Abstract
Introduction: In recent years, production of nutraceuticals by adding bioactive compounds and nutrients has been grown substantially. These compounds are generally sensitive to environmental or gastrointestinal conditions and their bioavailability is limited due to destructive reactions. One of the common ...
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Introduction: In recent years, production of nutraceuticals by adding bioactive compounds and nutrients has been grown substantially. These compounds are generally sensitive to environmental or gastrointestinal conditions and their bioavailability is limited due to destructive reactions. One of the common methods to reduce or prevent these kind of problems, is microencapsulation of valuable compounds in some materials which can protect them against environmental conditions, and enabling them to controlled release from trapped compounds at specific time and place. Orange peel oil, contains some important bioactive compounds such as limonene that is used in a variety of beverages, foods, cosmetics, pharmaceuticals and chemicals. D-limonene is the main constituent of orange peel oil, because it makes an 80-95% fraction of the orange peel oil volatile compounds, depending on fruit variety. In addition to its technological characteristics (flavor), D limonene can stop or delay the initiation of cancer. It can also be used as a safe alternative to antimicrobial compounds. Nevertheless, technological limitations (hydrophobic structure, high reactivity, sensitivity to oxidation and volatility) often avoid suitable use of this compound as a dietary supplement. Polysaccharides are among of the basic materials which are applied more in this field. Several factors such as cheap and easy access, having active groups interacting with hydrophobic and hydrophilic compounds, biodegradation, biocompatibility and relatively high thermal resistance, have turned them to be superior to lipid and protein carriers. One of the most important polysaccharide compounds existing in nature, is starch. It can be used as a carrier in encapsulation processes with different purposes, having advantages such as inexpensive, non-toxic, capable of recrystallization, the ability to form film and complex and resistant to various degrees of enzymatic hydrolysis. Spatial configuration of amylose is changed in the presence of ligands such as iodine and linear alcohols, resulting in a left-handed helix which can trap ligands within or between curvatures derived from glucose connections. One of the major structures which is created in the interaction of amylose and lipophilic substances, is known as V-amylose structure. V-amylose is a left-handed helix with an inner hole which ligands can be placed within it. The aim of this study was to determine the effectiveness of amylose in nanoencapsulation of limonene as a bioactive compound with desirable sensory characteristics using a thermo-mechanical stress.
Materials and methods: Based on the analysis of pure limonene samples (Sigma-Aldrich) as well as samples used in this study, more than 92% of examined sample comprised of D-limonene. In order to prepare amylose nanoparticles containing limonene, 0.1 molar solution of potassium hydroxide (Merck, Germany) was prepared in deionized water and then high amylose corn starch (HACS) (Sigma-Aldrich (St. Louis, MO, USA) with 70% amylose was added to it in the ratios of 2: 4% while stirring continuously for 30 minutes at 80°C. Limonene was then used in the ratios of 5: 10% of HACS was added to the suspension and stirring continued for 1 minute. Initial suspension has been processed by using ultrasound system (Model UP100- Hescheler Company, Germany) with 100 W power and frequency of 30 kHz for 9 and 18 minutes. The viscosity of amylose suspensions containing nanoparticles with different formulations was measured by using a capillary viscometer (Schott-Gerate-Capillary-Viscometer-525-00- Germany). Size and zeta potential was measured by using dynamic light scattering (DLS) and Nanotrac Flex In-situ Particle Size Analyzer devices and Microtrac ZETA-check determined. The morphology of nanoparticles was studied using a scanning electron microscopy (TESCAN-Vega3- Czech Republic). Microencapsulation efficiency and loading efficiency were determined by using spectrophotometry.
Results and Discussion: In all formulations, particle sizewere less than 50 nm. Starch granules were exposed to cavitation stress by applying the ultrasonic process .The constant formation of bubbles creates a mechanical impact with high energy on starch granules during bursting. Fast impingement of fluid to granule surfaces, hitting particles to each other as well as resistant of the granules against fluid stream cause breaking of starch particles into nanoparticle scales. The highest amount of zeta potential was related to the sample which had the highest starch and limonene concentration. Amylose concentration had the main effect on zeta potential changes. Electrostatic charges can be the main reasons for the higher zeta potential in samples with 4% amylose concentration. More increasing in surface active agents of amylose, namely ionized hydroxyl groups of glucose molecules leads to increasing in surface charge, and results in zeta potential. The most impact on solutions viscosity is related to amylose concentration. Generally, increasing the amylose concentration leads to increasing the solution viscosity, in other side, with ultrasound treatment, the amount of this index was reduced and the solution became more fluent. Microencapsulation and loading efficiency values ranged between 28-82% and 0.38-1.63% respectively. The limonene concentration had the most impact on the efficiency in various formulations. At similar treatments with %4 amylose concentration and 9 min sonication period, by increasing the amount of limonene from %5 to 10, microencapsulation and loading efficiency were increased from %31 to %82 (%62 growth) and from 0.52 to 1.41 (%63 growth) respectively.
Hossein Mirsaeedghazi; Zahra Emam-Djomeh
Abstract
Limonene is a major flavor Producing Compound in orange - flavored soft drinks. It is an important parameter in marketability of products. Effect of molar fraction, time and CO2 on Limonene activity coefficient was evaluated using Dortmund-UNIFAC thermodynamic model. Results showed that activity coefficient ...
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Limonene is a major flavor Producing Compound in orange - flavored soft drinks. It is an important parameter in marketability of products. Effect of molar fraction, time and CO2 on Limonene activity coefficient was evaluated using Dortmund-UNIFAC thermodynamic model. Results showed that activity coefficient decreased by increasing molar fraction. Also, activity coefficient was in minimum level at 30 days storage and increased before and after this period of time. CO2 had a negative effect on Limonene activity coefficient.
