Establishment And Application Of Comprehensive Evaluation System For Freshness Of Frozen Food In Refrigerator

The production of fruit and vegetable is obviously seasonal, regional, and perishable itself, fruit and vegetable fresh-keeping problem has become increasingly prominent. Refrigerator is a commonly used food refrigeration appliance, the storing food sensory quality directly reflects the performance of the refrigerator and the actual effect. This study chose seven different brand three-door refrigerators, respectively select the size, color, texture relatively consistent Fengxiang strawberries, Hongdeng cherries,circular spinach,cucumbers,get on a 8 d plant study at the same temperature regulation (4℃)in different area (placed in a freezer, crisper and changing greenhouse).Sensory experiment used six descriptive analysis members, the 9 scaling method about the gloss, hardness, cooked smell and overall impression of fruit and vegetable was applied to sensory evaluation. Physical and chemical indicators to determine the weightlessness rate, hardness, color, soluble solids content, vitamin C content, chlorophyll content.Using the method of variance analysis, drawing comparison, select the refrigerator food samples determination conditions (including storage days, storage layer, the determination of the sample), principal component analysis (PCA) is adopted to improve the physical and chemical indicators of selection and the weight, using the fuzzy mathematics method for sensory index of the selection and determination of weight, so as to build a refrigerator food freshness evaluation system. The main content of the research and the results are as follows:1.The determination of refrigerator food samples to choice(1) the days of storage of the influence of the physical and chemical, sensory indexCombine the physical and chemical and the sensory index changes for analysis of variance analysis results and graphic analysis in different storage time, found that the change of the physical and chemical indexes of different storage time is not the same, at the beginning of the storage of 4 d, sensory index had significant difference (P<0.05), so the storage 4 d is the key test of time.(2)the storage layer of the influence of the physical and chemical, sensory indexFor different storage layers of various physical and chemical indicators of changes in the graphic analysis, combining with the prototype layer is the actual situation of different cold storage area, therefore, the evaluation index selection and the weight and the construction of a comprehensive evaluation system should choose all the storage layer.(3) determine the pending sampleIn the same storage conditions, strawberry, cucumber, spinach, cherry, the samples to be measured to the change of the physical and chemical index and sensory index of Pearson correlation analysis, it is concluded that:strawberry, cucumber, spinach, cherry, the weightlessness rate, vitamin C, gloss, hardness, overripeness, global impression has a significant positive correlation (P<0.05). Therefore, in the screening evaluation indexes and the weight determination,as well as the construction of a comprehensive evaluation system can choose a representative sample for research, comprehensive consideration, choose spinach for study.2.Construction of the comprehensive evaluation system① In the same storage conditions, strawberry, cucumber, spinach, cherry, the samples to be measured to the change of the physical and chemical index and sensory index of Pearson correlation analysis, it is concluded that:strawberry, cucumber, spinach, cherry, the weightlessness rate, vitamin C, gloss, hardness, overripeness, global impression has a significant positive correlation (P<0.05).Therefore, in the screening evaluation indexes andthe weight determination,as well as the construction of a comprehensive evaluation system can choose a representative sample for research, comprehensive consideration, choose spinach for study. ② Using principal component analysis (PCA) to determine the physical and chemical index weight, get the corresponding principal component expression, (physical and chemical comprehensive evaluation function):Y1=0.572 X1+0.075 X2+0.572+0.595 X4, X3 Y2= 0.229 X1+0.883 X2 X3 0.356-0.356 X4,Y=0.648+0.352 Y1 Y2③ Fuzzy mathematics method is used to determine weight of the sensory index, it is co ncluded,F=0.059*glossiness+0.293*crimp percent+0.101*hardness+0.037*green flavour+0.01 2* overripeness+0.498*global impression-(0.451*weight loss rate+0.359*chromatism +0.237* chlorophyll loss+0.363*Vitamin C loss)3. Application of the comprehensive evaluation systemComprehensive physical and chemical index and sensory index, it is concluded that the total fresh F:F=P-Y. By calculating different prototype score for the determination of the freshness of spinach, it is concluded that the score of the freshness of seven refrigerator refrigerator 4 is 75.5, refrigerator 2 is 74.31, refrigerator 5 is 70.47, refrigerator 6 is 64.17, refrigerator 7 is 63.14,refrigerator 1 is 61.26,refrigerator 3 is 61.17,evaluating effect of preservation of refrigerator prototype and analyze the reasons.