Influence of plasticizer with different functional groups on thermoplastic starch

Abstract

Retrogradation of amorphous thermoplastic starch (TPS) films obtained by compression molding of spray dried modified potato starch was investigated. The aim was to investigate the influence of plasticizers with similar molecular weight but different functionality, i.e., isoleucine, asparagine and malic acid, on the properties of plasticized powder and TPS films. Combinations of malic acid with glycerol, urea, and maltodextrin were also evaluated. Except for isoleucine formulated starch, all samples were obtained as amorphous powders and films. Malic acid was identified as a strong antiretrogradation agent as it inhibited recrystallization of starch over the full range of humidity levels. Malic acid was also found to inhibit the retrogradation of formulations containing urea, glycerol and maltodextrin. The converse of the strong inhibition implied strong moisture absorption and high strain at break values, and low tensile strengths. Malic acid was also identified as a potential crosslinking agent to control swelling of starchbased products.

Surface photo-crosslinking of plasticized thermoplastic starch films

“…Samples were compressed at 25 bar for 5 min. The molding temperature for all samples was 140°C [5,7].…”

“…Malic acid was also found to inhibit the retrogradation of mixed formulations containing the acid and urea, glycerol or maltodextrin. This study again showed that reduced retrogradation leads to high moisture absorption and high strain at break with loss of tensile strengths [7].…”

“…It has been reported that citric acid [12] and malic acid [7] can form strong hydrogen bond interactions with starch and improve its thermal and water stability, and inhibit retrogradation. However, incorporating both citric and malic acid substantially reduced the tensile stress of the TPS films [7,12].…”

Mechanical and barrier properties of starch-based films plasticized with two- or three component deep eutectic solvents

“…The most used starch plasticizers are water and glycerol, but other compounds like polyols, e.g. sorbitol, mannitol, xylitol (Mathew & Dufresne, 2002;Talja, Helén, Roos & Joupilla, 2007), amines: urea (Lourdin, Coignard, Bizot & Colonna, 1997;Wang, Cheng & Zhu, 2014, ethanolamine (Schmitt et al, 2015) triethanolamine (Jost & Stramm, 2016), carboxylic acids or their salts (Lourdin et al, 1997;Niazi, Zijlstra & Broekhuis, 2015), sugars or their mixtures with other plasticizers (Teixeira, Da Róz, Carvahlo & Curvelo, 2007) and its derivatives like isosorbide (Battegazzore, Bocchini, Nicola, Martini & Frache, 2015) glycol/alginate mixtures (López et al, 2015) and ionic liquids (Wilpiszewska & Spychaj, 2012) can be applied as plasticizers.…”

“…Carboxylic acids like citric or malic acid are mainly non-toxic and can be obtained from natural origin. They can act not only as crosslinking agents but also as plasticizers (Niazi et al, 2015). Carboxylic acids act in a dual way, they crosslink starch materials by forming ester bonds between their carboxyl groups and hydroxyl groups onto polymeric chains but may also cause chain scission by acidic hydrolysis.…”