A review on nutritional, bioactive, toxicological properties and preservation of edible flowers

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.

Mixed-Mode Solar Drying and its Effect on Physicochemical and Colorimetric Properties of Zompantle (Erythrina Americana)

A mixed-mode solar drying was developed to evaluate the physicochemical and colorimetric properties of Zompantle (Erythrina americana). A 22-factorial design was used; the operation mode (mesh shade and direct) and airflow (natural convection and forced convection) were established as factors in this design. The initial moisture content in the Zompantle flower was reduced from 89.03% (w.b) to values that ranged from 3.84% to 5.84%; depending on the operation mode of the dryer, the final water activity ranged from 0.25 to 0.33. The Zompantle's components as proteins (4.28%), antioxidant activity (18.8%), carbohydrates (4.83%), fat (0.92%), fiber (3.71%), ash (0.94%), and total soluble solids (3°Brix) increased as the water was evaporated during the drying. The increment in the Zompantle's components depends on the operation mode; in direct mode and natural convection, the proteins, antioxidant activity, carbohydrates, fat, fiber, ash, and total soluble solids were 6.99%, 61.69%, 79.05%, 1.20%, 3.84%, 8.70%, and 45 °Brix, respectively. The total drying efficiency was 14.84% with the direct mode and natural convection (DM-NC) and 17.10% with the mesh shade and natural convection (MS-NC). The Hue angle measures the property of the color; the indirect mode and natural convection keep the hue angle close to the initial value (29.2 °). The initial chroma value of the Zompantle flower was 55.07; the indirect mode and natural convection kept high saturation (37.58); these dry conditions ensured a red color in the dehydrated Zompantle. Dehydrated Zompantle's flowers could have several practical applications, such as an additive in traditional Mexican cuisine.

Nutritional, Fatty Acids, (Poly)phenols and Technological Properties of Flower Powders from Fuchsia hybrida and Alcea rosea

Fuchsia hybrida (pena pena) and Alcea rosea L. (malvagoma) are predominant flowers in the "Horchata" infusion, a traditional beverage in southern Ecuador, to which some medicinal properties are attributed. However, there is very little published information about these two flower species. The current study aimed to obtain two dehydrated powders of these flowers and to determine their chemical composition, physicochemical and technological properties, polyphenols, and fatty acids profile. In both powdered flowers, carbohydrates predominated, with a significant content of dietary fiber and fructose. The fat content was low, mainly comprising polyunsaturated fats (62% pena pena and 52% malvagoma), with a significant presence of omega-3 (C18:3n-3,6,9) and omega-6 (C18:2n-6,9) fatty acids, showing a better n-6/n-3 balance in the malvagoma flowers. Pena pena flowers are highlighted by high anthocyanin and ellagic acid amounts, whereas malvagoma contains a high content of flavanones. In conclusion, the studied powder flowers, could be used in the formulation of new foods or as source of anthocyanins as food colorants.

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.

Comprehensive Analysis of 34 Edible Flowers by the Determination of Nutritional Composition and Antioxidant Capacity Planted in Yunnan Province China

The main purpose of this study was to reveal the nutritional value and antioxidant activity of 34 edible flowers that grew in Yunnan Province, China, through a comprehensive assessment of their nutritional composition and antioxidant indices. The results showed that sample A3 of Asteraceae flowers had the highest total flavonoid content, with a value of 8.53%, and the maximum contents of vitamin C and reducing sugars were from Rosaceae sample R1 and Gentianaceae sample G3, with values of 143.80 mg/100 g and 7.82%, respectively. Samples R2 and R3 of Rosaceae were the top two flowers in terms of comprehensive nutritional quality. In addition, the antioxidant capacity of Rosaceae samples was evidently better than that of three others, in which Sample R1 had the maximum values in hydroxyl radical (^·OH) scavenging and superoxide anion radical (^·O₂^-) scavenging rates, and samples R2 and R3 showed a high total antioxidant capacity and 2,2-diphenyl-1-pyridylhydrazine (DPPH) scavenging rate, respectively. Taken together, there were significant differences in the nutrient contents and antioxidant properties of these 34 flowers, and the comprehensive quality of Rosaceae samples was generally better than the other three families. This study provides references for 34 edible flowers to be used as dietary supplements and important sources of natural antioxidants.

Hibiscus acetosella: An Unconventional Alternative Edible Flower Rich in Bioactive Compounds

The interest in the consumption of edible flowers has increased since they represent a rich source of bioactive compounds, which are significantly beneficial to human health. The objective of this research was to access the bioactive compounds and antioxidant and cytotoxic properties of unconventional alternative edible flowers of Hibiscus acetosella Welw. Ex Hiern. The edible flowers presented pH value of 2.8 ± 0.00, soluble solids content of 3.4 ± 0.0 °Brix, high moisture content of about 91.8 ± 0.3%, carbohydrates (6.9 ± 1.2%), lipids (0.90 ± 0.17%), ashes (0.4 ± 0.0%), and not detectable protein. The evaluation of the scavenging activity of free radicals, such as 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), of the flower extract was better than the results observed for other edible flowers (507.8 ± 2.7 μM TE and 783.9 ± 30.8 μM TE, respectively) as well as the total phenolic composition (TPC) value (568.8 ± 0.8 mg GAE/g). These flowers are rich in organic acids and phenolic compounds, mainly myricetin, and quercetin derivatives, kaempferol, and anthocyanins. The extract showed no cytotoxicity for the cell lineages used, suggesting that the extract has no directly harmful effects to cells. The important bioactive compound identified in this study makes this flower especially relevant in the healthy food area due to its nutraceutical potential without showing cytotoxicity.

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.

Physicochemical characteristics and antioxidant capacity of Ecuadorian paramo flowers

Ecuador is a megadiverse country with a wide variety of floral species that have been little studied. In this context, the study's objective was to evaluate the physicochemical characteristics and the antioxidant activity of several floral species of paramo of Pichincha Province in Ecuador. Thus, the weight, size, color, pH, soluble solids, moisture and ash of fresh flower was quantified. In addition, carotenoids, phenolic compounds and antioxidant activity were quantified in lyophilized powder. The results obtained showed that the flowers of Werneria nubigena were the longest (43,80 cm); Brugmansia x candida the widest (9,88cm) and heaviest (9,22g); Tristerix longebracteatus presented high soluble solids content (21,5 °Brix), Lupinus microphyllus high pH (14,00), Ceanothus maritimus high titratable acidity (0,26%), Castilleja integrifolia high ash content (6,42%) and Bidens ferulifolia high moisture content (95,73%). In addition, the highest ranges of total carotenoids and total phenolics were presented by yellow Bidens ferulifolia (24,81 µg β-carotene/g PS) and Fuchsia vulcania (531,77 mg EAG /g PS), respectively. Finally, it was found in Bomarea multiflora high values of antioxidant capacity (182,08 trolox eq. µmol/ g PS). These results suggest that the paramo flowers contain essential bioactive compounds that could be used for food, medicinal and cosmetic purposes. Keywords: Bioactive compounds, carotenoids, phenolic compounds, Andean flowers

Identification and Quantification of Bioactive Compounds in Organic and Conventional Edible Pansy Flowers (Viola × wittrockiana) and Their Antioxidant Activity

The use of edible flowers has become increasingly popular as a good source of bioactive compounds. Many flowers can be consumed, but there is a lack of information about the chemical composition of organic and conventional flowers. Organic crops represent a higher level of food safety because pesticides and artificial fertilizers are prohibited. The present experiment was carried out with organic and conventional edible pansy flowers of different colors: double-pigmented violet/yellow and single-pigmented yellow flowers. In fresh flowers, the contents of dry matter and polyphenols (including phenolic acids, flavonoids, anthocyanins, carotenoids, and chlorophylls) and the antioxidant activity were determined by the HPLC-DAD method. The results showed that organic edible pansy flowers contained significantly more bioactive compounds, especially polyphenols (333.8 mg/100 g F.W.), phenolic acids (40.1 mg/100 g F.W.), and anthocyanins (293.7 mg/100 g F.W.) compared to conventional methods. Double-pigmented (violet/yellow) pansy flowers are more recommended for the daily diet than single-pigmented yellow flowers. The results are unique and open the first chapter in a book on the nutritional value of organic and conventional edible flowers.

Effect of Modified Solar Dryers on Colorimetric and Physicochemical Properties of Pumpkin Flower (Cucurbita maxima)

This study aimed to evaluate the solar dryers' cover material effects on the colorimetric and physicochemical properties of pumpkin flowers (Cucurbita maxima). A direct cabinet solar dryer was designed using three cover types: polycarbonate, polyethylene, and aluminum with selective surface (titanium oxide coating). A unifactorial experimental design with three levels was adopted. Pumpkin flower stability was assured by reducing the initial moisture content (95.22%) and water activity (0.989) to 3.15% and 0.276 in the polycarbonate dryer, to 3.03% and 0.279 in the selective surface dryer, and 5.19% and 0.364 in the polyethylene dryer. The drying kinetics showed that the drying time needed to achieve the moisture equilibrium was 480, 540, and 720 min in the respective dryers, depending on the ambient conditions. The initial pumpkin flower hue angle was 76.52°; however, this value decreased to 74.81, 69.52, and 70.23° in the dryers with polycarbonate, polyethylene, and the selective surface respectively; this behavior indicates a pumpkin flower tendency to orange color. The dryer with the selective surface obtained the best properties in pumpkin flowers. The pumpkin flower showed an initial total soluble solid of 1.5°Brix increased to 30°Brix in the polycarbonate and polyethylene dryers and 39°Brix in the selective dryer. The titanium oxide dryer observed an increment in ascorbic acid content from 3.5 to 8.806 mg/100 g, whereas 6.45 and 5.87 mg/100 g in the polycarbonate and polyethylene dryer, respectively.

Synthesis of Integrated Flower Waste Biorefinery: Multi-Objective Optimisation with Economic and Environmental Consideration

The improper disposal of flower waste from cultural activities is one of the main challenges in certain countries such as India. If the flower waste is not managed properly, it causes a number of environmental issues. Therefore, various technologies have been developed to transform flower waste into value-added products. To integrate multiple technologies holistically to maximise the energy and material recovery, an integrated flower-waste biorefinery is required. Since there are a wide range of technologies available that can convert the waste into multiple products, there is a need to develop a systematic approach to evaluate all the technologies. This research proposes a systematic approach to synthesise an integrated flower-waste biorefinery based on different optimisation objectives, e.g., maximum economic performance and minimum environmental impact. Due to the conflicting nature between the two objectives, a fuzzy optimisation approach has been adapted to synthesise a sustainable integrated flower-waste biorefinery that satisfies both objectives at once. The efficacy of the proposed approach is demonstrated through a case study in India based on the optimised results with fuzzy optimisation—a synthesised flower-waste integrated biorefinery with economy performance of $400,932 and carbon emission of 46,209 kg CO2/h.

Antioxidant Effect of Pumpkin Flower (Cucurbita maxima) in Chicken Patties

In this work, the antioxidant effect of pumpkin flower powder was evaluated in chicken patties. For this purpose, three drying methods were proposed to obtain the pumpkin flower powder and preserve its properties (antioxidants, color, odor): foam-mat drying, freeze drying, and oven drying. The drying process of the powder plays an important role in the conservation of bioactive compounds. The foam-mat drying method would allow the preservation of these compounds after cooking and after cold storage due to encapsulation like mechanism of the added proteins. Thus, these powders were selected as the most adequate vehicle to incorporate in the formulation, since patties with these additives presented the better antioxidant scores for DPPH, ABTS, and FRAP even after 7 days of storage. In addition, total polyphenolic content and the presence or thiobarbituric acid reactive substances (TBARS) were better scored in samples with the pumpkin flowers. The incorporation of the pumpkin flower additives in the patty formulation improved sensorial attributes of the chicken patties and consumers acceptance after cold storage.

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.

Nutritional Value and Antioxidant Activity of Fresh Pumpkin Flowers (Cucurbita sp.) Grown in Poland

Pumpkin flowers, in their composition, contain many bioactive ingredients that have a beneficial effect on the human body. The aim of the research was to evaluate the antioxidant activity and chemical composition of flowers of various species and varieties of pumpkins: Amazonka, Ambar, Atlantic Giant, Bambino (Cucurbita maxima L.), Butternut, Muscade de Provence, Rouge vif d’Etampes (Cucurbita moschata Duch.), and Miranda (Cucurbia pepo L.). The flowers came from flowering pumpkin shoots, grown in Poland (Krakow). The total polyphenols, carotenoids, total sugar contents, antioxidant activity, and fatty acid composition were determined. The content of dry matter, protein, ash, fat, and selected minerals were also determined. Pumpkin flowers of the Atlantic Giant variety were characterized by the highest content of total polyphenols and sugars and antioxidant activity. They also showed the highest percentage of n-myristic acid (C14:0) and docosanoic acid (C22:0). The energy value of fresh pumpkin flowers, of all varieties, was low and averaged 22 kcal/100 g. Fresh pumpkin flowers are a significant source of iron, covering 60–80% of the EAR standard for adults (Atlantic Giant and Bambino varieties).

Ornamental Flowers Grown in Human Surroundings as a Source of Anthocyanins with High Anti-Inflammatory Properties

Flowers have always accompanied people thanks to their manifold aesthetic properties. Some species have also become a component of the human diet. Recent years have seen an increased interest in edible flowers and, consequently, research has been undertaken to determine their chemical composition. Dyes that are abundantly contained in flowers, whose role is to attract pollinating animals, are recognized substances with health-promoting properties. Anthocyanins are a group of dyes that are very common in petals and other parts of flowers. Studies carried out in the twentieth and twenty-first century on flowers growing in temperate climates have found very strong antioxidant and anti-inflammatory properties of anthocyanins. Therefore, flowers used by humans for centuries to decorate their surroundings may become an easily available source of nutrients and health-promoting substances. This paper discusses the health-promoting properties of anthocyanins and collects literature on anthocyanin content in edible flowers commonly grown on balconies, terraces, and roofs in countries of temperate climate.

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.