Pod Morphology, Primary and Secondary Metabolite Profiles in Non-grafted and Grafted Carob Germplasm Are Configured by Agro-Environmental Zone, Genotype, and Growing Season

Sugars and phenols in carob tree fruits from different producing countries: A short review

In the last two decades, important advances have been made in the chemical analysis of the fruit of carob tree. After harvesting, the fruits (also known as dry pods) are ground. The seeds can then be separated from the pulp, which represents 80-90 % of a pod's weight. The health benefits of carob pulp derivatives are well-recognized, and carob pulp-based food products are becoming increasingly available to consumers. The major carob-producing countries are in southern Europe and northern Africa, including the Mediterranean islands, and carob pulp products are normally prepared and consumed regionally. In this review, we compare the sugar and phenol profiles of carob pods harvested from different countries in the Mediterranean basin while accounting for the different cultivars and soil conditions in each sample area. We conclude that pod nutritional composition varies widely among countries, making it necessary for future, multi-year studies to more closely evaluate how climate and soil properties affect the phenol and sugar contents of fruits from the same trees or cultivars.

Assessing the biodiversity and the impact of pollinators on carob production

As the current climate crisis intensifies, drought resistant crops are becoming more important due to their ability to withstand the increasingly hotter and drier summers. Such crops are valuable for pollinators as they provide food resources for wild and managed species. The carob tree (Ceratonia siliqua L.) represents an example of a heat- and drought- resistant crop, able to grow in dry areas with practically no inputs. The current study assessed over two growing seasons the diversity of wild bees and other pollinators relying on carob flowers, as well as the contribution of animal pollination to carob production. Carob flowers were subjected to two treatments: Open pollination, where inflorescences were left untreated, and wind pollination, where inflorescences were bagged in a mesh during blooming. Weekly observations during blooming showed that Apis mellifera was the most frequent floral visitor followed by wild bees and wasps. Carob flowers were visited by at least 10 different wild bee species. Open-pollinated flowers produced significantly more pods, with the benefit ranging from 4 to 16 times higher production, depending on the region. Open pollination led to pods with greater weight, length and number of seeds compared to pods derived from wind pollination. The results of the current study highlight the importance of animal pollination to carob production, as well as the significance of carob trees to wild bee conservation.

Aridity Gradients Shape Intraspecific Variability of Morphological Traits in Native Ceratonia siliqua L. of Morocco

The carob tree (Ceratonia siliqua L.) is a significant fruit tree in the Mediterranean region with cultural, biological, and ecological importance. Despite its importance, intraspecific trait variability (ITV) in carob trees has been largely overlooked in previous studies. Understanding ITV and its relationship with environmental conditions is crucial for conservation and breeding programs. In this study, we investigated the variability of carob pod and seed-related traits across different ecological scales in 25 studied populations in Morocco. Significant differences in morphological traits were observed between carob populations at various ecological levels, and pod-related traits exhibited greater variability than seed traits. Correlation analysis revealed strong associations between carob morphological traits and environmental conditions, with altitude and aridity index playing an influential role. The aridity gradient was strongly related to changes in pod size, seed number, and size, as well as seed yield. Our findings highlight an important ITV reaching 45% at the intra-population level, 36.5% at the inter-geographic level, and 30% at the inter-population level. Overall, this study contributes valuable insights into the ecology and adaptation of carob trees, emphasizing the importance of considering intraspecific variability when studying this remarkable species. This knowledge is critical for addressing the challenges posed by climate change and human activities on the long-term survival and ecological functioning of carob populations.

Linking Colorimetric Variation with Non-Volatile and Volatile Components of Carob Flour

Chromatic variation was examined for its association with flour composition and quality. Carob samples from variable altitudes and genetic backgrounds were milled and assessed for colorimetric parameter L* (lightness) and analyzed for phenols, tannins, antioxidant capacity, soluble carbohydrates (HPLC-RID), organic acids and protein (IC-CD), and volatile organic compounds (VOCs; HS-SPME/GC-MS). Higher altitudes and grafted genotypes yielded lighter-colored flours of higher antioxidant potential, phenols, tannins, sucrose, and malic acid concentrations. VOCs were mainly acids, esters, aldehydes, ketones, and alcohols. Acids were the most abundant and correlated negatively with L*, though correlation for many individual acids was non-significant, including 2-methyl-propanoic acid, widely considered the carob signature aroma (cheesy acidic buttery). The compositional and quality indexing potential of L* is more robust for grafted than non-grafted material, owing putatively to a narrower genetic basis. Antioxidant capacity and concentrations of phenolics, tannins and sucrose correlated positively with L*, indicating increased levels in carob flours sourced from grafted trees at higher altitudes. These flours also have a lower content of reducing sugars, the implication of which in the darkening of carob flour warrants further investigation. Overall, L* constitutes a reliable index for ranking carob flours for key compositional attributes and may be further reinforced by multiple-year data.

Genome Size Variation across a Cypriot Fabeae Tribe Germplasm Collection

DNA content is an important trait linked to the evolutionary routes of taxa and often connected to speciation. In the present study, we studied C-values variation across the Cypriot Fabeae gene pool. Several hundred plants (Vicia spp., Lens spp., Pisum spp.) were sampled across Cyprus. Accurate estimates were established by flow cytometry and propidium iodine staining for 155 discrete populations/accessions. A ten-fold variation was detected across lineages with 1C DNA content varying from 1.584 pg for V. cretica (ARI02420) to 13.983 pg for V. faba (ARI00187). In general, flow cytometry was precise for the characterization of species, even though there were instances of genome overlapping across taxa. Most analyses in the current work refer to species that have not been characterized before by flow cytometry (or any other DNA content estimation method). Still, a correlation to C-values previously reported in Kew Plant DNA C-values database was attempted. A high degree of correlation except for V. dalmatica was established. The evaluation of genome size trait in relation with the Fabeae phylogeny, revealed that Pisum and Lens genera were rather homogenous, but an astonishing fluctuation was shown for Vicia spp. Moreover, it was established that genome up- or down-scaling was not directly linked to speciation drivers. The genomic size measurements presented here could deliver extra quality control for the identification and characterization of taxa in germplasm collections, particularly in cases where species share morphological characters.

Phenolic Profile, Antioxidant Activity, and Chemometric Classification of Carob Pulp and Products

In recent years, carob and its derived products have gained wide attention due to their health-promoting effects, which are mainly attributed to their phenolic compounds. Carob samples (carob pulps, powders, and syrups) were analyzed to investigate their phenolic profile using high-performance liquid chromatography (HPLC), with gallic acid and rutin being the most abundant compounds. Moreover, the antioxidant capacity and total phenolic content of the samples were estimated through DPPH (IC₅₀ 98.83-488.47 mg extract/mL), FRAP (48.58-144.32 μmol TE/g product), and Folin-Ciocalteu (7.20-23.18 mg GAE/g product) spectrophotometric assays. The effect of thermal treatment and geographical origin of carobs and carob-derived products on their phenolic composition was assessed. Both factors significantly affect the concentrations of secondary metabolites and, therefore, samples' antioxidant activity (p-value < 10^-7). The obtained results (antioxidant activity and phenolic profile) were evaluated via chemometrics, through a preliminary principal component analysis (PCA) and orthogonal partial least square-discriminant analysis (OPLS-DA). The OPLS-DA model performed satisfactorily, differentiating all samples according to their matrix. Our results indicate that polyphenols and antioxidant capacity can be chemical markers for the classification of carob and its derived products.

Carob: A Sustainable Opportunity for Metabolic Health

Carob (Ceratonia siliqua L.) is an evergreen tree that belongs to the Leguminosae family and grows in the arid and semi-arid regions of the Mediterranean basin. The carob tree is resistant to droughts and salinity, while its deep root systems allow CO₂ to sink, mitigating global warming effects. Traditionally, carob has been used to produce animal feed, but for many years, it was excluded from the human diet. Nowadays, agricultural and industrial sectors exploit carob fruit, also referred to as carob pod, and its primary products (i.e., flour, powder and syrup) to develop a variety of foods and beverages. The nutritional composition varies depending on the carob part but also on genetic, cultivar, seasonal and environmental factors. Despite the high sugar content, the carob pod is rich in insoluble fiber and microconstituents including phenolic compounds, inositols (mainly d-pinitol) and vitamins. In the present review article, we aimed to (a) highlight the role of carob cultivation in addressing climate change challenges and the need for sustainability, and (b) summarize the effects of carob consumption on obesity and related metabolic disorders.

Use of agro-industrial by-products containing tannins for the integrated control of gastrointestinal nematodes in ruminants

Previous studies have illustrated that different bioactive legume fodders containing condensed tannins might represent one of the options for integrated sustainable control of gastrointestinal nematodes (GIN) in ruminants, which may help address the worldwide development of resistance to synthetic anthelmintics. More recently, impetus has been given to assess the potential antiparasitic activity of less conventional resources, represented by different agro-industrial by-products (AIBPs). This review presents in vitro and in vivo results obtained with a range of tannin-containing AIBPs of various geographical and botanical origins, namely AIBP of nuts, temperate and tropical barks, carob, coffee and cocoa. They tend to confirm the "proof of concept" for their antiparasitic effects and also for other aspects of ruminant production in an agro-ecological context. Socio-economic aspects of the exploitation of such non-conventional resources are also discussed as potential models of the circular economy, by using waste. The different modes of use of these resources are presented in this review, as well as strengths, weaknesses, opportunities, and threats (SWOT) analyses to illustrate the advantages and limitations of on-farm use.

Configuration of the Volatile Aromatic Profile of Carob Powder Milled From Pods of Genetic Variants Harvested at Progressive Stages of Ripening From High and Low Altitudes

Carob powder is increasingly valued as a substitute for cocoa and as a flavor-enhancing component of processed foods. However, little is known about the impact of preharvest factors such as fruit maturity, genotype and altitude on its volatile organic compounds (VOCs) composition. The current study examined the VOCs composition of powder milled from pods of two genotypes cultivated at 15 and 510 m altitude and harvested at six progressive stages of maturity, ranging from fully developed immature green (RS1) to late ripe (RS6). Fifty-six VOCs categorized into acids, esters, aldehydes, ketones, alcohols, furans, and alkanes were identified through HS-SPME GC-MS analysis. Maturity was the most influential factor, followed by altitude and least by genotype. Aldehydes and alcohols correlated positively (r = 0.789; p < 0.001), both accumulated in immature carobs and decreased with progressive ripening, resulting in the attenuation of green grassy aroma. Conversely, acids increased with ripening and dominated the carob volatilome at full maturity, correlating negatively with aldehydes and alcohols (r = −0.835 and r = −0.950, respectively; p < 0.001). The most abundant VOC throughout ripening (17.3-57.7%) was isobutyric acid, responsible for the characteristic cheesy-acidic-buttery aroma of carob powder. The pleasurable aroma detected at the immature stages (RS2 and RS3) was traced to isobutyrate and methyl isobutyrate esters, rendering unripe green carob powder a potential admixture component for improving the aroma of novel food products. Lower altitude favored the accumulation of acids linked to less pleasant aroma, whereas isobutyric acid was more abundant at higher altitude. This constitutes a significant indication that higher altitude enhances the characteristic carob-like aroma and sensory quality of carob powder.

Anti-Cancer Activity and Phenolic Content of Extracts Derived from Cypriot Carob (Ceratonia siliqua L.) Pods Using Different Solvents

Extracts derived from the Ceratonia siliqua L. (carob) tree have been widely studied for their ability to prevent many diseases mainly due to the presence of polyphenolic compounds. In this study, we explored, for the first time, the anti-cancer properties of Cypriot carobs. We produced extracts from ripe and unripe whole carobs, pulp and seeds using solvents with different polarities. We measured the ability of the extracts to inhibit proliferation and induce apoptosis in cancer and normal immortalized breast cells, using the MTT assay, cell cycle analysis and Western Blotting. The extracts' total polyphenol content and anti-oxidant action was evaluated using the Folin-Ciocalteu method and the DPPH assay. Finally, we used LC-MS analysis to identify and quantify polyphenols in the most effective extracts. Our results demonstrate that the anti-proliferative capacity of carob extracts varied with the stage of carob maturity and the extraction solvent. The Diethyl-ether and Ethyl acetate extracts derived from the ripe whole fruit had high Myricetin content and also displayed specific activity against cancer cells. Their mechanism of action involved caspase-dependent and independent apoptosis. Our results indicate that extracts from Cypriot carobs may have potential uses in the development of nutritional supplements and pharmaceuticals.

Combined use of β-cyclodextrin and ionic liquid as electrolyte additives in EKC for separation and determination of carob's phenolics-A study of the synergistic effect

In this work, a simple, reliable, and fast capillary electrophoretic method was developed and validated for the simultaneous determination of 12 polyphenolic compounds, the most frequently found in carob's pulp and seeds. The present work deals with the development of a novel dual electrophoretic system based on the combined use of β-CD and ionic liquid (IL) as buffer additives. A baseline separation of the target analytes was achieved in less than 10 min by using a BGE consisting of 35 mM borate along with 15 mM β-CD and 3 mM l-alanine tert butyl ester lactate (l-AlaC₄ Lac) IL as buffer additives at pH 9.5, a temperature of 25°C, and an applied voltage of 30 kV. The application of the developed electrophoretic method to real samples enabled the identification and quantification of the main phenolic constituents of both ripe and unripe carob pulp extracts. The results revealed the predominance of gallic acid in both ripe (183.92 μg/g carob pulp) and unripe (205.10 μg/g carob pulp) carob pulp and highlighted the great influence of the ripening stage on carobs polyphenolic composition, with unripe pods being more enriched in polyphenols (total phenolics detected: 912.58 and 283.13 μg/g unripe and ripe carob pulp).