QUALITY AND OXIDATIVE STABILITY OF AUSTRALIAN OLIVE OIL ACCORDING TO HARVEST DATE AND IRRIGATION

Does Variability Affect the Performance of Front-Face Fluorescence Spectroscopy? A Study Case on Commercial Lebanese Olive Oil

The potential of front-face fluorescence spectroscopy coupled with chemometric techniques, namely multiple linear regression (MLR) applied on parallel factor (PARAFAC) scores and partial least squares (PLS), was tested on Lebanese olive oil samples possessing natural variability within their chemical parameters. Ninety-six olive oil samples have been harvested at different dates and from two seasons, processed using different extraction methods, collected from different altitudes and other factors that can increase the variability of the samples' chemical composition. Fluorescence excitation-emission matrices (EEM) of the collected samples were measured, and the relationship between them and the chemical parameters was examined. Twenty-two MLR regression models based on PARAFAC scores were generated, the majority of which showed a good correlation coefficient (R > 0.7 for ten predicted variables). A second model using PLS on the unfolded EEM was also conducted to improve the regression and to assess if it can handle the variability in hand. However, similar results, with a slight improvement over the MLR model, were obtained. In a non-experimental design, such variability may hinder the potentials of front-face fluorescence; however average to good MLR and PLS models were obtained, predicting the Lebanese olive oil deterioration quality parameters and fatty acid content.

Early Harvest Effects on Hydrophilic Phenolic Components of Extra Virgin Olive Oils Cvs. 'Ayvalık', 'Memecik' and 'Topakaşı'

The study was conducted to determine the effects of cultivar, harvest period and their interaction on the hydrophilic phenolic components extra virgin olive oils of the cultivars 'Ayvalık', 'Memecik' and 'Topakaşı'. Olives were collected at three different harvesting periods; (1) early harvest period-1 (Beginning of spotting), (2) early harvest period-2 (End of spotting), and (3) optimum harvest period. Oils were extracted using an abencor system. HPLC (High-performance liquid chromatograph) technique was used to quantify The phenolic compounds including: tyrosol (p-HPEA), hydroxytyrosol (3,4-DHPEA), luteolin, rutin, quercetin, catechin, sinapinic acid, p-coumaric acid, cinnamic acid, vanillin, vanillic acid, ferulic acid and gallic acid were quantified using HPLC. The results indicated that the effects of harvest period on the phenolic components were variety dependent. At the early harvest period-1, 'Memecik' and 'Topakaşı' had the highest efficiency in luteolin, cinnamic acid, vanillic acid, and ferulic acid contents, while 'Ayvalık' had the highest efficiency in hydroxytyrosol, sinapinic acid, p-coumaric, vanillin and ferulic acid contents. At the optimum harvest period, 'Ayvalık' had the highest efficiency in luteolin, tyrosol and gallic acid contents, while 'Topakaşı' had the highest efficiency in tyrosol, hydroxytyrosol and rutin content. The highest phenolic content was detected in the early harvest period-1. The content of tyrosol linearly increased with the progress of maturity harvest period, whereas the contents of the sinapinic acid, vanillin, vanilic acid and ferulic acid decreased. The oils of 'Memecik' variety had significantly higher phenolic content than those of 'Ayvalık' and 'Topakaşı' varieties.

The Selenium Supplementation Influences Olive Tree Production and Oil Stability Against Oxidation and Can Alleviate the Water Deficiency Effects

Foliar fertilization with selenium (Se) may well be beneficial in increasing the nutritional and qualitative values of food in Se-deficient regions such as the Mediterranean Basin, and may contribute to an increase in drought resistance in plants. The present study has considered detachment force, flesh firmness, pigmentation, fresh and dry weight, and oil content of olive drupes from Se fertilized olive orchards (Olea europaea L.) under drought stress and well-watered conditions. This study has also evaluated the total Se, Se amino acid, phenol, carotenoid and chlorophyll contents of EVOO, plus its oxidative stability against oxidation. While there was no change in the ripening indexes and the production of olives generally, Se application did increase the total Se, Se methionine, phenol, and carotenoid and chlorophyll contents. The higher concentration of these (bio) chemical compounds in EVOO obtained from Se fertilized plants might well suggest enhanced antioxidant activity. Consequently, EVOO obtained from Se fertilized trees possesses a higher nutritional value and, as indicated by the greater oxidative stability against oxidation, longer shelf life. In addition, under water deficient conditions, a higher fresh olive weight corresponds to a higher level of phenol, carotenoid and chlorophyll, and the chlorophyll-to-carotenoid ratio in Se fertilized trees would appear to confirm the positive role of selenium in alleviating damage caused by drought stress conditions.

Olive Cultivation in the Southern Hemisphere: Flowering, Water Requirements and Oil Quality Responses to New Crop Environments

Olive (Olea europaea L.) is a crop well adapted to the environmental conditions prevailing in the Mediterranean Basin. Nevertheless, the increasing international demand for olive oil and table olives in the last two decades has led to expansion of olive cultivation in some countries of the southern hemisphere, notably in Argentina, Chile, Perú and Australia. While the percentage of world production represented by these countries is still low, many of the new production regions do not have typical Mediterranean climates, and some are located at subtropical latitudes where there is relatively little information about crop function. Thus, the primary objective of this review was to assess recently published scientific literature on olive cultivation in these new crop environments. The review focuses on three main aspects: (a) chilling requirements for flowering, (b) water requirements and irrigation management, and (c) environmental effects on fruit oil concentration and quality. In many arid and semiarid regions of South America, temperatures are high and rainfall is low in the winter and early spring months compared to conditions in much of the Mediterranean Basin. High temperatures have often been found to have detrimental effects on olive flowering in many olive cultivars that have been introduced to South America, and a better understanding of chilling requirements is needed. Lack of rainfall in the winter and spring also has resulted in an urgent need to evaluate water requirements from the flower differentiation period in the winter to early fruit bearing. Additionally, in some olive growing areas of South America and Australia, high early season temperatures affect the timing of phenological events such that the onset of oil synthesis occurs sooner than in the Mediterranean Basin with most oil accumulation taking place in the summer when temperatures are very high. Increasing mean daily temperatures have been demonstrated to decrease fruit oil concentration (%) and negatively affect some aspects of oil quality based on both correlative field studies and manipulative experiments. From a practical standpoint, current findings could be used as approximate tools to determine whether the temperature conditions in a proposed new growing region are appropriate for achieving sustainable oil productivity and quality.

Comparison of some chemical parameters of a naturally debittered olive (Olea europaea L.) type with regular olive varieties

Some olives grown in Karaburun peninsula in the west part of Turkey and mostly coming from Erkence variety lose their bitterness while still on the tree and are called Hurma among locals. This olive type does not require further processing to remove the bitter compounds. In this study, sugar, organic acid and fatty acid profiles of Hurma, Erkence (not naturally debittered) and Gemlik (commonly consumed as table olive) olives were determined throughout 8weeks of maturation period for two consecutive harvest seasons, and the results were analysed by principal component analysis (PCA). PCA of sugar and organic acid data revealed a differentiation in terms of harvest year but not on variety. Hurma olive is separated from others due to its fatty acid profile, and it has higher linoleic acid content compared to others. This might be an indication of increased desaturase enzyme activity for Hurma olives during natural debittering phase.

Olive orchard amended with olive mill wastewater: effects on olive fruit and olive oil quality

The aim of this work was to study the effects of agronomic application of olive mill wastewater (OMW) in a field of olive trees on olive fruit and olive oil quality. Agronomic application of OMW increased significantly the fungal:bacteria ratio, whereas the root colonisation and the photosynthetic rates decreased significantly. Consequently, the oil content expressed as a percentage of dry weight, decreased significantly after agronomic application of OMW. Land spreading of OMW altered the relative proportion of individual olive fruit sugar and decreased significantly the nitrogen (N) and phosphorus (P) of the fruit. A significant increase was observed in total phenol content of oil after agronomic application of OMW. alpha-Tocopherol content, on the contrary, decreased with OMW application. The fatty acid composition of the oil was not affected by the treatments. To our knowledge, this is the first report of change in the olive fruit and olive oil quality following agronomic application of OMW.

Chemistry and health of olive oil phenolics

The Mediterranean diet is associated with a lower incidence of atherosclerosis, cardiovascular disease, and certain types of cancer. The apparent health benefits have been partially attributed to the dietary consumption of virgin olive oil by Mediterranean populations. Most recent interest has focused on the biologically active phenolic compounds naturally present in virgin olive oils. Studies (human, animal, in vivo and in vitro) have shown that olive oil phenolics have positive effects on certain physiological parameters, such as plasma lipoproteins, oxidative damage, inflammatory markers, platelet and cellular function, and antimicrobial activity. Presumably, regular dietary consumption of virgin olive oil containing phenolic compounds manifests in health benefits associated with a Mediterranean diet. This paper summarizes current knowledge on the physiological effects of olive oil phenolics. Moreover, a number of factors have the ability to affect phenolic concentrations in virgin olive oil, so it is of great importance to understand these factors in order to preserve the essential health promoting benefits of olive oil phenolic compounds.