Utilization of lentil flour as a biopolymer source
for the development of edible films
Gulum Sumnu ,
Mecit H. Oztop ,
Department of Food Engineering, Middle East Technical University, 06800 Ankara, Turkey
Department of Food Engineering, University of Necmettin Erbakan, 42090 Konya, Turkey
Department of Physics, Gazi University, 06500 Ankara, Turkey
Correspondence to: G. Sumnu (E-mail: firstname.lastname@example.org)
Lentils are one of the cheapest and most nutritional protein sources for vegetarians. Our objective in this study was to
evaluate the feasibility of using lentil flour as a raw material for the development of edible films and to investigate the effects of the
glycerol concentration (C
5 1%, 1.5%, and 2%) and process temperature (T
; 70 and 90 8C) on the physical properties of these films.
The films were characterized via their density; water solubility; thermal, morphological, and chemical characteristics; water vapor per-
meability (WVP); and tensile and optical properties. The lentil flour films were highly transparent and had lower water solubility val-
ues yet similar WVPs and mechanical properties compared to most other biodegradable films. An increase in C
led to the formation
of more flexible films with increased hydrophilicity. A T
of 90 8C resulted in yellower, more transparent films with increased stiffness
compared to a T
of 70 8C. In this study, lentil flour was shown to be an ideal source for edible film production.
2018 Wiley Periodi-
cals, Inc. J. Appl. Polym. Sci. 2018, 135, 46356.
biodegradable; films; packaging
Received 4 November 2017; accepted 9 February 2018
Biodegradable packaging materials made out of biopolymers
from natural and renewable sources, in addition to reducing
environmental pollution, could also ensure food safety and
security by minimizing the potential risks of monomer migra-
tion related to direct contact with synthetic polymers.
mers used in edible and/or biodegradable film formation
include polysaccharides, such as starches, pectins, alginates, cel-
lulose derivatives, carrageenans, chitosan, gums, fibers, and pro-
teins such as soy proteins, wheat gluten, corn zein, sunflower
proteins, whey, gelatin, casein, and keratin.
Edible films or
coatings formulated either with one or a combination of these
components could act as a barrier against mass transfer and,
thereby, extend the shelf life of foods.
An ideal edible film
should have low water, gas, and oil permeabilities and adequate
mechanical properties to ensure that its integrity is preserved
throughout its shelf life.
To this day, studies on the utilization of flour as a raw material
for film formation have been relatively few. Some agricultural
products whose flours have shown promising results as edible
films include bananas,
Lentils are small legume seeds belonging to the Lens
culinaris species and the Leguminosae (Fabaceae or Papiliona-
Lentils are gluten-free, low in fat, and high in
dietary fiber and other nutrients, such as protein, vitamins, and
Carbohydrates, of which a major portion is starch,
constitute the highest portion of lentils (almost 60 wt %).
The source of the biopolymer is the most important factor in
defining the final film characteristics of biopolymer films. The
amylose–amylopectin ratio, amino acid profile, and fiber con-
tent are the dominant parameters shaping the film’s proper-
However, to the best of our knowledge, the film-
formation potential of lentils as a raw material still has not
been elaborately studied. As such, there has been only one study
that used lentil protein for edible film formation; this study was
carried out by Bamdad et al.
The facts that their lentil protein
films were relatively effective as moisture barriers and had good
mechanical properties is promising for lentil flour films. How-
ever, to our surprise, there have been no studies in the literature
using lentil flour for edible film formation.
As in synthetic polymers, the addition of property modifiers are
necessary to achieve desirable physical and mechanical
Additional Supporting Information may be found in the online version of this article.
2018 Wiley Periodicals, Inc.
J. APPL. POLYM. SCI. 2018, DOI: 10.1002/APP.46356
46356 (1 of 10)