Abstract A study of the physicochemical, structural, nanomechanical properties at macro, micro and nanometric scales was carried out to determine which features have the greatest influence on the firmness of selected apple cultivars (Golden Delicious, Granny Smith, Gala and Red Delicious). Physicochemical assays, microscopy techniques, image analysis, nanoindentation and spectroscopy were used to characterize the properties of the four selected apples. The data were analyzed using principal component analysis, Pearson analysis and multiple linear regression to classify apple cultivars. These techniques were also used to identify which physicochemical, micro, and nanostructural as well as nanomechanical features were most associated with apple firmness. This allowed for the creation of a mathematical model (R2 = 0.97) for the prediction of apple firmness from evaluated variables. It was determined that the cellular architecture, stiffness of cell walls and crystallinity index of cellulose fibers were the most important factors in explaining the variability of firmness in the studied apples. This research provides novel and valuable information for understanding the role of cellular architecture, micro and nanostructure, as well as nanomechanical properties in the firmness of the studied cultivars.

中文翻译：

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阐明四种苹果品种硬度差异的物理化学、结构和纳米力学研究

摘要 对宏观、微观和纳米尺度的物理化学、结构、纳米力学特性进行了研究，以确定哪些特征对选定的苹果品种（金冠、格兰尼史密斯、Gala 和红冠）的硬度影响最大。物理化学分析、显微镜技术、图像分析、纳米压痕和光谱学被用来表征四种选定苹果的特性。使用主成分分析、Pearson 分析和多元线性回归对数据进行分析，以对苹果品种进行分类。这些技术还用于确定哪些物理化学、微观和纳米结构以及纳米力学特征与苹果的硬度最相关。这允许创建数学模型（R2 = 0。97）用于根据评估变量预测苹果硬度。确定了细胞结构、细胞壁的刚度和纤维素纤维的结晶度指数是解释所研究苹果硬度变化的最重要因素。这项研究为理解细胞结构、微米和纳米结构以及纳米力学特性在所研究品种的硬度中的作用提供了新颖而有价值的信息。