Department of Plant Biology, Ecology and Earth Sciences (Research Group FBCMP), Extremadura University, Badajoz, Spain.
European University of the Atlantic, Scientific and Technological Park of Cantabria, Santander, Spain.
PLoS One. 2019 Apr 18;14(4):e0215540. doi: 10.1371/journal.pone.0215540. eCollection 2019.
The phenolic composition and content of olive fruit are some of the attributes that determine oil quality. This composition depends on the olive variety, the cultivation system, and the fruit's ripeness. This study considered two olive varieties (Manzanilla and Morisca), under two water regimes (irrigated and rainfed), harvested at three stages of maturation (S1, S2, and S3), over three consecutive campaigns (2011, 2012, and 2013). The accumulation of phenols in the fruit was found to depend only on the stage of ripeness, while the flavonoid and phenylpropanoid contents depended also on the variety and the water regime. Superoxide dismutase (SOD) activity was linked to O2- production, which in turn depended on water regime, variety, and stage of maturation (this last being a process involving ROS). The peroxidase (POX) activity seemed only to depend on ripeness, while polyphenol oxidase (PPO) activity varied from year to year as well as presenting a strong ripeness dependence that was in clear coherence with the levels of phenolic compounds that the olives accumulate. All these relationships between the variables and the factors conform a dataset with the structure of a multidimensional array that is difficult to interpret using conventional techniques of statistical analysis. This work takes a novel approach (MultiDimensional Scaling associated with a Partial Triadic Analysis, MDS-PTA) to the analysis of this type of data structure which allows its correct interpretation. The analysis showed that the state of maturation of the olives is the most clearly discriminating factor, far more so than the cultivar, water regime, or year. Thus, the phenols and the total antioxidant activity (FRAP) showed strong clustering, being closely related in all three years studied. The oxidant and antioxidant activities showed a certain tendency to cluster, although in these cases the year also had an influence as a factor, indicating that these parameters depend more on external factors and less on ripeness.
橄榄果实的酚类成分和含量是决定油质的一些属性。这种成分取决于橄榄品种、栽培系统和果实的成熟度。本研究考虑了两个橄榄品种（曼萨尼拉和莫利萨），在两种水分制度（灌溉和雨养）下，在三个成熟阶段（S1、S2 和 S3）收获，在三个连续的季节（2011、2012 和 2013）进行。研究发现，果实中酚类物质的积累仅取决于成熟阶段，而类黄酮和苯丙烷类物质的含量也取决于品种和水分制度。超氧化物歧化酶（SOD）活性与 O2-的产生有关，而 O2-的产生又取决于水分制度、品种和成熟阶段（这是一个涉及 ROS 的过程）。过氧化物酶（POX）活性似乎只取决于成熟度，而多酚氧化酶（PPO）活性则因年份而异，并且与橄榄积累的酚类化合物水平有很强的相关性。这些变量和因素之间的所有关系构成了一个具有多维数组结构的数据集，使用传统的统计分析技术很难解释。本工作采用一种新的方法（多维尺度分析与部分三角分析，MDS-PTA）来分析这种数据结构，使其能够得到正确的解释。分析表明，橄榄的成熟状态是最具区分力的因素，远远超过品种、水分制度或年份。因此，在所有三年的研究中，酚类物质和总抗氧化活性（FRAP）表现出强烈的聚类，它们之间的相关性很强。氧化剂和抗氧化剂的活性表现出一定的聚类趋势，尽管在这些情况下，年份也是一个影响因素，这表明这些参数更多地取决于外部因素，而较少取决于成熟度。
