cosmetics

Chapter 4

Comparison of Palm- and Tallow-Based Soaps:Specifications, Formulations, and Performance

Ainie Kuntom and Luis Spitz

Malaysian Palm Oil Board (MPOB), Malaysia; and L. Spitz, Inc., Skokie, Illinois, USA

Introduction

Soap is one of the oldest detergents manufactured and a classic toiletry. It is madefrom fatty acids derived from oils and fats. The traditional fats and oils used tomake soap are tallow and coconut oil. With the expansion of the oleochemicalindustry, raw materials for soap making—fatty acids with C12–C18 hydrocarbonchains—are now easily available. Besides tallow, other sources of C16–C18 fattyacids are palm oil and palm stearin, a fractionated product of palm oil, whilesources for C12–C14 fatty acids are palm kernel oil and coconut oil. The two maintypes of soap noodles are based on tallow and palm. Other types of vegetable oilsoap bases are also available. Tallow-based soap is usually a blend of tallow, ani-mal fats, and coconut or palm kernel oil. Palm-based soap is a blend of palm oil orpalm stearin with palm kernel oil or a combination of all three. The uniqueness ofpalm-based soap is that all of the fatty acids necessary for the base are derivedfrom one source (palm fruits) and thus it is totally vegetable based (Fig. 4.1).

Soaps are produced by two primary methods: saponification of fats and oils orneutralization of distilled fatty acid blends derived from the oleochemical industry.Neutralization of distilled fatty acids is a simpler and cleaner manufacturing practicethan fats and oils saponification; it also produces glycerine as a by-product. The result-ing glycerine has to be treated, evaporated, and distilled to obtain saleable, refinedglycerine. Traditionally tallow-based soap is prepared by saponification of the triglyc-erides, but soap manufacturers that either produce or purchase fatty acids use the neu-tralization route to prepare the soap base. In this chapter the term soap base will referto the dry soap noodles (pellets). Palm-based soap is usually manufactured throughneutralization of fatty acids; however, some manufacturers still use the oil route tomake soap. The quality of soap bases produced depends on the quality of raw materi-als. The choice of raw materials depends on several factors, such as acceptable costrange, producer manufacturing capabilities, and the targeted properties of the products.

Product performance depends on the ratio of the various fatty acids in theblend. Even though soap contains a range of fatty acids from C12–C18 hydrocarbonchains, the proportion of these fatty acids has to have the correct ratio to produce aproduct with good performance. Some of the characteristics of fats and oils used insoap making are shown in Table 4.1.

Copyright © 2004 AOCS Press

Tallow, palm oil, and palm stearin have similar chemical properties and simi-lar fatty acid compositions. Coconut oil and palm kernel oil are the normal contrib-utors of the C12–C14 fatty acids; however, palm kernel olein (a by-product of palmkernel fractionation) can also be a source of these fatty acids. The chemical proper-ties of the fatty acids derived from these oils are shown in Table 4.2. The increasein conversion from oils and fats to fatty acids is assisted by the expansion of theoleochemicals industry where a wide range of distilled fatty acids is available forthe soap manufacturers. These fatty acids have the flexibility and versatility to suitthe requirements of the soap producers. The oleochemical industry offers fattyacids for soap bases and specially pre-blended distilled fatty acids for soap making.

Fig. 4.1. Palm fruits.

TABLE 4.1 Characteristics of Fats and Oils

Properties

Saponification Iodine Titer Melting point GlycerineFats and oils value value (°C) (°C) (%)

Coconut oil 250–264 7–12 20–24 23.0–26.0 13Tallow 192–202 48–52 40–47 40.0–47.0 10Palm kernel oil 245–255 14–19 20–28 24.0–26.0 12Palm kernel olein 231–244a 25–31 — 21.8–26.0a —Palm oil 196–202 50–55 40–47 27.0–50.0 10Palm stearin 193–206b 48 (max) 20–26 24.0–26.0 —

Sources: Witco Fats and Oils Brochure (1); aTang (3); bTang (2).

Palm Fruit MesocarpC16–C18 Fatty Acids

Palm Fruit KernelC12–C14 Fatty Acids


TABLE 4.2Distilled Fatty Acids for Soap Making

Properties

Saponification Acid Iodine Titer Unsaponifiable Lovibond color 5.25”Distilled fatty acids value value value (°C) matter (%) cell red-yellow

Coconut 266–278 265–277 5.0–10.0 22–27 0.5 0.8R–8.0YStripped coconut 251–263 252–260 5.0–12.0 27–30 0.5 0.3R–3.0YPalm kernelb 255–267 255–265 14.0–19.0 22–26 1.0a 0.5R–5.0YStripped palm kernelb 248–260 248–258 16.0–22.0 24–28 1.0a 0.5R–5.0YTallow — 198–207 36.0–65.0 39–49 1.5a 0.2R–0.9R

0.3Y–4.3YPalm oilb 205–214 205–212 46.0–57.0 45–49 1.0a 1.0R–4.0YPalm stearinb 206–218 206–216 28.0–38.0 48–54 1.0a 1.0R–4.0YSoap blend (T/C) — 214–222 36.0–42.0 40a 1.0a 0.4R–4.0YSoap blendc — 215–225 37.0–45.0 41–46 1.0a 0.3R–3.0Y(40PO/40POs/20PKO)amaximum.Abbreviations: Tallow, T; coconut, C; palm oil, PO; palm stearin, POs; palm kernel oil, PKO.Source: Witco (1), bCognis (4), cCognis (personal communication, 2003).


Toilet Soaps

A variety of commercial soaps are available on the market, but the major uses arefor toilet, laundry, and household purposes. Toilet soaps normally contain about70–80% Total Fatty Matter (TFM). The common fatty acid ratios used by theindustry are 80C16–C18:20C12–C14, 75C12–C18:25C12–C14, and 70C16–C18:30C12–C14. The C16–C18 oils, such as tallow, palm oil, and palm stearin, contributeto detergency and lather formation.

The characteristics of tallow and palm oil are so similar that palm oil can totally orpartially replace tallow for soap manufacturing. Palm stearin is also used at times as acost-effective replacement for tallow. Palm stearin yields 11% glycerine per unit of fat,while tallow yields only 10%; it also has a higher saponification value than tallow. Forthis reason a soap blend with palm stearin will require less palm kernel or coconut oil.

The C12–C16 lauric oils, coconut oil, palm kernel oil, and palm kernel olein,also contribute to detergency and lather formation. The lather formed from the lau-ric oils is larger and more voluminous compared with the C16–C18 oils; however,the C16–C18 oils have a more stable and thicker lather. Since the characteristics ofpalm kernel oil resemble coconut oil, palm kernel oil can be substituted directly forcoconut oil in soap production. Palm kernel olein, a fractionated product of palmkernel oil, being similar to coconut oil is also a good raw material for soaps andcan be used as a cheaper replacement for coconut oil.

The following abbreviations for the raw materials will be used in the rest ofthis chapter: tallow (T); coconut oil (CNO); palm oil (PO); palm oil stearin (POs);palm kernel oil (PKO); palm kernel oil olein (PKOo). For tallow-based soaps, theratios of fatty acids are 88T:12CNO, 85T:15CNO, 80T:20CNO, 70T:30CNO, and50T:50CNO. Palm-based soaps are usually made with ratios of 80PO:20PKO,75PO:25PKO, and 70PO:30PKO. Some other blends are 40POs:40T:20PKO,40PO:40POs:20PKO, and 70POs:30PKOo.

Soap Noodles (Pellets)

Formulations. The oleochemical industry provides a wide range of raw materials thatcan be used to formulate soap bases. In today’s market, there are various soap-baseformulations available to satisfy the needs of the manufacturers. Some of these formu-lations are shown in Table 4.3. In the tables, Soap Base refers to the vacuum-spray-dried soap in noodle (pellet) form. Noodles are offered from 6 to 12 mm in diameterand 10 to 30 mm in length. The properties of the soaps described in the table indicatethat even though the formulations vary, the basic properties are similar except for thepenetration value. Penetration value is a reflection of soap hardness; the lower thevalue the harder the soaps are, while higher values indicate a softer soap. If palm-based soaps contain distilled palm stearin fatty acid, the resultant bar soaps obtainedare slightly harder as the penetration values are lower (48 mm). Even though thestearin-containing soaps are harder, the foaming characteristics of the soaps is thesame as that of the other formulations.


TABLE 4.3 Distilled Fatty Acid Soap Blends

Properties

Distilled fatty acid Acid Total fatty Moisture Iodine Titer Free Sodium Penetration Foamsoap blends value matter (%) (%) value (°C) caustic (%) chloride (%) value (mm) volume (mL)a

90PO:10PKO 214 84 10 54.5 43.0 0.06 0.4 53 530/36585PO:15PKO 217 81 11 52.2 42.2 0.06 0.4 52 520/35580PO:20PKO 219 81 10 45.2 41.3 0.06 0.4 51 505/34575PO:25PKO 221 82 11 44.5 38.4 0.04 0.4 50 513/34370PO:30PKO 225 83 10 43.5 37.5 0.06 0.4 50 520/34060PO:40PKO 229 80 11 38.2 37.5 0.03 0.3 50 510/35040PO:40PS:20PKO 224 81 11 37.0 46.0 0.10 0.2 48 470/30680POs:20PKO 219 83 12 27.0 48.0 0.10 0.5 48 510/34570POs:30PKO 225 82 11 29.0 47.0 0.10 0.5 48 500/32565POs:35PKO 228 82 10 25.2 45.0 0.10 0.5 48 525/35560POs:40PKO 229 83 11 22.0 43.8 0.10 0.3 48 500/368aSee Glossary for foam volume test details for all tables that list foam volumes. Abbreviations: See Table 4.2.


The fatty acid composition of the soap blends based on the formulation in Table4.3 is shown in Table 4.4. This table describes the blends based on fatty acid composi-tions made up mainly of hydrocarbon chains of C12, C14, C16, and C18. Tallow-basedsoaps, even if they originate from different raw material (combination of tallow andcoconut oil or palm kernel oil), due to similarity in the fatty acid composition of theraw materials, will have similar base properties (Table 4.5). Formulations based on tal-low, palm stearin, and palm kernel oil blends are also available. The fatty acid compo-sition of the blends and the resultant soap properties are shown in Tables 4.6 and 4.7.A palm stearin and palm kernel olein blend can also produce a soap base with charac-teristics similar to other bases. Tables 4.8 and 4.9 show the properties of soaps basedon the formulations from these two types of oils.

Specifications. The technical specifications of standard tallow and palm soap basesare listed in Table 4.10. There are two types of standard palm soap bases, one with freecaustic and the other with free acid. During fatty acid neutralization, the alkali isalways added in excess of its stoichiometric requirement to ensure complete neutral-ization and leaving a free caustic (NaOH) content of 0.04–0.08%. The soap bases alsocontain Free Fatty Acid (FFA). The properties of palm and tallow soap bases are simi-lar except for the titer, in which palm soap bases have a higher and wider titer range,40–47°C compared to a tallow soap base. This is because some palm soap bases con-tain palm stearin, which contributes to the higher titer. The cleansing and the latheringperformances of both soap bases are similar because the fatty acid composition of bothsoap bases is similar.

Most of the soap bases contain preservatives to ensure the stability of the soaps.The function of preservatives is to prevent rancidity of the soap bases by chelatingmetal traces, thus protecting the fatty acids in the soap from oxidation.

Toilet Soaps

Traditional toilet soap bars are made from 80–85% tallow and 15–20% coconut orpalm kernel oil. This ratio has been expanded due to the availability of the soapbases with various combinations of the C16–C18 fatty acids and C12–C14 fattyacids. Vegetable-based soap bars commonly found in the market are made fromblends of palm oil and palm kernel oil or their fatty acids. The ratio of the blend isusually 80PO:20PKO, 85PO:15PKO, 40PO:40POs:20PKO, and 70POs:30PKO.Soap characteristics with these blend types are shown in Table 4.11. The propertiesof tallow-based soap bars analyzed by the Malaysian Palm Oil Board are shown inTable 4.12. The difference between the properties of tallow- and palm-based soapsis in the titer value. Palm-based soap bars have higher titer while most of the tal-low-based bars are between 36–39°C. Palm-based soap bars with blends contain-ing palm oil and palm kernel oil normally have titers in the range of 40–43°C,while those containing palm stearin normally have a higher titer of 43–46°C. Otherparameters are similar for both types of soap bars. One noticeable feature is thehigh free fatty acid in both tallow- and palm-based soap bars. Today most bar soap


TABLE 4.4 Fats and Oils Composition

Fats and oils composition

Caprylic Capric Lauric Myristic Palmitic Stearic Oleic LinoleicFats and oils C8:0 C10:0 C12:0 C14:0 C16:0 C18:0 C18:1 C18:2 Other

Tallow — — — 3.4 26.3 22.4 43.1 1.4 3.4Palm oil — — 0.3 1.1 43.1 4.6 39.3 10.7 0.9Palm stearin — — 0.7 1.5 55.7 4.8 29.5 7.2 0.6Coconut oil 7.6 7.3 48.2 16.6 9.0 3.8 5.0 2.5 —Palm kernel oil 1.4 2.9 50.9 18.4 9.7 1.9 14.6 1.2 —Palm kernel olein 4.3 3.7 42.6 12.4 8.4 2.5 22.3 3.4 0.4

Source: Witco (1).


TABLE 4.5 Fatty Acid Composition of Distilled Fatty Acid Blends

Fatty acid composition

Fatty acid Caprylic Capric Lauric Myristic Palmitic Stearic Oleic Linoleicsoap blends C8:0 C10:0 C12:0 C14:0 C16:0 C18:0 C18:1 C18:2 Other

90PO:10PKO 0.07 0.27 6.05 2.01 40.00 4.79 38.41 8.12 0.2885PO:15PKO 0.30 0.56 8.69 3.71 31.27 4.21 37.25 7.03 0.5180PO:20PKO 0.98 0.86 12.82 5.80 35.75 3.53 32.89 7.04 0.3375PO:25PKO 0.97 0.85 13.55 6.56 33.58 3.69 33.43 7.05 0.4270PO:30PKO 0.16 1.05 17.38 6.19 29.78 3.87 33.24 7.73 0.5860PO:40PKO 1.09 1.23 19.48 7.40 33.18 3.39 29.97 6.07 0.1640PO:40PS:20PKO 0.30 0.10 11.80 4.70 45.80 3.80 29.40 3.70 0.3380POs:20PKO 0.30 0.60 9.80 4.50 53.100 3.70 22.45 4.70 0.8270POs:30PKO 0.20 1.00 9.22 4.21 54.13 4.65 22.42 3.71 0.7365POs:35PKO 0.50 1.75 14.12 5.63 49.65 3.58 20.97 3.07 0.6760POs:40PKO 0.60 2.20 19.50 7.400 44.30 3.30 19.40 2.50 0.61

Abbreviations: See Table 4.2.

TABLE 4.6Distilled Tallow and Vegetable Fatty Acid Blends and Resultant Soap Properties

Soap properties

Tallow and vegetable Acid Titer Iodine Free caustic Moisture Penetration value Foam volumefatty acid soap blends value (°C) value (%) (%) (mm) (mL)a

80T:20PKO 216.4 39.1 34.4 0.1 8.9 35 406/38540T:40PS:20PKO 220.0 41.4 27.2 0.2 7.9 33 398/39060T:20PS:20PKO 218.9 39.4 31.1 0.2 8.5 33 400/394

Abbreviations: See Table 4.2.aSee Glossary.


TABLE 4.7 Distilled Tallow and Vegetable Fatty Acid Soap Blends Composition


Tallow and vegetable Caprylic Capric Lauric Myristic Palmitic Palmitoleic Stearic Oleic Linoleicfatty acid soap blends C8:0 C10:0 C12:0 C14:0 C16:0 C16:1 C18:0 C18:1 C18:2 Other

80T:20PKO 0.3 0.6 9.3 6.7 22.3 1.0 17.7 32.4 2.9 6.540T:40PS:20PKO 0.5 0.6 9.0 4.8 32.6 1.1 9.2 24.2 3.0 3.060T:20PS:20PKO 0.5 0.7 9.7 5.7 30.9 1.4 1.0 28.9 2.8 5.5

Abbreviations: See Table 4.2.

TABLE 4.8Vegetable Oil Blends and Resultant Soap Properties

Soap properties

Acid Titer Iodine Free caustic Moisture Penetration value Foam volumeVegetable oil soap blends value (°C) value (%) (%) (mm) (mL)a

90PS:10PKOo 179.3 47.3 27.9 0.12 14.3 48 340/19880PS:20PKOo 185.0 43.8 29.6 0.05 14.0 48 321/22070PS:30PKOo 188.4 42.0 27.5 0.20 15.2 50 336/23660PS:40PKOo 190.7 41.2 27.8 0.09 15.2 52 340/21550PS:50PKOo 195.9 40.4 25.4 0.10 17.6 54 365/222

Abbreviations: Palm kernel oil olein, PKOo; see Table 4.2.aSee Glossary.


TABLE 4.9 Fatty Acid Composition of Vegetable Oil Soap Blends


Vegetable oil Caprylic Capric Lauric Myristic Palmitic Palmitoleic Stearic Oleic Linoleicsoap blends C8:0 C10:0 C12:0 C14:0 C16:0 C16:1 C18:0 C18:1 C18:2 Other

90PS:10PKOo 0.3 0.4 4.8 2.7 60.3 0.2 3.9 22.2 4.4 0.780PS:20PKOo 0.6 0.7 8.5 3.7 53.5 0.1 4.5 22.5 4.1 1.870PS:30PKOo 1.1 1.0 13.2 5.1 48.8 0.1 4.0 22.3 4.1 0.560PS:40PKOo 1.4 1.3 16.3 6.0 44.0 0.1 3.9 22.4 3.9 0.650PS:50PKOo 1.7 1.5 20.6 7.6 39.1 0.1 3.8 21.5 3.4 0.5

Abbreviations: See Tables 4.2 and 4.8.


TABLE 4.10Standard Soap Basesa

Specifications

Total fatty Moisture Free fatty acid Free caustic NaCl GlycerineStandard soap bases matter (%) (%) (%) (%) (%) (%)

SNTB 10, 15, 20, 25, 30, 35, and 40b 78–81 11.0–14.0 1.3* — 0.6* 0.5*SNTB 10, 15, 20, 25, 30, 35, and 40 78–81 11.0–14.0 — 0.05* 0.6* 0.5*N3020 and N4020 78–81 10.5–13.0 2.0* — 0.4–0.7 1.0*N3021 and N4021 78–81 10.5–13.0 — 0.05* 0.4–0.7 1.0*Palmsabun® 6000, 7000, 7500, and 8000 79–81 10.5–12.5 1.3* — 0.4–0.6 —SEO 8020c 78** 13.5* 1.3* — 0.6* —SEO 8020 78** 13.5* — 0.05* 0.6* —SEO 7525 78** 13.5* 1.3* — 0.6* —SEO 7525 78** 13.5* — 0.05* 0.6* —SEO 7030 78** 13.5* 1.3* — 0.6* —SEO 7525 79–82 13.5* — 0.05* 0.5* —SEO 7525 79–82 13.5* 1.3* — 0.5* —D215P 77–83 8.0–15.0 — 0.00–0.06 0.3–0.6 0.3–0.7Prisavon 9220 78–81 11.5–13.5 1.0–3.0 — 0.4–0.6 1.5–1.8Prisavon 9240 79–82 10.0–13.0 — 0.01–0.05 0.3–0.5 0.2–0.4Taurus 134 75.5–80.5 10.0–12.0 — 0.10* 0.3–0.7 4**Polaris 134 75.5–80.5 10.0–12.0 0.6 — 0.8 7–9

Sources: aReferences 5–9, 13, and Southern Edible Oil Sdn. Bhd (personal communication).bThe numbers next to the SNTB bases denote the lauric acid content in the soap and the balance is an equal blend of RDB palm oil and palm stearin.cThe numbers next to the SEO bases denote the palm oil (PO) to palm kernel oil (PKO) ratios, e.g., SEO 7525 consists of a 75/25 PO/PKO blend.*Maximum; **minimum.


producers prefer to use free fatty acid rather than free alkali type bases. The latheringproperties, indicated by the foam volume of the soap bars in Tables 4.11 and 4.12,show that the foam volume of both types of soap bars is within the same range.

Superfatting

Superfatting is the addition of fatty materials, be it fats and oils or fatty acids, tosoap bars. The main objectives of superfatting are to neutralize the free alkali inthe soap before it is dried into dry soap base, improve the lather volume and latherthickness, enhance skin feel, and prevent bar soap cracking.

The type and level of superfatting agent used determine the desired propertiesof the final product. In most cases superfatting is done through the addition of fattyacids or neutral oils at a level that would not impede processing and would not bedetrimental to the final properties of the soap products. Stearic acid, palm oil fattyacid, and coconut fatty acids are the most commonly used superfatting agents. Inmost cases the amount added is usually in the range of 5–10%.

Formulations. Palm-based soaps with formulations of 70POs:30PKO and 40POs:40PO:20PKO superfatted with 2, 4, and 6% distilled fatty acids increase the freefatty acid content of the soap bases as shown in Table 4.13. Tables 4.14, 4.15, and4.16 show the properties of soap bases superfatted with glycerine, coconut oil, andolive oil, respectively. The higher the amount of these superfatting agents, the soft-er the soap bases will be.

Specifications. Some soap bases are superfatted with fatty acids; this smallamount of free fatty acid provides moisturizing effects, good skin feel, mild, givesbetter lather volume, and adds good plasticity to soap (Table 4.17).

It is noted that in Table 4.10 for most palm soap bases that the free acid is1.3%; in order to obtain a soap base with free acid, the excess alkali of the standardalkaline soap base is neutralized with fatty acids of the main blend or other fattyacids, such as palm oil, palm kernel oil, palmitic acid, or lauric acid. The presenceof this free fatty acid provides better perfume release, since free alkali tends toreact with certain compounds in the perfume. Soap bases containing these freefatty acids are in demand when compared to the alkali-free soap bases.

NoMar bases prevent marring, which marks soaps. Specialty soaps displayed inbaskets and other types of containers are prone to marring as they touch each other.This unsightly damage can occur with unwrapped and wrapped soap bars as they ageand lose moisture. Table 4.18 lists suppliers of specially formulated NoMar bases forthe prevention of soap marring.

Transparent and Translucent Soaps

The raw materials used to manufacture transparent and translucent soaps have to bepure, with minimum color, to ensure that the final products have good transparency or


TABLE 4.12Tallow-Based Toilet Soaps

Properties

Tallow-based Total fatty matter Moisture Free fatty acid Free caustic Sodium chloride Titer Foam volumetoilet soaps (%) (%) (%) (%) (%) (°C) (mL)a

Fa 75 7.0 1.7 — 0.6 39.0 495/335Dial 78 11.0 3.7 — 1.4 37.0 500/335 Coast 82 11.5 0.8 — 0.6 36.2 535/375Tone 81 10.0 3.4 — 1.1 36.7 560/410Safeguard 82 9.3 0.7 — 0.7 36.6 530/375Irish Spring 79 8.5 8.3 — 1.5 34.2 340/170Palmolive 75 11.2 — 0.04 0.3 37.6 560/410Ivory 71 21.0 — 0.03 0.7 36.6 480/330

aSee Glossary.

TABLE 4.11Palm-Based Toilet Soaps

Properties

Palm-based Total fatty matter Moisture Free fatty acid Free caustic Sodium chloride Titer Foam volumetoilet soaps (%) (%) (%) (%) (%) (°C) (mL)a

Zaitun 81–85 9–11 1.3–3.8 — 0.5–0.7 46–47 410/240Palmolive 80–84 9–13 4.0–6.0 — 1.2 46–47 380/210Lux 81–84 9–13 1.0–3.0 — 1.0 41–44 495/330May 82–86 8–11 1.0–3.0 — 0.5 45–47 410/240Kao 80–84 9–11 7.0** — 0.7–1.0 39–40 400/230Nona 80–81 9–10 — 0.05* 1.0* 43–44 510/280Ria 79–81 10–13 — 0.03 0.5 42–43 535/380

*Maximum, **minimum.aSee Glossary.


TABLE 4.13Soap Bases Superfatted with Distilled Soap Fatty Acids (DFA)

Properties

Total fatty Free fatty Sodium Penetration FoamSuperfatted soap blends with matter acid Moisture Free caustic chloride value volumedistilled fatty acids (DFA) (%) (%) (%) (%) (%) (mm) (mL)a

70POs:30PKO 76 — 16 0.16 0.5 50 415/230with 2% (DFA) 77 1.3 17 — 0.5 51 340/205with 4% (DFA) 78 1.3 14 — 0.5 51 240/107with 6% (DFA) 77 3.7 16 — 0.5 62 270/112

40POs:40PS:20PKO 76 — 14 0.15 0.5 46 470/305with 2% (DFA) 80 1.3 12 — 0.5 51 490/335with 4% (DFA) 78 3.2 15 — 0.5 52 355/185with 6% (DFA) 83 6.8 10 — 0.5 74 360/175

Abbreviations: See Table 4.2. aSee Glossary.

TABLE 4.14Soap Bases with Glycerine

Properties

Total fatty matter Moisture Free caustic Sodium chloride Penetration value Foam volumeSoap bases with glycerine (%) (%) (%) (%) (mm) (mL)a

70POs:30PKO 82 11 0.10 0.5 48 500/325with 1% glycerine 83 11 0.10 0.4 51 505/337with 2% glycerine 84 12 0.10 0.4 52 517/340

40POs:40PO:20PKO 81 11 0.20 0.2 48 470/306with 1% glycerine 80 11 0.10 0.4 66 520/350with 2% glycerine 81 11 0.10 0.5 75 500/340



TABLE 4.15Soap Bases with Coconut Oil

Properties

Total fatty Free fatty Moisture Free caustic Sodium Penetration value FoamSoap bases with coconut oil matter (%) acid (%) (%) (%) chloride (%) (mm) volume (mL)a

70POs:30PKO 82 — 11 0.1 0.2 38 485/315with 2% coconut oil 86 1.0 12 — 0.4 43 517/375with 4% coconut oil 86 1.0 10 — 0.4 44 507/375with 6% coconut oil 86 1.0 11 — 0.4 48 512/375

40POs:40PO:20PKO 81 — 11 0.2 0.5 46 465/300with 2% coconut oil 81 0.4 11 — 0.5 46 480/314with 4% coconut oil 84 0.6 9 — 0.5 48 475/318with 6% coconut oil 90 0.6 10 — 0.5 78 485/325


TABLE 4.16Soap Bases with Olive Oil

Properties

Soap bases Free caustic Free fatty acid Moisture Total fatty matter Sodium chloride Penetration value Foam volumewith olive oil (%) (%) (%) (%) (%) (mm) (mL)a

70POs:30PKO 0.1 — 11 82 0.2 38 480/308with 2% olive oil — 0.2 12 85 0.4 39 538/355with 4% olive oil — 0.1 10 86 0.4 57 550/357with 6% olive oil — 0.1 11 86 0.4 70 558/380

40POs:40PO:20PKO 0.2 — 11 81 0.5 46 473/305with 2% olive oil — 0.4 11 81 0.5 46 467/300with 4% olive oil — 0.6 9 84 0.5 48 490/346with 6% olive oil — 0.6 10 90 0.5 78 478/335



translucency. About half of a transparent soap formula is soap produced from tal-low, RBD (Refined, Bleached and Deodorized) palm oil, RBD palm kernel oil,coconut oil, castor oil, rosin, and other fats and oils. The remaining ingredientsinclude additives such as sucrose, sorbitol, glycerine, ethanolamide, coconut dieth-nolamine, triethanolamine (TEA), propylene glycol, α-olefin sulfonate (AOS),sodium cocoyl isethionate (SCI), sodium lauryl ether sulfate (SLES), and alcohol(10).

Transparent soaps are made by the batch cast (poured, molded) process.Companies that do not manufacture their own transparent products can purchasealready formulated translucent bases by producers of Melt and Pour (M&P)-type spe-cialty bases. The M&P base can be easily melted; fragrance, color, additives toenhance bar performance, and even interesting inserts can be added to the melted

TABLE 4.17 Superfatted Soap Basesa

Total fatty Free fattymatter Moisture acid NaCl Glycerine

Superfatted soap bases (%)

SNSF-20 78–81 11.0–14.0 3.0–5.0 0.6* 0.5*SNSF-30 78–81 11.0–14.0 3.0–5.0 0.6* 0.5*SNSF-40 78–81 11.0–14.0 3.0–5.0 0.6* 0.5*Palmsabun® 8005 80–82 10.5–12.5 2.5–4.5 0.4–0.6 —Palmsabun® 7505 80–82 10.5–12.5 2.5–4.5 0.4–0.6 —Palmsabun® 7005 80–82 10.5–12.5 2.5–4.5 0.4–0.6 —D225P 73–83 10.0–14.0 2.5–5.0 0.4–1.0 0.5–1.5Prisavon 1650*** 81–84 8.0–11.0 1.0* 0.4–0.7 1.0–1.4Prisavon 9218 78–81 11.5–13.5 1.0–3.0 0.4–0.6 1.5–1.8Prisavon 9242 70–77 11.0–14.0 1.5–2.5 0.3–0.5 1.1–1.5Prisavon 9244 80–83 9.0–11.0 1.5–2.5 0.4–0.6 1.4–2.0Prisavon 9245 78–81 11.0–14.0 1.5–2.5 0.4–0.6 1.4–2.0

Sources: aReferences 5, 6, 8, and 9.*Maximum; **minimum; ***preservative free.

TABLE 4.18 NoMar Soap Bases

Properties

NoMar soap bases Total fatty matter (%) Moisture (%) Glycerine (%)

Pace-HGL 74** 13* 6–8Plastibar 69–75 11–15 6–8Prisavon 9259 69.5–73.5 13–15 6–8Opal 508 72–77 11–14 6–8

Sources: aReferences 5, 8, 9, and 11.*Maximum; **minimum.


base. The finished product is poured into molds where it solidifies. Molds of manytypes and shapes are available from several suppliers. M&P soap making has becomepopular with homemade and specialty gift type soap makers. Stephenson PersonalCare (11) offers a wide range of M&P products under the “Crystal” name.

Unlike transparent soaps, translucent soaps are extruded continuously. Mosttranslucent soaps contain sorbitol, glycerine, propylene glycol, and some have TEA;the moisture content should be at least 15%. In the past, other additives were also usedbut were slowly eliminated because they provided no extra transparency enhance-ment. During the last few years, several major companies launched many translucentsoaps, packaged in transparent packaging materials worldwide. Firms that do not pro-duce their own translucent soap but have bar soap finishing equipment can buy fin-ished translucent bases (Table 4.19).

Laundry Bars

Laundry bar soaps are used for general household cleaning and manual washing.With the advent of detergent powders and bars, laundry soaps have become lesspopular and their use is declining. There are three types of laundry bar products onthe market, namely laundry soap bars, synthetic laundry bars, and combo laundrybars. Soap bars primarily contain anhydrous soap as the surfactant, syndet barscontain only synthetic surfactant, and combo bars are a mixture of soap and syn-thetic surfactant.

Few laundry soap bases are offered, since most companies make their laundrybars starting from raw materials instead of buying the base. Palm laundry soapbases are offered by Pan-Century’s Edible Oils Sdn. Bhd. and Southern Edible OilsSdn. Bhd. The technical specifications are shown in Table 4.20. The laundry soapbar market is very large in many developing countries, but it is very limited in theindustrialized regions and therefore only three brands were analyzed (Table 4.21).

TABLE 4.19 Translucent Soap Basesa

Total fatty Moisture Free fatty GlycerineTranslucent soap bases matter (%) (%) acid (%) (%)

PACE TL2001 67** 15.0* 3.0* 6–8ISC Diamond 67–73 15.0–18.0 2.8–3.4 7–10

(as oleic acid)Prisavon 1979 65–70 13.0–15.0 2.0–3.0 7–8Prisavon 1984 64–69 13.5–16.0 2.0–3.0 7–8Pearl 510 and 511 63–68 15.0–18.0 1.5–2.5 6–8

(as stearic acid)Trident & Aries 254 66.5–72.5 14.5–18.0 1.75–2.5 6–8

(as stearic acid)

Sources: aReferences 5, 8, 9, 11, and 13.*Maximum; **minimum.


TABLE 4.20Palm Laundry Soap Bases

Properties

Moisture Free fatty acid Free caustic Sodium chloride TiterPalm laundry soap bases Total fatty matter (%) (%) (%) (%) (%) (°C)

SNTC 10 78–81 11.0–14.0 1.3a 0.05a 0.6a 44–48SNTC 20 78–81 11.0–14.0 1.3a 0.05a 0.6a 42–46SNLW-1 75b 18a 1.3a 0.1a0 0.6a —SNLW-2 70b 23a 1.3a 0.1a0 0.6a —SNLC-1 75b 18a 1.3a 0.1a0 0.6a —SNLC-2 70b 23a 1.3a 0.1a0 0.6a —SEOL 65b 18–23 — 0.05a 0.5 46–48aMaximum.bMinimum.Sources: Pan-Century Edible Oil Sdn. Bhd. (5), and Southern Edible Oil Sdn. Bhd. (personal communication).

TABLE 4.21Palm-Based Laundry Bar Soaps

Properties

Palm-based Moisture Free fatty acid Free caustic Sodium chloride Titerlaundry bar soaps Total fatty matter (%) (%) (%) (%) (%) (°C)

Buruh 70–75 15–20 3.0 0.05 0.5 46–48Mysore 82 8 — 0.04 0.4 40–48Jabon 71 27 — 0.05 0.4 40–48


Conclusion

In summary the properties of tallow soap bases and palm soap bases are similarexcept for titer. The higher titer in some palm soap bases is attributed to the incor-poration of palm stearin in the soap blend; however, the performance of both typesof soap bases is similar. Hardness of the soaps due to high titer can be addressedby the addition of superfatting agents. The amount added will depend on the natureof the superfatting agents and their effect on the properties of the final soap bars.

Two of the major competitors for toilet bar soaps are the body washes and theliquid soaps. In Western Europe liquid body wash sales exceed bar soap, while inthe United States bar soap consumption is still higher but the use of liquids hasbeen growing yearly. In the Asian market, bar soap dominates the market becauseit is cheaper than liquid soap, contains more surfactant, has long shelf life, and iseasy to transport.

Liquid body wash is also popular; this is due to the presence of various skin-careadditives in the products. Nevertheless, bar soap manages to overcome this drawbackby adding natural skin-care and facial-care ingredients. These natural ingredients areusually plant extracts with special properties. This can be seen in the range of translu-cent and transparent soap bases produced by Stephenson Personal Care. Besides theuse of natural additives, bar soap manufacturers are also keeping up with the presenttrend of low pH soaps by producing less alkaline soap through superfatting with fattyacids, adding surfactant, and incorporating emollients or moisturizers. Thus, the soapmanufacturers have to be creative in producing soaps with different properties, func-tions, and variations to satisfy this greater demand.

Glossary

Acid Value (AV). The acid value is the number of milligrams of potassium hydrox-ide (KOH) necessary to neutralize the fatty acids in 1 g of sample. Higher AV materi-als allow faster-appearing but less stable suds creation. Lower AV materials allowslower-appearing but more stable suds formation. A lower AV means more cleansing(detergency). AV is used for fatty acids only to provide an estimate of SV. The AVfor fatty acids is very close to the SV. The AV is usually ~2 points lower than the SV.

Fatty Acids. Fatty acids are linear, mainly even carbon–numbered long-chain hydro-carbons with a terminal carboxyl group. Unsaturated fatty acids are those with one ormore double bonds in their carbon chain structure.

Free Alkalinity (Free Caustic). Free alkalinity is the amount of alkali content presentin a sample expressed as a percentage weight of free sodium hydroxide (NaOH). Thehigher the free alkalinity, the greater the skin irritation from soap. The higher the alka-linity, the greater the cleaning power of soap. For toilet soaps, lower alkalinity is pre-ferred for a better product stability with respect to color and odor. For laundry soaps,higher alkalinity is preferred for better cleansing properties of the product.


Free Fatty Acid (FFA). This is the free fatty acid content present in a sample com-monly expressed as oleic acid, but it can also be expressed as palmitic acid orstearic acid.

Free Glycerine. The amount of free glycerine present in the sample expressed as apercentage weight of the total sample. It is perceived as a moisturizer. Glycerine levels≤2% will harden soap. Levels > 2% yield a softer and stickier soap. Glycerine is usedas a processing aid for low-moisture, high-titer products.

Foam Volume. This is the measure of the foamability of a cleansing product. Thefoam volumes (mL) listed in the tables were determined using a 0.1% soap solutionplaced in a measuring cylinder and agitated with a perforated paddle stirrer for 30strokes. The initial measurement (first number) was recorded after the end of the agita-tion and the final foam volume (second number) was recorded 5 min after the agitationstopped. There are different foam test protocol methods. The Ross Miles method is themost widely used. All of the methods give relative volumes and are used for lathercomparison. There is no standard method giving absolute values.

Iodine Value (IV). The iodine value is a measure of the unsaturation (double bonds)in fats, oils, and fatty acids. It is expressed in terms of the number of grams of iodineabsorbed by 100 g of sample (% iodine absorbed). The higher the IV, the higher thedegree of unsaturation and the greater the vulnerability for rancidity. As the IV levelincreases, soaps become softer and stickier. Foaming and cleansing increase as the IVincreases and decrease as the IV decreases in higher-chain saturated fatty acids.Coconut oil (IV range of 7–12) is an exception. It produces the hardest soap and thefastest sudsing, but lacks suds stability.

Lovibond Color. This is a color measurement of the fats, oils, and fatty acids deter-mined with a Lovibond Tintometer. A 5.25” glass cell containing the sample is com-pared with Lovibond glass red (R) and yellow (Y) color standards and the colors arerecorded in R and Y units. The R value is the color-controlling value. An R value ≤1.0is preferred for the production of white soaps. An R value > 2.5 will result in off-white(darker color) soaps.

Melting Point. The temperature expressed in °C at which a triglyceride or fattyacid liquefies.

Moisture Content. This is the amount of volatile material present in a sampleexpressed as a percentage weight.

Penetration Value. This is a measure of bar soap hardness. It is expressed as thedepth (mm) to which a penetrometer needle penetrates a bar of soap when subjected toa 50-g weight. The deeper the needle travels, the softer the soap.


Saponification Value (SV). The saponification value is defined as the number of mil-ligrams of potassium hydroxide (KOH) required to saponify 1 g of sample. SV is usedto determine the average molecular weight (MW) of fats and oils being saponified,using the formula: MW = 56,100/SV. Mixtures of high- and low-SV stocks providevery desirable levels of sudsing and cleansing. Typically, 10–30% of high-SV and90–70% of low-SV triglycerides are used.

Sodium Chloride. The amount of sodium chloride (NaCl) present in a sampleexpressed as a percentage weight of sodium chloride or simply chloride. Sodium chlo-ride is one of the most critical ingredients for soap processing and product attributes.Sodium chloride hardens the soap, but high levels can create “cracking” and decreasesudsing. In standard nonsuperfatted low coco soaps, the level should not exceed 0.5%.The chloride level increases in nonsuperfatted soaps, depending upon the level ofcoco/palm kernel soap in the product. It can be as high as 2–3% in high coco-contain-ing soaps. Superfatted soaps can have up to 1.5% sodium chloride without detrimentaleffects.

Titer. This is the measure of the solidification point of fatty matter (fats, oils, andfatty acids) measured in °C. Higher titer provides harder soap. Lower titer providesbetter cleansing (with longer-chain fatty acids or triglycerides).

Total Fatty Matter (TFM). Total fatty matter is expressed as the fatty acidsobtained from soap and is the sum of the free fatty acid, the fatty acid obtainedfrom soap, and the unsaponifiables. The test method used for determination ofTFM requires the splitting of soap using mineral acids and then the extraction ofthe fatty matter using petroleum ether. Total fatty matter does not include the fattymatter generated by nonsoapy synthetic actives. The TFM of triglyceride is theamount of fatty acids produced by splitting the oil. The TFM of fatty acids is thetotal weight of fatty acids. Fatty acids are 100% TFM.

Unsaponified and Unsaponifiable matter (U&U). The unsaponified matter con-sists of neutral unreacted fat, which is not saponified. The unsaponifiable matterincludes substances frequently found dissolved in fats and oils that cannot besaponified with caustic alkalies but are soluble in ordinary fat solvents. U&U com-prises the amount of substances soluble in petroleum ether present in the sampleand is expressed as a percentage weight. High unsaponifiable content makes soapsticky and can lead to discoloration. Unsaponifiables contribute to the emolliencyand skin-feel attributes of soap bars. They basically act as “superfatting” agentsand are a part of the TFM.

Note: For detailed analytical testing procedures please consult the official AOCSMethods.


Soap Calculations

Two Routes to Soap Making

Two primary routes exist for soap making (14).

1. TriglyceridesRCOOCH2 CH2OH

| |RCOOCH + 3NaOH → 3RCOONa + CHOH

| |RCOOCH2 CH2OHTriglyceride + caustic soda → soap + glycerine

2. Fatty acidsRCOOH + NaOH → RCOONa + H2OFatty acid + caustic soda → soap + water

Fat Blend Calculations

The SV, IV, and titer are all additive of the proportional values of fat blend compo-nents. The SV, IV, and titer of an 80/20 blend of tallow (SV 197, IV 45, titer 41)and coconut oil (SV 257, IV 10, titer 22) can be calculated per Table 4.22.

Caustic Soda Requirement Calculations

The saponification of a fat blend results in the formation of soap and glycerine (Eq. 1).

triglyceride + 3 NaOH → 3 RCOONa + glycerine [1]

The fat blend and caustic soda are mixed in a nearly stoichiometric ratio, with~0.1–0.5% excess of alkali. The molecular weight of the fat blend is calculated perEquation 2.

MWfat = 56.1SV

× 3 ×1000 = 168,300SV

[2]

TABLE 4.22 Calculation of SV, IV, and Titer of an 80/20 Tallow/Coconut Oil Blend

Fat component (%) SV Titer (°C) IV

Tallow 80 197 × 80% 41 × 80% 45 × 80%Coconut oil 20 257 × 20% 22 × 20% 10 × 20%Blend 100 209 37.2 38


Problem 1. Calculate the MW of an 80/20% blend of tallow (SV 197) andcoconut oil (SV 258).

The amount of caustic soda required to saponify a fat blend of known SV can becalculated via Equation 3.

Problem 2. Calculate the amount of caustic soda (50%) required to saponify 500lb of an 80/20% (SV 209) tallow/coconut oil blend.

Saponification Products—Quantity Calculations

The Quantity of SoapThe amount of soap produced in a saponification reaction can be calculated fromEquations 4–6.

triglyceride + 3 NaOH = 3 soap + glycerine1 mol 3 × 40 = 120 3 mol 92

MWtallow = 168,300197

= 854

MWcoco = 168,300258

= 652

MW80/ 20 T / C = (854 × 80%) + (652 × 20%) = 813.6

SV1000

× MWNaOH

MWKOH

= SV1000

× 4056.1

= SV × 0.000713g/ g [3]

NaOH50% = SV × 0.00071350

×100

= 209 × 0.00071350

×100g/ g

= 0.298g/ g × 500 lb = 149 lb

soapwt = MWfat + 120 − 92 = MWfat + 28

= fatwt

fatMW

× fatMW + 28( )

= fatwt × SV

168,300

× 168,300SV

+ 28

[4]

[5]

[6]


The Quantity of Glycerine

Glycerine liberated in a saponification mixture can be calculated from Equation 7.

Since triglyceride + 3 KOH = soap + glycerol,

For fat blends with high levels of FFA, the following calculation will give theglycerine content of the saponification mixtures (Eq. 8):

Problem 3. Calculate the amounts of soap and glycerine produced in the saponifi-cation of a blend of 250 lb of tallow (SV 197) and 250 lb of coconut fatty acid (AV260; SV 260).

In this case, fatwt = 500 lb, and

SV AV Tallow 197 × 50% = 98.5

Coconut fatty acid 260 × 50% = 130 260 × 50% = 130

TG = SV – AV= (SV [tallow] + SV [coconut fatty acid] – AV= (98.5 + 130) – 130= 228.5 – 130= 98.5

glycerine % = SV1000

× 92168.3

×100

= SV × 0.0547

glycerinewt = SV × 0.0547 × fatwt

100[7]

fat triglyceride , (TG) = SV − AV

glycerine % = TG1000

× 92168.3

×100

glycerine % = TG × 0.0547 [8]

glycerinewt = TG × 0.0547= 98.5 × 0.0547= 5.39%= 5.39 × 500 / 100= 26.95 lb (from Eq. 8)

TG = SV – AV= (SV [tallow] + SV [coconut fatty acid]) – AV= (98.5 + 130) – 130= 228.5 – 130= 98.5

(continued p. 138)


The amount of caustic soda required for this reaction can be calculated perEquation 3.

NaOHwt = 228.5 × 0.000713 × 500= 81.46 lb (100% NaOH)

Total Fatty Matter (TFM) Calculation

For product specifications purposes, TFM of a fat mixture is obtained from triglyc-eride (TG) mass, less its glycerine content, plus water (Eq. 9).

triglyceride + 3 H2O = 3 RCOOH + glycerine3 × 18 = 54 fatty acid 92

Fatty Acid Blend Calculations

The following three methods are utilized in the calculation of fatty acid and alkalireactants: the molecular weight (MW) method, the gram-mole (G-Mole) method,and the acid value (AV) method.

soapwt = 500

168,300× 228.5

× 168,300228.5

+ 28

(from Eq. 6)

= 0.679 × 76= 519 lb

TFM = (TG + 54) − 92

= TG − 38

TGeq.wt = 56.1SV

×1000

FFAeq.wt = TG − 38 / 3( )

=56,100

SV

− 12.66

TFN% =FFAeq.wt

TGeq.wt


In the molecular weight method, the fatty acid and alkali are blended in theratio of their molecular weights. The G-Mole method is a variant of molecularweight method; the reactants are mixed in their grams per mole ratio. The acidvalue method permits the blending of fatty acids and alkalis on the basis of the acidvalue of the fatty acid utilized in the neutralization reaction.

NaOHwt = FAwt × AV × 0.713 × NaOH (%)

Since molecular weight and acid value are interrelated: MW = 56.1/AV ×1000, the molecular weight method will be described in more detail in this chap-ter.

For fatty acids, the acid value (AV), titer, and saponification value (SV) areall additive of the partial moieties present in the blend. Thus, for a blend of tallowand coconut fatty acids in a 80/20% ratio, the AV of the blend is 218 (Table 4.23).

Caustic Soda Requirement Calculations

For the reaction, RCOOH + NaOH = RCOONa + H2O, use Equation 10.FAMW 40 (FAMW + 22) 18

FAMW = 56.1AV

×1000 = 56,100AV

NaOHwt = FAwt

FAMW

× 40

= FAwt

(56,100 / AV)

× 40

= FAwt × AV × 40

56,100[10]

TABLE 4.23 Calculation of the Acid Value of a Fatty Acid Blend

Fatty acid component % AV

Tallow (AV 305) 80 205 × 80% = 164Coconut (AV 270) 20 270 × 20% = 54

Total = 218


Fatty Acid Neutralization Products

The Quantity of Soap Produced

Soap produced in the neutralization reaction can be calculated per Equations 11and 12.

The Amount of Water Produced

This is calculated as per Equation 13.

Formula Adjustments

Occasionally, the fatty acid blends or neat soap mixtures require an adjustment ofblend composition due to a weighing or calculation error. This section describespractical approaches to handling such manufacturing problems.

Fatty Acid Blend Molecular Weight Adjustment

This adjustment usually requires the addition of a fatty acid of molecular weightlower or higher than the molecular weight of the blend to be adjusted. Equation 14can be used for this purpose.

Let x = portion of fatty acid to be added.

(1 – x) = portion of fatty acid blend to be adjusted.

x (FA added)MW + {(1 – x) × [FA (initial blend)MW]} = FA (final blend)MW [14]

Problem 4. You have a tallow/coconut fatty acid blend of MW 244. How muchtallow fatty acid (MW 274) should be added to it to convert it into a blend of MW255?

From Equation 14, let x = portion of tallow fatty acid (MW 274) to be added;(1 – x) = portion of initial blend (MW 244).

soapwt = FAwt

FAwt

× FAwt + 22( )

= FAwt

FAwt

× 56,100AV

− 22

waterwt = FAwt

FAMW

×18

[11]

[12]

[13]


x(274) + [(1 – x)244] = 255

(274x) + (244 – 244x) = 255

(274x) – (244x) = 255 – 244

30x = 11

x = 0.37; or 37%

(1 – x) = 100 – 37 = 63%

Thus, fatty acid blend (initial) = MW 244 × 63% = 153.7

tallow fatty acid added = MW 274 × 37% = 101.3

final blend = MW 255

An alternative to this calculation is described in Equation 15.

Let initial fatty acid weight = Wt1; MW = MW1

final fatty acid weight = Wt2; MW = MW2; and

fatty acid added weight = x; MW = MW3

Problem 5. You have a 100-lb blend of fatty acid, MW 244. How much of a fattyacid of MW 274 should be added to it to make a final blend of MW 255?

Thus, FA initialwt = 100 lb (63%) Fa initialMW: 244 × 63% = 153.7

FA addedwt = 58 lb (37%) Fa addedMW: 274 × 37% = 101.3

FA final blendwt = 158 lb FA final blendMW: = 255

Alkalinity/Acidity Adjustment

In cases of the downward adjustment of the acidity of superfatted formulas,Equation 16 can be used, where FFA refers to the free fatty acid to be neutralized.

FA addedwt = Wt1

x

− Wt1

x = MW3 − MW2

MW3 − MW1

x = 274 − 255274 − 244

= 1930

= 0.633

FA addedwt = 1000.633

− 100 = 58.0 lb

[15]


Problem 6. A neat soap batch (400 lb) was found to contain 3% FFA (MW 280).How much NaOH (50%) should be added to it to make it neutral?

The upward adjustment of the FFA level of a neat soap blend is done via Equation 17.

Problem 7. You have a 400-lb batch of neat soap with FFA (MW 280) of 1%.How much FFA (MW 280) should be added to it for a final FFA (MW 280) con-tent of 2% in the neat soap?

The adjustment of a formula of high alkalinity, via the addition of a fatty acid,is performed by Equation 18.

FFAwt = soapwt × FFA%

NaOHadded = FFAwt

FFAMW

× 40

= FFAwt

FFAMW

× 40NaOH%

×100

FFAwt = 400 × 3% = 12 lb

NaOHadded = 12280

× 40

50×100

= 3.4 lb

conversion factor, CF =soapwt − (soapwt × FFA initial% )

soapwt − (soapwt × FFA final% )

FFA addedwt = (CF × soapwt ) − soapwt

CF = 400 − (400 ×1%)400 − (400 × 2%)

= 400 − 4400 − 8

= 1.01

FA addedwt = (1.01 × 400) − 400 = 4.0 lb

alkaliwt = soapwt × alkalinity%

FA addedwt = alkaliwt × FAMW

alkaliMW

[16]

[17]

[18]


Problem 8. A 400-lb batch of neat soap has an alkalinity of 1.6% (as NaOH). Howmuch of a fatty acid of MW 280 should be added to it to make the net soap neutral?

The molecular weight interconversion of fatty acids can be calculated viaEquation 19.

Problem 9. A soap bar sample contains 2% coconut fatty acid (MW 207) as thesuperfat. Convert this and express it as tallow fatty acid (MW 273) superfatvalue.

Problem 10. You have a 400-lb batch of soap containing 2% coconut fatty acid(MW 208) as the superfat. How much additional coconut fatty acid should beadded to it so that this batch contains a total of 4% super-fat, expressed as stearicacid (MW 274)?

In this example, we need to determine the amount of coconut fatty acid presentinitially in the soap, the above quantity expressed as stearic acid, the additionalamount of coconut fatty acid required, and that quantity expressed as stearic acid.

From Equation 19,

The above quantity of stearic acid to be added should then be converted intothe coconut fatty acid equivalent, as per Equation 19.

alkaliwt = 400 ×1.6% = 6.4 lb as NaOH

FA addedwt = 64 × 28040

= 44l8 lb

FFAA

FFAB

= MWA

MWB

2FFAB

= 207273

FFAB = 2 × 273207

= 2.63%

stearic FAinitial = 208274

× 274 × 2208

= 2.63%

FFAadded = FFAcalculated − FFAIinitial

= 4.0 − 2.63

= 1.37%

[19]


The batch contains now a total of 8.0 + 4.16 = 12.16 lb (3.01%) of coconutfatty acid. This is equivalent to 4% stearic acid, as per Equation 19.

The calculation for the adjustment of alkalinity follows: The alkalinity of a for-mula containing FFA can be increased as per Equation 20.

First, calculate the amount of alkali needed to bring the formula to neutralityvia Equation 16. Then, the amount of additional alkali needed to reach the desiredalkali level is calculated.

Problem 11. For a 400-lb batch of neat soap containing 2% FFA (MW 270), howmuch NaOH should be added to increase the alkalinity (as NaOH) to 0.1?

The alkalinity of a formula, which is already alkaline, can be increased furtherby Equation 20; the alkalinity of a formula can be decreased by the addition of afatty acid via Equation 18.

Problem 12. A 400-lb batch of neat soap contains 2% FFA (MW 270). How much ofa 30% NaOH solution should be added to it to bring the FFA level to 1% (MW 208)?

alkalinity adjustment, AA = alkali final%

100− alkali initial%

100

alkaliwt = AA × soapwt

alkali%

FFAA

FFAB

= MWA

MWB

FFAA

1.37= 208

274

FFAA = 1.37 × 208274

= 1.04% = (400 ×1.04%) = 4.16 lb

From Equation 16, FFAwt = 400 × 2% = 8 lb

NaOH added = 8270

× 40 = 1.18 lb

From Equation 20, AA =0.1100

− 0100

= 0.001

NaOHwt = 0.001 × 400100

×100 = 0.4 lb

NaOH total added = 1.18 + 0.4 lb = 1.58 lb ×100

[20]


A combination of equations will be used for this calculation.

Now, the batch requires 400 × 1% = 4 lb FFA (MW 208). Thus, excess FFA (MW208) = 6.16 – 4 = 2.16 lb. To neutralize 2.16 lb of fatty acid with 30% NaOH,Equation 16 is utilized:

To summarize in molar equivalents, the formulas containing free fatty acidswill have the following weight ratios:

coconut fatty acidwt < stearic acidwt

To illustrate, 5% coconut fatty acid, MW 208 (as FFA) = 6.6% stearic acid,MW 274 (as FFA). In other terms, it will take a greater quantity of stearic acid thancoconut fatty acid to neutralize a given quantity of alkali.

Acknowledgments

We would like to thank Dr. Yusof Basiron, the Director General of the Malaysian Palm OilBoard for his support and permission to write this chapter. Appreciation is also extended tothe various companies for the information they supplied and also to Dr. Hamirin Kifli for hissuggestions and support.

References

1. Witco Corporation, Fatty Acids, Glycerine and Triglycerides, Oleochemicals BookletUSA, 1997, pp. 9–11, 16.

2. Tang, T.S., Composition and Properties of Palm Oil Products, in Advances in Oil PalmResearch, edited by Y. Basiron, B.S. Jalani, and K.W. Chan, Malaysian Palm Oil Board,Selangor, Malaysia, May 2000.

3. Tang, T.S., Specification for Palm Kernel Stearin, in Malaysian Standard, MS 1437,SIRIM Publications, Shah Alam, Selangor, Malaysia, 1998, pp. 2–3.

FFAwt = 400 × 2% = 8 lb

From Equation 19,

8FFAB

= 270208

FFAB = 8 × 208270

= 6.16 lb

30% NaOH added = 2.16208

× 4030

×1.38 lb


4. Cognis Oleochemicals (M) Sdn. Bhd., Oleochemicals—Distilled Fatty Acids, Selangor,Malaysia, 2003.

5. Pan-Century Edible Oils Sdn. Bhd., Soap Noodle Products Specifications, Johore Bahru,Malaysia, 2003.

6. Derichem Sdn. Bhd., Penang, Malaysia, Product Specifications, 2003.7. KSP Manufacturing Sdn. Bhd., Natsoap®—Soap Noodles Brochure No. 02-1.9.97,

Selangor, Malaysia, 1997.8. The Dial Corporation, Industrial Chemicals Division, Soap Base Pellets Data Sheets,

Scottsdale, Arizona, 2003.9. Uniqema, PrisavonTM Personal Wash Product Data Sheets, Gouda, the Netherlands, 2004

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11. Stephenson Personal Care, Soaps Product Specifications, Stephenson Group, Bradford,UK, 2003.

12. Tan, L.P., The Future of Palm-Based Soap in Asia Pacific, in Proceedings of the 2001PIPOC International Palm Oil Congress (Oleochemical), Malaysian Palm Oil BoardPublication, Bandar Baru Bangi, Selangor, Malaysia, 2001, pp. 80–85.

13. Bradford Soap Works, Inc., Product Specification Tables, West Warwick, Rhode Island,2004.

14. Gupta, S., Chemistry, Chemical, and Physical Properties & Raw Materials, in SoapTechnology for the 1990’s, edited by L. Spitz, AOCS Press, Champaign, Illinois, 1991,pp. 48–93.


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