How Agronomic Factors Affects Olive Oil Composition And Quality

Olive oil is one of the most popular vegetable oils worldwide but several factors might affect its quality and composition, from the tree to the spoon. Olive oil quality and composition is mainly influenced by olive fruit characteristics, and therefore all aspects that influence their development have a crucial effect on olive products. Those factors include the selection of olive cultivar, its cultivation, degree of crop intensification and production systems, agricultural practices, including irrigation and fertilization, olive pests and diseases management, all these factors clearly defining the composition of olive fruits and the inherent quality and properties of olive products. In the last decades, huge modifications in olive tree cultivation have been observed, related essentially with two great factors: development of olive cultivations in new producing areas and crop intensification in traditional producing areas. Generally, most agronomic factors, including crop density, farming system, irrigation and fertilization, have no substantial effects on fresh olive oil quality parameters and classification. Nevertheless, a considerable incidence of olive pests and diseases can easily take fresh olive oils to the lampante category. In opposition, all agronomic factors seem to influence olive oil composition. Antioxidants are the main affected components, with a crucial effect on olive oil sensorial attributes, bioactive and nutritional properties, as well as its oxidative stability. In present chapter the influence of diverse agronomic factors on olive fruits and olive oils production, composition and quality, is reviewed and discussed, giving special importance to olive farming-systems, fertilization and irrigation, as well as the incidence of olive pests and diseases.info:eu-repo/semantics/publishedVersio

Microwave Heating: A Time Saving Technology or a Way to Induce Vegetable Oils Oxidation?

Microwave heating features modern lifestyle. The use of this technology enables a significant reduction in the time dedicated to prepare meals and opens new perspectives at the industrial level. In this chapter we report the combined effect of time/applied potency of microwave heating in comparison to conventional electric oven on the quality of vegetable oils. In general, the degradation pattern of vegetable oils under microwave heating was similar to that expected from other conventional heating methods, including oxidation, hydrolysis and polymerization. Nevertheless, microwave heating induced higher degradation extent, as confirmed by the physical and chemical evaluations reported, reducing the nutritional value of lipids. The combination of temperature and energy effects induced by microwaves, which could have strengthened the heating effect might lead to zonal overheating in the oils, a situation that deserves technological improvement. Nevertheless, most of the published studies compared high exposure times and temperatures, unusual on microwave domestic procedures, except for microwave frying. Therefore, the vegetable oils behavior under real cooking practices, power settings, and combined interaction of different ingredients, needs to be further exploit in order to provide concise information from nutritional, technological and health points of view. Based on these prospects and scientific findings the use of microwave is not discouraged, but vegetable oils heating should be reduced to the minimum, in order to reduce the degradation extent of important compounds, as lipossoluble vitamins, essential fatty acids, and phenolics, while reducing the formation of potentially hazard components, the oxidized lipids

Actividade antioxidante de azeitonas verdes descaroçadas produzidas em Trás-os-Montes: estudo do efeito da cultivar.

A azeitona de mesa e parte integrante da dieta Mediterrânica, sendo considerada uma fonte importante de antioxidantes. Em Trás-os-Montes, no inicio do Outono, são processadas de forma artesanal um tipo de azeitona de mesa denominada "alcaparras". Para 0 seu processamento, os frutos são colhidos verdes, partidos, retirado o caroço e introduzidos em agua, mudada diariamente, durante aproximadamente uma semana ate que possam ser consumidos. De uma maneira geral, o factor cultivar não e tido em conta no processamento, apesar de apresentarem composição química e propriedades tecnológicas distintas. Assim, com o presente trabalho pretendeu-se estudar 0 efeito da cultivar na actividade antioxidante das "alcaparras". Neste sentido, foram processados lotes de azeitonas verdes descaroçadas monovarietais, à escala laboratorial das cultivares Cobrançosa, Madura!, Negrinha de Freixo, Santulhana e Verdeal Transmontana

Identification of leaf volatiles from olive (Olea europaea) and their possible role in the ovipositional preferences of olive fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae)

The olive fly, Bactrocera oleae (Rossi), is a monophagous pest that displays an oviposition preference among cultivars of olive (Olea europaea L.). To clarify the oviposition preference, the olive leaf volatiles of three olive cultivars (Cobrançosa, Madural and Verdeal Transmontana) were assessed by headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) at six different periods of olive fruit maturation and degrees of infestation. A total of 39 volatiles were identified, mainly esters and alcohols, with a minor percentage of aldehydes, ketones and terpenic compounds, including sesquiterpenes. At sampling dates with higher degrees of infestation, cv. Cobrançosa had, simultaneously, significantly lower infestation degrees and higher volatile amounts than the other two cultivars, with a probable deterrent effect for oviposition. The green leaf volatiles (GLVs) (Z)-3-hexen-1-ol and (Z)-3-hexen-1-ol acetate) were the main compounds identified in all cultivars, together with toluene. The abundance of GLVs decreas ed significantly throughout maturation, without significant differences among cultivars, while toluene showed a general increase and positive correlation with olive fly infestation levels. The results obtained could broaden our understanding of the roles of various types and amounts of olive volatiles in the environment, especially in olive fly host selection and cultivar preference.The authors are grateful to the Portuguese Foundation of Science and Technology for financial support through the project EXCL/AGR-PRO/0591/2012 “Olive crop protection in sustainable production under global climatic changes: linking ecological infrastructures to ecosystem functions”. R. Malheiro thanks FCT, POPH-QREN and FSE for PhD grant (SFRH/BD/74675/2010). This manuscript is part of Ricardo Malheiro PhD Thesis.info:eu-repo/semantics/publishedVersio

Volatile changes in cv. Verdeal Transmontana olive oil: From the drupe to the table, including storage

This study focused on the volatile changes in cv. Verdeal Transmontana throughout the entire olive oil processing chain, from the drupe to olive oil storage up to 12 months, while correlating it with quality parameters and sensory quality. During crushing and malaxation, the volatiles formed were mainly “green-leaf volatiles” (GLVs), namely (E)-2-hexenal, hexanal, and 1-hexanol. Centrifugation and clarification steps increased the total volatile amounts to 130 mg kg−1. However, clarification also increased nonanal and (E)-2-decenal contents, two markers of oxidation, with a noticeable loss of phenolic compounds and oxidative stability. During storage, the total volatile amounts reduced drastically (94% at 12 months after extraction), together with the positive sensory attributes fruity, green, bitter, and pungent. Despite being classified as extra-virgin after one year of storage, peroxides and conjugated dienes were significantly higher while there was a reduction in antioxidant capacity as well as in phenolic compounds (less 50%) and oxidative stability (57%). The present work allowed concluding that the extraction process modulates the volatile composition of olive oil, with a concentration of volatiles at the clarification step. During storage, volatiles are lost, mainly eight months after extraction, leading to the loss of important sensory attributes.Ricardo Malheiro thanks FCT, POPH-QREN and FSE for the Post- Doctoral grant (SFRH/BPD/111901/2015). The authors thank the Casa Santo Amaro and their owners for the samples availability and the kindness for allowing the use of their facilities to extract the oils.info:eu-repo/semantics/publishedVersio

Olive cultivar and maturation process on the oviposition preference of Bactrocera oleae (Rossi) (Diptera: Tephritidae)

The olive fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), is a key-pest in the main olives producing areas worldwide, and displays distinct preference to different olive cultivars. The present work intended to study oviposition preference towards three Portuguese cultivars (Cobrançosa, Madural, and Verdeal Transmontana) at different maturation indexes. Multiple oviposition bioassays (multiple-choice and no-choice) were conducted to assess cultivar preference. No-choice bioassays were conducted to assess the influence of different maturation indexes (MI 2; MI 3, and MI 4) in single cultivars. The longevity of olive fly adults according to the cultivar in which its larvae developed was also evaluated through survival assays.Cultivar and maturation are crucial aspects in olive fly preference. Field and laboratory assays revealed a preference towards cv. Verdeal Transmontana olives and a lower susceptibility to cv. Cobrançosa olives. A higher preference was observed for olives at MI 2 and MI 3. The slower maturation process in cv. Verdeal Transmontana (still green while the other cultivars are reddish or at black stage) seems to have an attractive effect on olive fly females, thus increasing its infestation levels. Olive fly adults from both sexes live longer if emerged from pupae developed from cv. Verdeal Transmontana fruits and live less if emerged from cv. Cobrançosa. Therefore, olive cultivar and maturation process are crucial aspects in olive fly preference, also influencing the longevity of adults.The authors are grateful to the Portuguese Foundation of Science and Technology for financial support through the project EXCL/AGR-PRO/0591/2012 ‘Olive crop protection in sustainable production under global climatic changes: linking ecological infrastructures to ecosystem functions’ and Pest-C/EQB/LA0006/2013. Ricardo Malheiro thanks FCT, POPH-QREN and FSE for PhD grant (SFRH/BD/74675/2010). This manuscript is part of Ricardo Malheiro PhD Thesis.info:eu-repo/semantics/publishedVersio

Borage, calendula, cosmos, Johnny Jump up, and pansy flowers: volatiles, bioactive compounds, and sensory perception

The aim of the present work was to study the main volatile and bioactive compounds (monomeric anthocyanins, hydrolysable tannins, total flavonoids, and total reducing capacity) of five edible flowers: borage (Borage officinalis), calendula (Calendula arvensis), cosmos (Cosmos bipinnatus), Johnny Jump up (Viola tricolor), and pansies (Violaxwittrockiana), together with their sensory attributes. The sensory analysis (10 panelists) indicated different floral, fruity, and herbal odors and taste. From a total of 117 volatile compounds (SPME-GC-MS), esters were most abundant in borage, sesquiterpenes in calendula, and terpenes in cosmos, Johnny Jump up, and pansies. Some bioactive and volatile compounds influence the sensory perception. For example, the highest content of total monomeric anthocyanins (cosmos and pansies) was associated with the highest scores of colors intensity, while the floral and green fragrances detected in borage may be due to the presence of ethyl octanoate and 1-hexanol. Therefore, the presence of some volatiles and bioactive compounds affects the sensory perception of the flowers.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT, Portugal) for the financial support provided by the research grant [SFRH/BD/95853/2013] and FCT/MEC for the financial support to QOPNA research Unit [FCT UID/QUI/00062/2013], through national funds and when applicable co-financed by the FEDER, within the PT2020 Partnership Agreement, and to REQUIMTE through the Project [PEst/UID/ QUI/50006/2013]. The authors are also grateful to FCT (Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013).info:eu-repo/semantics/publishedVersio

Improvement of sensorial and volatile profiles of olive oil by addition of olive leaves

The changes caused by the addition of olive leaves (0, 5, and 10%) during the extraction of olive oil and malaxation time (20, 30, and 30 min) in the volatile profile and sensory attributes of olive oil from cv. Cobrançosa were studied. To investigate such transformations, a central composite designs from the Response Surface Methodology (RSM) was used, retrieving 13 runs combining leaf percentages and malaxation times. Each run was extracted in triplicate (39 olive oils overall). Sensory attributes were improved to leaves addition, mainly green and fruitiness attributes in olfactory and gustatory-olfactory sensations, but high malaxation times ( > 30 min) reduced pungent and bitter notes. Leaves addition increased the amounts of total volatiles, particularly the GLV's (green leaves volatiles) (E)-2-hexenal, (Z)-3-hexenal, and (Z)-3-hexenyl acetate, directly correlated with the improved sensory attributes. RSM models a showed positive linear effect with leaves addition, but a negative effect with malaxation time. These results suggest the use of olive leaves as effective odorants for the olive mill industry, while enabling the reduction of malaxation times and by-product amounts. Practical applications: The results obtained clearly open new lines of research to use olive leaves, a sub-product of olive oil extraction, in a valuable way. Olive leaves can be used as natural sources of odorants for olive oils. Furthermore, their use during the extraction of olive oils from overmature olives may also lead to an improvement of the volatile fraction and provide enhanced sensory properties to the consumers, thus conferring an added value to these oils. Another important practical application is the extraction process. In our work, we advise to optimize both the percentage of leaves and the malaxation time as much as possible, as they facilitate both sensory and volatile fractions of the extracted olive oils. Sensory attributes are improved to leaves addition, mainly green and fruitiness attributes in olfactory 17 and gustatory-olfactory sensations, but high malaxation times ( > 30 min) reduced pungent and bitter 18 notes. Leaves addition increase the amounts of total volatiles, particularly the GLV's (green leaves 19 volatiles) (E)-2-hexenal, (Z)-3-hexenal, and (Z)-3-hexenyl acetate, directly cor related with the improved 20 sensory attributes. RSM models a show positive linear effect with leaves addition, but a negative effect 21 with malaxation time. These results suggest the use of olive leaves as effective odorants for the olive mill 22 industry, while enabling the reduction of malaxation times and by-product amounts.Ricardo Malheiro thanks FCT, POPH-QREN and FSE for the Post-Doctoral grant (SFRH/BPD/111901/2015).info:eu-repo/semantics/publishedVersio

Chemical characterization of “Alcaparras” stoned table olives from Northeast Portugal

Commercial stoned table olives named "alcaparras" from Trás-os-Montes (Portugal) were chemically characterized. During three consecutive years (2004-2006) 30 samples (10 per year) were examined for their nutritional value (moisture, crude protein, total fat, ash, carbohydrates, and energy), with a detailed report of the fatty acids and tocopherols composition. Water was the major constituent (72.5 ± 5.5%), followed by fat (14.6 ± 5.1%). The average amount of protein and ash were 1.1% and 3.4%, respectively, reporting unusual ash values for table olives, related to the technological process. One hundred grams of fresh stoned table olives presented an average energetic value of 156 kcal, lower than most table olives. The lipids are rich in oleic acid (average of 77.7 ± 2.0%), followed by palmitic acid and linoleic acid. Samples showed an average of total tocopherols of 1.2 mg/100 g of fresh weight, being α-tocopherol the most abundant. Table olives are important sources of MUFA, as olive oil, recognized as a preventive factor in diseases in which free radicals are implicated, complemented by the amounts of vitamin E, with both antioxidant and vitamin action.The authors are grateful to INTERREG III A Program, Project PIREFI for financial support of this work.info:eu-repo/semantics/publishedVersio