Seeds as Potential Sources of Phenolic Compounds and Minerals for the Indian Population.

Seeds are major sources of nutrients and bioactive compounds for human beings. In this work, the chemical composition and physicochemical properties of 155 Indian seeds (belonging to 49 families) are reported. Moisture and ash were measured with reference protocols from AOAC; total polyphenols and flavonoids were measured with spectrophotometric methods after extraction with organic solvents, and mineral elements were determined by X-ray fluorescence spectrophotometry. Total phenolic compounds, flavonoids and mineral contents (Al, Ba, Ca, Cl, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, P, Rb, S, Sr, Ti, V and Zn) were found to vary in the ranges 182−5000, 110−4465 and 687−7904 mg/100 g (DW), respectively. Noticeably, polyphenol contents higher than 2750 mg/100 g were observed in 18 seeds. In addition, mineral contents >5000 mg/100 g were detected in the seeds from Cuminum cyminum, Foeniculum vulgare, Commiphora wightii, Parkia javanica, Putranjiva roxburghii, Santalum album and Strychnos potatorum. Botanical and taxonomical variations in the proximate characteristics of the examined seeds are also discussed.

Mineral-nutrient relationships in African soils assessed using cluster analysis of X-ray powder diffraction patterns and compositional methods.

Soil mineral compositions are often complex and spatially diverse, with each mineral exhibiting characteristic chemical properties that determine the intrinsic total concentration of soil nutrients and their phyto-availability. Defining soil mineral-nutrient relationships is therefore important for understanding the inherent fertility of soils for sustainable nutrient management, and data-driven approaches such as cluster analysis allow for these relations to be assessed in new detail. Here the fuzzy-c-means clustering algorithm was applied to an X-ray powder diffraction (XRPD) dataset of 935 soils from sub-Saharan Africa, with each diffractogram representing a digital signature of a soil's mineralogy. Nine mineralogically distinct clusters were objectively selected from the soil mineralogy continuum by retaining samples exceeding the 75 % quantile of the membership coefficients in each cluster, yielding a dataset of 239 soils. As such, samples within each cluster represented mineralogically similar soils from different agro-ecological environments of sub-Saharan Africa. Mineral quantification based on the mean diffractogram of each cluster illustrated substantial mineralogical diversity between the nine groups with respect to quartz, K-feldspar, plagioclase, Fe/Al/Ti-(hydr)oxides, phyllosilicates (1:1 and 2:1), ferromagnesians, and calcite. Mineral-nutrient relationships were defined using the clustered XRPD patterns and corresponding measurements of total and/or extractable (Mehlich-3) nutrient concentrations (B, Mg, K, Ca, Mn, Fe, Ni, Cu and Zn) in combination with log-ratio compositional data analysis. Fe/Al/Ti/Mn-(hydr)oxides and feldspars were found to be the primary control of total nutrient concentrations, whereas 2:1 phyllosilicates were the main source of all extractable nutrients except for Fe and Zn. Kaolin minerals were the most abundant phyllosilicate group within the dataset but did not represent a nutrient source, which reflects the lack of nutrients within their chemical composition and their low cation exchange capacity. Results highlight how the mineral composition controls the total nutrient reserves and their phyto-availability in soils of sub-Saharan Africa. The typical characterisation of soils and their parent material based on the clay particle size fraction (i.e. texture) and/or the overall silica component (i.e. acid and basic rock types) alone may therefore mask the intricacies of mineral contributions to soil nutrient concentrations.

Portable X-ray fluorescence (pXRF) calibration for analysis of nutrient concentrations and trace element contaminants in fertilisers.

With the increasing popularity of local blending of fertilisers, the fertiliser industry faces issues regarding quality control and fertiliser adulteration. Another problem is the contamination of fertilisers with trace elements that have been shown to subsequently accumulate in the soil and be taken up by plants, posing a danger to the environment and human health. Conventional characterisation methods necessary to ensure the quality of fertilisers and to comply with local regulations are costly, time consuming and sometimes not even accessible. Alternatively, using a wide range of unamended and intentionally amended fertilisers this study developed empirical calibrations for a portable handheld X-ray fluorescence (pXRF) spectrometer, determined the reliability for estimating the macro and micro nutrients and evaluated the use of the pXRF for the high-throughput detection of trace element contaminants in fertilisers. The models developed using pXRF for Mg, P, S, K, Ca, Mn, Fe, Zn and Mo had R2 values greater or equal to 0.97. These models also performed well on validation, with R2 values greater or equal to 0.97 (except for Fe, R2val = 0.55) and slope values ranging from 0.81 to 1.44. A second set of models were developed with a focus on trace elements in amended fertilisers. The R2 values of calibration for Co, Ni, As, Se, Cd and Pb were greater than or equal to 0.80. At concentrations up to 1000 mg kg-1, good validation statistics were also obtained; R2 values ranged from 0.97-0.99, except in one instance. The regression coefficients of the validation also had good prediction in the range of 0-100 mg kg-1 (R2 values were from 0.78-0.99), but not as well at lower concentrations up to 20 mg kg-1 (R2 values ranged from 0.10-0.99), especially for Cd. This study has demonstrated that pXRF can measure several major (P, Ca) and micro (Mn, Fe, Cu) nutrients, as well as trace elements and potential contaminants (Cr, Ni, As) in fertilisers with high accuracy and precision. The results obtained in this study is good, especially considering that loose powders were scanned for a maximum of 90 seconds without the use of a vacuum pump.

Comprehensive nutrient analysis in agricultural organic amendments through non-destructive assays using machine learning.

Portable X-ray fluorescence (pXRF) and Diffuse Reflectance Fourier Transformed Mid-Infrared (DRIFT-MIR) spectroscopy are rapid and cost-effective analytical tools for material characterization. Here, we provide an assessment of these methods for the analysis of total Carbon, Nitrogen and total elemental composition of multiple elements in organic amendments. We developed machine learning methods to rapidly quantify the concentrations of macro- and micronutrient elements present in the samples and propose a novel system for the quality assessment of organic amendments. Two types of machine learning methods, forest regression and extreme gradient boosting, were used with data from both pXRF and DRIFT-MIR spectroscopy. Cross-validation trials were run to evaluate generalizability of models produced on each instrument. Both methods demonstrated similar broad capabilities in estimating nutrients using machine learning, with pXRF being suitable for nutrients and contaminants. The results make portable spectrometry in combination with machine learning a scalable solution to provide comprehensive nutrient analysis for organic amendments.

Chemical Composition of Abrus precatorius L. Seeds

Aims: A. precatorius seed powder is traditionally used in Ayurveda, Siddha and Unani medicine. The objective of present work is to describe the oil, starch, protein, polyphenol and mineral composition of A. precatorius seeds. Methodology: Legumes from A. precatorius were collected, and seeds were manually separated. Dried seeds in powder form were employed for the various analyses: solvent extraction was used for elucidation of the oil percentage value; starch content was determined by the enzymatic method; total polyphenol and flavonoid contents were spectrophotometrically analyzed using Folin-Ciocalteu and aluminum chloride as the color developing reagents, respectively; and X-ray fluorescence (XRF) was used for the mineral contents assessment. Results: The seed kernel consisted of stored oil (3.2%), protein (92.0%) and starch (4.8%). The total polyphenol and flavonoid contents were 24710 and 2520 mg/kg (dw). A remarkably high content of polyphenols was observed in the seed coat and the seed pod. P, S and (mainly) K nutrients were hyper-accumulated in the seed kernel. The seeds showed a glass transition at -21°C, two endothermic peaks at 109°C (dehydration and protein unfolding) and at 209°C, and a calorific value (~406 kcal/100 g dw) that exceeded those of Pisum sativum L., Lens culinaris Medik. and other common pulses. Conclusions: The seed kernel from A. precatorius was mainly composed of stored protein, with low oil and starch contents. High contents of polyphenols, K, Mg, Ca and Fe were found in the seeds. Heavy metals were below the safety limits established for human consumption.

Chemical Composition of Caesalpinioideae Seeds

Aims: Caesalpinioideae species have great medicinal and food values. In this work, six Caesalpinioideae species that grow abundantly in central India were selected for chemical investigation: Delonix regia, Entada gigas, Leucaena leucocephala, Mimosa pudica, Parkia javanica and Senna siamea. The objective of the present work is to describe the phytochemical and mineral composition and the bioaccumulation potentialities of the seeds from aforementioned species. Methodology: Spectrophotometric, enzymatic and X-ray fluorescence spectrophotometric techniques were used for the quantification of polyphenols, starch and mineral contents, respectively. Results: The sum of the total concentrations of 17 macro- and micronutrients (P, S, Cl, K, Rb, Mg, Ca, Sr, Cr, Mn, Fe, Co, Cu, Zn, Se, Mo and Pb), oil, protein and total starch in the six seeds were in the 20253-78489 mg/kg, 3.1-30.1%, 52.9-91.5% and 5.4–41.0% range, respectively. The highest concentrations of Fe, oil and phenolics were observed in M. pudica seeds. Both thermal and spectral characteristics allowed to differentiate M. pudica and P. javanica seeds (with the highest caloric contents) from the seeds from the other species. Conclusion: The selected Caesalpinioideae seeds are potential sources of the nutrients (i.e., P, S, K, Mg, Ca and Fe) and polyphenols, which are needed for biological metabolism and human health. The presence of heavy metals was well below safety limits, enabling their medicinal uses.

Characterization of Polyphenols and Mineral Contents in Three Medicinal Weeds

Aims: Common weeds Rorippa palustris (L.) Besser, Euphorbia rothiana Spreng. and Schoenoplectiella articulata (L.) Lye are used for food, medicinal, green biofertilizer and biosorbent applications. In this work, their polyphenol and mineral contents have been characterized. Methodology: Samples from aforementioned three plants were manually collected in Raipur city (CG, India) and processed for the analyses. Folin-Ciocalteu and aluminum chloride were used for the spectrophotometric determination of polyphenols. The mineral contents were quantified by X-ray fluorescence. Results: The total concentration of 20 elements (viz. P, S, Cl, As, Se, K, Rb, Mg, Ca, Sr, Ba, Al, Ti, Cr, Mn, Fe, Co, Zn, Mo and Pb), total polyphenol and flavonoid contents in the leaves ranged from 46372 to 71501, from 47877 to 73791 and from 1950 to 9400 mg/kg, respectively. Remarkable concentrations of several nutrients (P, S, Cl, K, Mg, Ca and Fe) were observed. Conclusion: The biomass from medicinal weeds R. palustris, E. rothiana and S. articulata featured very high K, Ca and Fe contents. Other nutrients (polyphenols, flavonoids, P, S, Cl and Mg) were identified at moderate levels. These species may hold promise as bioindicators.

Phenolic and Mineral Characteristics of Seed Coats and Kernels from 24 Species from Raipur Area, India

Aims: The objective of the present work is the investigation of the physicochemical characteristics of seed coats and kernels from 24 species with medicinal and food applications. Methodology: Seeds from 24 species (2 herbs, 11 vines and 11 trees), belonging to 13 families, were sampled in Raipur (India) in 2017. The collected seeds were dried and weighed, after which seed coats were manually peeled and separately weighed. Phenolic and mineral contents in the seed coats and kernels were analyzed by spectrophotometric and X-ray fluorescence (XRF) techniques, respectively. Results: The seed coat fraction represented from 12% to 95% of the seed mass, depending on the species. The concentrations of total polyphenols, flavonoids and minerals in the seed coats varied from 1800 to 32300 mg/kg, from 1200 to 26900 mg/kg, and from 5876 to 36499 mg/kg, respectively. In the seed kernels, TPh, Fla and minerals ranged from 780 to 31760 mg/kg, from 300 to 12020 mg/kg, and from 12595 to 40810 mg/kg, respectively. P, S, K, Mg, Ca and Fe were found to be the main macro- and micro-elements. Seed coats from Loganiaceae, Phyllanthaceae, Lauraceae and Rutaceae families featured the highest total polyphenol contents, and those from Lauraceae and Rutaceae families showed the highest flavonoid concentrations. The highest total mineral contents corresponded to seed coats from Lauraceae, Rutaceae and Euphorbiaceae families. Conclusion: Indian-laurel and curry tree stand out as promising phytochemical and nutrient sources.

Nutritional, Spectral and Thermal Characteristic of Lamiaceae Seeds

Aims: Species of the family Lamiaceae possess a rich tradition of use for flavoring and medicinal purposes. This paper focusses on the nutritional and thermal characteristics of the seeds from eight species belonging to this family: Gmelina arborea Roxb. ex Sm., Hyptis suaveolens (L.) Poit., Leonotis nepetifolia (L.) R.Br., Ocimum americanum L., Ocimum sanctum L. (Rama Tulsi), Ocimum tenuiflorum L. (Krishna Tulsi), Origanum vulgare L. and Tectona grandis L.f. Methodology: The oil, starch, total polyphenol, flavonoid and mineral contents for aforementioned seeds were determined. Fourier-transform infrared (FTIR) spectroscopy was used to assess the phytoconstituents. Thermogravimetric/derivative thermogravimetric analyses (TG/DTG) and differential scanning calorimetry (DSC) analyses were performed to analyze the decomposition patterns. Results: The concentrations of oil, starch, total polyphenol, flavonoids and minerals for the seeds from the eight plants under study ranged from 11.8 to 50.4%, from 0.22 to 1.84%, from 295 to 5842 mg/kg, from 1660 to 12680 mg/kg and from 11756 to 33927 mg/kg, respectively. Unsaturated oils, polyphenols and lignin were recognized by vibrational spectroscopy. The sequence of thermal effects in the seed pyrolysis process above 100°C have been put in relation to seed protein crystallization (endotherm at 200°C), oxidation reactions and degradation of hemicellulose and other fiber components (at around 300°C), and decomposition of polyunsaturated (at 357°C) and mono-unsaturated (at 391°C) triglycerides. Conclusion: Lamiaceae seeds are potential food alternatives to cereals.

Evaluation of the Phytochemical and Mineral Characteristics of Some Selected Sapotaceae Plants

Aims: To study the spectral and thermal characteristics, and the oil, starch, polyphenol and mineral contents of seeds and leaves from three Sapotaceae species, provided that trees and shrubs of this family are an important source of nutritional and functional products. Methodology: Leaves and seeds from three Sapotaceae plants, namely Moa tree (Madhuca indica J. F. Gmel.), Chico sapote (Manilkara zapota (Linn.) van Royen) and Spanish cherry (Mimusops elengi Linn.), were collected in the Raipur area of Chhattisgarh, India. Their physicochemical characterization (including oil, polyphenol, starch and mineral contents; functional groups; and thermal degradation patterns) was carried out by using various techniques, viz. solvent extraction, spectrophotometry, enzymatic digestion, X-ray fluorescence (XRF) and Fourier-transform infrared (FTIR) spectroscopies, thermogravimetric/derivative thermogravimetric (TG/DTG) and differential scanning calorimetry (DSC), respectively. Results: The three Sapotaceae seeds under study were found to contain polyphenol, mineral, starch and oil contents in the 1850–23180 mg/kg, 11390–19385 mg/kg, 6.7–9.1% and 9.8-54.1% range, respectively. Their leaves and seed coats featured total phenolic contents in the 24260–28600 mg/kg and 7810–23060 mg/kg range, respectively, and mineral contents in the 8823–27462 mg/kg and 3619–15884 mg/kg range, respectively. The functional groups of the phytochemicals, studied by FTIR, were assigned. Their thermal decomposition patterns, which involved loss of water and volatile organic compounds, proteins, oil and starch/cellulose, were also described. Conclusion: The Sapotaceae leaves, seed coat, kernel and cake are enriched with very high contents of starch, proteins, polyphenols and minerals, suggesting their possible valorization in human food, animal feeding and as herbal medicines.

Nutritional and Spectral Characteristics of Terminalia Plants

Aims: Terminalia spp. is medicinal plants that belong to Combretaceae family, widely used in traditional Ayurvedic medicine. In this work, the nutritional constituents of the leaves, seed kernel and seed coat from four Terminalia species (T. arjuna, T. bellirica, T. catappa and T. chebula) are reported. Methodology: Polyphenol and flavonoid contents were analyzed spectrophotometrically by using Folin-Ciocalteu and aluminum chloride as reagents, respectively; mineral contents were quantified by using X-ray fluorescence; and the functional groups of the phytochemicals were investigated by infrared spectroscopy. Results: The total concentration of 20 macro- and micronutrients and heavy metals (viz. P, S, Cl, K, Rb, Mg, Ca, Sr, Ba, Al, Ti, Cr, Mn, Fe, Co, Cu, Zn, Mo, As and Pb), and the total polyphenol and flavonoid contents in the seed kernels ranged from 1754 to 65521 mg/kg, from 2150 to 51100 mg/kg and from 63 to 42300 mg/kg, respectively. Polyphenol and mineral contents for the Terminalia spp. seed coats and leaves were also determined. The enrichment in each of aforementioned elements with respect to the soil content was calculated. The vibrational spectra of the leaves and seed coats agreed with a composition rich in lignin, hemicellulose, cutin, pectin and flavonoids, while those of the seed kernels were in accordance with the presence of unsaturated oils, protein, and fiber. Conclusion: Various parts of the four Terminalia species under study (T. arjuna, T. bellirica, T. catappa and T. chebula) featured high contents of nutrients and polyphenols needed for biological metabolism and human health. In addition, heavy metals were only present at traces level, indicating that these Terminalia plants would be safe for medicinal uses.

Quantification of total element concentrations in soils using total X-ray fluorescence spectroscopy (TXRF).

Total X-ray fluorescence spectroscopy (TXRF) determines concentrations of major and trace elements in multiple media. We developed and tested a method for the use of TXRF for direct quantification of total element concentrations in soils using an S2 PICOFOX™ spectrometer (Bruker AXS Microanalysis GmbH, Germany). We selected 15 contrasting soil samples from across sub-Saharan Africa for element analysis to calibrate the instrument against concentrations determined using the inductively coupled plasma-mass spectroscopy (ICP-MS) standard method. A consistent underestimation of element concentrations using TXRF compared to ICP-MS reference analysis occurred, indicating that spectrometer recalibration was required. Single-element recalibration improved the TXRF spectrometer's sensitivity curve. Subsequent analysis revealed that TXRF determined total element concentrations of Al, K, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Ga accurately (model efficacy/slope close to 1:1 line, and R(2)>0.80) over a wide range of soil samples. Other elements that could be estimated with an acceptable precision (R(2)>0.60) compared with ICP-MS although generally somewhat under- or overestimated were P, Ca, As, Rb, Sr, Y, Pr, Ta and Pb. Even after recalibration, compared to ICP-MS the TXRF spectrometer produced underestimations for elements Na, Mg, Ba, Ce, Hf, La, Nd, W and Sm and overestimations for elements Bi, Tl and Zr. We validated the degree of accuracy of the TXRF analytical method after recalibration using an independent set of 20 soil samples. We also tested the accuracy of the analysis using 2 multi-element standards as well as the method repeatability on replicate samples. The resulting total element concentration repeatability for all elements analyzed were within 10% coefficient of variability after the instrument recalibration except for Cd and Tl. Our findings demonstrate that TXRF could be used as a rapid screening tool for total element concentrations in soils assuming that sufficient calibration measures are followed.

Applicability of near-infrared reflectance spectroscopy (NIRS) for determination of crude protein content in cowpea (Vigna unguiculata) leaves.

There is uncertainty on how generally applicable near-infrared reflectance spectroscopy (NIRS) calibrations are across genotypes and environments, and this study tests how well a single calibration performs across a wide range of conditions. We also address the optimization of NIRS to perform the analysis of crude protein (CP) content in a variety of cowpea accessions (n = 561) representing genotypic variation as well as grown in a wide range of environmental conditions in Tanzania and Uganda. The samples were submitted to NIRS analysis and a predictive calibration model developed. A modified partial least-squares regression with cross-validation was used to evaluate the models and identify possible spectral outliers. Calibration statistics for CP suggests that NIRS can predict this parameter in a wide range of cowpea leaves from different agro-ecological zones of eastern Africa with high accuracy (R (2)cal = 0.93; standard error of cross-validation = 0.74). NIRS analysis improved when a calibration set was developed from samples selected to represent the range of spectral variability. We conclude from the present results that this technique is a good alternative to chemical analysis for the determination of CP contents in leaf samples from cowpea in the African context, as one of the main advantages of NIRS is the large number of compounds that can be measured at once in the same sample, thus substantially reducing the cost per analysis. The current model is applicable in predicting the CP content of young cowpea leaves for human nutrition from different agro-ecological zones and genetic materials, as cowpea leaves are one of the popular vegetables in the region.