Bioprocessing Approaches to Synthesize Bio-based Surfactants and Detergents - Food and Industrial Bioproducts and Bioprocessing - page 239

Lyle LLC (Loudon, TN) (Shelley 2007); glyceric acid via fermentation (Habe et al ., 2009 );
and polyglycerol, through homogeneous or heterogeneous catalysis (Barrault et al ., 2004 ).
Mono-, di-, and oligo-saccharides derived from starches, cellulose, and other naturally-
derived polysaccharides, such as glucose, xylose, N-acetylglucosamine, maltose, and
cellobiose are additional inexpensive choices. Monosaccharide derivatives are also important
sources of hydrophiles. Sugar alcohols (e.g., sorbitol and xylitol) are readily produced from
monosacharides via hydrogenation (Wen et al ., 2004 ), electrochemical reduction (Tang
et al ., 2004), and microbial transformation utilizing oxidoreductases (Liu et al ., 2010 ).
Sorbitan, molecules typically consisting of a five-member ring that contain an oxygen atom,
formed from the dehydration of sorbitol, are commonly used to prepare non-ionic surfactants.
Oxidation of sacchharides produces furfuryl (De Jong and Marcotullio , 2010 ) and
levoglucosanyl (Lakshmanan and Hoelscher, 1970) compounds, also potentially valuable
hydrophiles. Glycols, components of alkyl glycosides and esters, are produced via
fermentation of saccharides (Werpy and Petersen, 2004).
Polyol-based surfactants serve as an example of “non-ionic” surfactants, amphiphiles
with polar “head” groups that are uncharged. Some “anionic” and “cationic” surfactants,
amphiphiles possessing negatively and positively charged polar groups, are also bio-based
(Hayes, 2009). However, surfactants described herein, obtained through bioprocessing, are
non-ionic surfactants. Phospholipids serve as bio-based “zwitterionic” surfactants.
Amino acids can serve as surfactant hydrophiles via covalent attachment to their
carboxylic acid and/or amino functional groups (Infante et al ., 2009a , 2009b ; Husmann,
2008). In addition, amino acids can be converted into ethanolamine and isopropylamine
(from serine and threonine, respectively) (Scott et al ., 2007), which serve as hydrophiles for
cationic surfactants (Otero, 2009). DNA-derived bio-based surfactants have also been
synthesized (Leal et al ., 2006 ; Xu et al ., 2005 ; Bilalov et al ., 2004 ).
Many nonionic surfactants contain poly(ethylene glycol), or equivalently, poly(ethylene
oxide), as their hydrophile, through covalent attachment to fatty acyl, fatty alcohol, or fatty
amine groups. This hydrophile is typically formed from petroleum-derived ethylene via
synthesis of ethylene oxide, a material that is carcinogenic, mutagenic, highly flammable,
volatile, and reactive. However, in Brazil ethylene has now been derived from bioethanol
formed from fermentation of sugar cane (Gielen et al ., 2008 ).
In addition to derivation via covalent attachment of bio-derived lipophiles and hydrophiles,
bio-based surfactants can be more directly synthesized from bio-renewable resources.
Mono- and di-acylglycerols are readily obtained through hydrolysis of TAG. Phospholipids
are directly obtained from soapstock, gums, and other oleochemical processing co-products.
Lysophospholipids, common emulsifiers in foods that also play important physiological
roles in phospholipid metabolism and treatment of arteriosclerosis, are obtained from
chemical or enzymatic hydrolysis of phospholipids (D'Arrigo and Servi, 2010). As described
in the following, several naturally-occurring surfactants, “biosurfactants,” can be produced
from fermentation.
10.3 INDUSTRIAL BIO-BASED SURFACTANTS
Several bio-based surfactants are being produced on an industrial scale today. Methyl ester
sulfonates (MES), derived from coconut or palm FAME (Figure 10.2), are bio-based
replacements for petroleum-derived linear alkylbenzene sulfonates (LAS) in cold-water
laundry detergents found in commercial products such as “Care Coldwash” (Danlind,