nvestigated as part of an effort to develop an inexpensive,
recyclable, paper product exhibiting good water
vapor and grease resistance. The composition (dry basis)
of the isolate 127-3 selected for this study was: 83%
protein; 16% lipid; 0.22% starch. The estimated cost of
the isolate product is about $1/lb. The method used to
apply zein isolate to the brown Kraft paper significantly
affected its grease resistance. Both methods of coating
application were exposed from 1 to 4 h and the stained
areas measured (compare Table 1 and Table 2). The
percent area stained for paper coated with approximately
the same amount of zein isolate was lower when
the coating was applied as a spray. On an hourly basis
the area stained for eight coated samples was 13.8 (
10.8% when the isolate was brushed on the paper and
3.0 ( 2.8% when applied as a spray. For the remainder
of this study the isolate was sprayed on the paper. The
grease permeation for zein isolate sprayed on brown
Kraft paper was found to be independent of loading
levels at concentrations above 30 mg/16 in.2 (Figure 1).
This critical loading level was lower than previously
observed for zein-paraffin wax coated paper (Parris et
al., 1998).
Kraft paper coated with zein isolates improved the
water vapor barrier properties of the paper. For five
different isolates, WVTR values ranged from 881.0 to
1521.9 (g/m2 day) and were reduced approximately 40%
when paper was coated with about 0.1 g/16 in.2 of isolate
(Table 3). Water vapor resistance is primarily attributed
to the coating level and its lipid content. The lipid
content and composition of the isolate were examined
and compared to the lipids present in the milled corn.
The lipid profiles for milled corn and zein isolate 127-3
are shown in Figures 2 and 3. The principal lipid
components detected by evaporative light scattering