Traditional and Emerging Feedstocks for Food and Industrial Bioproduct Manufacturing - Food and Industrial Bioproducts and Bioprocessing - page 5

sugars prior to microbial fermentation (Sun et al ., 2003; Sun and Tomkinson, 2003; Sun and
Sun, 2001). Wheat straw contains many bioactive compounds, including PC and PS (Sun and
Sun, 2001 ; Irmak et al ., 2005; Dunford and Edwards, 2010). Recovery of these high value
bioactive compounds during or prior to bioconversion of wheat straw to bioproducts could
improve the feasibility of the conversion process and may improve the efficiency of the
hydrolysis of cellulose and hemicellulose and the subsequent fermentation process.

1.2.1.3 Utilization

Wheat is a vital component of human diet in many countries. In the United States about
17-18% of total daily calories are acquired from foods derived from wheat. In some other
countries wheat-based foods may provide two thirds, even more of the daily caloric intakes
(Bushuk and Rasper, 1994). In the United States about 70% of wheat is utilized for human
consumption, 24% as animal feed and the remainder for seed or industrial products. The
main reason for using a small fraction of wheat in industrial products is due to high demand
for wheat for food and feed applications.
Annetts and Audsley (Annetts and Audsley, 2003) defined the term “biorefinery” as “a
factory consisting of a collection of processes which takes agricultural inputs from the
surrounding area, and produces a wide range of products which are specifically targeted at
different market uses and are refined to their specification”. Wheat is an excellent crop to
demonstrate the “biorefinery” concept. Current and emerging processing techniques present
tremendous opportunities for converting wheat fractions - flour, milling industry by-products
(bran, shorts and germ) and straw - in to a broad range of bioproducts. In fact, the economic
viability of multiproduct wheat biorefinery systems has been examined by various groups
(Dorado et al ., 2009 ; Annetts and Audsley, 2003 ; Clark, 2007 ; Dunford, 2007 ; Koutinas
et al ., 2004). For example, a process for producing a generic wheat-based fermentation
feedstock with two liquid streams, one rich in glucose and one rich in nitrogen, was
developed and successfully used for the production of ethanol, lactic acid, pigment and
glycerol (Webb and Wang, 1997; Koutinas et al ., 2004 ).
Currently excess straw is baled for use as livestock bedding or low-grade animal feed
providing minimal economic return. Straw represents a significant opportunity for fiber
substitution. Pulp from straw is already being partially substituted for wood fiber in some
paper and paperboard products (Mckean and Jacobs, 1997). Advanced cellulose hydrolysis
technologies are being developed for converting straw to biofuels and other industrial
bioproducts (Szczodrak, 1988; Ahring et al ., 1996 ; Saha et al ., 2005 ). Recovery and conversion
of surface waxes and other bioactive compounds present in wheat straw into high value
products, such as insecticides, nutracueticals and cosmeceutical ingredients, may improve the
economic feasibility of other commodity or lower value products generated in a biorefinery
(Dunford and Edwards, 2010; Irmak et al ., 2005 ; Clark, 2007 ). Waxes derived from sustainable
plant products have a growing market for the replacement of both synthetic (petroleum derived)
and animal product derived waxes including lanolin obtained from sheep's wool (Clark, 2007).

1.2.2 Corn
1.2.2.1

Production

Maize or corn (Zea mays) has a long history as a domesticated crop. Today corn is the most
widely grown cereal crop in the world. In 2008, world corn production was 826.3 million
tonnes (USDA-FAS, 2008). It is estimated the grain yield will reach 1.2 tonnes/ha