The purpose of this project is to develop a microencapsulation technique to be used in cold process soap making to prevent seizing of the soap. It was found that seizing in soap is caused by an increased rate of reaction due to the introduction of scent oil, such as clove oil, which reacts rapidly with sodium hydroxide. As a result, to better improve the characteristics of soap in Hampden-Sydney College's production of handcrafted soap bars, the creation of a microencapsulation process to protect the scent oils would be very beneficial.
Microencapsulation is a very long, tedious process and unfortunately there is limited research regarding a successfully procedure for using microencapsulation in the soap making business. However, combining many of the procedures currently available can aid the process of developing a procedure. Research states that the microencapsulation process requires the application of a shell material to the particles. Additionally, there are a few processes found for using a benefit agent for encapsulation; note that benefit agents are considered materials that have a positive effect to the substrate, in our case, skin. <xref linkend="R5"/>
Also, benefit agents for the skin are water insoluble products that can protect, moisturize, or condition the skin after using the bar of soap.<xref linkend="R5"/> This procedure involves the application of a shell to the particles. This process involves melting the benefit and carrier agent in a beaker and adding the mixture to a solvent solution of the shell material. As a result, the encapsulating material is established holding the scent. In this case, the benefit agents being used are waxes such as carnauba and beeswax. <xref linkend="R6"/>
Although microencapsulation has not been studied in detail at Hampden-Sydney College, the technology of microencapsulation is a prominent topic in today's scientific community. Most people have come in to contact with the scratch-and-sniff perfume advertisements located in many news stand magazines; the way this technology works is through microencapsulation. Additionally, microencapsulation relies on the rupture of the shell to release its contents. There are various ways in which core material can be freed from a microcapsule including rupture, dissolution, phase separation, melting, and diffusion of the cell wall <xref linkend="R1"/>. For soap making, it seems best suitable to use the mechanism of dissolution of the wall. In addition, this process which is used in many microencapsulation processes is nearly 80% effective <xref linkend="R2"/>.
The reason why much interest is sparked in the soap making community regarding microencapsulation is because this technology is widely and successfully used in many other products including food, perfumes, and laundry detergents. It seems fit that the process in which laundry detergent uses microencapsulation would benefit microencapsulation in handcrafted soap making.
However, the microencapsulation technique used in laundry detergent production makes use of a water-soluble polymer where upon contact with water, shell dissolution occurs and the scent is released<xref linkend="R1"/>. We have found that a physical microencapsulation technique, in which a hard outer shell is ruptured to release the scent oil, is best for handcrafted soap makers. Our technique involves the creation of a microcapsule using clove oil, carnauba wax, water, and a small amount of lye.
Clove oil is the most widely used scent oil in cold process soap making. Additionally, the single largest component of clove oil is eugenol. Therefore, during experimentation eugenol was treated as clove oil. More so, eugenol is a phenol and a very weak acid. ><xref linkend="R3"/>.
<figure id="lab_eugenolstructure"><title>Structure of Eugenol</title> <mediaobject><imageobject><imagedata fileref="lab_eugenolstructure1.pdf" format="PDF" scale="50"/></imageobject></mediaobject> </figure>
Also, carnauba wax is safe from sodium hydroxide because wax does not react with sodium hydroxide. As a result, the eugenol is safely protected within the walls of the carnauba wax. We hypothesized that the use of eugenol as the scent oil and carnauba wax as a coating agent will prevent rapid soldification of our soaps.
The diagram below depicts our hypothesis. Palm oil, lye, and our microcapsules are added to a mixing jar. Upon mixing, soaponification occurs at a normal rate of reaction. As a result, the scent oil remains protected within the walls of the microcapsules.
<figure id="lab_hypothesisdiagram"><title>If Hypothesis Supported</title> <mediaobject><imageobject><imagedata fileref="lab_hypothesisdiagram1.pdf" format="PDF" scale="50"/></imageobject></mediaobject></figure>
On the other hand, the diagram below depicts the addition of eugenol without any form of protection from the sodium hydroxide. Notice that upon mixing, soaponification occurs at a much faster rate of reaction due to the production of sodium eugenolate.
<figure id="lab_fastratediagram"><title>Scent Oil without Protection</title> <mediaobject><imageobject><imagedata fileref="lab_fastratediagram1.pdf" format="PDF" scale="50"/></imageobject></mediaobject></figure>
Also included in this research investigation is a few quality assurance issues including saponification value determination and residual total alkali determination for the specific soaps produced from this seizing project. Because real-world oils are composed of complex mixtures of fatty acid triglycerides, we can never know the exact saponification value of each and every soap. In addition, due to the variation of composition of oils from supplier to supplier it is necessary that we conduct a saponification value investigation of each oil we encounter. More so, saponification values can be calculated using a variety of methods from the use of methanol to the use of ethanol. It will be our purpose to determine which method of saponification value calculations is easiest for hand crafted soapmakers. Lastly, our investigation leads us to test if our sample soap has fully saponified; this process is completed through the residual total alkali test, which "assigns a numerical value which may be tracked as the soap ages." <xref linkend="R21"/>
<bibliomixed id="R1">Franjione, John, Niraj, Vasishtha <citetitle>The Art and Science of Microencapsulation.</citetitle>, Technology Today: 1-6, 1995.</bibliomixed>
<bibliomixed id="R2">Brenner, Joseph <citetitle>Process of encapsulating an oil and product produced thereby</citetitle>, U.S. Patent 3,971,852 , 1976.</bibliomixed>
<bibliomixed id="R3">McDaniels, Robert <citetitle>Essentially Soap.</citetitle> Krause Publications: April 2000.</bibliomixed>
<bibliomixed id="R5">Finucane, Kevin Michael Corr, James Joseph Ornoski, Gregory Alan Coyle, Laurie Ann <citetitle>Extruded soap and/or detergent bar compositions comprising encapsulated compounds. </citetitle>, 2001.</bibliomixed>
<bibliomixed id="R6">Shefer, Adi; Shefer, Samuel David <citetitle>Multi - component controlled delivery system for fabric care products and delivery system production. </citetitle>, 2003.</bibliomixed>
<bibliomixed id="R21">Dunn, Kevin M.<citetitle>Scientific Soapmaking: The Chemistry of Handcrafted Soap </citetitle>, 2005 (Draft).</bibliomixed>