CAJ | 학술논문

为了探究果蔬多孔膜包装内水分的传递规律，优化并控制包装内的适宜相对湿度条件，降低果蔬失水及袋内凝水对果蔬采后品质的影响，该文对果蔬冷藏期间的蒸腾及包装内水蒸气向膜外扩散的过程进行了分析，并根据Fick扩散模型对多孔膜平衡调湿包装进行设计计算，确定开孔面积与袋内相对湿度的关系，利用计算结果将开孔面积调节到一定范围，能够使包装内形成一个平衡的、且适合于果蔬保鲜需要的最佳相对湿度条件，既可避免包装袋透湿性过小导致凝水现象，又可防止透湿性过大造成的产品失水严重影响品质的问题，从而更好地保持产品品质。以250 g包装的双孢菇在2℃、80%相对湿度条件下贮藏对平衡调湿包装进行了试验验证，结果表明，适宜的开孔（11个直径2 mm的孔，孔的总面积约34.6 mm2）能够避免凝水的生成，且产品在贮藏10 d后的失重率为4.9%±0.2%，较好地保持产品的贮藏品质，保鲜期可达13 d，试验数据与模型预测值具有较高的吻合度，研究结果为采后果蔬平衡调湿包装的设计及实际应用提供了参考。
위료탐구과소다공막포장내수분적전체규률，우화병공제포장내적괄의상대습도조건，강저과소실수급대내응수대과소채후품질적영향，해문대과소랭장기간적증등급포장내수증기향막외확산적과정진행료분석，병근거Fick확산모형대다공막평형조습포장진행설계계산，학정개공면적여대내상대습도적관계，이용계산결과장개공면적조절도일정범위，능구사포장내형성일개평형적、차괄합우과소보선수요적최가상대습도조건，기가피면포장대투습성과소도치응수현상，우가방지투습성과대조성적산품실수엄중영향품질적문제，종이경호지보지산품품질。이250 g포장적쌍포고재2℃、80%상대습도조건하저장대평형조습포장진행료시험험증，결과표명，괄의적개공（11개직경2 mm적공，공적총면적약34.6 mm2）능구피면응수적생성，차산품재저장10 d후적실중솔위4.9%±0.2%，교호지보지산품적저장품질，보선기가체13 d，시험수거여모형예측치구유교고적문합도，연구결과위채후과소평형조습포장적설계급실제응용제공료삼고。
Fruits and vegetables contain large amounts of water, parts of which are easily lost under low relative humidity conditions because the water vapor pressure at the surface of fresh products is slightly below saturation. Loss of water from fresh products can lead to skin wrinkling, loss of crispiness, and undesirable color changes. Controlling water loss is an important means to maintain quality of postharvest fruits and vegetables. Fruits and vegetables are usually packaged within plastic film and stored at refrigeration temperature in order to prevent excessive water loss and to extend shelf life; however, the low water vapor permeability (WVP) of films combined with the fresh products transpiration rapidly brings about saturation humidity (~100% RH) of the package atmosphere. The saturated in-pack RH condition and inevitable external temperature fluctuation can result in the condensation of water on the inner surface of the packaging film and on the contained products, and lead to defects in the external appearance of commodities and accelerate microbial growth. Equilibrium modified humidity packaging (EMHP) is an effective method for decreasing water loss and avoiding the occurrence of condensed water by modifying the permeability of the packaging film through perforation and optimally regulating the in-package equilibrium water vapor pressure. The water loss of fruits and vegetables packaged in perforated film was influenced by both of transpiration rate of products and the transmission rate of water vapor to the outside of the package. The transmission processes of water vapor in headspace include two ways:permeation through film and diffusion through holes. Water vapor transmission in a perforated package occurs almost entirely through the perforations due to the high permeability of perforated film. Several mathematical models about mass transfer have been proposed, and the majority of them focus on predicting and controlling O2 and CO2 exchange in perforation-mediated modified atmosphere packaging in order to create the desired atmosphere for preservation of fresh fruits and vegetables. Little research has been done so far to measure the equilibrium relative humidity within package. Under certain storage temperature, the above two processes are results of water vapor deficit between the commodity and the gas surrounding the commodity and two sides of film, and follow different mathematical models. If there is a good balance of water vapor press, the constant relative humidity in a package can be obtained. Transpiration affects the main quality characteristics of fresh products, and water loss must be controlled within 4.9%±0.2%to avoid loss of freshness in fresh produce, and it is an important parameter to be considered while designing packaging. So, the area of perforation can be calculated based on the total amounts of water loss and mathematical models about water vapor transmission. The objective of our research is to analyze water vapor transmission rate (WVTR) in different perforation areas and design the equilibrium modified humidity packaging according to mathematical model based on Fick’s law of diffusion. The proper relative humidity within each package can be obtained through regulating perforation area, and avoiding excess water loss and production of condensed water. The model was validated with mushrooms (Aagaricus bisporus) packaged in perforated plastic bags at 2℃. The results showed that different perforation areas can affect water loss and shelf life of mushrooms, and the method can guide the design of equilibrium modified humidity packaging for mushrooms storage.