New olive-pomace fertilizer tested with a 2-tiers approach: Biomarkers on Eisenia fetida, physiochemical effects on Solanum lycopersicum and Olea europaea

Every year, the olive oil industry generates a substantial amount of pomace, a semi-solid residue made up of skin, pulp, pit, and kernel fragments. Rather than being disposed of, the pomace can be dried and transported to an extraction facility where pomace oil can be extracted. Utilizing its high thermal capacity, the extracted pomace can be used as a supplementary fuel in the drying process, resulting in the production of ashes. In this study, the effect of pomace waste applied to the soil was investigated by testing two mixtures with different proportions of de-oiled pomace flour and kernel ash (50:50 and 70:30, respectively) in powder and pellet form. We used a dual approach, evaluating the effects of the mixtures on both soil communities and plant physiology and productivity, to assess the actual usability of the fertilizer in agriculture. The biomarker approach was valuable in assessing the sublethal effects of the two mixtures in powder form in soil. After 30 days of exposure, the bioindicator organism Eisena fetida showed lipid peroxidation, glutathione S-transferase and lactate dehydrogenase levels similar to the control, while lysozyme activity was reduced in all treatments. The powder mixture was lethal to the tomato plants, while there was no evidence of any damage to the olive trees. During 60 days of monitoring, both mixtures in pellet form showed a slight increase in physiological parameters, suggesting a benefit to the photosynthetic system. The improved carbon assimilation in tomato plants treated with the mixtures results in increased plant productivity, both in terms of number and weight of fruits, while maintaining the antioxidant content. This study paves the way for the use of the pomace mixture as a soil improver, thus increasing the value of this waste product.

Olive Leaf Extracts from Three Italian Olive Cultivars Exposed to Drought Stress Differentially Protect Cells against Oxidative Stress

Olive leaves are an abundant by-product of olive oil production. Olive leaf extracts (OLEs) are rich in polyphenols, which can be used for health benefits. As polyphenols are the main antioxidant molecules in plants, plants typically increase their polyphenol content when exposed to drought stress. However, the phenolic profile of OLEs can vary in relation to the origin and variety of the plant material. In this work, olive leaf extracts from three different Italian olive cultivars (Giarraffa, Leccino, and Maurino) both exposed and not exposed to drought stress were studied in terms of antioxidant properties and profile, intestinal permeation, and protection against oxidative stress of human umbilical vein endothelial cells (HUVECs), since HUVECs are considered a model to study a wide range of diseases. OLEs from stressed Maurino and Giarraffa plants showed the highest increase in antioxidant capacity compared to controls. The phenolic profile of Maurino' was mainly increased by water deficit, with a large increase in the compounds oleuropein and luteolin-7-O-rutinoside. All tested extracts exposed to a water deficit protected HUVECs against oxidative stress by reducing ROS production, and this effect was more pronounced in OLEs from Giarraffa and Maurino exposed to drought stress compared to all other extracts. Finally, OLE from the stressed Giarraffa group showed a higher apparent permeability of antioxidant molecules than that of Maurino.

Pasta Enriched with Carrot and Olive Leaf Flour Retains High Levels of Accessible Bioactives after In Vitro Digestion

The aim of this research was to evaluate the levels of antioxidants and polyphenols in pasta enriched with either carrot or olive leaf flours after simulating gastrointestinal digestion. Pasta samples were prepared with fixed amounts of carrot and olive leaf flours (15% and 6% of the total mixture, respectively). We measured the antioxidant capacity and polyphenol content at different stages of the pasta production process, starting from the initial flour to the cooked pasta, and tested samples of the liquid component and solid waste resulting from the digestion process. The antioxidant activity was measured by the FRAP method, while the polyphenol content was measured by the Folin-Ciocalteu method. Vitamin E contents were measured by HPLC. The pasta enriched with carrot (1.26 ± 0.05 mmol/100 g) and olive leaf (2.9 ± 0.07 mmol/100 g) exhibited higher antioxidant power compared to the unenriched pasta (0.8 ± 0.1 mmol/100 g). The polyphenol content followed a similar trend, with values of 131.23 ± 3.08 for olive flour-enriched pasta, 79.15 ± 1.11 for carrot flour-enriched pasta, and 67.5 ± 1.39 for the wheat-only pasta. The pasta samples maintained their antioxidant and polyphenol levels even after undergoing the simulated digestion process. Significantly, the liquid component of the pasta with olive leaf flours had the highest levels of antioxidants and polyphenols during all stages of the digestion process. According to the results of this study, pasta enriched with carrot and olive leaf flours shows promising potential for improving nutritional and functional properties by increasing antioxidant and polyphenol content. The samples were also evaluated by a sensory panel, which showed that fortification modified the perception of some organoleptic attributes without affecting the overall taste of the pasta.

Tomato Biodiversity and Drought Tolerance: A Multilevel Review

Ongoing global climate change suggests that crops will be exposed to environmental stresses that may affect their productivity, leading to possible global food shortages. Among these stresses, drought is the most important contributor to yield loss in global agriculture. Drought stress negatively affects various physiological, genetic, biochemical, and morphological characteristics of plants. Drought also causes pollen sterility and affects flower development, resulting in reduced seed production and fruit quality. Tomato (Solanum lycopersicum L.) is one of the most economically important crops in different parts of the world, including the Mediterranean region, and it is known that drought limits crop productivity, with economic consequences. Many different tomato cultivars are currently cultivated, and they differ in terms of genetic, biochemical, and physiological traits; as such, they represent a reservoir of potential candidates for coping with drought stress. This review aims to summarize the contribution of specific physio-molecular traits to drought tolerance and how they vary among tomato cultivars. At the genetic and proteomic level, genes encoding osmotins, dehydrins, aquaporins, and MAP kinases seem to improve the drought tolerance of tomato varieties. Genes encoding ROS-scavenging enzymes and chaperone proteins are also critical. In addition, proteins involved in sucrose and CO₂ metabolism may increase tolerance. At the physiological level, plants improve drought tolerance by adjusting photosynthesis, modulating ABA, and pigment levels, and altering sugar metabolism. As a result, we underline that drought tolerance depends on the interaction of several mechanisms operating at different levels. Therefore, the selection of drought-tolerant cultivars must consider all these characteristics. In addition, we underline that cultivars may exhibit distinct, albeit overlapping, multilevel responses that allow differentiation of individual cultivars. Consequently, this review highlights the importance of tomato biodiversity for an efficient response to drought and for preserving fruit quality levels.

Distinct Tomato Cultivars Are Characterized by a Differential Pattern of Biochemical Responses to Drought Stress

Future climate scenarios suggest that crop plants will experience environmental changes capable of affecting their productivity. Among the most harmful environmental stresses is drought, defined as a total or partial lack of water availability. It is essential to study and understand both the damage caused by drought on crop plants and the mechanisms implemented to tolerate the stress. In this study, we focused on four cultivars of tomato, an economically important crop in the Mediterranean basin. We investigated the biochemical mechanisms of plant defense against drought by focusing on proteins specifically involved in this stress, such as osmotin, dehydrin, and aquaporin, and on proteins involved in the general stress response, such as HSP70 and cyclophilins. Since sugars are also known to act as osmoprotectants in plant cells, proteins involved in sugar metabolism (such as RuBisCO and sucrose synthase) were also analyzed. The results show crucial differences in biochemical behavior among the selected cultivars and highlight that the most tolerant tomato cultivars adopt quite specific biochemical strategies such as different accumulations of aquaporins and osmotins. The data set also suggests that RuBisCO isoforms and aquaporins can be used as markers of tolerance/susceptibility to drought stress and be used to select tomato cultivars within breeding programs.

Effects of Drying Methods and Temperatures on the Quality of Chestnut Flours

The demand for chestnut flour is growing because of its use in gluten-free products. Previous studies have correlated the quality of chestnut flours to the drying temperature and technology applied. This work is a novel study on the role of the traditional drying method with a wood fire in a “metato” building for flour compared with a food dryer at 40 °C or 70 °C. The contents of antioxidants, total polyphenols and sugars were determined as well as the presence of toxic volatiles or aflatoxins. The flour, resulting from the traditional method, presented lower polyphenol content and antioxidant power compared to the others. The content of the sugars was similar to the flours obtained after drying with hot air, both at 40 °C and 70 °C. The toxic volatile molecules, furfural, guaiacol, and o-cresol, were found. There was no correlation between the aflatoxin content and the presence of damage in chestnut fruits. The traditional method should not be abandoned since it confers a pleasant smoky taste to the product, but it is necessary to regulate the level and steadiness of temperature. Future research needs to be directed to the quantification of harmful volatile compounds and their correlation with the quantity of smoke emitted by the wood fire.

Cocoa Bar Antioxidant Profile Enrichment with Underutilized Apples Varieties

The impact of dried apples (Malus × domestica Borkh.) addition on improving the antioxidant characteristics of dark chocolate was evaluated. The antioxidant activity was measured through DPPH scavenging activity and showed an increase in the cocoa bar with ‘Nesta’ dry apple (17.3% vs. 46.8%) in comparison to cocoa mass. The 15 polyphenols analyzed by UHPLC-ESI-MS/MS indicated great variability among the apple varieties. Quercetin was detected in the highest concentrations (ranged from 753.3 to 1915.5 µg g−1), while the lowest were for kaempferol 7-O-glucoside, measured only in ‘Mora’ and ‘Nesta’ cocoa bars (from 0.034 to 0.069 µg g−1, respectively). P-coumaric acid, trans-ferulic acid, and chlorogenic acid contribute largely to the antioxidant activity in cocoa bars. Principal component analysis shows that a cocoa bar with the addition of ‘Nesta’ dry apple differ from others due to its higher content of polyphenols (1614 ± 61.8 mg gallic acid equivalents per 100 g). In conclusion, data confirm that cocoa bars with dry apples might be considered as a polyphenol-enriched food.

Italian Tomato Cultivars under Drought Stress Show Different Content of Bioactives in Pulp and Peel of Fruits

Background: This study aims to evaluate the performance, in terms of accumulation of antioxidant compounds in fruits, of nine local and three commercial Italian tomato cultivars subjected to drought stress. The same local cultivars had been previously studied at morpho-physiological level. Methods: The present manuscript analyzes drought stress as a tool to increase the amount of secondary metabolites that can enhance fruit quality. Nutraceutical characterization of the fruits was performed by analyzing the content of antioxidants, phenols, flavonoids, lycopene, ascorbic acid (vitamin C), rutin, caffeic acid, and naringenin. At the same time, plant sensitivity to stress during the reproductive phase was monitored in terms of flower abscission, fruit drop, and seed germination. Results: Perina turns out to be the tomato cultivar with the best nutraceutical properties in the absence of stress while the Quarantino cultivar is so for flavonoid content (control plants) and lycopene and vitamin C content (stressed plants). Perina and Quarantino are the cultivars with the best response to drought and Perina has the highest concentrations of bioactives. Quarantino responds most effectively to stress in the reproductive phase. Conclusions: data confirm that drought stress increases bioactive production in some local cultivars of tomato, which produce higher quality fruits.

Olive Varieties under UV-B Stress Show Distinct Responses in Terms of Antioxidant Machinery and Isoform/Activity of RubisCO

In recent decades, atmospheric pollution led to a progressive reduction of the ozone layer with a consequent increase in UV-B radiation. Despite the high adaptation of olive trees to the Mediterranean environment, the progressive increase of UV-B radiation is a risk factor for olive tree cultivation. It is therefore necessary to understand how high levels of UV-B radiation affect olive plants and to identify olive varieties which are better adapted. In this study we analyzed two Italian olive varieties subjected to chronic UV-B stress. We focused on the effects of UV-B radiation on RubisCO, in terms of quantity, enzymatic activity and isoform composition. In addition, we also analyzed changes in the activity of antioxidant enzymes (SOD, CAT, GPox) to get a comprehensive picture of the antioxidant system. We also evaluated the effects of UV-B on the enzyme sucrose synthase. The overall damage at biochemical level was also assessed by analyzing changes in Hsp70, a protein triggered under stress conditions. The results of this work indicate that the varieties (Giarraffa and Olivastra Seggianese) differ significantly in the use of specific antioxidant defense systems, as well as in the activity and isoform composition of RubisCO. Combined with a different use of sucrose synthase, the overall picture shows that Giarraffa optimized the use of GPox and opted for a targeted choice of RubisCO isoforms, in addition to managing the content of sucrose synthase, thereby saving energy during critical stress points.

Morpho-Physiological Classification of Italian Tomato Cultivars (Solanum lycopersicum L.) According to Drought Tolerance during Vegetative and Reproductive Growth

Irrigation is fundamental for agriculture but, as climate change becomes more persistent, there is a need to conserve water and use it more efficiently. It is therefore crucial to identify cultivars that can tolerate drought. For economically relevant crops, such as tomatoes, this purpose takes on an even more incisive role and local agrobiodiversity is a large genetic reservoir of promising cultivars. In this study, nine local Italian cultivars of tomatoes plus four widely used commercial cultivars were considered. These experienced about 20 d of drought, either at vegetative or reproductive phase. Various physio-morphological parameters were monitored, such as stomatal conductance (gs), photosynthesis (A), water use efficiency (WUE), growth (GI) and soil water content (SWC). The different responses and behaviors allowed to divide the cultivars into three groups: tolerant, susceptible, and intermediate. The classification was also confirmed by a principal component analysis (PCA). The study, in addition to deepening the knowledge of local Italian tomato cultivars, reveals how some cultivars perform better under stress condition than commercial ones. Moreover, the different behavior depends on the genotype and on the growth phase of plants. In fact, the Perina cultivar is the most tolerant during vegetative growth while the Quarantino cultivar is mostly tolerant at reproductive stage. The results suggest that selection of cultivars could lead to a more sustainable agriculture and less wasteful irrigation plans.

Molecular investigation of Tuscan sweet cherries sampled over three years: gene expression analysis coupled to metabolomics and proteomics

Sweet cherry (Prunus avium L.) is a stone fruit widely consumed and appreciated for its organoleptic properties, as well as its nutraceutical potential. We here investigated the characteristics of six non-commercial Tuscan varieties of sweet cherry maintained at the Regional Germplasm Bank of the CNR-IBE in Follonica (Italy) and sampled ca. 60 days post-anthesis over three consecutive years (2016-2017-2018). We adopted an approach merging genotyping and targeted gene expression profiling with metabolomics. To complement the data, a study of the soluble proteomes was also performed on two varieties showing the highest content of flavonoids. Metabolomics identified the presence of flavanols and proanthocyanidins in highest abundance in the varieties Morellona and Crognola, while gene expression revealed that some differences were present in genes involved in the phenylpropanoid pathway during the 3 years and among the varieties. Finally, proteomics on Morellona and Crognola showed variations in proteins involved in stress response, primary metabolism and cell wall expansion. To the best of our knowledge, this is the first multi-pronged study focused on Tuscan sweet cherry varieties providing insights into the differential abundance of genes, proteins and metabolites.

Chronic heat stress affects the photosynthetic apparatus of Solanum lycopersicum L. cv Micro-Tom

Tomato (Solanum lycopersicum L.) is one of the most widely cultivated crops in the world. Tomato is a plant model and the relationship between yield and biotic/abiotic stress has attracted increasing scientific interest. Tomato cultivation under sub-optimal conditions usually negatively impacts growth and development; in particular, heat stress affects several cellular and metabolic processes, such as respiration and photosynthesis. In this work, we studied the effects of chronic heat stress on various cytological and biochemical aspects using the Micro-Tom cultivar as a model. Photosynthetic efficiency decreased during heat stress while levels of post-photosynthetic sugars (sucrose, fructose, glucose and glucose 6-phosphate) oscillated during stress. Similarly, photosynthetic pigments (lutein, chlorophyll a, chlorophyll b and β-carotene) showed an oscillating downward trend with partial recovery during the stress-free phase. The energetic capacity of leaves (e.g. ATP and ADP) was altered, as well as the reactive oxygen species (ROS) profile; the latter increased during stress. Important effects were also found on the accumulation of Rubisco isoforms, which decreased in number. Heat stress also resulted in a decreased accumulation of lipids (oleic and linoleic acid). Photosynthetically alterations were accompanied by cytological changes in leaf structure, particularly in the number of lipid bodies and starch granules. Prolonged heat stress progressively compromised the photosynthetic efficiency of tomato leaves. The present study reports multi-approach information on metabolic and photosynthetic injuries and responses of tomato plants to chronic heat stress, highlighting the plant's ability to adapt to stress.

Drought Stress Affects the Response of Italian Local Tomato (Solanum lycopersicum L.) Varieties in a Genotype-Dependent Manner

Drought stress is one of the most severe conditions for plants, especially in the face of the emerging problem of global warming. This issue is important when considering economically relevant crops, including the tomato. For these plants, a promising solution is the valorization of local agrobiodiversity as a source of genetic variability. In this paper we investigated how six Italian tomato varieties react to a prolonged period of water depletion. We used a multidisciplinary approach, from genetics to plant physiology and cytology, to provide a detailed overview of the response of plants to stress. The varieties analyzed, each characterized by a specific genetic profile, showed a genotype-specific response with the variety 'Fragola' being the most resistant and the variety 'Pisanello' the most susceptible. For all the parameters evaluated, 'Fragola' performed in a manner comparable to that of control plants. On the contrary, 'Pisanello' appeared to be more affected and showed an increase in the number of stomata and a drastic increase in antioxidants, a symptom of acute oxidative stress. Our work suggests the existence of a valuable reservoir of genetic biodiversity with more drought-tolerant tomato genotypes opening the way to further exploitation and use of local germplasm in breeding programs.

Nutraceutical Characteristics of Ancient Malus x domestica Borkh. Fruits Recovered across Siena in Tuscany

Background: A diet rich in fruits and vegetables contributes to lowering the risk of chronic diseases. The fruits of Malus x domestica are a rich dietary source of bioactive compounds, namely vitamins and antioxidants, with recognized action on human health protection. Tuscany is known for its rich plant biodiversity, especially represented by ancient varieties of fruit trees. Particularly noteworthy are the many ancient Tuscan varieties of apple trees. Methods: Sugar quantification via HPLC and spectrophotometric assays to quantify the antioxidant power and total polyphenol content revealed interesting differences in 17 old varieties of Malus x domestica Borkh. recovered in Siena (Tuscany). Results: The quantification of antioxidants, polyphenols, and the main free sugars revealed that their content in the old fruits was often superior to the widespread commercial counterparts ('Red Delicious' and 'Golden Delicious'). Such differences were, in certain cases, dramatic, with 8-fold higher values. Differences were also present for sugars and fibers (pectin). Most ancient fruits displayed low values of glucose and high contents of xylitol and pectin. Conclusions: The results reported here suggest the possible use of ancient apple varieties from Siena for nutraceutical purposes and draw attention to the valorization of local old varieties.

Agrobiotechnology Goes Wild: Ancient Local Varieties as Sources of Bioactives

The identification and use of species that have best adapted to their growth territory is of paramount importance to preserve biodiversity while promoting sustainable agricultural practices. Parameters including resistance to natural conditions (biotic and abiotic risk factors), biomass and fruit productivity, and phytochemical content with nutraceutical potential, could be used as quantitative markers of the adaptability of plants to wild environments characterized by minimal human impact. Ancient varieties, which are plant varieties growing in regional territories and not destined for market distribution, are a source of unique genetic characters derived from many years of adaptation to the original territory. These plants are often more resistant to biotic and abiotic stresses. In addition, these varieties have a high phytochemical (also known as bioactives) content considered health-beneficial. Notably, the content of these compounds is often lower in commercial cultivars. The use of selected territorial varieties according to the cultivation area represents an opportunity in the agricultural sector in terms of biodiversity preservation, environmental sustainability, and valorization of the final products. Our survey highlights the nutraceutical potential of ancient local varieties and stresses the importance of holistic studies (-omics) to investigate their physiology and secondary metabolism.

Functional Molecules in Locally-Adapted Crops: The Case Study of Tomatoes, Onions, and Sweet Cherry Fruits From Tuscany in Italy

The human diet is characterized by highly energetic molecules, but it also requires non-energetic compounds that are equally useful for cell functioning and for preserving the organism's health status. These "functional" molecules are represented by a wide variety of plant secondary metabolites, such as terpenoids, vitamins and polyphenols with antioxidant power. Widespread commercial crop varieties often contain scarce levels of functional molecules, because they have been mostly selected for productivity, rather than for the content of secondary metabolites. Different scenarios (global economic situation, foreseeable environmental changes) are pushing farmers to review the use of high yield crops and to focus on the valorization of locally-adapted plants. This renewed interest is strengthened by the growing need of consumers for functional foods with beneficial effects on human health and by the willingness to promote sustainable low-input agricultural practices exploiting local climate, soil, water, and (micro)biota. Here, we want to discuss a specific case study concerning locally-adapted crops in Tuscany (Italy). Analyses of nutraceutical molecules in locally-grown crop varieties (namely tomatoes, sweet cherries and onions) have shown that they are characterized by substantially higher functional molecule contents than commercial varieties. Our goal is to promote the high-throughput study of locally-adapted varieties to understand, in a medium-term perspective, whether the cultivation of such plants is a valuable support for the diet and an adequate local economic resource. Such plants can provide a boost to the regional economy, by diversifying the local crop-market landscape. Moreover, the exploitation of locally-grown plants results in the manufacture of fully-traceable products (from the raw bioresource to the finished product) with a "0 km" concept that minimizes the C footprint.

Sensory profiling and consumer acceptability of new dark cocoa bars containing Tuscan autochthonous food products

A new set of cocoa bars named Toscolata^® were developed containing top‐quality extra virgin olive oil, dried apples cultivars, and chestnut flour. The present work has been conducted to define the sensory profile of these products through tasting by trained experts and consumers to study the acceptability, preference, and quality perception. The four sensorial profiles of the bars differed in the level of persistence, bitterness, aromaticity, acidity, astringency, and tastiness. In particular, the sour attribute could be traced to the presence of dried apple. Bars containing apple and chestnut flour obtained higher acceptance ratings, compared to those with extra virgin olive oil. The bar with chestnut flour was preferred by consumers who considered it to be sweeter due to the presence of natural sugars, which lowered the bitter sensation of cocoa. These results showed that the selection of the preferred bar by consumers was mainly based on the level of bitterness and, in particular, elderly consumers expressed a strong preference for the sweetest product. As far as we know, this is the first study comparing the results of a panel of expert tasters with that of consumers in the tasting of dark chocolate.

Impact of Raw and Bioaugmented Olive-Mill Wastewater and Olive-Mill Solid Waste on the Content of Photosynthetic Molecules in Tobacco Plants

Disposal and reuse of olive-mill wastes are both an economic and environmental problem, especially in countries where the cultivation of olive trees is extensive. Microorganism-based bioaugmentation can be used to reduce the pollutant capacity of wastes. In this work, bioaugmentation was used to reduce the polyphenolic content of both liquid and solid wastes. After processing, bioaugmented wastes were tested on the root development of maize seeds and on photosynthesis-related molecules of tobacco plants. In maize, we found that bioaugmentation made olive-mill wastes harmless for seed germination. In tobacco, we analyzed the content of RuBisCO (ribulose-1,5-bisphosphate carboxylase oxygenase) and of the photosynthetic pigments lutein, chlorophylls, and β-carotene. Levels of RuBisCO were negatively affected by untreated wastewater but increased if plants were treated with bioaugmented wastewater. On the contrary, levels of RuBisCO increased in the case of plants treated with raw olive-mill solid waste. Pigment levels showed dissimilar behavior because their concentration increased if plants were irrigated with raw wastewater or treated with raw olive-mill solid waste. Treatment with bioaugmented wastes restored pigment content. Findings show that untreated wastes are potentially toxic at the commencement of treatment, but plants can eventually adapt after an initial stress period. Bioaugmented wastes do not induce immediate damages, and plants rapidly recover optimal levels of photosynthetic molecules.