Hydrophobic Starch-Based Films Using Potato Washing Slurries and Spent Frying Oil

Abstract

Starch is a promising candidate for preparing biodegradable films with useful gas barriers and thermoplastic capabilities. However, these materials are hydrophilic and brittle, thus limiting their application range. To overcome these drawbacks, it has been hypothesized that starch can be hydrophobized and plasticized during the starch-based film production using a single-step approach and following transesterification principles. In this work, KOH powder and spent frying oil (SFO) were used as an alkaline catalyst and a source for triacylglycerides, respectively, to promote the modification of starch. Different ratios of SFO (w/w related to the dried starch weight) were tested. When compared to the neat films (without a catalyst and SFO), the incorporation of at least 15% SFO/KOH gave rise to transparent, hydrophobic (water contact angles of ca. 90∘), stretchable (ca. 20×), elastic (ca. 5×), and water tolerant starch-based films, contrary to the films produced without the catalyst. ATR-FTIR and 1H NMR revealed structural differences among the produced films, suggesting that starch was modified with the SFO-derived fatty acids. Therefore, adding KOH during the potato starch/spent frying oil-based film’s production was determined to be a promising in situ strategy to develop starch-based materials with improved hydrophobicity and flexibility, while valorizing the potato chip industry’s byproducts.

Potato Chips Byproducts as Feedstocks for Developing Active Starch-Based Films with Potential for Cheese Packaging

“…The esterified fatty acids (EFAs) content was determined by GC-FID, in triplicate, as fatty acid methyl esters (FAMEs) after the alkaline-catalyzed transesterification of the esterified fatty acids of the sample. For this, heptadecanoate methyl ester (0.03 mg/mL prepared in n-hexane) and KOH methanolic solution (2M) were used [ 6 ]. A DB-FFAP column (30 m × 0.32 mm and 0.25 μm of film thickness, J&W Scientific Inc., Folsom, CA, USA) was used.…”

“…The starch/BrE-based films were produced by solvent casting following a previously described method [ 6 ], with the addition of the BrE at different proportions (5%, 10%, and 15% w / w , starch dry weight). Briefly, a water dispersion of freeze-dried potato starch (40 g/L) was prepared, and 12 g/L of glycerol was added as well as BrE in different proportions (2 g/L, 4 g/L, and 6 g/L.…”

“…The CIELab coordinates L* (luminosity), b* (yellow/blue), and a* (red/green) were determined using a CR-400 Chroma Meter. The total color difference (ΔE) was also assessed [ 6 ].…”

“…Potato washing slurries have been used to recover starch to develop bioplastics with physicochemical and barrier properties competitive with the ones provided by commercial potato starch [ 5 ]. To improve the elastic and hydrophobic properties of starch-based films, spent frying oil [ 6 ] and waxes recovered from potato peels [ 5 ] have been used. In addition, potato peel phenolic extracts [ 7 ] have demonstrated the potential to improve the antioxidant activity and UV-light barrier properties of starch-based films.…”

Synergizing Multi-Plasticizers for a Starch-Based Edible Film

“…A well-recognized weaknesses for starch-based films currently used is the instability of mechanical performances. Under dry conditions the starch film becomes brittle, but in high humility conditions it becomes very soft and loses mechanical strength mainly due to the instability of plasticizers [ 7 , 15 , 16 , 17 ] and retrogradation [ 18 ].…”