不同贮藏条件下荷花粉脂质氧化与色泽降解动力学模型

为了减少干燥后荷花粉贮藏过程中品质的劣变,该研究选用可真空和避光的包装材料,分别研究了30 d贮藏过程中温度(4、20、30℃)、光照(避光、非避光)和氧气(真空、常压)对荷花粉黄色度值(b*值)、过氧化氢值(peroxide value,POV)和硫代苯巴比妥酸反应底物值(thiobarbituric acid reactive substances,TBArs)变化动力学的影响;同时,采用零阶和一阶数学模型对试验数据进行模拟。结果表明:贮藏温度对荷花粉贮藏过程中品质劣变具有显著影响。在避光真空包装条件下,温度为20和30℃贮藏30 d,与4℃贮藏条件相比,荷花粉黄色度值显著降低(P0.05),POV值和TBArs值显著上升(P0.05);贮藏温度为4℃,真空包装贮藏发现,光照对荷花粉POV值的影响不显著(P0.05),但明显加快了脂质氧化的传播速度,非避光条件下贮藏30 d,TBArs值上升了7.42 mg/kg;零阶模型可较好的预测荷花粉贮藏过程中脂质TBArs值的变化,一阶模型可较好的预测荷花粉贮藏过程中黄色度和脂质POV值的变化规律。研究结果为脱水后荷花粉贮藏过程中品质劣变规律的探索及贮藏条件的选择提供了一定的基础。

Lipid oxidation and color degradation kinetics under different storage conditions of pollen

Pollen is the male reproductive material of plants and rich in various nutrient and functional substances, including protein, lipid of pollen, polysaccharide, vitamins and mineral, which are benefit for human health. Because of its relatively high moisture content, and its sensitive to microbial spoilage and fermentation, fresh pollen has very short shelf-life. Drying is the most frequently used method for pollen preservation as it can prevent the growth and reproduction of microorganisms and minimize many of the moisture-mediated degradation reactions to enhance shelf-life. However, due to high lipid content of pollen, their oxidation and rancidity arise serious quality problems during unsuitable storage, such as undesirable color, odour, flavor, etc. Therefore, a quantitative investigation of the change kinetics of pollen quality during storage is critical for selecting proper package method and storage conditions. As one of the most important organoleptic evaluation indicators of most foods and agricultural products, unsuitable color changes affect the market value and sale quantity significantly. Yellowness value, as the trait color of pollen, was selected as one of the quality attributes in current research. Lipid oxidation is closely related to quality degradation and flavor of food. The peroxide value (POV) and thiobarbituric acid reactive substances value (TBArs) were used to evaluate the first-order and second-order lipid oxidation of pollen during storage, respectively. The higher the POV and TBArs values are, the more severe the oxidation of lipid is. In current work, effects of different package factors (illumination and oxygen) and storage temperatures (4, 20, and 30℃) on the changes of yellowness value (b* value), peroxide (peroxide value, POV) and thiobarbituric acid reactive substances (TBArs) were investigated during pollen storage. The aims of the study were: 1) to explore the impact of temperatures on color and lipid oxidation at vacuum and without illumination package; 2) to explore the impact of illumination on color and lipid oxidation at 4℃ with vacuum package; 3) to explore the impact of oxygen on color and lipid oxidation at 4℃ without illumination package; 4) to establish the kinetics model ofb* value, POV and TBArs based on zero-order and first-order models during 30 d storage period. Results showed that, a higherb* value of pollen was obtained under storage temperature of 20 and 30℃ compared with 4℃ (P<0.05); no significant change(P>0.05) was found for the POV value of pollen during storage at 4℃ for 30 days, while significant increasing (P<0.05) were observed for storage at temperature of 20 and 30℃, respectively. In addition, the effect of light on POV of pollen during storage was not significant. But, the illumination could enhance the acceleration of TBArs value, which increased 7.42 mg/kg after 30 days storage. Zero-order model could well predict the TBArs changes kinetics of pollen during storage, while the first-order model could well describeb* value and POV value variation. The results could provide a theoretical support for selecting of storage strategies and conditions, which are benefits for reducing the quality degradation and prolong the shelf-life of pollen.