A mixed model applied to joint analysis in experiments with coffee blends using the least squares method

ABSTRACT The aim of the present study was to propose a mixed model for a sensory analysis of four experiments with blends of different standards of quality, including the species Coffea Arabica L. and Coffea Canephora. Each experiment differed in the proportions used to formulate the blends and the concentrations used in preparing the beverages, these being 7% and 10% coffee powder for each 100 ml of water. The response variables under analysis were the sensory characteristics of the beverage found in an assessment made by a group of trained tasters, considering taste, bitterness and a final score. Each description followed a numerical rating scale of intensity that ranged from 0 to 10. The model was implemented using the least squares method; this led to the conclusion that including random parameters in the model, represented by the experiments, made it possible to compare the effect of each component simultaneously for each of the experiments.摘要：本研究旨在针对四项采用不同品质等级拼配方案的咖啡实验构建混合模型，所涉拼配原料包含阿拉伯咖啡（Coffea Arabica L.）与中果咖啡（Coffea Canephora）两个品种。每项实验在拼配比例与饮品制备浓度上存在差异，其中每份100ml水分别对应7%与10%的咖啡粉添加量。本研究分析的响应变量为经一组培训合格品评员评估得到的饮品感官特性，涵盖风味、苦味及最终得分三项指标，每项指标均采用0至10分的强度数值评分量表进行评定。本研究采用最小二乘法完成模型实现，最终得出结论：在以实验为载体的模型中纳入随机参数后，可实现对各实验中各组分作用效果的同步对比。