压缩机变频冷藏对胡萝卜货架期品质和活性氧积累的影响

Effects of refrigeration of variable frequency compressor on quality of shelf life and accumulation of reactive oxygen species of carrots

中文关键词:  变频  冷藏  货架期  品质  活性氧  胡萝卜  抗氧化

英文关键词:frequency conversion  refrigeration  shelf life  quality  reactive oxygen species  carrot  antioxidant

中文摘要:

      目的 探讨压缩机变频冷藏节能和冷藏效益, 并研究压缩机变频冷藏对胡萝卜货架期品质和活性氧积累的影响。方法 选用制冷系统压缩机变频和定频的两种冷库, 对采收胡萝卜分别进行32 d低温冷藏, 随后货架期室温贮藏12 d, 采用电表计量法测定冷藏中前期变频库和定频库的主机和蒸发器冷风机的耗电量, 温度记录仪测定对内外温度变化, 并用感官、色差仪、质构仪和理化分析方法测定货架期胡萝卜糠心、色泽、质地、味觉和营养等品质指标变化规律, 采用试剂盒和分光光度法对货架期胡萝卜超氧阴离子(oxygen free radical, OFR)和过氧化氢(hydrogen peroxide, H2O2)两种活性氧含量和过氧化物酶(peroxidase, POD)、超氧化物歧化酶(superoxide dimutase, SOD)、过氧化氢酶(catalase, CAT)和抗坏血酸过氧化物酶(ascorbate peroxidase, APX)抗氧化酶活性进行分析。结果 压缩机变频能节约制冷系统主机和冷藏总体电量, 但压缩机变频库的定频蒸发器冷风机加速了电量消耗; 压缩机变频还提高了降温速率并稳定了垛内温度; 变频库冷藏显著降低货架后期胡萝卜糠心指数, 提高货架期胡萝卜的黄色值和饱和度, 维持硬度和咀嚼性, 提高了可溶性固形物含量, 延缓了类胡萝卜素、可溶性蛋白和维生素C含量的下降。同时, 变频库冷藏可降低胡萝卜货架期的OFR和H2O2含量, 提高货架期POD、SOD、CAT和APX抗氧化酶活性。结论 压缩机变频冷藏具有一定节能和降温效果, 从而抑制货架期胡萝卜活性氧积累, 最终维持较好的胡萝卜货架期品质, 但压缩机变频冷库的节能效益还有待进一步提高。

英文摘要:

      Objective To explore the energy-saving and cooling efficiency of refrigeration with compressor frequency conversion and study the effects of compressor frequency conversion refrigeration on the shelf life quality and accumulation of reactive oxygen species of carrots. Methods Two types of cold storage with variable frequency and fixed frequency refrigeration system compressors were selected for 32 d of cold storage of harvested carrots, followed by 12 d of storage at room temperature during the shelf life. The power consumptions of the main machine and evaporator cooling fan of 2 kinds of refrigeration in the early stage of refrigeration were measured by electricity metering, and the temperature changes inside and outside the stack of storage carrots were determined by the temperature recorder. Meanwhile, the quality indexes such as hollowing degree, color, texture, taste and nutrition were analyzed by sensory evaluation, portable colorimeter, texture analyzer and physicochemical analysis methods. In addition, the content of reactive oxygen species including superoxide anion and hydrogen peroxide and the activities of antioxidant enzymes including POD, SOD, CAT, and APX in carrot during shelf life were determined by the kit and spectrophotometric method. Results The compressor frequency conversion could save the main machine’s and the refrigeration system’s overall power. However, the constant frequency evaporator cooling fan of the compressor frequency conversion system accelerated the power consumption. Moreover, the cooling rate was improved, and the temperature was stabilized inside the stack in frequency compressor refrigeration. Furthermore, compressor frequency conversion refrigeration could significantly inhibit the increasement of carrot hollowing degree index, enhance the b* value and c* value, maintain the high hardness and chewiness, enhance the content of soluble solids, delay the decline of carotenoid, soluble protein and vitamin C. Meanwhile, the content of OFR and H2O2 incarrots was reduced, and the antioxidant enzyme such as POD, SOD, CAT and APX in carrots were enhanced during the shelf life after compressor frequency conversion refrigeration. Conclusion Compressor frequency conversion refrigeration has certain energy-saving and cooling effects, which can inhibit the accumulation of reactive oxygen species in carrot shelf life and ultimately maintain good carrot shelf life quality. However, the energy saving efficiency of compressor frequency conversion cold storage needs to be further improved.