Development And Application Of Indicator Film Base On Highland Barley β-glucan

With food packaging playing an increasingly important role in food quality and safety,food intelligent packaging as a new type of packaging technology has become a research hotspot.Freshness indicator film is a kind of intelligent film material for packaging food,which can monitor the changes of packaged food quality and internal environment,and feedback food freshness information through color.The current research on freshness indicator film mainly focuses on using anthocyanin as p H indicator and changing the color of anthocyanin to judge the freshness of food according to the reaction between the gas released during the change of packaged food and anthocyanin.The average content of β-glucan in highland barley is the highest among cereals,and it is a good source of β-glucan.Therefore,this study uses highland barley β-glucan(HBBG)as a film-forming substrate to prepare freshness indication film and construct real-time intelligent packaging,while optimizing the performance of the indication film and using the prepared film material for pork preservation and pork freshness indication,with a view to developing a new type of intelligent packaging.The details of the study are as follows:Firstly,the hydrophobicity of highland barley hordein(HBH)was used to improve the water vapor barrier and reduce the water solubility of the HBBG film.The infrared spectra showed that HBBG and HBH were bonded by non-covalent interaction;X-ray diffraction patterns and scanning electron microscopy showed good compatibility between HBBG and HBH;thermogravimetric analysis showed that the addition of HBH could improve the thermal stability of HBBG film.When the addition of HBH reached 6%(w/w,HBBG-HBH base),the tensile strength and elongation at break of the composite film increased by 53.4% and 7.4%compared with the control group,with the best mechanical properties;the water vapor transmission rate and oxygen transmission rate decreased by 46.8% and 54.4% compared with the control group,with the best barrier properties;and the composite film had the largest water contact angle,the lowest moisture content and water solubility,and hydrophobicity was the strongest.Secondly,black rice bran anthocyanin(BRA)was selected as the indicator to prepare freshness-indicating films,and the effect of the addition of BRA on the performance of the indicating films was investigated.Infrared spectroscopy,X-ray diffraction and SEM analysis showed that BRA was uniformly distributed in the film matrix and formed hydrogen bonds with the film matrix,which disrupted the dense structure of the blend film and increased the free volume of the film.Although the tensile strength and surface hydrophobicity of indicator film decreased,the elongation at break,water vapor permeability and oxygen permeability increased,the indicator film still had good physical properties.When the addition of BRA reaches 5%(w/w,HBBG-HBH base),the indicator film had ability of absorbing UV light,and the antioxidant ability is significantly improved.Moreover,the color of the indicator film changed significantly within 2 min in ammonia gas,and the color change is more obvious as the time is extended to 20 min,indicating that the prepared indicator film had the potential to detect the freshness of pork.Finally,carbon quantum dots were used as antimicrobial agents to prepare freshness indicator films with antimicrobial ability,and they were used for freshness indication of pork.The results showed that the addition of appropriate carbon quantum dots not only increased the mechanical,barrier and antioxidant properties of the indicator film,but also inhibited the growth of Escherichia coli and Staphylococcus aureus;the color still changed significantly within 2 min in ammonia;when applied to the freshness indication of pork,the total volatile basic nitrogen,thiobarbituric acid reactive substances and p H value of pork were reduced,and the indicator film underwent color changes visible to the naked eye on the eighth day of storage to distinguish the freshness of pork.In summary,the addition of HBH effectively improved the barrier capacity of HBBG film,which is a good substrate for the preparation of bio-based films;the addition of BRA make the film material with significant antioxidant capacity and freshness indication function;the addition of carbon quantum dots realized the antibacterial property of the film,maintains the freshness indication function of the film and prolongs the service life of the film.