Mineral content of bee pollen from Serbia

Evaluation of Environmental and Nutritional Aspects of Bee Pollen Samples Collected from East Black Sea Region, Turkey, via Elemental Analysis by ICP-MS

Honeybee pollens are good food sources in terms of their mineral contents and are specific to the regions they are collected. In addition, they may be used as bioindicators in the assessment of environmental pollution based on their potentially toxic element contents. In the present study, mineral element composition and potentially toxic element levels of honeybee pollen samples collected from various cities in East Black Sea Region of Turkey (18 samples) were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave assisted acid digestion. The method validation was performed by using CRM (Certified Reference Material-BCR®279-Sea Lettuce-Ulva lactuca) to evaluate the accuracy and precision. Elemental composition of honeybee pollens were detected within the following ranges (minimum-maximum, mg kg^-1 dry pollen); Mn (manganese): 11.579-117.349, Fe (Iron): 34.865-811.043, Zn (zinc): 17.707-56.223, Se (selenium): 0.422-0.722, Cr (chromium): 0.848-6.949, Cu (copper): 7.510-26.344, Mg (magnesium): 549.921-2149.716, Ca (calcium): 726.575-2201.837, Na (sodium): 36.518-120.283, Pb (lead): < 0.005-0.622, Cd (cadmium): 0.039-1.390, Ni (nickel): 2.317-21.710, and As (arsenic): 1.331-2.248. Recommended daily allowance, target hazard quotients, hazard index, and carcinogenic risk values of the pollens were calculated with the help of these results. In considering THQ values, pollens were determined to be safe for the consumption of both genders. Based on the carcinogenic risk calculation, most of the pollens examined in this study were categorized as moderately risky. Monitoring studies can be used to identify new sources of contamination or the origin and spread of a particular element. Hence, bee pollens can also be considered as potential bioindicators of toxic metal pollution. HIGHLIGHTS: • Mineral content and potentially toxic metal levels of 18 honeybee pollens were determined. • Recommended daily allowance (RDA) values were calculated. • The nutritional aspects of honeybee pollen samples were evaluated. • Hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR) estimation of honeybee pollens were assessed. • The potentiality of honeybee pollens as a bioindicator for pollution was discussed.

The colors of Tuscan bee pollen: phytochemical profile and antioxidant activity

Bee pollen's nutritional and beneficial health properties depend on the botanical origin and storage conditions. Palynological analysis determines the botanical composition of the multiflora and colour fractions. This study aimed to characterize the phytochemical profile and antioxidant activity of Tuscan bee pollen stored at freezing temperature for 2 years to verify the preservation of nutraceutical properties of the multiflora and colour fractions. Polyphenols, flavonoids content, antioxidant activity and volatile compounds profiles were measured. Non-terpene derivatives (acids and aldehydes) represented the main class of volatile compounds in most analysed samples. Among the colour fractions, coral showed significant differences in the antioxidant compounds. In the multiflora were also determined the soluble sugar content (128.33 mg/g of fresh weight) and mineral content, with the prevalence of K, organic N and Ca. The results suggest that the freezing storage of bee pollen for a long period can be still used as food.

Concentration of essential and non-essential elements and carcinogenic / non-carcinogenic health risk assessment of commercial bee pollens from Turkey

BACKGROUND

Bee pollen, known as a natural super-food with valuable nutritional ingredients, is regarded as a good indicator of ecotoxic substances, such as potentially toxic elements (PTEs). Therefore, this study aims to examine the concentrations of selected PTEs (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Se, Sn, Sr, V, Zn) in bee pollen purchased from online markets in Turkey and perform a health risk assessment to identify the potential risk to consumers.

METHODS

The quantitative analyses were conducted by inductively coupled plasma optical emission spectrometry (ICP-OES).

RESULTS

The mean values of essential PTEs in decreasing content order were Mg > Fe > Zn > Mn > Cu > Ni > Se > Cr > Mo >Co = V. Regarding the results of the study, daily consumption (40 g for adult or 20 g for children) of commercial bee pollen can recompense 20-35 % of daily Cu, Mn, Se requirements for children, adults, pregnant, and breastfeeding women. The decreasing content order of non-essential elements was Al > Sn > Sr > Ba > Pb > As. Cadmium and Hg concentrations were below the detection limits in all the samples. In terms of food and public health; detection of the PTEs concentrations is necessary to assess the quality and safety of bee pollen before consumption. According to the carcinogenic and non-carcinogenic risk assessments; commercial pollen consumption does not pose a health risk to either children or adults for the PTEs monitored in this study.

CONCLUSION

We conclude that bee pollen is an ideal indicator for the monitoring of environmental pollution of PTEs and also a valuable source of essential elements. This study highlights the need to develop standards that regulate acceptable concentrations of PTEs.

Biscuits Enriched with Monofloral Bee Pollens: Nutritional Properties, Techno-Functional Parameters, Sensory Profile, and Consumer Preference

Bee pollens are potential functional food ingredients as they contain essential nutrients and a wide range of bioactive compounds. The aim of this study was to investigate the effects of enrichment with monofloral bee pollens on the nutritional properties, techno-functional parameters, sensory profile, and consumer preference of biscuits. Biscuits were prepared according to the AACC-approved method by substituting wheat flour with pollens of rapeseed (Brassica napus L.), phacelia (Phacelia tanacetifolia Benth.) and sunflower (Helianthus annuus L.) at 2%, 5% and 10% levels. The macronutrient composition of the biscuits was determined: crude protein content (Kjeldahl method), crude fat content (Soxhlet extraction), ash content (carbonization), moisture content (drying), carbohydrate content (formula). Their total phenolic content (TPC) and in vitro antioxidant capacity (FRAP, TEAC, DPPH) were determined spectrophotometrically. The colour of the biscuits was measured using a tristimulus-based instrument, and their texture was characterized by using a texture analyser. Sensory profile of biscuits was determined by qualitative descriptive analysis (QDA). The consumer acceptance and purchase intention of the biscuits were also evaluated, based on the responses of 100 consumers. Additionally, an external preference map was created to illustrate the relationship between consumer preference and the sensory profile of the biscuits, and penalty analysis was conducted to identify directions for product development. Phacelia pollen appeared to be the most effective for improving the nutritional quality of biscuits. The addition of phacelia pollen at the 10% substitution level increased the protein content and TPC of the control biscuit by 21% and 145%, respectively. Significant changes (p < 0.05) were also observed regarding the colour and texture of biscuits. The results of the QDA revealed that biscuits containing pollens of different botanical sources have heterogeneous sensory attributes. The biscuit containing sunflower pollen at the 2% substitution level was preferred the most (overall liking = 6.9 ± 1.6), and purchase intentions were also the highest for this product. Based on the results of the present study, it is recommended to use sunflower pollen for developing pollen-enriched foods in the future.

Probiotics as a promising prophylactic tool to reduce levels of toxic or potentially toxic elements in bees

Bees are precious living beings for our planet. Thanks to their essential service of pollination, these insects allow the maintenance of biodiversity and the variety and amount of food available. Unfortunately, we are observing an increasingly devastating reduction of bee families and other pollinating insects for factors related to human activities, environmental pollution, diseases and parasites, compromise of natural habitats, and climate change. We show that probiotics can protect bees from element pollution. We collected bees, beeswax, honey, pollen, and propolis directly from hives in a rural area of central Italy to investigate the content of 41 elements in control (not supplemented with probiotics) and experimental (supplemented with probiotics) groups. Our data show a significantly lower concentration of some elements (Ba, Be, Cd, Ce, Co, Cu, Pb, Sn, Tl, and U) in experimental bees than in control groups, indicating a possible beneficial effect of probiotics in reducing the absorption of chemicals. This study presents the first data on element levels after probiotics have been fed to bees and provides the basis for future research in several activities relating to the environment, agriculture, economy, territory, and medicine.

Distribution and statistical analysis of major and trace elements in the bee pollen from the territory of Republic of Kosovo

The objective of this study was the determination of major and trace elements in the bee pollen samples from the whole territory of Republic of Kosovo. Pollen, as a natural plant product, is exposed to different contaminations absorbed by plants from the soil through the root system or with water intake, as well as to pollutants of different origins, including anthropogenic ones, deposited directly on pollen. In total 67 pollen samples were collected in 2019. The samples were analyzed for 27 macro and microelements by using ICP-AES and ICP-MS. The mean content of major elements in bee pollen was 4065, 3455, 1375 and 549 mg/kg for K, P, Ca and Mg, respectively. The range of the contents for some potentially toxic elements was 11.9-139.1, 1.9-16, 0.11-6.25, 0.01-0.329 and 0.001-0.38 mg/kg for Zn, Cu, Pb, Cd and As, respectively. Three groups of elements of mixed origin were identified through factor analysis: the first and the third Factors, are mostly of geogenic origin (Ag, Li, Al, Fe, Ca, Sr, K, Mg and P and Co, Ni, Cr, Cu and Mn) and the second Factor association is related to anthropogenic processes (Sb, As, Pb, Tl, Sn and Cd).

Annual Development Performance of Fixed Honeybee Colonies linked with Chemical and Mineral Profile of Bee Collected Pollen

Climate change affects plant phenology and, as a result, can damage nectar and pollen sources, which are the basic needs of bees during flowering. This situation creates nutritional stress for bee colonies in the region. Changing climatic conditions, the use of agricultural lands adversely affects honeybees and beekeepers. The aim of this study is to determine the annual development performance of fixed honeybee colonies linked with the chemical and mineral profile of bee collected pollen. According to the research findings, in terms of colony development parameters, the number of bee frames (9.17) was found to be at the highest level in May, and in terms of brood area (4652.35 cm 2 ) in April (p<0.05). March, April, and May are the most abundant months in terms of pollen collection of the colonies (p<0.05). The pollen samples collected are rich in potassium, sodium, calcium, magnesium, silicon, and iron. There are differences between months in terms of pollen sources and mineral levels. Especially in stationary beekeeping, additional feeding is required during critical periods. The existing flora is insufficient for the future of the honey bee. In periods when the flora is weak, important plants for the honey bee should be grown in the region.

Phytochemical content, especially spermidine derivatives, presenting antioxidant and antilipoxygenase activities in Thai bee pollens

Background

Bee pollen (BP) is full of useful nutrients and phytochemicals.Its chemical components and bioactivities depend mainly on the type of floral pollen.

Methods

Monofloral BP from Camellia sinensis L., Mimosa diplotricha, Helianthus annuus L., Nelumbo nucifera, Xyris complanata, and Ageratum conyzoides were harvested. Crude extraction and partition were performed to yield solvent-partitioned extracts of each BP. Total phenolic content (TPC) was assayed by the Folin-Ciocalteu method, while the flavonoid content (FC) was measured by the aluminium chloride colorimetric method. Antioxidant capacity was measured by the (i) 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, (ii) 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) scavenging activity and its Trolox equivalent antioxidant capacity (TEAC), and (iii) ferric reducing antioxidant power (FRAP). All samples were tested for lipoxygenase inhibitory (LOXI) activity. The most active sample was enriched by silica gel 60 column chromatography (SiG60-CC) and high performance liquid chromatography (HPLC), observing the chemical pattern of each fraction using thin layer chromatography. Chemical structure of the most active compound was analyzed by proton nuclear magnetic resonance and mass spectrometry.

Results

Dichloromethane (DCM)-partitioned BP extracts of H. annuus L. and M. diplotricha (DCMMBP) showed a very high TPC, while DCMMBP had the highest FC. In addition, DCMMBP had the strongest DPPH and ABTS radical scavenging activities (as a TEAC value), as well as FRAP value. Also, DCMMBP (60 µg/mL) gave the highest LOXI activity (78.60 ± 2.81%). Hence, DCMMBP was chosen for further enrichment by SiG60-CC and HPLC. Following this, the most active fraction showed higher antioxidant andLOXI activities with an EC₅₀ for DPPH and ABTS of 54.66 ± 3.45 µg/mL and 24.56 ± 2.99 µg/mL (with a TEAC value of 2,529.69 ± 142.16 µmole TE/g), respectively, and a FRAP value of 3,466.17 ± 81.30 µmole Fe²⁺/g and an IC₅₀ for LOXI activity of 12.11 ± 0.36 µg/mL. Triferuloyl spermidines were revealed to be the likely main active components.

Conclusions

TPC, FC, and spermidine derivatives played an important role in the antioxidant and antilipoxygenase activities in M. diplotricha bee pollen.

Bee pollens as biological indicators: An ecological assessment of pollution in Northern Turkey via ICP-MS and XPS analyses

In this study, pollens were collected from 25 different locations of Northern Turkey to investigate pollution monitoring. Surface chemistry of pollen samples was characterized by X-ray photoelectron spectroscopy (XPS). Then the concentrations of certain elements (Li, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Ba, and Pb) in pollen samples were determined by inductively coupled plasma mass spectrometry (ICP-MS) for the evaluation of environmental pollution. The levels of elements were detected in the following ranges (minimum-maximum, mg/kg dry pollen): Li (0.18-0.39), Al (24.98-308.04), V (6.18-98.58), Cr (1.05-6.81), Mn (13.85-95.91), Fe (52.20-326.26), Co (0.15-0.34), Ni (1.66-10.79), Cu (8.61-19.01), Zn (20.47-70.02), As (1.22-2.65), Se (0.39-0.67), Cd (0.05-0.74), Ba (0.73-16.30), and Pb (0.00-0.26). It has been concluded that there is a correlation between the pollen samples with high heavy metal concentrations and traffic density as these regions are closer to the road in the northern region. It is exposed to pollution from various sources such as intensified urbanization and tourism activities carried out on land and sea; industrial activities are increasing rapidly due to the opportunities offered by the coastal areas, sea transportation, and agricultural, domestic, and industrial pollution coming from the inner regions through rivers and streams. In this sense, pollens can be used as potential bio-indicators for monitoring heavy metal pollution and gives an idea about how we can use them for future assessing purposes.

Wild Bee Nutritional Ecology: Integrative Strategies to Assess Foraging Preferences and Nutritional Requirements

Bees depend on flowering plants for their nutrition, and reduced availability of floral resources is a major driver of declines in both managed and wild bee populations. Understanding the nutritional needs of different bee species, and how these needs are met by the varying nutritional resources provided by different flowering plant taxa, can greatly inform land management recommendations to support bee populations and their associated ecosystem services. However, most bee nutrition research has focused on the three most commonly managed and commercially reared bee taxa—honey bees, bumble bees, and mason bees—with fewer studies focused on wild bees and other managed species, such as leafcutting bees, stingless bees, and alkali bees. Thus, we have limited information about the nutritional requirements and foraging preferences of the vast majority of bee species. Here, we discuss the approaches traditionally used to understand bee nutritional ecology: identification of floral visitors of selected focal plant species, evaluation of the foraging preferences of adults in selected focal bee species, evaluation of the nutritional requirements of focal bee species (larvae or adults) in controlled settings, and examine how these methods may be adapted to study a wider range of bee species. We also highlight emerging technologies that have the potential to greatly facilitate studies of the nutritional ecology of wild bee species, as well as evaluate bee nutritional ecology at significantly larger spatio-temporal scales than were previously feasible. While the focus of this review is on bee species, many of these techniques can be applied to other pollinator taxa as well.

New Insights into Potential Beneficial Effects of Bioactive Compounds of Bee Products in Boosting Immunity to Fight COVID-19 Pandemic: Focus on Zinc and Polyphenols

The coronavirus disease 2019 (COVID-19) is an epidemic caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2). Populations at risk as well as those who can develop serious complications are people with chronic diseases such as diabetes, hypertension, and the elderly. Severe symptoms of SARS-CoV-2 infection are associated with immune failure and dysfunction. The approach of strengthening immunity may be the right choice in order to save lives. This review aimed to provide an overview of current information revealing the importance of bee products in strengthening the immune system against COVID-19. We highlighted the immunomodulatory and the antiviral effects of zinc and polyphenols, which may actively contribute to improving symptoms and preventing complications caused by COVID-19 and can counteract viral infections. Thus, this review will pave the way for conducting advanced experimental research to evaluate zinc and polyphenols-rich bee products to prevent and reduce the severity of COVID-19 symptoms.

Rapid and Accurate Approach for Honeybee Pollen Analysis Using ED-XRF and FTIR Spectroscopy

Since honeybee pollen is considered a “perfectly complete food” and is characterized by many beneficial properties (anti-inflammatory, antioxidant, anti-bacterial, etc.), it has begun to be used for therapeutic purposes. Consequently, there is a high need to develop methods for controlling its composition. A thorough bee pollen analysis can be very informative regarding its safety for consumption, the variability of its composition, its biogeographical origin, or harvest date. Therefore, in this study, two reliable and non-destructive spectroscopy methods, i.e., ED-XRF and ATR–FTIR, are proposed as a fast approach to characterize bee pollen. The collected samples were derived from apiaries located in west-central Poland. Additionally, some commercially available samples were analyzed. The applied methodology was optimized and combined with sophisticated chemometric tools. Data derived from IR analyses were also subjected to two-dimensional correlation spectroscopy. The developed ED-XRF method allowed the reliable quantification of eight macro- and micro-nutrients, while organic components were characterized by IR spectroscopy. Principal component analysis, cluster analysis, and obtained synchronous and asynchronous maps allowed the study of component changes occurring dependently on the date and location of harvest. The proposed approach proved to be an excellent tool to monitor the variability of the inorganic and organic content of bee pollen.

Multielemental Analysis of Bee Pollen, Propolis, and Royal Jelly Collected in West-Central Poland

Beehive products possess nutritional value and health-promoting properties and are recommended as so-called "superfoods". However, because of their natural origin, they may contain relevant elemental contaminants. Therefore, to assess the quality of bee products, we examined concentrations of a broad range of 24 selected elements in propolis, bee pollen, and royal jelly. The quantitative analyses were performed with inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES) techniques. The results of our research indicate that bee products contain essential macronutrients (i.e., K, P, and S) and micronutrients (i.e., Zn and Fe) in concentrations depending on the products' type. However, the presence of toxic heavy metals makes it necessary to test the quality of bee products before using them as dietary supplements. Bearing in mind that bee products are highly heterogenous and, depending on the environmental factors, differ in their elemental content, it is necessary to develop standards regulating the acceptable levels of inorganic pollutants. Furthermore, since bees and their products are considered to be an effective biomonitoring tool, our results may reflect the environment's condition in west-central Poland, affecting the health and well-being of both humans and bees.

Investigation of Concentration and Distribution of Elements in Three Environmental Compartments in the Region of Mitrovica, Kosovo: Soil, Honey and Bee Pollen

The abundances of selected elements in different environmental compartments, namely soil, honey, and bee pollen, was determined in this study. For that purpose, sixteen soil and honey samples, and nine pollen samples were taken in the region of Mitrovica, Kosovo. The concentration of elements was measured by ICP-AES and ICP-MS. Pollution level concentrations of Pb, Zn, As, and Cd were observed in soil. The level of soil pollution was estimated by calculating pollution indices. Pb was also observed at high concentrations in honey, as was Cd and Pb in pollen. Pearson’s correlation coefficients revealed mostly weak and moderate correlations of the concentrations of the eight selected elements among the soil, honey, and pollen samples. Several groups of elements with geogenic and anthropogenic origin were identified by hierarchical cluster analysis. The concentrations of selected heavy metals for soil and honey were compared to those in neighboring countries, and those for pollen with samples from Turkey, Serbia, and Jordan.

Chemical constituents and phytochemical properties of floral maize pollen

Currently, bee-gathered pollen (bee pollen) is commonly used worldwide as a dietary supplement and is recognized for its curative properties. Floral pollen is also important but is less recognized due to a lack of investigation. This study aims to determine the morphological characteristics and nutritional and phytochemical properties of floral maize pollen. Fresh pollen grains harvested from a farm of maize plants are yellow in colour and spheroid in shape. They change to amber and indented prismatic solid shapes when dehydrated. The main composition of floral maize pollen is carbohydrates (44.30±3.73%), followed by moisture (23.38±5.73%), crude proteins (17.16±3.13%), crude fibres (9.56±0.92%), and ash (4.98±0.11%), while the lowest content is observed for crude fats (0.62±0.06%). The predominant mineral is potassium (768.50±11.40 mg 100 g-1), followed by sodium (695.10±9.70 mg 100 g-1), calcium (147.20±12.60 mg 100 g-1), and magnesium (97.30±2.9 mg 100 g-1). The microelements (with average values) consist of iron (49.50±3.30 mg 100 g-1) and zinc (30.00±3.70 mg 100 g-1). Excellent phytochemical properties add value to floral maize pollen. Maize pollen contains a high total phenolic content (TPC) and total flavonoid content (TFC) of 783.02 mg GAE 100 g-1 and 1706.83 mg QE 100 g-1, respectively, and possesses strong antioxidant activity of 10.54 mg mL-1. Maize floral pollen and derived products can serve as future food resources for human consumption and as a source of functional and bioactive compounds in nutraceutical and pharmaceutical industries.

Moroccan Monofloral Bee Pollen: Botanical Origin, Physicochemical Characterization, and Antioxidant Activities

In this study, eight monofloral bee pollen samples were collected from different apiaries in Morocco. Botanical origins of the bee pollen samples were determined by scanning electron microscopy (SEM), and the physicochemical parameters (pH, moisture, ash, and the mineral contents) were determined. Total phenolic, flavones/flavonols contents were evaluated, and the antioxidant potential was assessed using total antioxidant capacity, DPPH, ABTS, and reducing power assays. Data showed that pH, moisture, and ash content values ranged between 4.19 ± 0.17 and 4.82 ± 0.36, 10.7 ± 0.04% and 26.8 ± 0.01%, and 1.81 ± 0.10% and 4.22 ± 0.08%, respectively. Potassium and magnesium were the most abundant minerals in bee pollen samples; heavy metals were not detected except for two samples (P5 and P6) where a very small amount of lead was found. The protein content in these samples varied between 19.86 ± 0.36 mg/100 g and 30.32 ± 0.12 mg/100 g of bee pollen. The phenolic content, flavones/flavonols content, and total antioxidant capacity were 21.87 ± 1.80 mgEAA/g, 2.37 ± 0.16 mgEAA/g, and 6.23 ± 0.21 mgEAA/g, respectively. High scavenging activity of DPPH and ABTS radicals was found in P2 with the lower IC50 of 0.245 ± 0.009 mg/ml and 0.19 ± 0.005 mg/ml, respectively. The lower EC50 was 0.133 ± 0.036 mg/ml found in P1 for the reducing power test. The current study is considered to be the first step to the standardization of Moroccan bee pollen.

Phytochemicals, mineral contents, antioxidants, and antimicrobial activities of propolis produced by Brunei stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami

The present study focused on the evaluation of phytochemical properties, essential mineral elements, and heavy metals contained in raw propolis produced by stingless bees Geniotrigona thoracica, Heterotrigona itama, and Tetrigona binghami found in the same ecological conditions and environment in Brunei Darussalam. The results indicated that propolis of the three stingless bee species mainly consisted of lipids (45.60–47.86%) and very low carbohydrate (0.17–0.48%) and protein contents (0.18–1.18%). The propolis was rich in mineral elements, thus good sources of minerals, while they contained low concentrations of all heavy metals. Propolis of the different bee species could be distinguished based on their mineral compositions. The vibrational and absorption spectra suggested that propolis contains π-conjugated aliphatic and aromatic compounds as well as aromatic acids having amine, ester, carbonyl, alkyl, and hydroxyl functional groups which might be attributed to the presence of phenolic and flavonoid compounds. The antioxidant capacity of the propolis, based on radical scavenging activity of their ethanol extract, was in line with their total phenolic content. The ethanol extract of the propolis also showed antimicrobial activities against four bacterial strains (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa). The propolis showed slightly higher antibacterial activity against Gram-positive (B. subtilis and S. aureus) bacteria, indicating that the antimicrobial active compounds could be associated with flavonoids, which were quantified to be approximately comparable in all the propolis.

Room temperature solvent extraction for simple and fast determination of total concentration of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen by FAAS along with assessment of the bioaccessible fraction of these elements using in vitro gastrointestinal digestion

BACKGROUND AND AIM

Bee pollen is recognized to be a source of different nutrients, including minerals. As a food supplement, its quality and safety due to concentrations of essential macro- and microelements, and harmful trace elements has to be verified. Fast and simple element analysis of bee-collected pollen can be regarded as an important part of its quality assurance and control. The present study aimed at developping a new method for determination of selected elements (Ca, Cu, Fe, Mg, Mn, Zn) of bee pollen based on solvent extraction and completely avoiding a high temperature treatment with concentrated reagents. In addition, in vitro gastrointestinal digestion was used to assess bioavailability of elements from this food supplement.

METHODS

Bee pollen samples were dried and pulverized. Total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn were determined by flame atomic absorption spectrometry (FAAS) in sample solutions obtained by wet digestion (WD) in concentrated HNO₃ or alternatively by solvent extraction (SE) with diluted solutions of HNO₃. Gastrointestinal digestion was mimicked using simulated solutions of gastric and intestinal juices followed by determination of Ca, Cu, Fe, Mg, Mn and Zn concentrations in the bioaccessible fraction by FAAS.

RESULTS

A new simple and fast method for determination of total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen was developed and validated. The method combined room temperature, two-hour SE with 0.5 mol L^-1 HNO₃ with FAAS measurements versus simple standard solutions. It provided precision within 1-5 % and trueness better than 8%, and was shown to be suitable for fast analysis of different polyfloral bee pollens. In vitro gastrointestinal digestion revealed that elements were well (70-85 % for Ca, Mg) and fairly (27-43 % for Cu, Fe, Mn, and Zn) bioaccessible from bee pollen. By pouring with water and swelling overnight, bioaccessibility of studied elements from such prepared bee pollen was increased on average by less than 15 % (Mn), 20 % (Ca, Cu, Fe, Zn) or 30 % (Mn).

CONCLUSIONS

Avoiding long-lasting, high-temperature wet digestion with concentrated reagents, the proposed sample treatment along with FAAS provided precise and true results of total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen. The method was simple and fast, and enabled to analyze a higher number of samples. Simulated gastrointestinal digestion of bee pollen have shown for the first time that Ca and Mg are the most bioaccessible from this bee product. Bioaccessibility of Cu, Fe, Mg, and Zn from bee pollen are close to or lower than 40 %.

Macro- and trace elements content in honeybee pollen loads in relation to the harvest season

The content of macro-and trace elements in honeybee pollen loads collected from the Al-Ahsa oasis, Saudi Arabia during spring, summer, autumn, and winter in 2018/2019 were determined. After critical screening and observation, we found that the major pollen floral resources were rapeseed, sunflower, summer squash, and date palm. The highest values of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P) and manganese (Mn) were found in pollen loads trapped during spring and winter. The highest levels of copper (Cu) and iron (Fe) were found from pollen loads harvested during autumn, while the highest content of zinc (Zn) was found in pollen loads collected during the summer. Higher concentrations of the essential elements (Na, K, Ca, Mg and P) for human nutrition found in pollen loads collected during the spring and winter seasons, make them valuable food supplements. Finally, the elements contained in pollen loads can be related to the season of pollen load collection.

Botanical Origin and Nutritional Values of Bee Bread of Stingless Bee (Heterotrigona itama) from Malaysia

Bee bread is the bee-collected pollen with the mixture of honey and bee salivary enzymes, stored inside the bee hive. Malaysia has limited information on bee bread collected by the stingless bee Heterotrigona itama. Therefore, this study aims to determine the botanical origin and nutritional values of bee bread from H. itama. Melissopalynological analysis was performed using scanning electron microscopy (SEM) to determine the bee bread’s botanical origin. The proximate analysis, water activity, sugar profile, amino acid profile, vitamin C content, mineral content, and heavy metal content of the bee bread were analyzed. From the results obtained, Bidens pilosa was found in bee bread from all sampling locations. Bee bread contained high protein (21.70–23.33%) and carbohydrate (57.06–58.89%) contents. Glucose was the predominant sugar found (average 11.499 g/100 g). Eight essential amino acids were quantified, and arginine was detected the highest. The major mineral element in the bee bread was potassium (average 6705.9 mg/kg), followed by phosphorus and magnesium. Toxic metals such as lead, mercury, cadmium, and arsenic were detected but within the safe limits permitted in food. The data obtained contribute towards expanding the knowledge on the nutritional information specifically for H. itama bee bread in Malaysia.

The Application of Pollen as a Functional Food and Feed Ingredient-The Present and Perspectives

Pollen is recognized as an excellent dietary supplement for human nutrition, which is why it can be found in different forms on the market (granules, capsules, tablets, pellets, and powders). But, the digestibility of pollen’s nutrients is strongly affected by the presence of a pollen shell, which can decrease the bioavailability of nutrients by 50% and more. Since consumers have become more aware of the benefits of a healthy diet and the necessity to improve pollen digestibility, different pollen-based functional food products have been developed and extensive studies were done to estimate the beneficial effects of pollen-based feed on animal growth, health, and rigor mortise stage. Considering the positive effects of pollen nutrients and phytometabolites on human and animal health, the aim of this paper was to give an overview of recent achievements in the application of pollen in the formulation of functional food and animal diets. Special attention was paid to the effects of pollen’s addition on the nutritional, functional, techno-functional, and sensory properties of the new formulated food products. Anti-nutritional properties of pollen were also discussed. This review points out the benefits of pollen addition to food and feed and the possible directions in the further development of functional food and feed for the wellbeing of everyone.

Comparison of Physicochemical Properties of Bee Pollen with Other Bee Products

The aim of this study was to compare the physichochemical composition of various bee products, namely, bee pollen, beebread, propolis, honey, and royal jelly. The samples (37 out of 53) were collected in Lithuania, several samples from other Europe countries (Italy, Denmark, Sweden, Slovakia, Poland, Spain, Republic of Malta, The Netherlands, Latvia, Ukraine) were used for comparison. Various quantities, such as pH, electrical conductivity, oxidation-reduction potential, NaCl content, refraction index, Brix value, total phenolic compound content, total flavonoid content and antiradical activity were measured. Together with the mentioned, the content of micro- and macroelements (As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Se, Sr, V and Zn), ultraviolet-visible spectroscopy absorption spectra were analysed. To our knowledge, the literature data about comprehensive comparison of various characteristics of bee products are scarce. Also, to the best of our knowledge, this is the first study revealing mineral content in Lithuanian bee pollen, beebread and royal jelly. The study exposed that bee pollen not only showed the highest values of pH, electrical conductivity and content of soluble solids, but also distinguished from the other samples by the highest flavonoid content (up to 48.3 mg/10 g), the absence of Cr, the presence of Co (0.011–0.100 mg/kg) and Sr (0.73–5.37 mg/kg) and the highest content of Ca (997–2455 mg/kg) and Mg (644–1004 mg/kg). Hierarchical clustering analysis was applied to group the tested samples according to the physicochemical analysis results and mineral content. The clustering analysis revealed that bee pollen formed separate group with the highest distance from the other samples in both cases.

Phenolic Composition Influences the Health-Promoting Potential of Bee-Pollen

Information on compositional, nutritional and functional properties of bee-pollen, as a health-promoting food, is essential for defining its quality. Concerning the nutritional importance of phenolic compounds, the aim of this study was to determine the phenolic profile and antioxidant activity of twenty-four bee-pollen samples collected from different regions of Serbia. High-performance thin-layer chromatographic (HPTLC) fingerprinting was used for profiling of bee-pollen samples according to the botanical type. HPTLC hyphenated with image analysis and a pattern recognition technique confirmed the grouping of samples caused by the specific phenolic composition of pollens of different botanical origin. Flavonoid glycosides in bee-pollen samples were identified by applying ultra-high-performance liquid chromatography (UHPLC) coupled with linear ion trap-Orbitrap mass spectrometry (LTQ Orbitrap MS). Eight out of twenty-seven flavonol glycosides were identified in bee-pollen samples for the first time. All analyzed bee-pollen samples showed a high number of phenolic compounds which may have therapeutic potential.

Urban honey - the aspects of its safety

To contribute to the development of urban beekeeping, we designed this study to obtain more information about the contamination of urban bee products with toxic metals, polycyclic aromatic hydrocarbons (PAHs), and pesticides. The samples of honey (N=23), pollen (N=13), and floral nectar (N=6) were collected from the experimental stationary apiary of the Belgrade University Faculty of Agriculture located in centre of Zemun (a municipality of the Belgrade metropolitan area) in 2015 and 2016. Metals (Pb, Cd, As, Cu, Zn, Fe, Mn, Ni, Cr, and Hg) were determined with inductively coupled plasma quadrupole mass spectrometry (ICP-QMS). Polycyclic aromatic hydrocarbons (PAHs) were analysed with high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Pesticides were analysed with gas chromatography - mass spectrometry (GC-MS). The honey samples were generally within the European and Serbian regulatory limits. The levels of all the 123 analysed pesticides were below the limit of quantification (LOQ). Regarding PAH levels in honey, the highest content was found for naphthalene. The elevated levels of Hg and Cr and of PAHs in the pollen samples indicated air pollution. Pesticide residues in pollen, however, were below the LOQ. In nectar, metal levels were relatively similar to those in honey. Our results suggest that the investigated urban honey meets the regulatory requirements for metals, PAHs, and pesticides and is therefore safe for consumption.

Mycotoxins and Mycotoxin Producing Fungi in Pollen: Review

Due to its divergent chemical composition and good nutritional properties, pollen is not only important as a potential food supplement but also as a good substrate for the development of different microorganisms. Among such microorganisms, toxigenic fungi are extremely dangerous as they can synthesize mycotoxins as a part of their metabolic pathways. Furthermore, favorable conditions that enable the synthesis of mycotoxins (adequate temperature, relative humidity, pH, and aw values) are found frequently during pollen collection and/or production process. Internationally, several different mycotoxins have been identified in pollen samples, with a noted predominance of aflatoxins, ochratoxins, fumonisins, zearalenone, deoxynivalenol, and T-2 toxin. Mycotoxins are, generally speaking, extremely harmful for humans and other mammals. Current EU legislation contains guidelines on the permissible content of this group of compounds, but without information pertaining to the content of mycotoxins in pollen. Currently only aflatoxins have been researched and discussed in the literature in regard to proposed limits. Therefore, the aim of this review is to give information about the presence of different mycotoxins in pollen samples collected all around the world, to propose possible aflatoxin contamination pathways, and to emphasize the importance of a regular mycotoxicological analysis of pollen. Furthermore, a suggestion is made regarding the legal regulation of pollen as a food supplement and the proposed tolerable limits for other mycotoxins.

Ecological stoichiometry of the honeybee: Pollen diversity and adequate species composition are needed to mitigate limitations imposed on the growth and development of bees by pollen quality

The least understood aspects of the nutritional needs of bees are the elemental composition of pollen and the bees' need for a stoichiometrically balanced diet containing the required proportions of nutrients. Reduced plant diversity has been proposed as an indirect factor responsible for the pollinator crisis. We suggest stoichiometric mismatch resulting from a nutritionally unbalanced diet as a potential direct factor. The concentrations and stoichiometric ratios of C, N, S, P, K, Na, Ca, Mg, Fe, Zn, Mn, and Cu were studied in the bodies of honeybees of various castes and sexes and in the nectar and pollen of various plant species. A literature review of the elemental composition of pollen was performed. We identified possible co-limitations of bee growth and development resulting mainly from the scarcity of Na, S, Cu, P and K, and possibly Zn and N, in pollen. Particular castes and sexes face specific limitations. Concentrations of potentially limiting elements in pollen revealed high taxonomic diversity. High floral diversity may be necessary to maintain populations of pollen eaters. Single-species crop plantations, even if these species are rich in nectar and pollen, might limit bee growth and development, not allowing for gathering nutrients in adequate proportions. However, particular plant species may play greater roles than others in balancing honeybee diets. Therefore, we suggest specific plant species that may (1) ensure optimal growth and production of individuals by producing pollen that is exceptionally well balanced stoichiometrically (e.g., clover) or (2) prevent growth and development of honeybees by producing pollen that is extremely unbalanced for bees (e.g., sunflower). Since pollen is generally poor in Na, this element must be supplemented using "dirty water". Nectar cannot supplement the diet with limiting elements. Stoichiometric mismatch should be considered in intervention strategies aimed at improving the nutritional base for bees.

Preliminary investigation of mineral content of pollen collected from different Serbian maize hybrids - is there any potential nutritional value?

BACKGROUND

Bee pollen has already proved to be a good supplement rich in iron and zinc. Studies on the application of flower pollen in the food industry and medicine have begun. Bearing in mind the prevalence of maize as a crop culture, its pollen will be easily available. The mineral composition of pollen of seven Serbian maize hybrids was analyzed in order to establish its nutritional value and the benefits of its implementation in the human diet using the inductively coupled plasma method.

RESULTS

The presence of twenty four different macro- (nine) and micronutrients (fifteen) was detected. The most common minerals were phosphorus and potassium, while arsenic, cobalt, lead, nickel and molybdenum were found in some samples.

CONCLUSION

Comparing the results obtained with recommended or tolerable dietary intake references for adults, it was found that maize pollen can be used as a very good source of zinc, iron, chromium and manganese for humans. With regard to selenium content, pollen samples proved to be moderately good source of this important micronutrient. Contents of some elements (Fe, Zn, Mn, Cr, Se, Al and V) showed significant differences depending on hybrid type. In some samples increased concentrations of aluminum and vanadium were recorded, which may pose a potential problem due to their toxicity. © 2016 Society of Chemical Industry.