| This is a time that economy and technology developed fast,and this is a time with a getting worse environmental issue.The well development of logistics industry stimulates fresh food packaging market develop fast.So,the market demand for fresh food packaging materials is also increasing.At present,fresh food packaging materials are mainly fresh-keeping film made of petroleum-based plastics such as polyethylene(PE)film.With the concept of sustainable development gaining popular support,there is an urgent need to develop green and environmentally-friendly functional fresh packaging materials.Starch edible packaging film is a kind of packaging film that uses starch as the substrate.It is not only biodegradable,but also has excellent freshness-preserving effects after adding green functional additives,and some can even be eaten with the package as nutritional ingredients.Under this background,this paper prepared the biodegradable edible films with good mechanical properties,hydrophobic properties and antioxidant properties.The research in this paper can be divided into the following three parts:The first part: This chapter used ultrasonic extraction to extract apple polyphenols from apple pomace.The single-factor experiment was conducted to investigate the effects of the four main influencing factors of extractant concentration,material-liquid ratio,extraction time,and extraction temperature on the extraction concentration of polyphenols in apple pomace.Finally,the best extraction process was further explored by means of response surface analysis condition.The optimal extraction conditions shown as below: ethanol concentration: 70%,material-liquid ratio: 1:25(g/m L),extraction time: 16 min,extraction temperature: 60 ° C,and the extracted apple residue polyphenol concentration was 14.44893 mg / m L.The second part: In this chapter,?-cellulose was used as the raw material,and nanocellulose(NCC)and microcrystalline cellulose(MCC)are prepared by using acid hydrolysis method and mechanochemical method,respectively.Then the surface hydrophobic modification method with stearic acid was used to prepare modified nanocellulose(M-NCC)and modified microcrystalline cellulose(M-MCC).Finally,they were added into the cassava starch edible films with different contents as the strengt agents,and each edible films are prepared by the casting method.Their performance were characterized,to explore their enhancement effects and the optimal additions.The results showed that M-NCC and M-MCC did enhance the mechanical and hydrophobic properties of the starch edible film,and the optimal addition amounts were 0.5% and 1.5%,respectively.The third part:Based on the first two chapters,this chapter used the apple pomace polyphenol extracted as the solvent of the film-forming liquid,and then the 0.5% M-NCC and 1.5% MMCC added respectively,finally,the apple pomace polyphenol / M-NCC starch film(PN film)and apple pomace polyphenol / M-MCC starch film(PM film)were prepared by casting method.At the same time,pure starch film(C film)and apple pomace polyphenol film(P film)were also prepared.The surface morphology,thermal stability,mechanical properties,hydrophobic properties,water vapor transmission properties,water solubility,oxygen transmission properties,and antioxidant properties of these four films were characterized and compared.The results show that the thermal stability of the PN film and PM film has decreased,but other properties have improved,indicating that they have good mechanical properties,hydrophobic properties and antioxidant properties,and can be used as a biodegradable fresh packaging materials. |
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