Cellular changes during cold-pressed ‘Hass’ avocado oil extraction : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology, at Massey University, Auckland campus, New Zealand

Cellular changes during cold-pressed extraction of ‘Hass’ avocado (Persia americana Mill.) and ‘J5’ olive (Olea europaea L.) were investigated to understand how each step in the process affects oil release from the tissue and to ascertain if and how cold-pressed oil yields were influenced by cellular changes. Electrical impedance spectroscopy (EIS), electrical conductivity, light microscopy and rheological measurements were used to examine avocado and olive flesh and pulp structure at defined processing steps during both commercial and laboratory-based cold-pressed oil extraction. Light microscopy revealed most parenchyma cells in the fruit flesh were ruptured after the destoning and grinding steps. Concomitantly, a significant reduction in electrical resistance and a concurrent increase in conductivity of pulp tissue occurred when cells were ruptured during the destoning and grinding process. Malaxing assisted aggregation of oil into larger droplets, observed by microscopy. Increasing malaxing time resulted in a decrease in the solid-like behaviour (G’) of fruit pulp and an increase in cold-pressed oil yield, which correlated with the oil droplets in the fruit paste coalescing together and becoming larger. Idioblast cells in avocado flesh appeared to remain unruptured and intact during the extraction process. In comparison to the cold-pressed oil extraction of ‘Hass’ avocado, olive oil was easier to recover from ‘J5’ olive during cold-pressed extraction (at lower temperatures and for shorter times) as the olive paste was less viscous allowing the oil droplets to aggregate more easily. Processing of avocado fruit at three different stages of ripening (minimally-, fully- and over-ripe) produced higher oil yields and decreased oil quality (based on % free fatty acids and peroxide value) with riper fruit. Intact fruit and fruit pulp from the over-ripe fruit had higher conductivity and lower electrical resistance values, which indicated more cell rupture occurred when softer, riper avocado fruit are processed. For avocado fruit at six different stages of maturity (harvested between September and April during the 2016/17 season), light microscopy results showed there were more unbroken parenchyma cells in early season, less mature fruit. Polysaccharides in the cell walls were more strongly bound to cellulose in early-season avocado fruit. Late season fruit had more cell disruption during extraction corresponding to higher conductivity and lower electrical resistance values; hence higher extraction yields with increasing maturity. No significant compositional changes of the polysaccharides in the cell walls occurred during malaxing, which indicated that the malaxing step only promoted aggregation of the oil droplets. The malaxing temperature and ultrasound treatment at 20–25 kHz did not assist with cellular disruption during extraction. Higher malaxing temperature reduced the viscosity and increased the mobility of oil droplets and oil droplets were more likely to collide and aggregate to form larger droplets, reducing the G’ of the pulp tissue. The oil yield significantly increased from 1.05% to 13.43% with malaxing temperature increasing from 30 to 50 ⁰C, for early season fruit. Ultrasound treatment at 20–25 kHz decreased the G’ of the avocado pulp and helped the oil to aggregate. In conclusion, the avocado flesh cellular structure ruptured more easily in softer and late maturity fruit contributing to increased oil yields. Malaxing time, temperature and ultrasound treatment at 20–25 kHz influenced the degree of oil aggregation in fruit pulp and therefore improved the cold-pressed oil yield. Olive pulp was less viscous or less solid like during malaxing, resulted in faster oil agglomeration

New techniques for the improvement of the elaboration processes of “estilo sevillano” table olives

La medida de la impedancia eléctrica ha demostrado ser útil para medir propiedades y características de productos agroalimentarios: calidad de frutos, contenido de humedad y capacidad de germinación en semillas o la resistencia de los frutos a las heladas. En el caso de aceitunas se ha usado para determinar contenido de grasa y el momento óptimo de recolección. En el presente trabajo se ha desarrollado un equipo basado en el System on Chip (SoC) AD5933 que ejecuta una transformada discreta de Fourier (DFT) de 1024 puntos para devolver el valor de la impedancia como módulo y fase y que trabajando junto a dos multiplexores analógicos AD706 y un reloj externo programable basado en un DDS sintetizado en una FPGA XC3S250E- 4VQG100C, permite la medida de la impedancia en productos agroalimentarios con un barrido en frecuencia desde 1 Hz a 100 kHz. Con esta aportación se demuestra cómo la impedancia eléctrica se ve afectada por la temperatura tanto en las aceitunas recién recolectadas como en las procesadas en salmuera y proporciona una nueva técnica para la mejora de los procesos de elaboración de la aceituna de mesa de estilo sevillano al caracterizar los cultivares empleando únicamente la impedancia eléctrica, redes neuronales (NN) e Internet de las cosas (IoT).Electrical impedance has shown itself to be useful in measuring the properties and characteristics of agri-food products: fruit quality, moisture content, the germination capacity in seeds or the frost-resistance of fruit. In the case of olives, it has been used to determine fat content and optimal harvest time. In this paper, a system based on the System on Chip (SoC) AD5933 running a 1024-point discrete Fourier transform (DFT) to return the impedance value as a magnitude and phase and which, working together with two ADG706 analog multiplexers and an external programmable clock based on a synthesized DDS in a FPGA XC3S250E-4VQG100C, allows for the impedance measurement in agri-food products with a frequency sweep from 1 Hz to 100 kHz. With this contribution, it is demonstrated how the electrical impedance is affected by the temperature both in the olives just harvested and in those processed in brine and provides a new technique for the improvement of the production processes of the “Estilo sevillano” table olives when characterizing cultivars using only electrical impedance, neural networks (NN) and Internet of things (IoT)

The extraction, quantification and application of high-value biological compounds from olive oil processing waste

Olive oil processing waste (pomace) as a by-product of the olive oil industry is regarded as a rich source of high-value biological compounds exhibiting antioxidant potential. The objective of the present work was to obtain a concentrated extract of high-value biological antioxidants from the pomace. The effect of extraction conditions on the concentration of the bioactive compounds in the extracts was investigated. The simultaneous recovery of both hydrophilic and lipophilic high-value biological compounds exhibiting antioxidant potential was achieved through a one-step extraction method under reduced pressure using a non-toxic solvent blend. A multilevel experimental design was implemented with the aim of optimising the recovery of selected compounds, namely, hydroxytyrosol, tyrosol, oleuropein, α-tocopherol and squalene from olive pomace by using solvent blends of n-heptane, d-limonene, ethanol and water. The factors considered were: extraction time, percentage composition of solvent blends and extraction temperature. The results suggested that a good recovery of the hydrophilic polyphenolic compounds, namely, hydroxytyrosol, tyrosol and oleuropein, as well as the lipophilic compounds, α-tocopherol and squalene may be achieved at a solvent temperature of 60°C at 400 mbar with a solvent blend of 30% n-heptane, 50% ethanol and 20% water and an extraction time of two hours. It was found that freeze-drying the pomace before extraction minimised production of artefacts, avoided degradation of biophenols, ensured long term stability of a reproducible sample and achieved better recovery of important hydrophilic and lipophilic bioactive compounds. Since the bioactive compounds are temperature sensitive, the extraction was performed under reduced pressure in order to reduce solvent reflux temperature and to improve extraction efficiency. The quantitative and qualitative determinations of the aforementioned high-value compounds were performed by high-performance liquid chromatography (HPLC), which revealed that the hydrophilic polyphenolic as well as the lipophilic α-tocopherol and squalene were present. In this study hydroxytyrosol, tyrosol, oleuropein, α-tocopherol and squalene were extracted from the pomace of two olive cultivars (Frantoio and Coratina). A comparison among the two cultivars showed quantitative differences between the two cultivars in all five high-value biological compounds and in the antioxidant capacity of the extracts evaluated by measuring the radical scavenging effect on 1,1-diphenyl-2- picrylhydrazyl (DPPH) free radical. Coratina cultivar was found to have a significantly higher antioxidant capacity than Frantoio due to the much greater oleuropein content in the Coratina compared to the Frantoio although Frantoio had a significantly greater amount of hydroxytyrosol. The stability of olive waste extracts stored at four temperatures was also investigated and the results show that increased temperatures caused greater extent of degradation of both the hydrophilic polyphenolic and lipophilic compounds. The proposed optimum storage condition for the olive pomace extracts was found to be at 5°C in the absence of light. The extracts were incorporated into two cosmetic formulations and were found, from a stability study, to be stable at room temperature and optimally stable at 5°C in the absence of light

Desarrollo de nuevos sistemas separativos para la determinación de biomoléculas en matrices vegetales

La presente memoria se enmarca dentro de las líneas de investigación del grupo de investigación, entre las que se encuentran: i) el desarrollo de materiales poliméricos con fines separativos, y ii) la puesta a punto de metodologías analíticas rápidas y fiables para el control de calidad en la industria de aceites vegetales y otros productos de interés agroalimentario. En consecuencia, los objetivos principales de esta Tesis Doctoral son: i) el diseño y optimización de soportes poliméricos modificados con nanopartículas metálicas (tales como el oro y la plata) para la extracción de proteínas en matrices vegetales, ii) la preparación y evaluación de sistemas de extracción de proteínas en dichas muestras asistida por enzimas y iii) el desarrollo de metodologías analíticas de separación rápidas y fiables con el fin de poder establecer el origen genético y botánico de diversos productos alimentarios. La presente memoria de Tesis Doctoral se divide en cuatro grandes bloques. El primer bloque consta de una introducción, donde se describen brevemente las muestras vegetales empleadas en esta Tesis Doctoral (fruto, hoja y aceite de olivo, frutos de la variedad Citrus (en concreto naranjas y mandarinas) y muérdago, correspondientes a los Capítulos 1-3, respectivamente). Además, se incluye una revisión actualizada de los métodos de extracción empleados durante la tesis: extracción en fase sólida (SPE), extracción asistida por enzimas y por último, el empleo de las bibliotecas combinatorias de ligandos peptídicos (CPLLs). El bloque de introducción concluye con una breve descripción de las técnicas analíticas empleadas en el desarrollo de la Tesis Doctoral (Capítulo 5). El segundo bloque (que engloba los capítulos 6-11) está dedicado al desarrollo de nuevas técnicas de extracción de proteínas en matrices de origen vegetal. Para ello, se han puesto a punto nuevos sorbentes, basados en materiales poliméricos sintetizados a partir del metacrilato de glicidilo (GMA), que son posteriormente modificados con nanopartículas metálicas (de oro y plata) para su uso como sorbentes en SPE. Por otro lado, la presencia de sistemas reticulares u organizados, presentes en los vegetales, requiere habitualmente de tratamientos relativamente “agresivos” con el fin de poder extraer los analitos diana. En este sentido, se han llevado a cabo estudios de extracción de proteínas asistidos por enzimas, empleándose tanto enzimas individuales como mezclas de las mismas. Gracias a la acción de estas biomacromoléculas, se facilita la ruptura de las membranas celulares, y por ende la extracción de los analitos para su posterior análisis y cuantificación. Estos pretratamientos de la muestra, sin duda, permitirán obtener resultados de mayor calidad. En este caso, se ha empleado dicha tecnología para la extracción de proteínas de diversos productos del olivo (hojas, huesos y pulpa), así como para muestras de naranja y mandarina, incluyendo tanto la piel como la pulpa de las mismas. Por último, se ha llevado a cabo un estudio del proteoma del muérdago mediante la extracción del mismo empleando las CPLLs, que son capaces de extraer y preconcentrar las proteínas de baja abundancia. La identificación del mapa proteico de esta planta ha permitido profundizar en un mayor conocimiento de sus propiedades medicinales. El tercer bloque (que engloba los capítulos 12-20) muestra el desarrollo de una amplia variedad de métodos de análisis para la determinación de diferentes compuestos en matrices de origen vegetal, tales como aceite de oliva, frutos y hojas de olivo, frutos de la variedad Citrus (naranjas y mandarinas), y muérdago). Dichas metodologías abarcan tanto técnicas de carácter cromatográfico (HPLC) y afines (CZE, CGE y CEC) así como de carácter espectrométrico (ATR-FTIR o DIMS). Se han desarrollado metodologías analíticas para la determinación de proteínas, TAGs, esteroles, ácidos grasos y péptidos. Además, en muchos de los capítulos, se han aplicado herramientas quimiométricas de análisis, en concreto, se han construido modelos de análisis discriminante lineal (LDA), para establecer la clasificación de muestras de aceites vegetales en función de su origen botánica, para la discriminación de productos del olivo, incluyendo aceites de oliva, en función de su variedad genética y en caso de los aceites de oliva, también para clasificarlos en función de su índice de madurez. En algunos de ellos, se ha aplicado la regresión lineal múltiple (MLR) para cuantificar mezclas binarias de diferentes variedades genéticasThis PhD thesis reports the development of novel separation systems to determine biomolecules from complex matrices, especially in vegetal samples. In the first part of this thesis, extraction methodologies were designed to isolate proteins, constituting a significant contribution in the sample preparation field. Thus, the development of novel in-house sorbents based on organic polymers modified with Au and AgNPs for SPE with improved properties, the proper selection of enzyme preparations (either alone or in mixtures) for efficient release of these biomacromolecules from plant cells, and the use of CPLLs to preconcentrate LAPs in complex matrices have been accomplished. Significant enhancements such as large protein extraction yield, tunable selectivity, cost-effective, environmentally friendly and other advantages should place the developed methodologies in a competitive position compared to commercial SPE materials or other traditional extraction methodologies (that imply the use of organic solvents). Another part covered by this thesis was the development of methods for the characterization and determination of several compounds in olive products using different chromatographic and spectrometric techniques. For this purpose, different profiles belong to components present in these matrices, such as proteins, TAGs, sterols and fatty acids were considered. These profiles allowed a discrimination of vegetable oils according to their botanical origin, and also the characterization and authentication of Spanish and Tunisian olive oils in relation to their genetic variety. The proposed methodologies are of utmost interest to assure product quality and to investigate fraudulent practices in food science. In this section of the PhD Thesis, and as required by the aforementioned regulation of the University of Valencia, a summary of the results shown in the successive articles jointly with Sections II and III and the most relevant conclusions of each work is briefly presented here

Mechanical, chemical and biological characterization of olive mill wastewaters

Mestrado em IPB-ESTGA indústria extrativa de azeite é uma atividade económica relevante nos países mediterrânicos. Contudo, do processo de extração resultam caudais volumétricos consideráveis de um efluente residual líquido, designado por águas-ruças (AG) que, se não for devidamente tratado, representa um grande problema de poluição ambiental. A composição físico-química das AG é muito variável, podendo ser caracterizada por uma alta carga orgânica, pH ácido, cheiro intenso a azeite e uma coloração castanho-escura. A alta complexidade orgânica contribui para a sua resistência à biodegradabilidade, causando efeitos ambientais nocivos. Não existe um tratamento padronizado para este resíduo, principalmente por limitações técnicas e económicas, mas as potencialidades para as AG em diversas áreas têm comprovado que podemos, hipoteticamente, transformar este efluente de um problema ambiental numa possível solução para muitos problemas industriais. O principal objetivo deste trabalho consiste na caracterização mecânica, química e das propriedades bioativas das águas-ruças geradas durante a produção de azeite em lagares que utilizam métodos de extração tradicionais e contínuos, determinando as principais diferenças nas características das águas-ruças de diferentes lagares e perceber quais as potencialidades que este fluído pode ter na indústria mecânica. Na caracterização mecânica estudaram-se as propriedades da viscosidade, condutividade térmica, calor específico e molhabilidade. A caracterização química incluiu o teor de água, densidade, composição em ésteres metílicos de ácidos gordos, ácidos gordos livres, índice de acidez, valor de pH, condutividade elétrica, sólidos totais, sólidos suspensos totais, carência química de oxigénio, carência bioquímica de oxigénio e a biodegradabilidade. Os parâmetros de bioatividade analisados foram as propriedades antioxidantes, com os fenóis totais e a captura de radicais DPPH, e as propriedades antimicrobianas foram determinadas pelo método de microdiluição em caldo face a diferentes bactérias Gram-positivo e Gram-negativo. De um modo geral, a caracterização mecânica demonstrou que as águas-ruças são um fluido não-newtoniano, com uma boa molhabilidade com os materiais testados (alumínio, latão, nylon e aço carbónico). As análises químicas mostram que este fluido tem um alto teor de água, com uma densidade semelhante à mesma, uma baixa taxa de biodegradabilidade, um pH ácido em torno de 4,7 e uma acidez que varia, conforme as amostras analisadas, entre 3,2 a 10,6 %. Os resultados biológicos demonstram que as águas ruças possuem um bom poder redutor, e um bom poder inibitório, especialmente contra os micro-organismos gram-negativos Klebsiella pneumoniae e Proteus mirabilis e contra os gram-positivos Enterococcus faecalis e Staphylococcus aureus.The olive oil production industry is a relevant economic activity in Mediterranean countries. However, in the process of extraction it is produced a large amount of an effluent called olive mil wastewaters (OMWW), which represents a large environmental problem. The physicochemical composition of the OMWW is very variable, and can be characterized by a high organic load, acidic pH, intense oily smell, and a dark brown colour. The high-level organic complexity contributes to their biodegradability resistance, causing negative environmental effects. There is not a globally standardised treatment for this residue, mainly due to technical and economically limitations, but the potentialities for the OMWW in various areas have proven that we can hypothetically turn this effluent from an environmental problem into a possible solution to many problems. The main objective of this study is the characterization of the mechanical, chemical, and of the bioactive properties of the wastewaters generated during the olive oil extraction in traditional and 3-phased continuous olive oil mills, analysing the main differences in the characterization of the OMWW from the different mills, and to understand some of the potential applications this fluid may offer in the mechanical industry. On the mechanical characterization were examined the properties of viscosity, thermal conductivity, specific heat, and wettability. The chemical characterization included water content, density, the composition of free fatty acid methyl esters, free fatty acids, acidity, pH value, electric conductivity, total solids, total suspended solids, chemical oxygen demand, biochemical oxygen demand, and biodegradability. The biological parameters analysed were the antioxidant properties, with total phenols and DPPH radicals’ capture, and the antimicrobial properties were determined by the broth microdilution method with Gram-positive and Gram-negative bacteria. In general, the mechanical characterization showed that the olive mill wastewaters have an hydrophilic behavior with the tested materials (aluminum, brass, nylon, and carbon steel). The chemical analysis concluded that this fluid has a high-water content, with a density similar to the water, a low rate of biodegradability, around 29 %, an acid pH of around 4.7, and an acidity that varies, according to the analyzed samples, between 3, 18 to 10.57%. The biological results obtained were satisfactory, with the OMWW showing good reducing power, and good inhibitory power, especially against the gram-negative microorganisms Klebsiella pneumoniae and Proteus mirabilis, and against the gram-positive Enterococcus faecalis e Staphylococcus aureus. Keywords: olive mill wastewaters; mechanical properties; chemical properties, biological properties

Research on Characterization and Processing of Table Olives

Written by experts in the field of table olives, this book is a source of recent research advances on the characterization and processing of table olives. Research papers are provided relating to the characterization of their composition of volatiles and the sensory profile; mineral composition and bioavailability; changes in bioactive components (chlorophylls) by processing; and new strategies to reduce sodium and additives for stabilizing the organoleptic properties and avoiding defects in table olives. Other research papers are included in relation to microbiological and chemical changes in table olives during spontaneous or controlled fermentation employing different cultivars, and the optimized use of starter cultures for the improvement of the different fermentative processes. In addition, this book includes an overview of the main technologies used for olive fermentation, including the role of lactic acid bacteria and yeasts characterizing this process, and of the processing and storage effects on the nutritional and sensory properties of table olives

Safety, Quality and Processing of Fruits and Vegetables

Nowadays, one of the main objectives of the fruit and vegetable industry is to develop innovative novel products with high quality, safety, and optimal nutritional characteristics in order to respond, with efficiency, to increasing consumer expectations. Various unconventional technologies (e.g., pulsed electric field, pulsed light, ultrasound, high pressure, and microwave drying) have emerged and enable the processing of fruits and vegetables in a way that increases their stability while preserving their thermolabile nutrients, flavour, texture, and overall quality. Some of these technologies can also be used for waste and byproduct valorisation. The application of fast noninvasive methods for process control is of great importance for the fruit and vegetable industry. The following Special Issue “Safety, Quality, and Processing of Fruits and Vegetables” consists of 11 papers which represent a high-value contribution to the existing knowledge on safety aspects, quality evaluation, and emerging processing technologies for fruits and vegetables

HydroSOStainable Table Olives and Olive Oil: Quality, Functionality and Acceptance in the European Market

Programa de Doctorado en Recursos y Tecnologías Agrarias, Agroambientales y AlimentariasOlive oil and table olives demand has been continuously increasing during the last decades due to their acclaimed health benefits, so, in order to increase productivity, the area under olive groves has increased and irrigation was implemented to enhance productivity. Nowadays, one of the main world challenges is the scarcity of water resources, and, given that agriculture is one of the most water demanding sectors it is important to develop water saving techniques to face this problem. When plants suffer water restrictions, the stress induced on its system can lead to an increased production of some functional and nutritional components. Based on that fact, the main hypothesis of this Doctoral thesis is that “The implementation of deficit irrigation strategies during different phenological stages of olive trees leads to the increase on functional and nutritional properties of table olives and olive oil”. These fruits were labelled as HydroSOStainable. For that purpose, “Manzanilla” raw and table olives after Spanish- style processing and “Arbequina” olive oil from water saving techniques had been studied (morphological, functional, nutritional and sensory characteristics). Concerning “Manzanilla” olives, two experiments were carried out: Experiment A was run in olive trees located in Sevilla, in Dos Hermanas (Spain), irrigation deficit strategies with different stress levels were applied during the pit hardening stage (stage II). Main results of these experiments indicated that saving water techniques applied during stage II made rounder, harder, lighter and greener olives than full irrigation. Minerals, antioxidants, total phenols, organic acids and sugars did not show statistical differences with the full irrigated olives. Polyphenolic profile was affected by water saving techniques and a moderate stress was the one producing the biggest changes as it increased the concentration of oleoside, elenoic acid glucoside, oleoside diglucoside, oleuropein and comselogoside, while the concentration of some polyphenols was decreased at higher stress levels. Regarding volatile composition and sensory analysis, some compounds were affected; esters were reduced with the stress while terpenes increased. Alcohols and phenolic compounds also increased on some samples. These changes affected the descriptive sensory analysis, hydroSOStainable table olives presented modified intensity of some attributes such as green-olive flavor, sourness, aftertaste, bitterness or crunchiness. Consumers did not perceive relevant differences among samples, except when olives were labelled with the HydroSOStainable logo. Those were the preferred table olives, and consumers were willing to pay higher prices for them. Finally, phenols bioaccessibility was not affected by the application of water saving techniques. Experiment B was run in olive trees located in Sevilla as well, in Coria del Río (Spain). Water deficit with different stress levels was applied during rehydration stage, just before harvest (stage III). In this experiment, hydroSOStainable olives presented a slight smaller size than control but the pulp:pit proportion was maintained. Antioxidant activity, total phenolic content and monounsaturated fatty acid (MUFA) content were highest with the highest water stress. Regarding the polyphenolic profile, hydroSOStainable table olives presented higher concentration of some polyphenols than control, such as luteolin-3-O-rutinoside, oleoside diglucoside, comselogoside, elenoic acid glucoside, dihydro-oleuropein and oleuropein. Finally, phenol bioaccessibility was not affected by the water stress. With respect to “Arbequina” olive oil, also two experiments took place: Experiment C: olive trees were located in Sevilla, in Carmona (Spain). Water restrictions were applied during pit hardening stage and one of the treatments was applied during the whole season. HydroSOStainable olive oils from Experiment C were classified as extra virgin olive oil (EVOO) and at moderate stress level applied during pit hardening the total phenolic content was increased, as well as oleic acid increase ~ 3.5 % of concentration and decreased the saturated fatty acids (SFAs). Some volatile compounds and sensory attributes also increased their concentration and intensity, respectively. Experiment D: olive trees were located in Ciudad Real (Spain), and the water saving techniques were applied during pit hardening stage. HydroSOStainable olive oils also were classified as EVOO and showed increased antioxidant activity and total phenolic content. These olive oils also improved the fatty acid profile as increased the MUFAs and decreased the SFAs. Volatile compounds and sensory descriptors were more balanced than in control oilLa demanda de aceite de olive y aceitunas de mesa ha sufrido un incremento durante las últimas décadas debido a los aclamados beneficios que aporta su consumo para la salud, por lo que su producción se ha visto incrementada y el cultivo del olivo se ha introducido en el regadío para poder incrementar su productividad. Como uno de los principales retos a los que nos enfrentamos hoy en día está la falta de recursos hídricos, siendo la agricultura uno de sus principales consumidores, por lo que es muy importante desarrollar técnicas de ahorro de agua en el campo para poder afrontar este problema. Al aplicar restricciones hídricas a las plantas, se produce un estrés en sus sistemas que puede derivar en un incremento en algunos de sus compuestos nutricionales y funcionales, por lo que la principal hipótesis de esta tesis doctoral es el incremento de las propiedades funcionales y nutricionales de las aceitunas de mesa y aceite de oliva procedentes de cultivos con estrategias de riego deficitario que se aplican durante diferentes estados fenológicos de crecimiento de las aceitunas. Estas aceitunas se han llamado HydroSOStenibles. Para llevarla a cabo, se han analizado aceitunas crudas y aderezadas siguiendo el estilo español de la variedad “Manzanilla” y aceites de oliva de la variedad “Arbequina” que proceden de estrategias de riego deficitario (características morfológicas, funcionales, nutricionales y sensoriales). Con respecto a las aceitunas “Manzanilla”, se han llevado a cabo dos experimentos: Experimento A: los olivos se sitúan en Sevilla, en Dos Hermanas (España). Las técnicas de riego deficitario, con diferentes niveles de estrés, se aplicaron durante la fase de endurecimiento del hueso (estadío II). Los principales resultados de este experimento indicaron que las estrategias de riego deficitario aplicadas durante el estadío II dieron aceitunas más redondas, duras, luminosas y verdes, lo que las hace más atractivas para los consumidores. Los minerales, antioxidantes, fenoles totales, ácidos orgánicos y azúcares no sufrieron cambios, mientras que el perfil polifenólico sí se vio afectado por el riego deficitario: con un estrés moderado se incrementó la concentración de oleósido, glucósido de ácido elenócio, diglucósido oleosido, oleuropeína y comselogósido mientras que un mayor estrés produjo el descenso de concentración de algunos polifenoles. Con respecto a los compuestos volátiles y el análisis sensorial, algunos compuestos se vieron afectados; los ésteres se redujeron con el estrés, mientras que los terpenos aumentaron. Los alcoholes y compuestos fenólicos aumentaron en algunas muestras. Estos cambios produjeron cambios en las intensidades de algunos atributos sensoriales como el aroma verde-aceituna, la acidez, el postgusto, el amargor o la crujibilidad. Los consumidores no percibieron estas diferencias entre muestras, pero al ser sometidos al efecto del logo, prefirieron las aceitunas de mesa hidroSOStenibles e indicaron que estaban dispuestos a pagar más por ellas. Por último, la bioaccesibilidad de fenoles no se vio afectada por las estrategias de riego deficitario. Experimento B: los olivos se sitúan en Sevilla también, concretamente en Coria del Río (España). Las estrategias de riego deficitario se llevaron a cabo durante la fase de rehidratación, justo antes de la cosecha (estadío III). Se aplicaron tratamientos con diferentes niveles de estrés. En este experimento, las aceitunas hidroSOStenibles fueron más pequeñas que el control, pero se mantuvo la proporción de pulpa. La actividad antioxidante, el contenido total de polifenoles y los ácidos grasos monoinsaturados aumentaron según aumentó el estrés hídrico. Con respecto al perfil polifenólico, las aceitunas hidroSOStenibles presentaron una mayor concentración de algunos polifenoles como la luteolina-3-O- rutinosido, diglucósido oleósido, comselogósido, glucósido de ácido elenoico, dihidro-oleuropeína y oleuropeína. Finalmente, la bioaccesibilidad de fenoles totales no se vio afectada por el riego deficitario.Los aceites de oliva de la variedad “Arbequina” también se dividen en dos experimentos: Experimento C: los olivos se sitúan en Sevilla, en la localidad de Carmona (España). Las restricciones se aplicaron durante la fase II y en uno de los tratamientos durante toda la temporada. Los aceites hidroSOStenibles se clasificaron como aceite de oliva virgen extra (AOVE) y, con un estrés moderado durante el endurecimiento del hueso, aumentó el contenido total de fenoles y la concentración de ácido oleico (~ 3.5 %). También disminuyó la concentración de ácidos grasos saturados (AGSs). Algunos compuestos volátiles y atributos sensoriales también aumentaron sus concentraciones e intensidades respectivamente. Experimento D: los olivos se sitúan en Ciudad Real (España). El riego deficitario se aplicó durante el endurecimiento del hueso. Los aceites de este experimento se clasificaron como AOVE. Se produjo un aumento de la actividad antioxidante y contenido total de polifenoles con el estrés hídrico. Se mejoró el perfil de ácidos grasos, ya que aumentó el contenido de ácidos grasos monoinsaturados y disminuyó el de saturados. Los compuestos volátiles y atributos sensoriales fueron más equilibrados que en el contro

Antioxidant Activity of Polyphenolic Plant Extracts

“Antioxidant Activity of Polyphenolic Plant Extracts” is a collection of scientific articles regarding polyphenols, that is, substances occurring naturally in plants and exhibiting many beneficial effects on human health. Among polyphenols’ interesting biological properties, their antioxidant activity is considered the most important. This book brings together experts from different research fields on topics related to polyphenols, such as their isolation and purification, assessment of their antioxidant activity, prevention from oxidative stress-induced diseases and use as food additives. The polyphenols used in the present studies are derived from a great variety of plants, ranging from well-known species to rare ones that are only found in specific regions. Moreover, some of the studies provide evidence that polyphenols may be used for the prevention and treatment of common diseases such as diabetes mellitus, Alzheimers’ disease, cardiovascular and intestinal diseases. Importantly, in several of the studies “green extraction methods” for the isolation of polyphenols were developed using modern technologies, where few or no organic solvents were used, in order to minimize environmental and health impacts