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Research Project: New Sustainable Processing Technologies to Produce Healthy, Value-Added Foods from Specialty Crops

Location: Healthy Processed Foods Research

Title: Comparative study on properties of edible films based on pinhao (Araucaria angustifolia) starch and flour

Author
item Daudt, Renata - UNIVERSITY OF RIO GRANDE DO SUL
item Avena Bustillos, Roberto
item Williams, Tina
item Wood, Delilah - De
item Külkamp-guerreiro, I.c. - UNIVERSITY OF RIO GRANDE DO SUL
item Marczak, L.d.f. - UNIVERSITY OF RIO GRANDE DO SUL
item Mchugh, Tara

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/29/2016
Publication Date: 3/30/2016
Citation: Daudt, R.M., Avena Bustillos, R.D., Williams, T.G., Wood, D.F., Külkamp-Guerreiro, I., Marczak, L., McHugh, T.H. 2016. Comparative study on properties of edible films based on pinhao (Araucaria angustifolia) starch and flour. Food Hydrocolloids Journal. 60:279-287.

Interpretive Summary: Petroleum-based packaging materials, commonly used in the food industry are non-renewable resources and are not biodegradable. Alternative replacements are needed to meet the needs of the food industry, consumers and the environment. Edible films and coatings as alternatives to plastic materials is becoming increasingly popular due to their capabilities of improving food quality and shelf-life. Starches have similar physical properties to plastics, are renewable, readily available and have good ability to form odorless, colorless, transparent, non-toxic and biologically degradable films. Pinhao seed is commonly grown in South America and it produces vast quantities of starch. The use of pinhao flour milled from whole seed rather than using its fractionated starch has the advantage of decreasing the process steps required to isolate the starch resulting in less waste production. In this study, we successfully developed edible films based on pinhao starch and pinhao flour plasticized with glycerol. We then evaluated the physical properties of the resulting hydrophilic films and compared starch-based and flour-based films with different glycerol contents. The glycerol content can be adjusted to tailor film properties to food application needs. These films may be used as edible coatings on vegetables and fruits, or even as packaging materials of dehydrated food.

Technical Abstract: The aim of this study was to develop and compare the properties of edible films based on pinhao starch and pinhao flour. Seven formulations were developed by casting methodology: 5% pinhao starch with 0, 1, 1.5, and 2% glycerol, and 5% pinhao flour with 1, 1.5, and 2% glycerol. The films were evaluated and compared to each other for thickness, morphological analysis by Scanning Electronic Microscopy (SEM), glass transition temperature (Tg), apparent porosity (Ø), water vapor permeability (WVP), tensile properties, color, opacity, and Fourier transform infrared analysis (FTIR). In addition, the raw materials were analyzed for moisture content, water activity (Aw), apparent porosity and pasting profile. Pinhao starch and flour did not show differences in moisture content and pinhao starch presented lower Aw, Ø, but higher peak viscosity than pinhao flour. Films made with pinhao starch exhibited lower thickness, Ø, WVP and opacity than pinhao flour films, but higher Young's modulus, tensile strength and elongation at break. In addition, films with higher amounts of glycerol exhibited higher WVP and elongation at break, with lower tensile strength and Young's modulus. The pinhao flour films structure presented irregularities and were rougher than pinhao starch films. Differences in glycerol content did not affect Tg values of these films. Flour films were yellowish and also had a higher opacity value. The FTIR spectra of pinhao starch and pinhao flour films showed similar IR absorbance patterns, with no structural change in the presence or absence of glycerol.