Mechanical properties of the RBP/gelatin blend film
To prepare the RBP blend films having better physical
property than the RBP/RA blend films, various
concentrations of gelatin were incorporated into the filmforming
solution to improve the physical properties of the
RBP film (Table 4). The thickness of the RBP/gelatin
blend film increased with increasing amounts of gelatin,
although the same amount of film-forming solution was
used. The TS of the RBP/gelatin blend film increased
when the gelatin content increased. The RBP film
containing 2.0% gelatin had a TS of 11.10 MPa, while the
film containing 4.0% gelatin had a TS of 23.90 MPa. Cao
et al. (24) reported that the TS increased as the gelatin
content increased. Li et al. (25) and Xiao et al. (26) also
reported an increase in the TS when gelatin was blended
with konjac glucomannan film, and they suggested that the
increase in TS could be due to the increase in hydrogen
bonding between gelatin and the film base materials. The
E of the film reflects the film’s stretch capability. Our
results showed that the E of the 4% RBP/4% gelatin blend
film had the greatest E (141.02%), while the 4% RBP/3%
gelatin blend film had the lowest (93.61%). In addition, theWVP was the lowest for the 4% RBP/4% gelatin blend
film, suggesting a suitable gelatin concentration for the
blend film (Table 4).
Based on the mechanical property of the film, the
suitable gelatin concentration for the RBP/gelatin film was
determined to be 4%, and various concentrations (4, 5, and
6%) of RBP were added to prepare the blend film to
examine the suitable RBP concentration (Table 5). The
thickness of the RBP/gelatin blend film increased with
increasing amounts of RBP, and the TS of the RBP/gelatin
blend film decreased as the RBP content increased. At a
given concentration of gelatin (4%), the 4.0% RBP film
had a TS of 23.90 MPa, while the 6.0% RBP film had a TS
of 20.50 MPa. In addition, the E of the RBP/gelatin blend
film decreased with increasing amounts of RBP, and the
WVP of the film was not affected by an RBP content of 4
or 5% but did slightly decrease with 6% RBP, probably due
to higher RBP content (Table 5).
In conclusion, various edible RBP films were prepared
through the addition of various plasticizers as well as the
blend of gelatin or RA into the film-forming solution.
Incorporation of RA or gelatin into the RBP film improved
the physical properties of the film. Among the films
studied in the present investigation, the RBP/gelatin blend
film containing 4% RBP/4% gelatin was suggested to be
the most suitable film, based on the physical property of
the films.