Development And Application Of Modified Atmosphere Packaging Bags With Silicon Rubber Window Of Four Fresh-Cut Vegetables

At present,there is a huge market demand for fresh-cut vegetables in China.The inappropriate air permeability of packaging may lead to product odor,aging,and even worsen discoloration.As a result,there is an urgent demand to develop modified atmosphere packaging（MAP）suitable for fresh-cut vegetables in China.The appropriative silicon rubber window can adjust the gas composition in packaging and meet the storage requirements of different fresh-cut vegetables.In this article,the appropriative silicon rubber windows for four different fresh-cut vegetables is firstly screened,and the modified atmosphere packaging bags with selected silicon rubber windows are then developed.The effects of silicon rubber window packaging bags are tested by fresh-cut potatoes,onions,cucumbers and broccoli.The main results are as follows:1.The suitable silicon rubber window for MAP of potatoes chips is:the permeability rates of O₂ and CO₂ are 5×10⁵ and 5×10⁵ cm³/m^2.d.atm respectively,the permeability ratio is 1:1,and the area is 0.5¹ cm²/kg.This packaging can inhibit the browning of potatoes chips to a certain extent,prevent the odor caused by anaerobic respiration,and extend the shelf-life to more than 6 days at 5℃.By comprehensive calculating the permeability of silicon rubber window and film,the suitable packaging permeability of O₂ and CO₂ for potatoes chips are 0.755⁰.959×10² and 1.709².677×10² cm³/kg.d.atm respectively.2.The suitable silicon rubber window for MAP of onion shreds and cucumber slices are:the permeability rates of O₂ and CO₂ are 4×10⁵ and 1.6×10⁶cm³/m^2.d.atm respectively and the permeability ratio is 1:4.The odor and oxidative browning of onion shreds can be avoided by applying a 3 cm²/kg silicon rubber window selected above,and the shelf-life can reach to 7 days at 5℃.The odor,effluent,decay and other problems of cucumber slices can be avoided by applying a35 cm²/kg silicon rubber window selected above,and the shelf-life can reach to 6days at 5℃.By comprehensive calculating the permeability of silicon window and film,the suitable packaging permeability of O₂ and CO₂ are 0.629².229×10² and0.209¹.229×10³ cm³/kg.d.atm for onion shreds,and 0.731¹.426×10³ and2.962⁷.122×10³ cm³/kg.d.atm for cucumber slices respectively.3.The suitable silicon rubber window for MAP of fresh-cut broccoli is:the permeability rates of O₂ and CO₂ are 3.6×10⁷ and 2.7×10⁷ cm³/m^2.d.atm respectively,the permeability ratio is 4:3,and the area is 0.5 cm²/kg.This packaging effectively solves the odor caused by hypoxia storage of broccoli,and extend shelf-life for 6 days at 5℃.By comprehensive calculating the permeability of silicon rubber window and film,the suitable packaging permeability of O₂ and CO₂ for fresh-cut broccoli are 1.301².535×10³ and 2.190⁴.824×10³ cm³/kg.d.atm respectively.In order to rapidly predict the stable concentration of gas components in silicon rubber window packaging of fresh-cut broccoli,the mathematical formulas of the relationship between the concentration of O₂ and CO₂（%）,the filling volume（X₁,g）,and film permeability（X₂,X₃,10⁴cm³/m²·d·atm）are:Y（O₂）=16.843-0.008X₁+1.591 X₂ and Y（CO₂）=5.264+0.008 X₁-2.338 X₃.Through the step-by-step training of the data by using the Matlab neural network,the measured value is highly correlated with the predicted value.4.Comparing the packaging of four fresh-cut vegetables,it is found that fresh-cut broccoli required the greatest gas permeability,followed by cucumber slices,and potato shreds chips required the lowest.Different vegetables have different requirements for gas permeability rates and permeability ratio,which leads to different requirements for the type and area of silicon rubber windows.Therefore,appropriative MAP should be developed for specific fresh-cut vegetable.