Arbutus unedo is a Mediterranean shrub or tree that produces edible fruits with promising applications for the food industry and nutraceutical applications. A deep understanding of the cell wall structure and modifications of its components during fruit softening would benefit the development of new food products and retail of fresh fruits. Aiming to enhance the valorization of A. unedo fruits, its cell wall was characterized, for the first time, during ripening. In this study, four distinct ripening stages (green, yellow, orange and red) were considered. Several preliminary quality parameters were determined. The nature of the compounds making part of the cell walls were elucidated through Fourier‑transform infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR) and spectral datasets were analyzed using unsupervised principal component analysis (PCA). High-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) was employed to assess monosaccharide composition, and lignin measurements were performed following the acetyl bromide soluble lignin methodology. In addition, scanning electron microscopy (SEM) analysis allowed to observe some relevant aspects of the microstructure of fruits. Significant modifications on the composition of these fruits were mostly found by the end of the ripening process when the fruits reached the red-ripe stage. Glucose, xylose and arabinose were determined as the major neutral cell wall sugars. Furthermore, the microscopy assessment unveiled the abundance of aggregated sclereids, and lignin measurements showed that A. unedo fruits are highly lignified. The richness in lignin and monosaccharides, such as glucose and xylose, may suggest the role displayed by that polyphenol and hemicelluloses like xylans and xyloglucans, which is supported by FTIR-ATR spectral assignments. It is hypothesised that the high amounts of xylose and lignin herein determined are highly associated with the sclereids. Relevant data were also obtained for the fundamental understanding of the ripening of other Ericaceae fruits and other berries.

Arbutus unedo是一种地中海灌木或树木，可生产可食用的水果，在食品工业和保健品应用中具有广阔的应用前景。深入了解水果软化过程中细胞壁结构及其成分的变化，将有利于新食品的开发和新鲜水果的零售。旨在提高A. unedo的价值果实，其细胞壁首次在成熟过程中得到表征。在这项研究中，考虑了四个不同的成熟阶段（绿色、黄色、橙色和红色）。确定了几个初步的质量参数。通过傅里叶变换红外光谱在衰减全反射模式 (FTIR-ATR) 中阐明构成细胞壁一部分的化合物的性质，并使用无监督主成分分析 (PCA) 分析光谱数据集。采用具有脉冲安培检测 (HPAEC-PAD) 的高性能阴离子交换色谱法来评估单糖组成，并按照乙酰溴可溶性木质素方法进行木质素测量。此外，扫描电子显微镜（SEM）分析可以观察水果微观结构的一些相关方面。这些果实的组成发生了显着的变化，主要是在果实达到红熟期的成熟过程结束时发现的。葡萄糖、木糖和阿拉伯糖被确定为主要的中性细胞壁糖。此外，显微镜评估揭示了聚集的巩膜的丰度，木质素测量表明A. unedo果实高度木质化。木质素和单糖（如葡萄糖和木糖）的丰富性可能表明多酚和半纤维素（如木聚糖和木葡聚糖）所发挥的作用，这得到 FTIR-ATR 光谱分配的支持。假设本文确定的大量木糖和木质素与巩膜高度相关。还获得了相关数据，以从根本上了解其他杜鹃花科水果和其他浆果的成熟。