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Effect of Drying Temperatures and Plasticizers on the Properies of Konjac Flour Film

Jomlapeeratikul, Prayoon, Poomsa‐Ad, Nattapol, Wiset, Lamul
Journal of food process engineering 2017 v.40 no.3
Amorphophallus, Cymbopogon, Zingiber montanum, air drying, ambient temperature, biopolymers, citrates, drying temperature, essential oils, flour, glycerol, heat pumps, konjac mannan, microstructure, modulus of elasticity, packaging, permeability, plasticizers, relative humidity, tensile strength, water vapor
Biopolymer films are increasing in popularity due to its environmental friendly. The objectives of this work were to study the effect of drying temperatures and plasticizer types on the physical and mechanical properties of films. Konjac glucomannan (KGM) was used for base film forming. A heat pump dryer was used for drying films at temperatures from 30 to 50°C. Film properties were compared with those of films dried at ambient temperature. The film properties were evaluated by film thickness, tensile stress at yield, percent elongation at yield, elastic modulus, water vapor permeability (WVP), transparency, and microstructure of film. Glycerol, lemongrass (Cymbopogon citrates) essential oil and plai (Zingiber cassumunar) essential oil were used as plasticizers. The result found that thickness, percent elongation at yield and WVP were decreased with increased drying temperature. However, tensile stress at yield and elastic modulus were increased when the drying temperatures increased. Moreover, films with essential oil were thicker, lower tensile stress at yield and elastic modulus and higher WVP than film without essential oil. Films without essential oil were compact, smooth surface and uniform microstructure than the films with essential oil. PRACTICAL APPLICATIONS: This research was to study the effect of drying temperature and plasticizer types on property of film. Film was made from konjac flour and drying by a heat pump dryer. The application of the heat pump in the drying process is to control of the relative humidity and drying temperature of the process. Heat pump dryer provides low relative humidity and low temperature; reduce the drying time and faster than hot air drying. Also essential oil used as plasticizer combined with konjac flour as film‐base could improve elasticity property and permeability of film were determined in order to produce packaging with good characteristics.