Review

Volume 27, September 2024, pages 1-14

Edible flowers: a sustainable source of natural food ingredient

Flowers are generally known and utilized for their radiated color and beauty. From old times, flowers have been a part of human life. Flowers are assumed as the sexual organs of a plant originating for attracting pollinators with their shape, color, and fragrance (Havananda and Luengwilai, 2019). Thus, the fundamental nature of any flower is the ornamental property. Some flowers are unique as they are secured for human consumption and thus, the flowers are termed ‘edible flowers’ (Shantamma et al., 2021). Consequently, the knowledge about edible flowers can relate to different streams of learning, which highlights ethnobotany, pharmacy, nutrition, aesthetics, culinary arts, and regional traditions (Chkhikvishvili et al., 2016). Compiling and documenting ancient recipes incorporating edible flowers has the potential to serve as invaluable reference material for professionals such as pharmacists, herbalists, nutritionists, chefs, and horticulturists. This resource can aid them in identifying flowers as valuable reservoirs of antioxidants and bioactive compounds (Zhou et al., 2020).

Edible flowers are utilized in different civilizations inclusive of decoration to foods regarding flavor, color, natural medicine, and art (Zhao et al., 2019). Research is being carried out to ensure the safety of edible flowers in different industries for human consumption and their safe levels are being studied. They have been conventionally applied in cooking cultures in various countries including the Middle East, Oriental, Asian, and European regions (Fragoso-Jiménez et al., 2019). Despite of under utilization of edible flowers as a part of their culinary in many countries, researchers from different fields are exploring the composition and health benefits of edible flowers. However, the safety of incorporating edible flowers into diets remains a challenge, primarily due to the scarcity of studies establishing safe daily consumption levels. Several species of edible flowers can be taken as a garnish or a delicacy and also as source of protein with essential amino acids. Edible flowers can play a major role in expanding the food market with unique nutritional and sensory characteristics. These flowers can be consumed in several ways as foams (molecular gastronomy), crystallized, powder, dry form (dried flowers or infusions), and fresh (Skrajda-Brdak et al., 2020). In addition to their traditional use for visual and aromatic purposes, there’s a growing recognition of flowers’ value as food. This shift is driven by consumers seeking natural ingredients with various health benefits. To cover the importance of edible flowers, this work discusses the major topics like morphology of flowers, nutritional value of flowers, health benefits of such flowers, their applications of edible flowers as functional food ingredients, other sources of applications, preservation of edible flowers, and toxicological effects on edible flowers. It provides a holistic understanding of the implications and considerations surrounding the consumption and utilization of edible flowers across various food and other industries.

Over the years, the medical and nutritional properties of flowers have been identified and utilized by our human ancestors and they have been forwarded to recent generations as ethnic cuisines and herbal medicines (Harmayani et al., 2019). Before studying the functionality, and nutritional value of different edible flowers, it is required to analyze the basic anatomy of edible flowers to perform precise identification of edible flowers, distinguishing them from harmful or toxic flowers, assess the edibility of a flower, examine the medicinal and nutritional properties, and enhance culinary experiences (Navarro-González et al., 2015). The basic anatomy of an edible flower is shown in Figure 1, while its detailed structure is provided in Table 1.

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Figure 1. Standard anatomy of edible flower.

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Table 1. Functions of flower parts

Edible flowers have different parts, characteristics, and features, but here are some usual things you might find in many of them. Some of the flowers already known to be edible include species of the genus Cynodidae, Cynodidae, Cynomysidae, R. canina, R. Gallica ‘Francesa’, R. canina, R. damascena ‘Alexandria’, dahlia (Dahlia mignonI), jasmine (Ixora chinensis), marigolds (Tagetes erecta), cassia flower (Cassia siamea), the flower of Sesbania grandiflora, Cantabria, Neem flower (Azadirachia indica), marshmallow (Althea officinalis), borage (Borago officinalis), dandelion (Taraxacum officinale), lily (Malay sylvestris), lotus (Nelumbo nucifera), turmeric (Lilium sp.), tulipa (Tulipa gesneriana), pansy (Viola tricolor), capuchin (Tropaeolum majus), mint (Mentha sp.), lilac (Syringa vulgaris), hemerocallis (Hemerocallis sp.), and chrysanthemum (Chrysanthemum sp.) (Pereira et al., 2020). Some edible flowers utilized for garnishing dishes are hibiscus, carnation, begonia, nasturtiums, Centaurea, rose, borage, and pansy. However, other edible flowers are more familiar to consumers as vegetables, like cauliflower, broccoli, and artichoke. Additionally, numerous flowers that are usually used for ornamental purposes have edible parts, which are hibiscus (Hibiscus rosa-sinensis), nasturtiums (Tropaeolum majus), rose (Rose spp.), borage, Centaurea (Centaurea cyanus), and pansy. Edible flowers from certain fruit trees can also be applied in cooking, including elderberry citrus blossoms (kumquat, grapefruit, lime, lemon, and orange) and blossoms (Sambucus spp.) (Fernandes et al., 2020). Furthermore, a few herb flowers are edible too, such as common sage (Salvia officinalis), mint (Mentha spp.), thyme (Thymus vulgaris), summer savory (Satureja hortensis), and alliums (garlic, chives, leeks). Although a vast range of edible flowers can be discovered around the world, only some flowers have been studied. Thus, a more comprehensive understanding of natural resources is required for increasing their acceptability as food elements and for ensuring safety. It is required to notice that not all the flowers do not meet the primary criteria of edible flowers including being, harmless, non-toxic, and giving nutritional value. Hence, flowers should have these qualities to be taken for human consumption.

Edible flowers have general characteristics like taste, health benefits, attractive nature, colors, better nutritional values such as antioxidants, minerals, vitamins, and sensory values, safer to eat as not having harmful allergens or toxins, cultural diversity, and ornamental use. Customers may reject flowers that have visual flaws. Thus, the acceptability of edible flowers by consumers depends on several factors like consumer profiles, flower characteristics, species, and social groups and how they are recommended. Edible flowers come in a wide variety of shapes, sizes, colors, and flavors, yet they share several common characteristics, as described in Table 2.

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Table 2. Functional uses and applications of edible flowers

These features impact whether the flower is appropriate for consumption or not. However, individuals will accept the food based on factors like psychological state, religion, ethnicity, health conditions, location, income, gender, and age (Rivas-García et al., 2021). Edible flowers are usually featured in gourmet dishes, but the gender, income, and education of persons will affect their willingness to consume edible flowers. In general, the color and appearance of the flowers play a major role in getting consumer’s interest whereas their probable health benefits are generally observed as lower significant. To conclude, the acceptability of edible flowers can vary among individuals and different groups based on their experiences, beliefs, and attitudes toward unconventional or novel food sources. Researchers and the food industry need to understand and study these factors to promote the broader use of edible flowers in culinary applications (Kumari et al., 2021).

The edible flowers have a better nutritional profile, providing dietary features like protein and fiber when including lower fat. Thus, they accomplish several dietary requirements, inclusive of vegans and vegetarians (Fernandes et al., 2017). Edible flowers come up with health improvements via bioactive compounds, and sensory and nutritional contributions. As discussed before, edible flowers have diverse parts like stigma, nectar, petals, pollen, and so on. It is suggested to eat the flowers after removing the stamens and styles of the flowers before consumption. Pollen is assumed as a rich source of carotenoids, flavonoids, amino acids, carbohydrates, proteins, and fat (Sotelo et al., 2007). However, it is consumed at a lower rate owing to the several allergic reactions correlated with it. The majority of edible flowers consist primarily of water (over 80%). The amount of total sugars, minerals, and dietary fiber varies across different flower types. Additionally, their fat and protein content is notably low. Flowers predominantly consist of moisture, including a huge portion by weight. Macronutrients like fibers and proteins are comprised of flowers (Grzeszczuk et al., 2014). This nutritional value changes among diverse parts of the flower. For example, pollen has unsaturated and saturated fatty acids, carbohydrates, and protein. Petals are identified for their richness in antioxidants, minerals, and vitamins, whereas nectar is loaded with terpenoids, alkaloids, and sugar (Navarro-González et al., 2015). The nutrient value of edible flowers can vary significantly depending on the specific type of flower and its growing conditions. However, a general overview of the potential nutrients found in edible flowers is provided in Table 3.

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Table 3. Overview of nutrients and health benefits in edible flowers

It’s important to note that the nutrient content of edible flowers can vary depending on factors such as species, growing conditions, and preparation methods. Additionally, edible flowers are often consumed in small quantities as garnishes, flavorings, or decorative elements rather than as primary sources of nutrition. As such, their contribution to overall nutrient intake may be relatively small compared to other foods in the diet.

The nutritional value of certain edible flowers is assessed based on energy, ash, protein, fat, fiber, carbohydrate, and moisture content. The energy of edible flowers denotes the overall calory consumption to offer different levels of energy (Rop et al., 2012). The mineral concentration in edible flowers is reflected by ash content comprising required nutrients. Most of edible flower has protein that is required for tissue growth and repair. Edible flowers often have lower fat content contributing to their complete nutritional profile. Some dietary fiber is included in edible flowers, which promotes gut health and aids digestion. Edible flowers offer a source of energy known as carbohydrates. The amount of water that exists in the flowers is referred to as the moisture content, which impacts their overall texture composition.

The nutritional composition of different edible flowers is discussed in Table 4. Aloe vera has 8.6 g of ash, 16.4 g of protein, 4.2 g of fat, 13.8 g of fiber, 56.8 g of carbohydrates, and a moisture content of 89.5 g (Asif et al., 2023). Aloe vera has a bit of ash, which contains important minerals that help our body work well. Aloe vera has lots of moisture and thus, it keeps hydrated. It has higher carbohydrates and offers a quick energy boost. The fiber content in aloe vera increases the digestive benefits whereas the lower fat in aloe vera may not be utilized as the dietary fat. Similarly, the nutritional value of some flowers is explained here. Saffron contains approximately 5–7 g of ash, 12–13 g of protein, 5–8 g of fat, and 4–5 g of fiber, and the carbohydrate content is not specified. Its moisture level falls between 10–12 g. These nutritional values provide insights into the nutritional components of each edible flower to give a better nutrientional value.

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Table 4. Nutritional value of diverse edible flowers

Edible flowers contain bioactive compounds that offer various health benefits, such as antioxidant, anti-inflammatory, anticancer, and neuroprotective effects. Their mineral content, antioxidant activity, and nutritional value make them important for human health (Mulík and Ozuna, 2020). These flowers help combat oxidative stress, which contributes to conditions like cancer, diabetes, and heart disease. Rich in fiber, amino acids, minerals, and vitamins, edible flowers have long been part of diets to boost health (Harmayani et al., 2019). This review explores the benefits of edible flowers, detailing their scientific names, origins, bioactive compounds, and food industry applications, as summarized in Table 5.

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Table 5. Bioactive compounds and health benefits of various edible flowers

A detailed description of the attributes and benefits of some edible flowers is listed as follows. Aloe Vera, known scientifically as Aloe barbadense miller, originates from Asian countries. It contains essential proteins, amino acids, anthraquinone, and anthrone, along with carbohydrates and vitamins. Aloe vera finds use in the food industry for prolonging shelf life and preservation. Moreover, it contributes to maintaining healthy body weight, cholesterol levels, and blood sugar levels (Asif et al., 2023; Shantamma et al., 2021). The Mango Flower, Mangifera indica, hailing from Southern Asia, boasts gallotannins, polyphenols (including phenolic, xanthones, and flavonoid acids), and carotenoids. Culinary applications include its incorporation in pickles. Medicinally, mango flower juice addresses various health conditions like heat exhaustion, dehydration, diarrhea, high cholesterol, and diabetes (Martin and He, 2009).

The Lotus Flower, Nelumbo nucifera, originating from Asia and Australia, offers carotenoids, amino acids, organic acids, and alkaloids. It features prominently in salads, soups, and desserts. Traditionally, it has been used for its beneficial effects on the spleen, and kidneys, and as a cardiotonic agent (Wang et al., 2003). The Purple Coneflower, Echinacea purpurea, native to North America, contains polyacetylenes, Rosmarinus acid, phenolic acid, aklomides, caffeic acid, and dichroic compounds. It extends to the tea industry and imparts protective attributes against cancer, inflammation, anxiety, and sugar irregularities. It strengthens the immune system, potentially reducing the risk of various diseases (Chiou et al., 2017). The Paris Daisy, scientifically known as Argyranthemum frutescens, hails from East Asia and Northeastern Europe. Rich in flavonoids and phenolic acids, it enhances the nutritional value of food products and holds a place in traditional medicine for conditions like diabetes and high blood pressure (Rop et al., 2012). These edible flowers offer a variety of bioactive compounds that come with potential health benefits and can be used in a range of culinary creations (Figure 1). Nonetheless, it’s important to consult with a healthcare professional before making major changes to your diet, even though these flowers show promising advantages.

Edible flowers are becoming well-known as unique foods, which are better for human health. These flowers contain phenolic compounds, which help to boost immunity and also cure stress-related issues (Domínguez-Perles et al., 2010). It also helps to protect the heart, liver, and brain, which assists in fighting against cancer and also boosts metabolism. Few flowers have medicinal properties to kill bad bacteria. These flowers might also assist in anti-aging properties for handling stress and inflammation. Due to the potential health benefits, high pigment concentration, bioactive properties, nutritional characteristics, and unique composition and concentration of antioxidant compounds, edible flowers are assumed to be functional foods (Rezende et al., 2019). It is also recognized as a functional food owing to its medicinal properties, culinary experimentation with the infusion of special colors, textures, and flavors into dishes, boosting the immune system, diabetes management, protection against neurodegenerative diseases, anti-inflammatory conditions, and weight management. The benefits of edible flowers are outlined as follows:

Edible flowers acquire promising functions for serving as practical and affordable functional elements results in several advantages because they increase their existence in easy and natural accessibility that cooperatively locates them as a cost-efficient choice for incorporating into a wide range of products (Trivellini et al., 2007). The flowers are easily available as there are a lot of flowers around. It makes it simpler to use or grow them with a lot of resources. Thus, the overall cost related to attaining flowers can be considerably lower and distinguished from other unique ingredients. Therefore, the widespread availability of edible flowers gives the cost-efficiency. The requirement for transportation and distribution networks is minimized owing to the availability of flowers in local environments, which minimizes extra costs (Rezende et al., 2019). Edible flowers are inexpensive and useful because they are everywhere, easy to get, and can fit into different things. Using them in products can make things better for customers without making things too expensive to make. But it’s important to be careful when getting the flowers and using them in case some people are allergic.

Edible flowers can be widely spread around the world, which has increased the potential of using edible flowers for different purposes and applications (Fernandes et al., 2020). They are easily available because they can be seen in various locations without many complications. This accessibility is increased owing to their natural existence in gardens, fields, and also in the wild. They sometimes grow naturally in diverse regions and can be pursued in open fields or gardens.

Edible flowers have several pharmaceutic and therapeutic components in them like natural antioxidants in the type of proanthocyanins (condensed tannins), anthocyanidins (malvidin-3-galactoside, malvidin-3-glucoside), tannins, hydroxycinnamic acid, hydroxycinnamic acid, phenolic acids (p-hydroxybenzoic acid and vanillic acid, ferulic acid, protocatechuic acid, gallic acid, homogentisic acid), flavonoids (catechin, quercetin, rutin, cyanidin-3, catechin, epicatechin), coumarins, glycosides, several phenolic compounds regarding flavones (luteolin, acaciin), natural pigments (anthoxanthin, lycopene, betalains, anthocyanins), and Vitamin E (Tocopherol) (Benvenuti et al., 2016; Kalemba-Drożdż et al., 2019). In general, edible flowers act as a huge source of antioxidants and thus, it has been a segment of both medicine and food. It serves as a probable protective agent that is accountable to confer antioxidative effects through the elimination of reactive oxygen species generated during metabolic endogenous activities. Edible flowers exhibit antioxidant activity that is considered to be dependent on the compositions of phytochemicals like anthocyanins, alkaloids, flavonoids, and phenols (Fernandes et al., 2018; Kozicka and Hallmann, 2023). Along with these compounds, the edible flowers can explore neuroprotective, anti-cancer, anti-obesity, and anti-inflammatory effects. Although flowers contain better natural nutrients, it is not verified explicitly and needs careful evaluation. The value range acquired for the antioxidant activity differs broadly among flowers. Though, it is complicated for comparing the antioxidant activity outcomes among flowers while using a similar technique (Siriamornpun et al., 2012). Through the valuable sources of antioxidants in edible flowers, they are utilized in the diet for increasing the health benefits of humans.

Consumers recognize flowers by different attractive properties like color, smell, taste, shape, size, and appearance. From the existing studies, the color of edible flowers plays a major role in preparing food (Zayed et al., 2020). Mostly, consumers often choose blue, orange, and yellow flowers. Color plays a major role in food and nutrition, which is an essential organoleptic property of edible flowers. The existence of anthocyanins and carotenoids is essential for the color of flowers. In these flowers, it is generally observed that the levels of total flavonoids also aim to increase while the amount of anthocyanins goes up. Edible flowers have a considerable impact on the color of food (Begum and Deka, 2019; Chen et al., 2020). While using edible flowers in the food recipes, their natural pigments depict beautiful and better colors, which increases the attractiveness of food. Flower color also imparts antioxidant ability to the flowers. Moreover, the natural colors produced by edible flowers do not harm human health and so, it is highly recommended.

Taste is the primary factor of the food industry, which influences the overall satisfaction, choices, and preferences of consumers. The edible flowers play a major role in increasing taste and enhancing the culinary experience in diverse ways (Liang et al., 2013). The composition of edible flowers comprises compounds, which increase the taste of food regarding phytochemical and phenolic compounds. These properties offer a pleasant and unique flavor to the food by edible flowers. in addition, the taste provided by edible flowers increases the refreshing and pleasant sensation regarding higher antioxidant ability (Massantini et al., 2022). To conclude, the taste of foods is increased by edible flowers, which increases the better food industry applications.

The edible flowers can fight against harmful microorganisms affected by particular compounds that trouble their growth. Antimicrobial properties originate from the phenolic compounds along with the specific compounds (Chen et al., 2020). In addition, antimicrobial effects are displayed by proteins. It gives a promising performance in human health and also extends the shelf life of preserved foods. Some edible flowers are recognized for their antimicrobial attributes, attributed to substances that inhibit the growth of particular microorganisms (Takahashi et al., 2020). Moreover, the existence of specific microorganisms exhibiting compounds decides the antimicrobial activity in edible flowers. Generally, those compounds show from the phenolic group. It is more probable for edible flowers to consider as a source of antimicrobial compounds for both the food and the human body, which serves to prevent food from deteriorating rapidly (Bahuguna et al., 2018). The presence of antimicrobial activity in edible flowers offers several advantages inclusive of food preservation, minimized growth of viruses, bacteria, and other pathogens to handle diseases, natural preservation of foods, less food waste, and enriching culinary experience.

In recent decades, edible flowers have primarily noticed their place as a culinary ingredient in food, owing to their bright colors, soft textures, unique flavors, and powerful nature (Petrova et al., 2020). Edible flowers have been added to beverages and salads like wines and tisanes. Extracts from these flowers have been used for enhancing flavors and aromas in several products. In addition, flowers and their extracts have maximized their roles to make spreads like dressings, marinades with vinegar, and also create food preserves or butter (Takahashi et al., 2020). It is highlighted that edible flowers are vastly considered in terms of culinary elements and also sources of value-added goods. Consequently, innovative products like flower-infused yogurt are also made (Pires et al., 2018). Several products like honey, liquors, vinegar, sauces, jellies, and jams have been produced from these edible flowers (Mlcek and Rop, 2011). Moreover, a vast range of beverages, candies, salads, ice cubes, and teas are prepared in diverse flavors based on the properties of edible flowers. Some flowers like Cardoon (Cynara cardunculus) are used for making cheese-related processes (Rampanti et al., 2023). The vegetable rennet is served from the enzymes extracted from these flowers. This collaborative usage of these flowers gives better probable applications and versatility of edible flowers across several product and culinary practices.

To conclude, edible flowers are taken as functional ingredients of foods owing to several properties like low cost, easily available, antioxidant effect of edible flowers, color, taste, polyphenols present in flowers, antimicrobial activity of flowers, and produce several value-added products.

As edible flowers are loaded with more nutrients and health benefits, they are being used for different applications since ancient times for various purposes (Mlcek and Rop, 2011) which are discussed in detail.

Cultural Traditions: Diverse cultures and civilizations had unique usage for edible flowers by considering their practices, values, and beliefs (Singh et al., 2020). These traditional values generally reflect the local resources and environment. Aesthetic Practices: Edible flowers are utilized in several aesthetic and personal adornment practices for body art, accessories, and garlands (González-Barrio et al., 2018). Beverages: Flowers were infused into beverages like wines and teas for lending specific fragrances and flavors. These infused-floral drinks are beneficial for both health improvements and taste. Garnishes and decorations: Edible flowers are utilized as decorative elements for ancient gatherings and feasts. These are applied for embellishing banquets, food displays, and tables to create visually stunning appearances (Kelley et al., 2003). Natural Dyes: Natural dyes are created for artworks, textiles, and fabrics, where their attractive colors add aesthetic value to crafts and clothing. Fragrances and aromatics: Flowers are employed for creating fragrant waters, scented oils, and perfumes, which aid to enhance living spaces and personal grooming. Symbolism and Rituals: Edible flowers are useful in religious and cultural practices to signify renewal, fertility, and purity. Medicinal Practices: The edible flowers mostly have medicinal properties for addressing several diseases and promoting health. Culinary Delights: Edible flowers are incorporated into ancient cultural cuisines for adding flavor, color, and visual enchantment to dishes. These flowers are utilized as ingredients in desserts, teas, salads, and soups to increase the sensory experience of food (Takahashi et al., 2020). Edible flowers as food additives: Flowers are utilized as flavorants and preservatives. They are commonly applied for tasting and for imparting aroma to pickled goods, vinegar, and oils. Throughout history, people have used edible flowers in different ways, including in their culture, cooking, and everyday life.

Edible flowers are widely being used in cosmetic and perfumery industries, as natural food colorants, used to garnish dishes due to their beauty, attractiveness, and pleasant color, also added as new food additives due to different nutraceutical and non-toxicity properties, they are also used in pharmaceutical industry because of phenolic compounds present in them, used in industry of confectionary for decorating cakes, cookies, and so on for different reasons, daily meal preparations owing to diverse and potent smells, colors, textures for increasing scent and flavors, and in beverage industries for making wines, sauces, and tisanes for flavoring beverages (dos Santos et al., 2018). Edible flowers are also beneficial as non-food applications as raw materials for creating cosmetic products, natural dyes, and perfumes. Especially, Jasmine flowers (Oleaceae family) are utilized in the fragrance industry owing to their rich composition of several aromatic compounds. Moreover, the edible flowers play an vital role in preparing essential oils (Zhao et al., 2019). Additionaly flowers that are rich in pigments usually results in producing vibrant colors by promoting the dye industries, and synthetic dyes in cosmetics like lipsticks.

Consumers are hugely adopting natural food products owing to concerns regarding probable artificial compounds or harmful effects. Edible flowers possess a biodegradable nature, generally owing to their higher water content and the issues related to the preservation of them over long durations (Zhao et al., 2019). Though, handling this issue focuses on integrating efficient processing techniques. Strengthening the production of edible flowers and their preservation in natural or better ways requires suitable methodologies, which focus on increasing the basic nutritional attributes, bioactive qualities preservation, managing costs, prolonging shelf life, and upholding freshness. Another major issue is their restricted availability due to their short lifetime and seasonal cycles (Shantamma et al., 2021). Regarding these complications, innovations are highly required. Some studies show that dehydrated or crystallized methods are suggested as the new solution. Even though new techniques give better preservation of perishable foods, their incorporation gives higher cost implications and also restricts their commercial viability. On the other hand, inventive drying schemes such as drying, microwave drying, dehumidified drying, vacuum drying, and hybrid drying are appearing as more suitable ways to retain the nutritional values and bioactive components in edible flowers. In general, edible flower preservation is performed with three major stages like pre-process, processing, and packaging methods.

• Pre-processing: It aims for handling and storing the flowers from the point of harvest until they reach the processing unit.
• Processing: During this stage, appropriate methods are employed to process the flowers, giving utmost importance to retaining their freshness and quality.
• Packaging: Finally, post-processing storage is complemented by suitable packaging methods to ensure extended shelf life and preservation.

Despite various attempts to extend the shelf life of edible flowers, they remain delicate and prone to sensitivity towards heat and other processing methods. The major complication lies in the preservation of edible flowers with their “fresh-like” qualities regarding the maintenance of freshness with traditional physical, biological, and chemical preservation techniques. These methods can impact the nutritional properties and sensory attributes of flowers. These preservation techniques are classified into two major groups of traditional and modern methods. Traditional methods involve processes like dehydration and osmosis, while modern methods encompass refrigeration, freezing, and freeze-drying (Falla et al., 2022). These methods can be further categorized based on their outcomes like preserving flavor, preservation of color and flavor while altering shape, and preserving shape, color, and flavor. Moreover, methods can be divided into short-term, medium-term, and long-term preservation methods considering the duration of preservation. Each approach has its advantages and considerations, with the ultimate goal of preserving the distinct qualities of edible flowers while extending their use and availability. Non-thermal techniques like pulsed electric field technology, ultrasound, high hydrostatic pressure (HHP), and irradiation have increased the interest as efficient alternatives for edible flower preservation (Siriamornpun et al., 2012). More recently, a range of advanced extraction techniques has emerged, including enzyme-assisted extraction, pulsed-electric field extraction, ultrasound-assisted extraction, microwave-assisted extraction, pressurized liquid extraction, and supercritical fluid extraction. These new techniques are being studied for solving the intricacies of preserving the unique qualities of edible flowers amidst the demands of food processing and preservation.

A few preservation techniques are discussed as follows. Drying: It is a simpler way of preserving flowers. Dried flowers are used in making infusions and tea-like beverages, which give colors to baked goods. It is used as decorative substances on candies, cookies, or cakes. While the drying process may cause a change in the flower’s appearance, it succeeds in partially maintaining both the color and flavor of the flowers over extended durations, sometimes lasting up to a year or even longer (Harmayani et al., 2019). Several drying techniques are used in the preservation of edible flowers, which are osmotic drying, sun drying, cool wind drying, vacuum microwave drying, freeze drying, and hot-air drying. Also, a combination of these techniques can be used. The traditional way of preparing tea petals is heat-based drying techniques like sun-drying and hot-air drying schemes. Though, it comes with several challenges of probable unrequited modifications in the nutritional and biochemical composition of edible flowers. Yet, the impact of these changes can be mitigated by strategically designing and selecting the appropriate drying process, considering specific flower attributes, available technology, and economic considerations. Cold preservation: Recently, cold preservation techniques like refrigeration and freezing are often utilized in preserving edible flowers. Refrigeration serves as a means to extend the longevity of flowers. Frozen edible flowers are utilized in application in bakery items and ice creams, contributing to a range of culinary delights. Cold storage or refrigeration assumes to a possible tool for increasing the shelf life of edible flowers (Kelley et al., 2003). Though, there is a possibility of occurring chilling injuries in some flowers. It helps in bacterial cell destruction and preserving the nutritional, chemical, and physical properties of flowers. Although the freezing process does reduce the activity of autolytic enzymes, it doesn’t completely deactivate them. To enhance preservation, a pre-treatment like blanching can be applied to render enzymes inactive before freezing. Low-temperature storage: Storing flowers at low temperatures can efficiently delay their aging process by slowing transpiration and respiration rates. In addition, it reduces enzymatic activities, which thus postpones microbial and autolytic spoilage. High hydrostatic pressure technology: HHP is a non-thermal technology, which is the primary preservation method used for operating in the pressure range of 200–800 MPa, and the process conditions may differ depending on the applications like the development of organic or preservative-free products, nutritional and functional characteristics of the product, microbial inactivation in raw and fresh commodities, and inactivation of the enzymes (Falla et al., 2022; Garzón and Wrolstad, 2009). HHP can increase the shelf-life of the product while retaining its nutrients, functionality of compounds, stability, and natural freshness. While using mild HHP treatments, the sensory property may be damaged regarding the incomplete inactivation of microbes and enzymes. In these conditions, the incorporation of several methodologies can acquire synergistic advantages, which result in lower maintenance and operational costs, and shorter treatment times. Irradiation: The shelf-life and safety of perishable foods are enhanced by the food irradiation technique, which is an economically suitable technique. Irradiation treatments are being beneficially utilized in the food industry for microbial decontamination, delay ripening, sprout inhibition, and insect disinfestations. It delays cell death to manifest physiological and biochemical properties (Koike et al., 2011). The food is exposed to ionizing radiations in the irradiation process majorly emitting electron gamma or beam radiations. The irradiation procedure does not affect the nutritional composition. The irradiated flowers have shown higher antioxidant activity and higher phenolic content. Photosynthetic Photon Flux Density (PPFD): PPFD is a metric of the amount of light energy available for photosynthesis per unit area, generally evaluated in micromoles of photons per square meter per second (µmol/m²/s). PPFD is significant in the context of edible flower preservation because it directly impacts the metabolic processes within the flowers (Fukai et al., 2018; Janarny et al., 2021). To keep edible flowers fresh and maintain their good qualities like color, taste, and overall freshness, it’s important to provide them with the right amount of light energy. This can be done by controlling how much light they get while they’re stored or being prepared. Making sure they get enough light energy helps their natural processes without harming them. So, knowing and controlling the light they receive is important to make sure edible flowers stay fresh and nice.

The recent studies on edible flower preservation are discussed in Table 6 with their processing conditions, along with the uses of edible flowers. This table serves as a comprehensive reference, summarizing recent findings on how edible flowers can be effectively preserved. This information is valuable for those interested in maintaining the quality and usefulness of edible flowers over time. Flowers are in different appearances and forms and are often consumed fresh. Thus, it is required to preserve edible flowers for making different culinary dishes and also in diverse ornament applications. The most common postharvest methods applied to these edible flowers are refrigeration, drying, canning in sugar, and preservation in distillates. If preservation techniques are utilized, then they must not harm the quality of flowers. Thus, the current research specifies that food irradiation and High Hydrostatic Pressure (HHP) technologies are utilized for extending the shelf life of edible flowers (Chen et al., 2020). The freeze-drying method is generally applied for acquiring positive outcomes in preparing culinary recipes and also in food industries as it preserves the nutritional effects and valuable bioactive compounds. In addition, it is required to analyze and consider several preservation and post-preservation techniques for consistent nutritional outcomes.

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Table 6. Analysis of different preservation techniques of edible flowers with their respective uses.

The edible flower consumption may have potential risks, which is studied in different research works as some can trigger adverse reactions or allergies whereas some edible flowers are nutritious, and safe, in which some flowers may not be appropriate for consumption (Koike et al., 2011). Identification of safe options for consumption is complicated. Generally, flowers from nurseries, florists, or garden centers are not to be consumed as they are usually treated with harmful pesticides (dos Santos et al., 2018). Few flowers could lead to conditions like asthma, allergies, and even complicated outcomes. Wild edible flowers are not a safer option for consumption owing to the contamination risks from neighbor poisonous plants. Edible flowers may have contaminants like chemical compounds and bacteria (Janarny et al., 2021). Moreover, edible flowers are assumed to be safe in some categories such as fruity flowers (e,g, vegetable, herb, citrus, and banana flowers) and ornamentals (e.g., daylilies, begonia, and calendula). Safer consumption is ensured by the identification and processing methods, where some recent studies show it is required to analyze gender, occupation, education beliefs, and knowledge about edible flowers for consumption (Bahuguna et al., 2018; Kim et al., 2000). Though, the toxic nature of some flowers is persisted. Poisonous flowers may contain harmful substances like pathogenic microorganisms, sulphite, or dimethoate.

For thousands of years, several cultures have prepared their food with flowers by conventional techniques. These flowers also have some medicinal values and thus, it is required to evaluate the potential of edible flowers. This review offers insights into nutritional benefits, health advantages, and better safety, preservation, and processing conditions of edible flowers. The edible flowers give a better flavor to the dishes, aromas, delightful flavors, bioactive properties, and nutrition to humans. Although flowers are used in cooking for a long time, modern approaches can produce more valuable products and increase their shelf life. Though, the study of processing and preservation has generally studied particular edible flowers alone, which leaves room for broader exploration. While edible flowers have great potential, there’s not enough scientific research to fully develop value-added products using them. However, new ways of drying and packaging them could change how we use flowers in the products we buy. To ensure safe use, rules should be made. Using flowers in food has a lot of possibilities and can help both now and in the future.

Conflict of interest

The authors declare no conflict of interest in this paper.