Preparation Of Nano-Packing And Effect On Preservation Quality Of Food

Strawberries are rich in nutrients and have high physiological post-harvest activities,but are susceptible to water loss,bruising and mechanical injuries due to their soft texture and lack of a protective find.Although numerous researches have been conducted on the storage of strawberry,the fresh-keeping and storage of strawberry has not been well solved. Chinese jujube is a native fi-uit of China and has a long history of over 2500 years.Some strategies have been used in order to minimize these undesirable changes,including heat treatments,edible coatings and modified atmosphere packing.However,most of these strategies are expensive and time-consuming.Thus,there is an urgent need to have alternative technologies to reduce the stem-end rots incidence and to inhibit the undesirable physicochemical changes during storage.Sauce beef was affluent in protein and water,and tended to get decayed with microorganism during room temperature storage.In recent years, the nanomaterial shows a great predominance in a wide range of fileds and is being given increasing attention.Based on above reasons,we investigated the effect of nano-packing on the storage of strawberry,jujube and sauce beef.The results are as follows:1.Nano-powder(nano-Ag 35%,nano-TiO₂ 40%,kaolin 25%) 30%,polyethylene 56% and cross-link reagents 14%were immingled in uniformity for 1h,then extruded to nano-granule after cooling by 1-2 minutes.38.5 Kg polyethylene granule and 1.5 Kg nano-granule were immingled for 0.5 h,and then the compound was made into films.The nano-packing films of 40μm thickness were employed to make bags of 30×45 cm.The O₂ and RH transmission rate of the nano-packing decreased 2.1%and 28.1%respectively compared with normal packing.2.Strawberry(Fragaria ananassa Duch.cv Fengxiang) harvested at the stage of mature were packed with nano-packing and regular polyethylene packing at 4℃storage and the sensory quality,physical and chemical quality and physiological indexes were analyzed. The results indicated that decreasing of ascorbic acid,titratable acid of strawberry packed with nano-packing were significantly inhibited compared with regular packing.Meanwhile, nano-packing could significantly inhibit the increasing of fruit decay rate,malondialdehyde (MDA) contents,total soluble solids as well as polyphenol oxidase(PPO) and pyrogallol peroxidase(POD) activity of strawberry in contrast with regular packing.3.Chinese jujube(Ziziphus jujuba Mill var.inermis(Bunge ) Rehd) fruits harvested at the stage of mature-green were packed with nano-packing at room temperature for 12 days to investigate the effects of nano-packing on preservation quality of Chinese jujube.The results indicated that the decreasing of fruit firmness,ascorbic acid,titratable acid of Chinese jujube packed with nano-packing were significantly inhibited compared with polyethylene packing.Meanwhile,nano-packing could significantly inhibited the increasing of fruit decay rate,malondialdehyde(MDA) contents,browning rate,total soluble solids,total soluble sugar,reducing sugar content of Chinese jujube.Additionally, the climacteric ethylene evolution of Chinese jujube was significantly delayed in nano-packing than polyethylene packing.4.Sauce beef was packed with nano-packing at room temperature for 28 days and the sensory quality,physical and chemical quality and micro indexes were determined to investigate the effects of nano-packing on preservation quality of sauce beef.The results showed:Nano-packing could significantly inhibit the increasing of bacteria and volatile base nitrogen(VBN) of sauced beef compared with normal packing.In conclusion,nano-packing could expand the shelf-life and improve the preservation qualities of strawberry,Chinese jujube and sauce beef,which provide a promising strategy for the storage of food stuff in the future.