The Biodiversity of Edible Flowers: Discovering New Tastes and New Health Benefits

Flower Species Ingredient Verification Using Orthogonal Molecular Methods

Flowers are gaining considerable interest among consumers as ingredients in food, beverages, cosmetics, and natural health products. The supply chain trades in multiple forms of botanicals, including fresh whole flowers, which are easier to identify than dried flowers or flowers processed as powdered or liquid extracts. There is a gap in the scientific methods available for the verification of flower species ingredients traded in the supply chains of multiple markets. The objective of this paper is to develop methods for flower species ingredient verification using two orthogonal methods. More specifically, the objectives of this study employed both (1) DNA-based molecular diagnostic methods and (2) NMR metabolite fingerprint methods in the identification of 23 common flower species ingredients. NMR data analysis reveals considerable information on the variation in metabolites present in different flower species, including color variants within species. This study provides a comprehensive comparison of two orthogonal methods for verifying flower species ingredient supply chains to ensure the highest quality products. By thoroughly analyzing the benefits and limitations of each approach, this research offers valuable insights to support quality assurance and improve consumer confidence.

Simultaneous Determination of 23 Pyrrolizidine and Tropane Alkaloids in Infusions from Dry Edible Flowers Using Optimized μSPEed® Microextraction Prior to Their Analysis by UHPLC-IT-MS/MS

A miniaturized solid-phase extraction of two tropane alkaloids (TAs) and twenty-one pyrrolizidine alkaloids (PAs) from infusions of dry edible flowers using optimized µSPEed® technique was developed. The optimization of the µSPEed® methodology involved testing different cartridges and comparing various volumes and numbers of loading cycles. The final conditions allowed for a rapid extraction, taking only 3.5 min. This was achieved using a C18-ODS cartridge, conditioning with 100 µL of methanol (two cycles), loading 100 µL of the infusion sample (seven cycles), and eluting the analytes with 100 µL of methanol (two cycles). Prior to their analysis by UHPLC-IT-MS/MS, the extracts were evaporated and reconstituted in 100 µL of water (0.2% formic acid)/methanol (0.2% ammonia) 95:5 (v/v), allowing for a preconcentration factor of seven times. The methodology was successfully validated obtaining recoveries ranging between 87 and 97%, RSD of less than 12%, and MQL between 0.09 and 0.2 µg/L. The validated methodology was applied to twenty samples of edible flower infusions to evaluate the safety of these products. Two infusion samples obtained from Acmella oleracea and Viola tricolor were contaminated with 0.16 and 0.2 µg/L of scopolamine (TA), respectively, while the infusion of Citrus aurantium was contaminated with intermedine and lycopsamine (PAs) below the MQL.

Characterization of the aroma profile of edible flowers using HS-SPME/GC-MS and chemometrics

In recent years the consumption of edible flowers has gained new popularity, and their use seems destined to grow thanks to their potential as functional elements and their ability to impart aroma to traditional foods. In this study, the volatile profile of several edible flowers was investigated to identify characteristic compounds to be used as product markers. 85 samples belonging to four cultivars were analyzed by HS-SPME/GC-MS. A PLS-DA was used to build a model capable of differentiating the investigated classes. The resulting model correctly predicted over 95% of the validation samples, highlighting a significant difference between the four types of edible flowers. The VIP analysis highlighted 29 compounds relevant for the characterization of different flowers, many of which were biologically active. The study aims to broaden the framework of objectively measurable tools useful for enhancing the qualitative peculiarity of one product compared to another and offering growth opportunities to emerging food chains.

First Insights on the Bioaccessibility and Absorption of Anthocyanins from Edible Flowers: Wild Pansy, Cosmos, and Cornflower

Edible flowers are regaining interest among both the scientific community and the general population, not only for their appealing sensorial characteristics but also from the growing evidence about their health benefits. Among edible flowers, those that contain anthocyanins are among the most consumed worldwide. However, little is known regarding the bioaccessibility and absorption of their bioactive compounds upon ingestion. The aim of this work was to explore, for the first time, the behavior of anthocyanin-rich extracts from selected edible flowers under different food processing conditions and after ingestion using simulated digestions, as well as their absorption at the intestinal level. Overall, the results showed that the monoglucoside and rutinoside anthocyanin extracts were less stable under different pH, temperature, and time conditions as well as different digestive processes in the gastrointestinal tract. There was a prominent decrease in the free anthocyanin content after the intestinal phase, which was more pronounced for the rutinoside anthocyanin extract (78.41% decrease from the oral phase). In contrast, diglucoside and rutinoside anthocyanin extracts showed the highest absorption efficiencies at the intestinal level, of approximately 5% after 4 h of experiment. Altogether, the current results emphasize the influence of anthocyanins' structural arrangement on both their chemical stability as well as their intestinal absorption. These results bring the first insights about the bioaccessibility and absorption of anthocyanins from wild pansy, cosmos, and cornflower and the potential outcomes of such alternative food sources.

Farming system impacts the bioactive compounds, microbial diversity, aroma and color in edible red mini-roses (Rosa chinensis Jacq.)

Mini-roses (Rosa chinensis Jacq.) is largely used in salty dishes and desserts. This study evaluated instrumental color, sugars, organic acids, phenolics, volatiles, and the indigenous microbiota (fungi and bacteria) in edible mini-roses farmed in discarded fruits biocompost and animal manure systems. A descriptive sensory analysis of flowers was also performed. Mini-roses farmed in biocompost had higher luminosity and intensity of instrumental red color, a higher concentration of phenolic compounds, including anthocyanins related to red color, and fructose than mini-roses farmed in animal manure (p < 0.05). Furthermore, mini-roses farmed in biocompost had higher concentrations of various volatiles (p < 0.05), including hexyl acetate and cis-3 -hexenyl butyrate related to the fruity aroma. Bacterial groups related to plant growth-promoting such as Stenotrophomonas and endophilic fungal groups such as Eurotiales sp, Pleosporales sp were found in higher abundance (p < 0.05) in mini-roses farmed in biocompost. Mini-rose farmed in biocompost also received higher score (p < 0.05) for fruity aroma and red color than mini-rose mini-roses farmed in animal manure. Results indicate that farming mini-roses using biocompost from discarded fruits impacts the synthesis of phenolics and volatiles, resulting in a more intense fruity aroma and red color. Findings also suggest that the microbiota of mini-roses farmed in biocompost or animal manure do not represent a major risk for the safety of these products.

Ethnobotanical study on edible flowers in Xishuangbanna, China

BACKGROUND

Edible flowers (EFs) represent valuable sources of both food and medicinal resources, holding the promise to enhance human well-being. Unfortunately, their significance is often overlooked. Ethnobotanical studies on the EFs are lacking in comparison with their botanical and phytochemical research. The practice of consuming flowers as food has a rich culture and long history in China, especially among different linguistic groups in Xishuangbanna, Yunnan. However, economic activities have led to a decline of this tradition. Consequently, preserving the traditional knowledge and culture tied to the EFs in Xishuangbanna becomes both essential and pressing.

METHODS

The field ethnobotanical survey was conducted in Xishuangbanna during five visits in April 2021 and May 2023, covering 48 villages and 19 local markets of all three county-level areas and 9 different linguistic groups. By conducting a comprehensive literature review and on-site field surveys, relevant information regarding the EFs of Xishuangbanna was systematically collected and documented. Additionally, the relative frequency of citation (RFC) values were calculated from the survey data.

RESULTS

A total of 212 taxa (including species and varieties) of EFs from 58 families and 141 genera were documented in the study area. The edible parts of flowers were classified into 13 categories including peduncle, petal, flower buds, inflorescence as a whole, and etc. They were consumed in 21 ways and as 8 types of food. The inflorescence was the most commonly consumed category, accounting for 85 species (40.1%) of the total categories. They always eat flowers as vegetables (184 species, 86.8%). The preparing form of stir-frying was the preferred food preparation method (138, 65.1%). The Xishuangbanna locals had profound knowledge of which EFs required specific processing to remove their toxicity or bitterness. The dishes can be made from either exclusively from the flowers themselves or by incorporating them alongside other plant parts like stems and leaves. Some EFs with high RFC value, such as Musa acuminata and Bauhinia variegata var. candida, showed significant cultural meanings. These edible flowers occupy specific positions in local traditional culture.

CONCLUSION

Traditional knowledge regarding edible flowers holds substantial significance and serves as a representative element of the flower-eating culture in Xishuangbanna. Nevertheless, this knowledge and cultural practice are currently decreasing. Serving as a bridge between tradition and modernity, the flower-eating culture, which derives from local people's practical experience, shows the potential of EFs and can be applied to the conservation of biocultural diversity, healthy food systems, and sustainable development.

A comparative metabolomics investigation of flavonoid variation in faba bean flowers

INTRODUCTION

Faba bean (Vicia faba L.) flowers are edible and used as garnishes because of their aroma, sweet flavor and attractive colors. Anthocyanins are the common plant pigments that give flowers their vivid colors, whereas non-anthocyanin flavonoids can serve as co-pigments that can modify the color intensity of flowers.

OBJECTIVES

To explore the polyphenol diversity and differences in standard and wing petals of faba bean flowers; and identify glycosylated flavonoids that contribute to flower color.

METHODS

Flower standard and wing petals from 30 faba bean genotypes (eight color groups with a total of 60 samples) were used for polyphenol extraction. Samples were analyzed using a targeted method and a semi-untargeted analysis using liquid chromatography-high resolution mass spectrometry (LC-HRMS) combined with photodiode array (PDA) detection. Compound Discoverer software was used for polyphenol identification and multivariate analysis.

RESULTS

The semi-untargeted analysis guided by the PDA detected 90 flavonoid metabolites present in faba bean flower petals. Ten anthocyanins largely influenced the flower colors, but other flavonoids (63 flavonols and 12 flavones) found with variable levels in different flower color groups appeared to also influence color, especially in mixed colors.

CONCLUSION

Analysis of the different colored faba bean flowers confirmed that the color variation between the flowers was mainly controlled by anthocyanins in brown, red and purple-red flowers. Of the other flavonoids, multiglycosylated kaempferols were abundant in white and brown flowers, monoglycosylated kaempferols were common in red and purple-red flowers, and quercetin and apigenin glycosides were abundant co-pigments in purple-red flowers.

Widely targeted metabolomics reveals the antioxidant and anticancer activities of different colors of Dianthus caryophyllus

Carnation is edible flower that has potent antioxidant properties and is used in traditional Chinese medicinal system and food industry. The phytochemicals responsible for these various proprieties, however, are not fully understood. Thus, in order to recognize metabolite diversity and variability in carnation flowers of different colors and to discover key metabolites that contribute to the differences in antioxidant and anticancer activities, widely targeted LC-MS/MS-based metabolomics analysis was conducted on purple, green, yellow, and white carnation flowers. We identified and chemically categorized 932 metabolites. Metabolic compounds varied significantly with flower color. Several flavonoids, organic acids, phenolic acids, and nucleotides and their derivatives were found to be specific differential metabolites in purple flowers. A total of 128 key differential metabolites were screened. The purple flowers were found to have the highest antioxidant and anticancer activities compared to the other colored flowers. Correlation analysis revealed that the 6-hydroxykaempferol-3,6-O-diglucoside, 6-hydroxykaempferol-7-O-glucoside, quercetin-3-O-sophoroside, and 2'-deoxyguanosine were found to be the major constituents of the antioxidant and anticancer activities. 2'-Deoxyguanosine has effective antiproliferative activity against A549 and U2OS cells for the first report. At the same time, the combination of 2'-deoxyguanosine with 6-hydroxykaempferol-3, 6-O-diglucoside, or quercetin-3-O-sophoroside have also been found to increase the antitumor activity of 2'-deoxyguanosine. These discoveries enrich information on the phytochemical composition of carnation of different colors and provide resources for the overall use and improvement of carnation flowers quality.

Flowers and Inflorescences of Selected Medicinal Plants as a Source of Triterpenoids and Phytosterols

Steroids and triterpenoids are compounds valued for their various biological and pharmacological properties; however, their content in medicinal and edible plants is often understudied. Flowers have been consumed since the ancient times as a part of traditional cuisine and as alternative medicines. Currently, the interest in medicinal and edible flowers is growing since contemporary consumers are incessantly seeking innovative natural sources of bioactive compounds. The aim of this report was the GC-MS (gas-chromatography-mass spectrometry) analysis of steroid and triterpenoid content in flowers, inflorescences and leaves of several plants (Berberis vulgaris L., Crataegus laevigata (Poir.) DC., Pulsatilla vulgaris Mill., Rosa rugosa Thunb., Sambucus nigra L. and Vinca minor L.), applied in herbal medicine in various forms, including isolated flowers (Flos), inflorescences (Inflorescentia) or aerial parts (Herba, i.e., combined flowers, leaves and stems). The most abundant source of triterpenoids was V. minor flowers (6.3 mg/g d.w.), whereas the steroids were prevailing in P. vulgaris flowers (1.8 and 1.1 mg/g). The profiles of triterpenoid acids and neutral triterpenoids in C. laevigata and S. nigra inflorescences were particularly diverse, involving compounds belonging to lupane-, oleanane- and ursane-type skeletons. The obtained results revealed that some flowers can constitute an abundant source of phytosterols and bioactive triterpenoids, valuable for utilization in functional foods, dietary supplements and cosmetic products.

Edible Flowers Used in Some Countries of the Mediterranean Basin: An Ethnobotanical Overview

Edible flowers are becoming an essential component of people's nutrition in the Mediterranean basin. In the last decades, many researchers also have focused their attention on the nutritional composition of the edible flowers, as well as their antioxidant and antimicrobial properties, including studies on their safety issues. Despite the growing interest in the use of flowers in human nutrition, the ethnobotanical literature is lacking coverage of some important issues, particularly those which concern the use of flowers in the folk tradition. Only recently, a review regarding the contribution of 32 edible flowers to the Mediterranean diet was published. The aim of the present review is to document the plant lore regarding the wild and cultivated edible flowers consumed in the Mediterranean basin. Based on the 112 studies reviewed, we documented 251 taxa as being used in the Mediterranean basin as edible flowers. The plant species belong to 45 families and 141 genera. Asteraceae (54 taxa) is the most frequently cited family. Sambucus nigra L. is the most cited species. This study can be the basis for future research on the supposed bioactivity and toxicity of wild and cultivated flowers.

Identification of the Toxic Compounds in Camellia oleifera Honey and Pollen to Honey Bees (Apis mellifera)

Identifying the components of Camellia oleifera honey and pollen and conducting corresponding toxicological tests are essential to revealing the mechanism of Camellia oleifera toxicity to honey bees. In this research, we investigated the saccharides and alkaloids in honey, nectar, and pollen from Camellia oleifera, which were compared with honey, nectar, and pollen from Brassica napus, a widely planted flowering plant. The result showed that melibiose, manninotriose, raffinose, stachyose, and lower amounts of santonin and caffeine were found in Camellia oleifera nectar, pollen, and honey but not in B. napus nectar, pollen, and honey. Toxicological experiments indicated that manninotriose, raffinose, and stachyose in Camellia oleifera honey are toxic to bees, while alkaloids in Camellia oleifera pollen are not toxic to honey bees. The toxicity mechanism of oligosaccharides revealed by temporal metabolic profiling is that oligosaccharides cannot be further digested by honey bees and thus get accumulated in honey bees, disturbing the synthesis and metabolism of trehalose, ultimately causing honey bee mortality.

Edible Flower Species as a Promising Source of Specialized Metabolites

Eating habits are changing over time and new innovative nutrient-rich foods will play a great role in the future. Awareness of the importance of a healthy diet is growing, so consumers are looking for new creative food products rich in phytochemicals, i.e., specialized metabolites (SM). The consumption of fruits, vegetables and aromatic species occupies an important place in the daily diet, but different edible flower species are still neglected and unexplored. Flowers are rich in SM, have strong antioxidant capacities and also possess significant functional and biological values with favorable impacts on human health. The main aim of this study was to evaluate the content of SM and the antioxidant capacities of the edible flower species: Calendula officinalis L. (common marigold), Tagetes erecta L. (African marigold), Tropaeolum majus L. (nasturtium), Cucurbita pepo L. convar. giromontiina (zucchini) and Centaurea cyanus L. (cornflower). The obtained results showed the highest content of ascorbic acid (129.70 mg/100 g fw) and anthocyanins (1012.09 mg/kg) recorded for cornflower, phenolic compounds (898.19 mg GAE/100 g fw) and carotenoids (0.58 mg/g) for African marigold and total chlorophylls (0.75 mg/g) for common marigold. In addition to the esthetic impression of the food, they represent an important source of SM and thus can have a significant impact if incorporated in the daily diet.

In Vitro and In Silico Studies to Assess Edible Flowers’ Antioxidant Activities

The incorporation of edible flowers in the human diet and culinary preparations dates back to ancient times. Nowadays, edible flowers have gained great attention due to their health-promoting and nutritive effects and their widespread acceptance by consumers. Therefore, edible flowers are ideal candidates for use in the design and development of functional foods and dietary supplements, representing a new and promising trend in the food industry. Thus, the present study attempts to assess the potential of various edible flowers against oxidative stress by applying a combination of in vitro, in silico and spectroscopic techniques. Specifically, the spectroscopic profiles of edible flower extracts were evaluated using ATR-FTIR spectroscopy, while their total phenolic contents and antioxidant/antiradical activities were determined spectrophotometrically. The most abundant phytochemicals in the studied flowers were examined as enzyme inhibitors through molecular docking studies over targets that mediate antioxidant mechanisms in vivo. Based on the results, the red China rose followed by the orange Mexican marigold exhibited the highest TPCs and antioxidant activities. All samples showed the characteristic FTIR band of the skeletal vibration of phenolic aromatic rings. Phenolic compounds seem to exhibit antioxidant activity with respect to NADPH oxidase, myeloperoxidase (MP), cytochrome P450 and, to a lesser extent, xanthine oxidase (XO) enzymes.

Impact of Drying Conditions on Antioxidant Activity of Red Clover (Trifolium pratense), Sweet Violet (Viola odorata) and Elderberry Flowers (Sambucus nigra)

Flowers of red clover (Trifolium pratense), sweet violet (Viola odorata) and elderflowers (Sambucus nigra) were dried by means of air drying at 30 °C and 50 °C and by freeze drying. The content of polyphenols was determined using the Folin–Ciocalteu reagent, while anthocyanins were quantified by the pH differential method. Antioxidant activities of aqueous and ethanolic extracts of the dried flowers were measured by the DPPH and ABTS assays, as well as FRAP and reducing power methods. The highest amount of polyphenols was determined in the ethanolic extracts of fresh red clover flowers (854.76 mg/100 g), while the highest concentration of anthocyanins was determined in the aqueous extracts of fresh sweet violet flowers (99.41 mg/100 g). The results showed that, in general, the extracts of red clover flower were characterized by the highest antioxidant activity, while the sweet violet extracts had the poorest antioxidant properties, although these values fluctuated depending on the method used. There was strong correlation between antioxidant activity and TPC (r = 0.9196, FRAP method). In most cases, freeze drying was found to be the best conservation method, retaining well the antioxidant properties of the tested flowers and the compounds determining these properties.

The Compositional Aspects of Edible Flowers as an Emerging Horticultural Product

Edible flowers are becoming very popular, as consumers are seeking healthier and more attractive food products that can improve their diet aesthetics and diversify their dietary sources of micronutrients. The great variety of flowers that can be eaten is also associated with high variability in chemical composition, especially in bioactive compounds content that may significantly contribute to human health. The advanced analytical techniques allowed us to reveal the chemical composition of edible flowers and identify new compounds and effects that were not known until recently. Considering the numerous species of edible flowers, the present review aims to categorize the various species depending on their chemical composition and also to present the main groups of compounds that are usually present in the species that are most commonly used for culinary purposes. Moreover, special attention is given to those species that contain potentially toxic or poisonous compounds as their integration in human diets should be carefully considered. In conclusion, the present review provides useful information regarding the chemical composition and the main groups of chemical compounds that are present in the flowers of the most common species.

Phytochemicals and Volatiles in Developing Pelargonium ‘Endsleigh’ Flowers

Rose-scented geranium (Pelargonium sp.) have been the subject of many studies concerning essential oil, unlike the edible flowers of scent Pelargonium despite the beneficial properties of chemical compounds present in such organ and the fragrances produced. Therefore, we investigated organic compounds, total phenols and the antioxidant activity of the flowers with particular attention to the volatile compounds emitted by flowers of Pelargonium ‘Endsleigh’ at three stages of development. We identified several major phenols and organic compounds that revealed significative difference compared with other Pelargonium flowers, and employing the solid-phase micro extraction (SPME) methodology we determined that the production of volatile compounds decreases during the flower development. In addition, the emission of volatiles is accomplished mainly by the sepals. In conclusion, to use Pelargonium ‘Endsleigh’ flowers, it is important in ensuring that they have not yet opened and that the sepals are in place.

Chemical, Nutritional and Sensory Characteristics of Six Ornamental Edible Flowers Species

Ornamental edible flowers can be used as novel nutraceutical sources with valuable biological properties. The purpose of this study was to establish nutritional, chemical, and sensory characteristics, antioxidant capacity (AC), and the relationship between their bioactive components and AC. The selected flowers Begonia × tuberhybrida, Tropaeolum majus, Calendula officinalis, Rosa, Hemerocallis, and Tagetes patula, can be easily collected due to their larger size. Their methanolic extracts were spectrophotometrically determined for polyphenols, flavonoids, and AC. Mineral elements were analyzed by atomic-absorption spectroscopy; crude protein was quantified by the Kjeldahl method. Eventually, 30 panelists evaluated sensory properties in 11 attributes. In addition, this study may serve to popularize selected blossoms. In flowers the contents of minerals were in this order: K > Ca > P > Mg > Na > Zn > Mn > Fe > Cu > Mo. AC ranged between 4.11 and 7.94 g of ascorbic acid equivalents/kg of fresh mass. The correlation coefficients between AC-total phenolics and AC-total flavonoids were r = 0.73* and r = 0.58*, respectively. It is also possible to observe a strong correlation between mineral elements and bioactive compounds. Hemerocallis was rated as the best and most tasteful; additionally, it exhibited the highest AC, total phenolic and flavonoid contents.