N: Nanoscale Food Science Thermomechanical and Morphological Properties of Nanocomposite Films from Wheat Gluten Matrix and Cellulose Nanoﬁbrils Fatemeh Raﬁeian, Mohammad Shahedi, Javad Keramat, and John Simonsen Abstract: The aim of this investigation was the optimization of preparing gluten ﬁlm containing cellulose nanoﬁbrils (CNF). An optimization procedure using central composite design (CCD) with three factors (CNF, glycerol, and sodium dodecyl sulfate (SDS) concentrations) was used in order to investigate the effect of these parameters on the mechanical (tensile strength—TS, elongation at break—ε b ) and thermal properties of gluten ﬁlms and to establish a formulation to depict the relationship between the mentioned factors and mechanical properties. Through regression analysis, it was found that TS and ε b well ﬁtted by quadratic polynomial equations (R 2 = 0.99 and 0.98, respectively) and the glycerol concentration was the most signiﬁcant factor inﬂuencing them. The optimization was based on maximizing TS and ε b . The optimum conditions determined using response surface methodology (RSM) were deﬁned as: CNF concentration, 11.129 g/100 g, glycerol concentration, 35.440 g/100 g and SDS concentration, 6.259 g/100 g. The predicted responses for these ﬁlm preparation conditions were a TS of 3.630 MPa and ε b of 86.033%. The veriﬁcation experiments were conducted under optimal conditions to compare predicted and actual values of dependent variables. This experiment indicated that both predicted and actual values (TS of 3.721 MPa and ε b of 88.935%) almost coincide each other and therefore the estimated models were reasonable and of high accuracy to predict dependent variables values. The scanning electron microscopy (SEM) images showed non-agglomerated and well dispersed CNF in the gluten matrix. Differential scanning calorimetry (DSC) results indicated that there is not any signiﬁcant difference (P > 0.05) between the glass transition temperature (T g ) of optimum nanocomposite (−29.12 ◦ C) and control ﬁlm (−29.64 ◦ C) and their thermogravimetric analysis (TGA) thermograms showed similar degradation behavior. Keywords: Cellulose nanoﬁbrils, ﬁlm, gluten, optimization, thermomechanical properties Practical Application: Several thousand tons of plastic goods are landﬁlled every year, increasing the problem of municipal waste disposal. This study investigates the optimum conditions for preparation of eco-friendly gluten-based composite reinforced with CNF, as a replacement of plastic packaging materials with the aim of reducing environmental pollution. Introduction Food packaging materials are typically composed of petrochemical-based polymers like polyoleﬁns, polyesters, and polyamides that are mostly preferred due to their availability in large quantities at low cost, favorable functionality characteristics like good tensile and tear strength, good barrier properties to O 2 and aroma compounds and heat sealability. Plastics, with their current global consumption of more than 200 million tones and annual growth of approximately 5%, represent the largest ﬁeld of application for crude oil outside the energy and transport sectors. This 5% crude oil consumption may appear comparatively small; however, it does emphasize how dependent the plastics industry is on oil. Increase in price of crude oil and natural gas caused by strong demand and political conﬂict also have a marked ef- fect on the plastics market (Sorrentino and others 2007; Siracusaa MS 20130464 Submitted 4/5/2013, Accepted 6/18/2013. Authors Raﬁeian and Simonsen are with Wood Science and Engineering, Oregon State Univ., 119 Richardson Hall, Corvallis, OR 97331, U.S.A. Authors Shahedi and Keramat are with Dept. of Food Science and Technology, Isfahan Univ. of Technology, Isfahan 84156–83111, Iran. Direct inquiries to author Raﬁeian (E-mail: Fatemeh.koupae@oregonstate.edu). and others 2008). Large amount of these plastics are discarded within a short time, remaining in garbage deposits and landﬁlls for decades (more than 30 years). Concerns over solid packaging waste are becoming increasingly important and deriving this signiﬁcant industry to utilize packaging ﬁlms and processes that have both user-friendly and eco-friendly attributes. Such ﬁlms, comprised of protein, polysaccharide, and/or lipid materials, are renewable, possibly edible, and can lead to innovative packaging applications (Weiss and others 2006). In view of this, the number of research reports on protein-based materials has increased as a result of the present interest in nonfood applications (Hernandez-Munoz and others 2004; Martin and others 2005). The growing demand for products and processes based on environmentally friendly and re- newable resources led us to consider wheat gluten (WG) as an interesting raw material for nonfood application areas, such as biodegradable packaging. WG, a mixture of proteins accounting for about 80% to 85% of wheat ﬂour proteins (Guan and others 2011), is an attractive agropolymer because of its high availability and good ﬁlm-forming properties (Lens and others 2003; Domenek and others 2004). Besides the biodegradability of WG ﬁlms, such materials exhibit effective barrier properties against lipids, gases such as oxygen, C  2013 Institute of Food Technologists R  N100 Journal of Food Science  Vol. 79, Nr. 1, 2014 doi: 10.1111/1750-3841.12231 Further reproduction without permission is prohibited