【作者】 赵亚；

【导师】 王相友；

【作者基本信息】 山东理工大学 ， 农产品加工及贮藏工程， 2013， 硕士

【摘要】 双孢蘑菇MA贮藏期间,菇体的高蒸腾速率和薄膜的低渗透率导致包装内环境相对湿度(RH)较高,微生物容易滋生,导致双孢蘑菇腐烂、变质。基于此,本论文研究了12种吸湿剂在不同温湿度下的吸湿特性,筛选出可用于双孢蘑菇MA贮藏适宜吸湿剂组合并进行实验验证。研究结果为双孢蘑菇MA贮藏中RH控制提供理论基础和技术手段。主要研究内容和结论分述如下：1.采用静态吸附法研究了无水氯化钙、3A分子筛、活性氧化铝球、硅藻土、膨润土、六偏磷酸钠、微晶纤维素、活性氧化铝粉、木糖醇、山梨糖醇、魔芋葡甘聚糖和壳聚糖等12种吸湿剂在不同温度(2、10、18℃)和RH(76%、86%、96%)下,15d内的吸湿量随时间变化的关系曲线。结果表明,对于同一吸湿剂,温度一定时,吸湿量随着RH的升高而增加：RH一定时,随着温度的升高吸湿量变化规律不明显。不同温湿度下,吸湿量由高到低的吸湿剂依次为：无水氯化钙(1.013～1.445g H2O g-1),木糖醇(0.006～0.833g H2O g-,其中最大吸湿量0.833g H2O g-1出现在10℃、RH96%,其它温湿度下范围为0.006～0.507g H2O g-1),六偏磷酸钠(0.251～0.791g H2O g-1),山梨糖醇(0.073～0.547g H20g-1),魔芋葡甘聚糖(0.143～0.531g H2O g-1),活性氧化铝球(0.178～0.409g H2O g-1),壳聚糖(0.149～0.314g H2O g-1),活性氧化铝粉(0.133～0.240g H2O g-1),3A分子筛(0.046～0.158g H2O g-1),微晶纤维素(0.052～0.145g H2O g-1),膨润土(0.002～0.114g H2O g-1),硅藻土(0.004～0.021g H2O g-1).2.采用Weibull模型拟合吸湿量数据,得到吸湿剂的吸湿动力学参数M∞和β,通过线性回归得到M∞和温湿度的关系。结果表明,除木糖醇和山梨糖醇外,Weibull模型与各吸湿剂的吸湿量数据拟合精度较高。M∞较高的吸湿剂为无水氯化钙(1.117～2.137g H2O g-1)、六偏磷酸钠(0.297～0.856g H2O g-1)和山梨糖醇(0.083～38.567g H2O g-1),其β值范围分别为：无水氯化钙(25.5～119.8h)、六偏磷酸钠(91.2～290.0h)和山梨糖醇(1.1-185.6h)。3A分子筛、壳聚糖、膨润土、六偏磷酸钠、微晶纤维素、木糖醇和山梨糖醇的M∞和温湿度间有较高的相关性(R2>81.2%),其中壳聚糖、膨润土和微晶纤维素的M∞受温度、RH的共同影响,而3A分子筛、六偏磷酸钠、木糖醇和山梨糖醇的M∞仅受RH的影响。3.吸湿剂的吸湿曲线和Weibull模型的拟合结果表明,吸湿剂实际测试结果和模型拟合结果基本一致。单一吸湿剂均不满足双孢蘑菇MA贮藏RH控制的需要。因此,以吸湿速度较快的无水氯化钙、山梨糖醇和吸附时间较长的六偏磷酸钠为复合吸湿剂,采用混料设计对其最适比例进一步筛选。结果表明,RH96%下,温度2、10℃时,无水氯化钙、山梨糖醇和六偏磷酸钠的最适编码值组合为：X1=0.3,X2=0.2,X3=0.5,对应的实际成分比例为无水氯化钙16%,山梨糖醇24%,六偏磷酸钠60%。4.为验证混合吸湿剂的效果及确定最适吸湿剂的用量,双孢蘑菇MA贮藏(200g双孢蘑菇／盒)过程中,添加不同质量(4g、8g、12g)的复合吸湿剂,以不加吸湿剂的双孢蘑菇作为对照(CK),研究其在温度2℃下,贮藏12d,双孢蘑菇各理化指标及微生物指标的变化。结果表明,同CK相比,添加吸湿剂处理显著推迟了双孢蘑菇呼吸越变和多酚氧化酶活性高峰来临的时间,增加了双孢蘑菇菇肉的白度值(L*)和贮藏前期的硬度,降低了贮藏前期多酚氧化酶的活性,显著抑制了双孢蘑菇表面微生物的生长,但对双孢蘑菇菇皮的l*值影响不显著。8g和12g处理显著增加了双孢蘑菇的失重率、膜透性,但4g处理和CK差异不明显。综合考虑,确定双孢蘑菇MA贮藏(200g双孢蘑菇/袋)时,最适复合吸湿剂为4g。更多还原

【Abstract】 During MA storage, high relative humidity (RH) conditions prevail in the packages due to the higher transpiration rates and lower water vapour transmission rates of fresh Agaricus bisporous. High humidity conditions lead to moisture condensation and favour microbial growth, which induce decay and deteriorate of the product. Moisture absorption characteristics of twelve moisture absorbers at different temperatures and humidities were investigated in this paper. The optimum compound absorbers and their ratios for MA storage of Agaricus bisporous were screened and verified. The results will provide theoretical basis and technique reference for the RH control during MA storage of Agaricus bisporous. The main research contents and conclusions are as follows:1. Static adsorption method was employed to investigate the moisture absorption characteristics of12different moisture absorbers or desiccants viz. calcium chloride (CaCl2),3A molecular sieve, activated aluminium oxide ball, diatomite, bentonite, sodium hexametaphoshpate, microcrystalline cellulose (MC), activated aluminium oxide powder, xylitol, sorbital, konjac glucomannan (KGM) and chitosan at different temperatures (2,10and18℃) and RHs (76%-,86%and96%).The results showed that moisture uptake increased with increasing RH for the same absorber at fixed temperature, while moisture uptake varied little with elevated temperature at fixed RH. The ranking sequence of moisture uptake capacity at different temperatures and RHs are CaCl2(1.013-1.445g H2O g-1), xylitol (0.006～0.833g H2O g-1, with the maximum moisture uptake of0.833g H2O g-1at10℃and96%RH, and0.006～0.507g H2O g-1at other temperature range), sodium hexametaphoshpate (0.251～0.791g H2O g-1), sorbital (0.073-0.547g H2O g-1), KGM (0.143-0.531g H2O g-1), activated aluminium oxide ball (0.178～0.409g H2O g-1), chitosan (0.149-0.314g H2O g-1), activated aluminium oxide powder (0.133～0.240g H2O g-1),3A molecular sieve (0.046～0.158g H2O g-1), MC (0.052-0.145g H2O g-1), bentonite (0.002～0.114g H2O g-1) and diatomite (0.004～0.021g H2O g-1). 2. The Weibull equation was used to fit the moisture content data of different desiccants and the model parameters of M∞and β were acquired. Non-linear regression analysis was adopted to develop the moisture absorption kinetics.The results showed that Weibull equation fitted well to the experimental data for all the desiccants except xylitol and sorbital. The moisture holding capacity (M∞) was higher for CaCl2(1.117～2.137g H2O g-1), sodium hexametaphoshpate (0.297～0.856g H2O g-1) and sorbital (0.083～38.567g H2O g-1) with β ranges of25.5～119.8h,91.2～290.0h and1.1～185.6h, respectively. The moisture holding capacity has higher correlation (R2>81.2%) with temperature and RH for3A molecular sieve, chitosan, bentonite, sodium hexametaphoshpate, MC, xylitol and sorbital. The moisture holding capacity was found to be dependent on the temperature and RH for chitosan, bentonite and MC. However, moisture holding capacity was only affected by RH for3A molecular sieve, sodium hexametaphoshpate, xylitol and sorbital.3. Consistency between moisture absorption kinetics data and Weibull model fitting can be observed. Because single desiccant can’t satisfy the need for RH control of MA storage of Agaricus bisporous, the CaCl2, sodium hexametaphoshpate and sorbital were therefore selected and the mixture design was used to ascertain the optimum mixture ratio of compound desiccants.The results showed that at temperature of2and10℃, RH of96%, the optimum code values of CaCl2, sodium hexametaphoshpate and sorbital were0.3,0.2and0.5, respectively. The actual ratio of CaCl2, sodium hexametaphoshpate and sorbital were0.16,0.24and0.60, respectively.4. The Agaricus bisporous of200g per package were stored at2℃with and without compound desiccants added to verify the RH control effectiveness and determine the optimum dosage of compound desiccants. The physicochemical and microbial indexes were detected during12-day storage.The results showed that compared with CK, the time of respiratory climacteric and polyphenol oxidase (PPO) activity peak dramatically delayed, while L*value and hardness of Agaricus bisporous increased. The microbial growth of Agaricus bisporous during MA storage was significantly inhibited by adding compound desiccants. The weight loss and member permeability of Agaricus bisporous significantly increased for treatments of8and12g compound desiccants, while they varied little for the treatment of4g and CK. Generally, the optimum dosage of compound desiccants for MA storage (200g/bag) of Agaricus bisporous was4g.更多还原