Journal of Microbiology and Biotechnology Research Scholars Research Library J. Microbiol. Biotech. Res., 2011, 1 (1): 29-34 (http://scholarsresearchlibrary.com/archive.html) Quality of Soaps Using Different Oil Blends Shoge Mansurat Oluwatoyin Ahmadu Bello University, Zaria, Kaduna state, Nigeria ABSTRACT Soaps are the sodium salts or potassium salts of stearic acids or any other fatty acids. They are prepared by the saponification process, which is, reacting the oil or fats which contain triglycerides with caustic soda (NaOH) to give the soap and glycerol, using equal amount of additives and varying the amount of caustic soda used and oils used. The soaps prepared are then analyzed and their properties were compared with that of some selected commercial soaps. The result shows that both the prepared soaps and the commercial soaps have the same properties and falls within the ph of 9.0-11.0. The production cost analyses of the prepared soaps were also compared to that of the selected commercial soaps. The production cost of the prepared soaps varies from that of the commercial soaps. Key words; saponification, triglycerides, glycerol INTRODUCTION Records mentioning the use of numerous soapy materials and cleansing agents date from ancient times show that soap has probably been used in some form or another as far back as pre-historic times (Microsoft Encarta premium suite, 2004). Soap is a chemical compound or mixture of chemical compounds resulting from the interaction of fatty acids or fat glycerides with an organic base 2. The alkaline metals usually used in soap making are sodium and potassium, which produce soluble soaps which are different from those made from divalent metals such as calcium and magnesium, which are insoluble. Fats are solid esters of fatty acids and glycerin while oils are the liquid glycerol esters of fatty acids at room temperature. The process which takes place when soap is formed from a fatty acid and alkaline metals by the action either of a caustic alkaline, for example soda in neutral oil or on a fatty acid is called saponification. Soap is soluble in and it has an excellent cleansing property. During the process of saponification (soap making) of neutral oil, glycerine is liberated into soap mass. (Oil/fats+caustic alkali=. 29
Soaps are produced by the saponification of glycerides with alkalis, usually NaOH for solid or bar soaps and KOH for liquid soaps. MATERIALS AND METHODS Auxiliary raw materials used in soap making Auxilliary raw materials provide certain conditioners or qualities to the soap, but they are added to the soap in solution only at soap formation stage. Some of these chemical materials are agents of emulsification, suspension and foaming, while some are builders and extenders and some are hardeners and conditioners (Kirk-Othman, 1963).Some of the auxiliary raw materials are; i. Sodium carbonate (soda ash) This is an auxiliary raw material without which soap can still be made, but when added to soap, it promotes emulsification and it enhances the formation of the foam in the soap. It also increases the volume of the soap and it can therefore be defined as an extender. Na 2 CO 3 produces heat when dissolved in almost like NaOH but it is less dangerous than NaOH. ii. Sodium sulphate This is another auxiliary raw material similar to soda ash. It helps in the binding effect of the soap chemicals and it induces the foaming ability of the soap. It is equally a binder or an extender. iii. Sodium silicate This is an auxiliary raw material that hardens the soap. It eases removal of dirt and prevents redeposition of dirt particles. It is sold usually in thick liquid form to the soap maker. iv. Perfumes This is a fragrant auxiliary raw material. The chemical gives a good odour to the soap. To prevent lye (NaOH) from eating up the perfume, it must be added as late as possible in the saponification process (Al Durtschi, 2000). General soap making procedure Equal amount of the Oil/fats were measured into a plastic container. It was warmed (just a little above its melting point) in order to hasten the reaction between the lye and the fat. A calculated amount of NaOH (lye) was weighed and a fixed amount of distilled was added to it. The caustic soda was stirred well using a pestle until it blends with the fat. The caustic soda was poured very gradually into it and stirred gently in one direction to enhance thorough mixing of the solution. The plastic container was insulated with pieces of cloths to prevent the fat from hardening before the soap mix properly. Calculated amount of sodium carbonate, sodium sulphate and sodium silicate was added into the soap mixture and it was stirred properly until it blends. The perfume was also added immediately with continuous stirring of the mixture. The soap mixture was poured into the mould and it was left for solidification and proper harden up (about 3-5 days). When the soap has fully cured (solidified), a thin white powdery layer on the outside of the soap might be noticed. This is soda ash and it forms as a result of CO 2 in the air interacting with the lye in the soap. Therefore, the outer layer should be covered with plastic wrap. After saponification nears completion (about 1-3 days depending on the oil type or fat used), the air barrier was removed to let the soap dry out. 30
This method was used to prepare different soap-type based on equivalent amount of Na 2 CO 3, Na 2 SO 4, distilled, sodium silicate, perfume and weight of oil while the amount of NaOH and the type of oil used were varied. Soap analysis Each of the prepared soaps were analyzed to determine the soap yield, nature of the soaps, solubility of the soaps in tap, distilled and hard, time taken to dissolve 1g of soap in 100ml of distilled and the ph of the soap at room temperature (at the first stage of curing and after 2 moths of curing). A comparative analysis was carried out using commercial soaps by determining their solubility and ph. Cost analysis of the soaps A production cost analysis was done using the amount of each reagent and each oils/fats to determine the approximate cost of each soap, compared to the cost of the commercial soaps. RESULTS AND DISCUSSIONS Yield and physical characteristics of the prepared soaps For soaps containing two or more different types of oils/fats, the oils/fats are in the same ratio for easy comparism. The percentage yield of the soaps ranges from 50% to 85%. This depends on the particular carboxylic acid and base that make up the soap 4. A decrease in ph was observed after 2 months of curing as shown below. The ph becomes constant when the saponification process stops (about 8 months). For a soap not to be lye heavy, the ph of the soap must range from 9.0 to 11.0 using a ph meter (Al Durtschi, 2000). This corresponds to the ph of the prepared soaps. The closer the ph of the soap is to neutral, the better the soap. Table 1; Yield and physical characteristics of the prepared soaps Soaps (1:1) Shea butter and castor oil soap Tallow and coconut oil soap Tallow and palm kernel oil soap Palm oil and castor oil soap Palm kernel oil soap Yield (%) Physical characteristics 60.2 Hard soap, 60 Hard soap, 76.2 Hard soap, 75.7 Hard soap, 75.8 Hard soap, Solubility test tap. Forms tap. Forms tap. Forms tap. Forms tap. Forms Time taken ph at ph after 2 to dissolve curing months 1g in 100mls stage of 9min. 24sec. 10.46 10.07 20min.45 sec. 27min.15 sec. 10.42 10.31 10.43 9.98 10min.8sec. 10.32 9.72 8min.10sec. 10.41 9.84 31
Peanut and 71.5 Hard soap, 17min.25sec. 10.45 10.25 cottonseed oil tap. Forms soap Tallow and olive 68.1 Hard soap, 20min.45sec. 10.57 10.50 oil soap tap. Forms 76 Hard soap, Palm kernel+ coconut+olive +sheabutter soap Garlic oil 81.2 Hard soap, Sheabuter olive oil and 64.8 Hard soap, Olive oil soap 78.1 Hard soap, Palm oil soap 51.6 Hard soap, tap. Forms tap. Forms tap. Forms tap. Forms tap. Forms Table 2; Physical properties of commercial soaps 9min.5sec. 10.01 9.60 15min.54sec. 10.52 10.31 18min.20sec. 10.56 10.43 9min.5sec. 10.49 10.20 23min. 10.5 10.37 Soaps Canoe soap (laundry GIV soap (toilet DOVE soap (toilet PLUS soap (laundry LUX soap (toilet JUMBO (laundry soap Physical characteristics well in well in well in well in well in well in Solubility test tap. Forms tap. Forms tap. Forms tap. Forms tap. Forms tap. Forms Time taken to dissolve 1g in ph of soap 100mls of 15min.41sec. 10.37 27min.46sec. 10.43 12min.39sec. 7.84 18min.8sec. 10.55 15min.48sec. 10.27 11min.27sec. 10.36 Commercial soaps The physical characteristics of the prepared soaps were compared to that of the commercial soaps. The selection of the commercial soaps was done randomly. Six of the commercial soaps were analyzed; three laundry soaps and three toilet soaps. The properties of the prepared soaps 32
are the same with that of the commercial soaps as shown below. The ph of the prepared soaps after 2months of curing is 9-10.5 this shows that they would be skin and fabrics friendly while the ph of the analyzed commercial soaps is between 10-11, apart from DOVE soap which has a ph of 7.84 (close to neutral and was prepared by the rebatch process) (Grolier incorporated, 1995) Production cost analysis of prepared soaps The cost implications of the soaps prepared were also analyzed. The analysis was based on cost of raw materials vis-à-vis the yield of soap. Table 3; Production cost analysis of prepared soaps Soaps Yield of soaps(g) Cost of soap production (naira) Cost per 1g of soap (naira) Shea butter and castor oil soap 66.44 157.11 2.46 Tallow and olive oil soap 55.77 66.65 1.13 Garlic oil soap 49.24 100.73 2.05 Palm oil and castor oil soap 52.86 141.35 2.67 Shea butter and olive oil soap 61.70 79.77 1.29 Tallow and palm kernel oil soap 52.46 71.93 1.37 Peanut and 55.98 57.89 1.03 cottonseed oil soap Coconut oil and tallow soap 67.16 92.90 1.38 Palm kernel oil soap 52.76 80.49 1.53 Palmkernel+ coconut+olive 52.65 88.82 1.69 +sheabutter soap Olive oil soap 51.20 69.93 1.37 Palm oil soap 38.73 39.13 1.01 Production cost analysis of commercial soaps The costs of the commercial soaps were also compared with the prepared soaps. As shown below; Table 4; Production cost analysis of commercial soaps Soaps Weight of soap (g) Cost of soap (naira) Cost per 1g of soap Canoe soap (laundry 200 35 18k GIV soap (toilet 80 30 38k DOVE soap (toilet 200 40 20k PLUS soap (laundry 100 150 1.50naira LUX soap (toilet 80 35 44k JUMBO soap (laundry 200 40 20k The cost production for commercial soap is higher than that of the prepared soaps as shown above because for commercial soaps, commercial grade of reagent is used which are generally cheaper than laboratory grade of reagents used for the production of the soaps. While for the prepared soaps, analytical grade of reagents were used. This gives precise yield of the laboratory soaps. The reagents and oils used in the production of the commercial soaps were bought in large quantities. This reduces the production cost of the soaps. 33
REFERENCES [1] Microsoft Encarta premium suite, Functions of soaps, 2006. [2] Kirk-Othman, Detergency, soap and surfactants, Encyclopedia of chemical technology, Interscience, New York, 1963. [3] Al Durtschi: http://waltonfeed.com/old/soap/soap.html, 2000 [4] Grolier incorporated, Soap. The Encyclopedia Americana, International edition, 1995, Vol. 30, 20:678; 25: 117-118. 34