Stability of zein‐based films and their mechanism of change during storage at different temperatures and relative humidity

Abstract

Mechanical properties are the important parameters of the film which reflected the resistance of the films during their shelf life. In order to evaluate the stability of zein films preserved at different temperature and relative humidity (RH), tensile strength (TS) and elongation at break (EB) of zein films plasticized with glycerol and PEG‐400 were observed during storage. Results showed that the EB decreased and TS increased during the first 6 days of storage at different RH and temperatures. RH which brought a maximum change in TS and EB were 43% and 65%, respectively. Films preserved at RH of 80% for 18 days lost its extensibility. Statistical analysis results showed that the correlations between the free sulphydryl content and mechanical properties at RH 43%, and between the moisture content and mechanical properties at RH 80% were more significant. A model was proposed to explain the change in TS and EB during zein film storage. Practical applications Zein is commonly produced from the by‐product of bio‐ethanol and starch industries and has excellent film‐forming properties. Pure zein film is brittle, which has limited their application. Many researches have focused on the improvement of the mechanical properties of zein films. As a packing material, zein film should have excellent stability during the shelf life of the packaged food. So a systematic study about the effect of temperature and relative humidity on the mechanical properties of zein film plasticized with glycerol and PEG‐400 during storage is necessary. The results presented in this paper would highlight the suitable applying environment of zein films, either actual or potential.

Incorporation of organic acids turns classically brittle zein films into flexible antimicrobial packaging materials

“…It seemed that zein in films stored at 25°C created much more intermolecular crosslinking interactions with OAs than those stored at 4°C. The higher TS of zein films stored at room temperature than those stored under refrigeration was also observed by Gennadios et al 45 and Guo et al 46 However, the former researcher group attributed this phenomenon to the evaporation of more water at elevated storage temperatures and the loss of this effective plasticizer while the latter group hypothesized that this phenomenon occurred due to the emerging interactions among zein molecules.…”

“…The mechanical properties of zein are not stable and need to be proved by detailed storage tests since interactions among film components and water absorption or drying of films during storage affect their mechanical properties 21,45,46 . The effect of storage at 4°C and 25°C on mechanical properties was investigated only with films loaded with 3.5% LA and MA since films with TA did not show sufficient flexibilities (Figure 2).…”

“…The mechanical properties of zein are not stable and need to be proved by detailed storage tests since interactions among film components and water absorption or drying of films during storage affect their mechanical properties. 21,45,46 The effect of storage at 4 C and 25 C on mechanical properties was investigated only with films loaded with 3.5% LA and MA since films with TA did not show sufficient flexibilities (Figure 2). The EB and TS of control zein films stored The higher TS of zein films stored at room temperature than those stored under refrigeration was also observed by Gennadios et al 45 and Guo et al 46 However, the former researcher group attributed this phenomenon to the evaporation of more water at elevated storage temperatures and the loss of this effective plasticizer while the latter group hypothesized that this phenomenon occurred due to the emerging interactions among zein molecules.…”

Storage-induced changes in plasticizer emigration and structural properties of soybean isolate protein-based composite films

“…Consulted the description of Guo et al [12], the moisture content of the SPI-based composite lms during storage was determined according to the ASTM D644-99 (ASTM standard test method for moisture content of paper and paperboard by oven drying)…”

Protein–TiO2: A Functional Hybrid Composite with Diversified Applications

“…Agudelo-Cuartas et al [37] mentioned that whey protein-based films showed great potential for packaging purposes (good mechanical properties); however, their high-water solubility (59%) and water vapor permeability (1.4 × 10 −10 g•m −1 •s −1 •Pa −1 ) limit their uses in foods with high water content (e.g., meat). According to Guo et al [38], the protein-based film's mechanical properties are influenced by storage conditions (temperature and relative humidity). They found that tensile strength and elongation at break of a zein film were negatively affected when relative humidity and temperature increased from 34% to 80% and from 5 to 35 • C, respectively.…”