Whenever, we think of sending flowers to someone, we are usually reminded of the roses or orchids and these are certainly great gifting options. However, in India, from time to time, flowers have also found their usage for different purposes.
In India, there are references to flowers and gardens in Sanskrit classics since 3000 BC, reflecting the country’s tradition in the usage of flowers primarily for ornamentation or decorative purposes. Flowers are of utmost importance during every occasion in India. There is a traditional or spiritual significance associated with flowers in India. Indian culture is a mixture of many sub-cultures and would seem like a bunch of beautiful bouquet of mixed flowers. Flowers are an essential part for Indians right from sunrise to sunset. In India, people start the day by offering flowers to their deities and they are also used on many occasions, such as weddings, other festive occasions, including various kinds of parties, social gatherings and much more.
Contrary to popular belief, flowers are more than just decorations for savoury dishes and sweets, which offer a unique combination of sensations, apart from enhancing the nutritional value of food. They can be consumed fresh (such as marigold flowers in salad), including in soups and drinks (wine, beer), sweets, jellies, as well as in condiments and colours in savoury dishes containing meat and fish. They are used in dried form (infusion, dried rose petals in desserts), powdered form, including in crystallized form or in the form of foam. It is common that some plants are known only for their biological or nutritional potential of their fruits or leaves, while such flowers are not usually part of the culinary, as is the case with passion fruit, chives and pumpkin. Some species are grown all over the world and marketed in Natura or are being used to produce spices, infusions, candies, cakes and functional foods, due to their bright colours, aroma and nutritional power.
On the other hand, edible flowers have been used historically, owing to their smell and appearance. Consuming functional foods containing naturally bioactive compounds in the right amounts can be beneficial for preventing, controlling or treating acute and chronic diseases. Edible flowers are abundant sources of vitamins, proteins, essential oils and antioxidants, especially when consumed naturally or minimally processed. Bioactive compounds present in edible flowers, such as secondary metabolites may also be present in other parts of plants and confer adaptive benefits. For example, they can help in reducing damage caused by environmental stress conditions, being heat, water loss, excessive UV radiation, etc. and also help in preventing infection caused by plant pathogens. In this context, the availability of novel analytical methods that involve the investigation of the reliability of therapeutic uses, the development of new functional products as well as the vast potential point that the potential economic and social impacts of edible flowers in the world economy still continue to remain unexplored. This review has been conducted to collect and disseminate information on edible flowers from recently published scientific work, which aims to relate nutritional and functional properties to edible flower species, including their biological activities as well as discuss perspectives on non-thermal processing that can help in the preservation of the flower quality.
Biological activities of Edible Flowers
Throughout history, Edible flowers with a wide geographic distribution have been used for medicinal purposes. For example, the use of roses to relieve menstrual problems, treat circulatory issues and more recently, cancer against the growth of cells. C. officinalis is known for its antioxidant, gastroprotective and hepatoprotective effects. Several other studies point to the role of edible flowers against bacteria and fungi in the treatment of chronic diseases such as Alzheimer’s and diabetes. These biological effects are closely related to the antioxidant properties of some of their constituents such as carbohydrates, lipids, proteins and DNA. Consumption of foods rich in antioxidant agents have been shown to reduce many pathologies associated with diseases such as diabetes and cardiovascular diseases, including respiratory and neurological diseases.
Edible flowers have also been studied as antimicrobial agents, with the aim of developing antibiotics that can create positive benefits for society, since there are many infectious diseases in the world. With this perspective, extracts from flowers of S. nigra were found to be present in vitro anti-bacterial activity against Staphylococcus, Bacillus cereus, Salmonella Typhimurium and Pseudomonas aeruginosa. Targeting Gram-positive bacteria (Streptococcus pyogenes, Staphylococcus aureus and Staphylococcus epidermidis), extract of flowers of Bellis perennis L., known as Marguerite, was active against all of them and also against one of seven Gram-negative bacteria tested, Enterobacter cloacea (Karakas et al., 2017). In the field of cancer, dahlia flowers and roses proved effective in inhibiting the growth of tumour cells in cervical and hepatocellular carcinoma, respectively, while B. variegata flowers presented cytotoxicity against cervical carcinoma cells. In another example, hibiscus extracts showed an important role as a co-adjuvant in the in-vitro treatment of breast cancer, acting selectively in the destruction of cancer cells, whereas with chemotherapy, reducing the destructive effect on healthy cells. Neurodegenerative diseases such as Alzheimer’s disease are another target of studies focusing on the bioactivity of edible flowers such as D. caryophyllus. Alzheimer’s is a cause of age-related dementia. Inhibition of the enzyme acetylcholinesterase is the target of some currently approved drugs and used to control the progression of Alzheimer’s disease by monotherapy or combined therapy.
To the extent that study identifies the health advantages of physiologically active components in flowers, they may still have the potential to be used as a food additive to help prevent chronic illnesses and even oxidation of foods. One of the most serious issues about flower intake is the possibility of poisoning. Edible flowers may provide a distinct flavour and a splash of colour to dishes. However, not all flowers are edible; thus, it is important to properly identify each species and understand which portions of the blooms should be ingested. Flowers from florists, nurseries and garden stores are frequently treated with pesticides, fungicides and herbicides that are not approved for use on food crops and these should not be used in formulated complementary foods.
The search for raw materials that are not only beneficial to health, but also those that do not cause undesirable sensorial changes to the final product has been gaining higher emphasis in recent times and has intensified higher interest in bioactive compounds of plant origin. These compounds possess huge commercial appeal, owing to their biological action and their use in the development of functional foods, apart from also becoming an alternative as food additives (dyes, flavourings, antioxidants and preservatives). Natural substances of vegetable origin make the food more attractive to the consumer, besides increasing the shelf life by bacteriostatic and bactericidal capacity. These substances delay the onset of deterioration and the growth of undesirable microorganisms. From the perspective of phytochemical research, it is possible to know the chemical constituents of plant species or to evaluate their presence in them.
Processing and preservation of Edible Flowers using novel methods of processing
Edible flowers are perishable due to the presence of high-water content, volatile chemicals and environmental circumstances that favour microbial development and deterioration. Improperly handled/stored edible flowers suffer from tissue browning, flower wilt, dryness, petal discolouration and abscission during the post-harvest period. The degradation process is related with physiological changes and catabolism, which are linked to quicker respiratory levels, water-moving weight reduction and/or improvements in macromolecules, enzyme behaviour and illnesses. To address these problems, fresh edible flowers are frequently preserved at low temperatures, putting storage expenses at risk. There is a scarcity of scientific data on the best practices for storing edible flowers and the elements that impact their freshness. They can also be dried or bottled in sugar syrup; however, this entirely changes their ‘fresh-like’ properties. Preserving edible flowers in their natural state is difficult, as physical, chemical and biological food preservation methods frequently fail to keep their ‘freshness.’
Traditional methods of processing edible flowers, such as sun drying and hot air drying have drawbacks such as long drying times, low drying rates and high temperatures, which may result in deterioration of colour, physicochemical and sensory properties of edible flowers due to prolonged heat exposure. Researchers and the emerging industry are working on innovative ways to preserve the nutritive and organoleptic qualities of edible flowers. In this regard, non-thermal processing procedures are gaining popularity in the food and fragrance sectors, among other developing technologies. They may inactivate bacteria without causing heat destruction of beneficial compounds and nutrients, thereby giving them a new appeal to consumers.
Non-thermal processing methods have shown to be particularly effective for a variety of food commodities, including fruit juices, meat, dairy products and vegetables. It has gained traction in recent years as a result of rising demand for foods with high nutritional content and ‘fresh-like’ features, offering a superior alternative to typical thermal processing methods. In the case of edible flowers, these techniques have shown promising results and major findings from recent studies are described in this section. The edible flowers business would benefit greatly from the extension of product shelf-life through the use of mild processing technologies that have no impact on organoleptic features. Furthermore, it satisfies the consumer’s need for minimally processed meals that are more akin to fresh items and do not include artificial preservatives.
The technology of using edible coatings had found promising applications for fresh agricultural products that can extend their shelf-life and quality. Edible coatings can provide a selective barrier to gas, water vapour and dissolved material displacement, as well as defence against mechanical disruption. This eases the internal oxygen partial pressure of fresh products and leads to decreased metabolic activity, deterioration, including offering support to retain volatile components. The Food Industry is paying increasing attention towards the use of edible coatings and cling wrap materials that are environmentally friendly and made from biological materials such as polysaccharides, protein and lipids. Minimally processed fresh-cut fruits and vegetables are coated using methods such as dipping, spraying and more recently, electro spraying technologies are being used, with an emphasis on uniform coating on the surface. However, only a few studies have been conducted to investigate the possibility of edible coatings on flower-like artichokes, brassica, broccoli and cauliflower.
Aside from processing, packaging is critical in protecting the quality of food items. Packaging technology has evolved significantly over the years, with the development of unique packaging solutions. The idea of Modified Atmosphere Packaging (MAP) focuses on prolonging the shelf life of commodities by changing the gas composition within the packaging in order to maintain the freshness of the food items. This, in turn, impacts respiration, ethylene synthesis, colour development, volatile component deposition and microbiological alteration in fresh items. High oxygen atmospheric packaging (HOAP) has also been examined for its influence on hydrogen peroxide generation and oxidative stress in blooming Brassica campestris L. ssp. It was discovered that rising oxygen levels might affect the quality of edible flowers, according to the control of the oxidative stress pathway. HOAP, on the other hand, may regulate reactive oxygen species (ROS) levels via ROS-related protein metabolism and by further inhibiting the activity of antioxidant-related enzymes, thereby changing the cell wall content. The nutritional and biochemical properties of edible flowers are greatly influenced by storage conditions and packing methods. While the MAP technology has shown encouraging results, the goal now is to establish the infrastructure required to manage large numbers. Several sophisticated sensing systems, including those that operate with the Internet of Things (IoT) and cloud-based techniques for robust monitoring and control have been appearing in the recent years. These are becoming used in supply chain management and commodity traceability of packaged items and they may also be used for the transportation and distribution of edible flowers.
Conclusion
Clearly, there is a great potential that exists for edible flowers and their consumption is set to increase in the coming years. These flowers possess a good nutritional profile by being a source of fibre or even protein with very low lipid content, therefore being able to meet many dietary demands, which include those who are vegetarians and vegans. In addition to antioxidant activity, literature has shown that these flowers have many important biological activities such as antitumour, antidiabetic, anti-inflammatory, antimicrobial, gastroprotective that go far beyond nutritional benefits.
The growing scientific interest in edible flowers is also of great social value, as more research on the same can only help to unravel more information on the flowers that are being used in human food by traditional communities. This can help to bring back the lost traditions among the people, which had disappeared among them, due to the huge migration of young people to large urban centres in the past few decades. This article also describes non-thermal ways for processing the edible flowers. While some of the techniques have the capacity to preserve the fresh-like characteristics of edible flowers, even non-thermal processing methods such as High Pressure Processing can cause damage to the delicate tissue structure of flowers. As a result, using hybrid techniques to lower the intensity of separate processing methods would be an optimal option for preservation. A processing procedure followed by low temperature storage can produce good outcomes. With these recommendations, the possibility for processing edible flowers utilizing such recently developed technology can be reintroduced, considering that the market for edible flowers has been growing in the recent years and there has been increasing consumer acceptance of edible flowers.
References:
1. Franzen, F. L., Lidório, H. F., & Oliveira, M. S. R. (2018). Edible flower considerations as ingredients in food, medicine and cosmetics. Journal of Analytical & Pharmaceutical Research, 7(3), 271-273.
2. Purohit, S. R., Rana, S. S., Idrishi, R., Sharma, V., & Ghosh, P. (2021). A review on nutritional, bioactive, toxicological properties and preservation of edible flowers. Future Foods, 4, 100078.
3. Shantamma, S., Vasikaran, E. M., Waghmare, R., Nimbkar, S., Moses, J. A., & Anandharamakrishnan, C. (2021). Emerging techniques for the processing and preservation of edible flowers. Future Foods, 4, 100094.
About the Authors:
Arun Kumar Gupta1 & Poonam Mishra2
1Assistant Professor, Department of Food Technology,
School of Applied and Life Sciences, Uttaranchal University.
2Professor, Department of Food Engineering & Technology,
Tezpur University.
Email ID: guptaarunkumar714@gmail.com
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