Zingiberaceae Rhizome Essential Oil: A Review of Chemical Composition, Biological Activity, and Application in Food Industry

Several of Zingiberaceae‘s rhizomes are aromatic and medicinal plants that have been used for thousands of years to enhance food’s taste, color, and aroma. The Zingiberaceae plant is found in various ecosystems in Southeast Asia, including cultivation areas and tropical rainforests. It can be found growing at the edge of the forest or well-rooted on the forest floor. This plant is one of the agroforestry product that usually used for cooking, perfume, dyes, and traditional medicine, especially ethnic medicine. Zingiberaceae products can be consumed in various forms, such as fresh, cooked, or boiled..This rhizome is effective in the treatment of several medical conditions such as digestive, respiratory, nervous, and muscle system problems, as well as other degenerative diseases. Phenolic compounds as secondary metabolites found in Zingiberaceae rhizome plants have been shown to have good biological activity for human health and as antibacterials in their applications in food and pharmaceutical products. The main objective of this review is to provide an overview of essential oils from Zingiberaceae rhizome commodities in terms of chemical components, biological activity, safety, and potential applications in the food industry. A number of literature search methods, in this article the narrative literature observation method is used, by searching for related keywords such as essential oils, zingiberaceae, rhizomes, phytochemicals, ginger, turmeric, ginger, Alpinia, in scientific article search engines such as Google Scholar, Scopus, Web search. of Science, and PubMed implemented. This narrative review will help researchers to describe research developments related to essential oils produced from the rhizome commodity of aromatic plants and medicinal plants from the Zingiberaceae family.The common use of rhizome essential oil in food and traditional medicine has attracted researchers worldwide for its application in the food industry. In this review, this topic is discussed in detail along with the results of scientific research supporting the application of essential oils in food and their functional properties, such as the main functional properties of antioxidant, antibacterial and antifungal.


Introduction
Plants with aromatic and medicinal properties have been used for various purposes such as adding flavor to food, for medicinal purposes, as preservatives, and for beauty and stress relief products.They are a promising natural alternative that offers benefits, safety, and sustainability (1,2).Nowadays, there is a growing demand for essential oils in industries such as perfume and cosmetics, agriculture, pharmaceuticals, food and beverages, and others.The primary objective is to replace synthetic products with essential oils that are natural and have health benefits, while also reducing adverse environmental impacts.Certain essential oils, including peppermint, pine, wintergreen, and eucalyptus, as well as their main components like carvacrol and limonene, have been found to possess potent antimicrobial, preservative, herbicidal, and antioxidant properties beneficial for the agro-food industry (3)(4)(5)(6)(7).Numerous studies have explored natural antimicrobial sources from plants, which contain compounds capable of replacing chemical preservatives and synthetic antimicrobial agents (8,9).
The essential oil industry mainly focuses on the extraction process from aromatic and medicinal plants using conventional and/or innovative techniques that differ in their impact on the final product's yield, composition and quality (10)(11)(12)(13).Herbal plant-derived essential oils have multiple uses in the food, cosmetic, and medical industries.They are utilized as anti-cancer, anti-viral, anti-bacterial, antidiabetic, and anti-lipid peroxidation agents.In nature, plants produce two types of compounds: primary metabolites and secondary metabolites.Primary metabolites, such as carbohydrates, proteins, lipids, and nucleic acids, are essential components found in all plant and animal families.On the other hand, secondary metabolites are produced by specific metabolic pathways in plants, and they are relatively small in quantity.Essential oils are an example of secondary metabolites, which are produced through secondary metabolism (4,13).
Herbs and spices, which consist of the roots of fragrant and medicinal plants, have played a significant role in human culture for centuries.They are used to improve the flavor, appearance, and scent of food.One example is the Zingiberaceae family, which includes over 1600 species of plants with deep roots that grow in Asia, Central America, South America, and Africa (14,15).Zingiberaceae grows in tropical forests and is classified into four tribes based on morphology: Globbeae, Hedychieae, Alpinieae, and Zingibereae.Wild Zingiberaceae are typically found growing in forests, lowlands, and streams where light intensity is low and humidity levels are high.While many species of Zingiberaceae have potential medicinal properties, only a few are currently utilized by local communities.Therefore, conservation efforts are necessary to protect wild Zingiberaceae and preserve their potency.The plants of the Zingiberaceae family have two main uses: as decorative plants and as spices.While they share similar physical characteristics, each member of the family has unique pharmacological and therapeutic properties.It is on this basis that in the herbal product industry, both food and pharmaceuticals, an authentication system is needed to obtain Zingiber species which have high therapeutic effects and are original phytoceuticals compared to other species (16,17).
The Zingiber plant is commonly used in traditional medicine due to its various pharmacological and physiological effects.Studies have shown that the rhizomes of the Zingiberaceae plant are effective in treating several medical conditions, including digestive, respiratory, nervous, and muscular system problems, as well as degenerative diseases.The plant can be used to treat a range of ailments such as nausea, vomiting, epilepsy, sore throat, coughs, colds, bruises, wounds, liver complaints, rheumatism, muscle aches, atherosclerosis, migraine headaches, high cholesterol, ulcers, and stomach discomfort (2,18,19).Phenolic compounds as secondary metabolites found in Zingiberaceae rhizome plants have been shown to have good biological activity for human health and as antibacterials in their applications in food and pharmaceutical products.
Research has demonstrated that gingerol, a phenolic compound found in ginger rhizome (Zingiber spp.), possesses chemopreventive properties due to its antioxidant and anti-inflammatory activity (20,21).The essential oil extracted from Zingiber rhizome is utilized as a natural preservative, for its antimicrobial potential, and to combat fungal infections and associated illnesses (16,(22)(23)(24).Essential oil from galangal root is a secondary metabolite extracted from the rhizome of Alpinia galanga (Linn.)Willd which also has potential in the development of food and pharmaceutical products due to its antibacterial, antioxidant, insecticidal and anti-inflammatory properties (25)(26).Galangal contains various classes of compounds, such as flavonoids, terpenoids, saponins, phenolic acids, and essential oils (27)(28).Meanwhile, the rhizome of Curcuma longa has a distinct spicy and aromatic taste due to its essential oil, which is dominated by the phytochemical group ar-, α-, and β-turmeron (30).This chemical composition has numerous health benefits, including cardiovascular protection, antihyperlipidemic, antiglycemic, antioxidant, antiplatelet, anti-inflammatory, and antiarthritic properties (31)(32)(33).
There is not a single published review article on essential oils from rhizome plants limited to the Zingiberaceae family as the agroforestry product that discuss bioactive activity, safety, and applications in the food industry.Although the potential for essential oils is enormous, because they have high concentration characteristics and if used without any carrier can irritate the body (34,35), a method is needed to exploit an efficient and appropriate method in the application of this essential oil.The aim of this review is to provide an overview of the chemical compounds, biological effects, safety, and potential uses of essential oils obtained from Zingiberaceae Rhizome commodities, which are agroforestry products.This will greatly help researchers to get an overview of research developments related to essential oils produced from certain aromatic and medicinal plant rhizomes.

Phytochemical Composition of Zingiberaceae Rhizome Essential Oil
Phytochemicals are a large group of plant-derived compounds assumed to be responsible for much of the disease protection conferred from diets rich in fruits, vegetables, herbs and spices, and plant-based beverages such as tea, including the agroforesty product that dominated wild plant and trees.Based on the chemical structure, they are classified into various groups, for instance, phenolid compounds, terpense, phytoestrogen, and phytosterols.Nowadays, scientific research is not only relying on the nutrition contents but their phytochemical composition is considered equally important to consume them as functional food and feed.The major component of the essential oil extracted from the Zingiberaceae rhizomes showed in Table 1.
Phenolic compounds are substances produced by plants through secondary metabolism.These compounds are made from phenylpropanoids biosynthesized from the shikimate pathway (53).There are numerous types of phenolic compounds with different molecular weights (as shown in Fig. 1), levels of complexity, and distribution.However, all phenolic compounds share a common characteristic of having an aromatic (phenyl) arene ring with at least one -OH group attached (51).Phenolic compounds are classified as weak acids because of the unstable nature of their phenolic hydroxyl groups found in their aromatic rings.These compounds are categorized based on their chemical diversity and the number of carbons present in their molecular structure.Additionally, the classification of phenolic compounds is based on the number and arrangement of carbon atoms, which can be grouped into phenolic acids, flavonoids, lignans, and stilbenes.There are many different types of flavonoids, including anthocyanins, proanthocyanidins, condensed tannins, isoflavonoids, flavones, flavonols, flavan-3-ols, and flavanones (52)(53)(54).On the other hand, phenolic acids can be categorized into hydroxycinnamic acids and derivatives of hydroxybenzoic acid.
Terpenes, also known as terpenoids, are a group of over 30,000 secondary metabolites that are derived from five-carbon isopentane unit molecules, which are commonly referred to as isoprene units.These molecules are produced through the mevalonate pathway with the help of terpene synthase and other enzymes.Terpenes are categorized by the number of carbons they contain.Monoterpenes are 10carbon terpenoids, hemiterpenoids are 5-carbon terpenes, sesquiterpenes are 15-carbon terpenoids, diterpenes are 20-carbon terpenoids, and triterpenes are 30-carbon terpenoids (55,56).Herbs and spices contain terpenes, which have been linked to various pharmacological properties.Studies have shown that terpenes possess antimicrobial, anticancer, anti-inflammatory, and anti-diabetic properties.
Several bioactive compounds experienced increase due to pre-treatment prior to extraction, such as size reduction and drying.The main compounds in rhizome plants of the Zingiberaceae family decreased during processing.The oil hydrocarbon content increases and the oxygenation compounds decrease because it is processed into dried ginger and oil (46).The composition of the phytochemicals contained varies depending on several factors, such as commodity origin, geographical conditions, extraction methods, cultivation conditions, harvest time, pre-drying treatment (57).The various genotypes possess different chemical compositions based on their inherent properties.Interestingly, the properties of a particular variety can impact the oil content of the rhizome, making it a useful factor in identifying highyielding varieties.In this regard, a review of research on essential oils from parts of rhizome plants is needed to be able to see the overall data sources from various species of rhizome plants from the Zingiberceae family.

Antioxidant activity
Numerous essential oils and their components have shown promise in decreasing food waste and boosting the shelf life of edibles in the short run (58)(59)(60).Some have already been authorized as food additives or flavorings, while others are presently being evaluated.Scientists are currently examining the possibility of encapsulating essential oils to stabilize and even enhance their antioxidant properties (61)(62)(63).Generally, rhizome essential oils and their derivatives have displayed their potential as biopreservatives, improving the physicochemical and organoleptic features of food ingredients, including meat, vegetables, and other agricultural and fishery products, either on their own or in combination with other plant extracts (64).Nanotechnology, specifically through the use of nanoemulsion and nanoencapsulation, can improve the properties of essential oils used in packaging and direct food products.This technology can regulate water solubility and stability (58-60, 65)

Antibacterial activity
In turmeric essential oil, oxygenated sesquiterpenes which are the dominant chemical components have a major role in biological activity (66).Turmerone, specifically α-, β-, and ar-, are the main components found in Curcuma longa essential oil (38,67,68).These components have attractive properties, including anticancer, anti-inflammatory, and antioxidant effects (69-71.Additionally, ar-turmerone has been identified as the most important component, followed by αand β-, in rhizome oil with potential benefits for human health.Importantly, ar-turmerone can also enhance the bioavailability and activity of other key turmeric components like curcumin (72).Studies have shown that this substance has antibacterial properties that can combat harmful pathogens like Clostridium perfringens and Escherichia coli (64,74,75).Moreover, it has been found to be more effective than aspirin in preventing platelet aggregation caused by collagen and arachidonic acid.Galangal oil also has antimicrobial activity against various food pathogenic bacteria.Galangal essential oil has antimicrobial activity against Gram-positive strains, namely S. aureus, S. epidermidis, and Listeria monocytogenes (72,76,77).A different study revealed that galangal extract was effective in inhibiting gram-positive strains, but had a lesser effect on gramnegative strains such as Salmonella sp., Enterobacter aerogenes, and P. aeruginosa (78).

Antifungal activity
The ar-turmerone compound shows interesting and promising medicinal properties, in reviews (1) it was written that there are several protections that can be performed, one of which is as an antifungal against dermatophytes (19).By adding turmeric essential oil to a film layer used in packaging, food can be better protected against microbial contamination.This has been demonstrated in studies where an edible coating made from achira starch (Canna indica L.) and containing 0.5% w/w turmeric rhizome oil reduced the growth of common pumpkin destructive fungi Penicillium and Cladosporium spp.by 41.6-60.3%for up to 15 days (62).The essential oil from turmeric rhizome has also been found to have antifungal properties against Aspergillus spp., including the common contaminant A. flavus found in cereals, legumes, juices, and fresh and dried fruits (79,80).A. flavus is one of the primary sources of aflatoxin, a highly problematic mycotoxin found worldwide (80,81).The essential oil derived from the rhizome of the Zingiber plant has been found to be effective against various fungal strains, including Fusarium spp.It can also inhibit the growth of fungi that are resistant to amphotericin B and ketoconazole (2).Additionally, studies have shown that the oil has significant antifungal activity against Candida glabrata, C.albicans, and Aspergillus niger.These findings suggest that the Zingiber plant's essential oil can be used as a natural preservative in food preservation and to treat bacterial and fungal diseases (83)(84).

Application of Zingiberaceae Rhizome Essential Oil in the Food Industry
Zingiberaceae rhizome essential oil is important in food industry as consumers want safer options without chemicals.Consumers value products that have preservatives of natural origin and clean labels or products without chemical additives.In the food industry, the most sought-after biological activity (as shown in Figure 1) is the ability to prevent the growth of harmful microorganisms.This is achieved through antimicrobial activity, which is used as a preservative in active packaging.This method has been proven to be effective in ensuring that food products have a longer shelf life and meet safety standards during processing and handling.Additionally, antioxidant activity and flavoring agents can also be used in food products.
It was discovered that various essential oils have broad effectiveness in fighting spoilage and harmful bacteria in food items, including turmeric (Curcurma longa) essential oil, ginger essential oil (Zingiber officinale, Zingiber cassumunar, Zingiber zerumbet var.Darcyi, Zingiber nimmonii, Zingiber var.Halabala , and Zingiber officinale Rosc.var.officinale), and galangal oil (Alpinia galanga) which are proven to possess the power to manage or eliminate different harmful microorganisms that exist naturally in food or already in the form of food products (20,49,59,85,86).One of the primary benefits of utilizing essential oils derived from plants is that they are considered safe for use in food (GRAS).Additionally, these oils possess a distinctive aroma due to compounds such as gingerol, shogaol, and zingiberene, and also exhibit antimicrobial properties (camphene, linalool, α-pinene, and borneol).It has been reported that they are effective against Aeromonashydrophila, Aspergillus niger, Bacillus subtilis, Bacilluscereus, Escherichia coli, Halococcusturkmenicus, Halococcusmorrhuae, Listeria monocytogenes, Mucorican spp, Pseudomosaeruginosa, Salinococcus roseus, Staphylococcusaureus, Salmonella spp., Vibrio cholera, Vibrio parahaemolyticus (60,87,88).
Certain rhizome essential oils have been deemed safe for consumption by both the European Commission and the United States FDA, and are classified as GRAS.One such oil is galangal rhizome essential oil, which is derived from dried and fresh galangal rhizome and has a mildly spicy scent (76).Studies have shown that galangal essential oil, traditionally used in food, can also serve as an antioxidant functional ingredient in sausages (89), biscuits (90), and liquors like Chartreuse and Angostura.It can also be added to soft drinks to delay lipid oxidation and increase the shelf life of food (28).

Safety of Zingiberaceae Rhizome Essential Oil
Regarding safety concerns, rhizome plants in the Zingiberceae family such as ginger, turmeric, galangal, and spices are included among the spices provided from natural sources, defined as Generally Recognized As Safe (GRAS) by the American Food and Drug Administration (FDA) (91).From clinical trials, there are several studies that have examined doses or doses that are considered safe enough for human consumption.The daily dose for oral administration of essential oils depends on the phytochemical compounds they contain, for example ginger, safe doses for adult human consumption range from 500 mg/day to 1000 mg/day; at these concentrations, side effects are rare and mainly in the form of gastrointestinal discomfort (92).Ginger contains metabolites such as 6-, 8-, and 10-gingerol and 6-shogaol, which can cause discomfort during digestion.However, clinical trials on healthy volunteers indicated that doses of up to 2000 mg did not result in toxicity (93).In preclinical studies using rats, it was found that lethal doses of ginger essential oil were more than 5 g/kg body weight, and there is a possibility of teratogenicity, embryonic loss, and mutagenicity (94).
The results suggest that the essential oil derived from the rhizomes shows activity against microorganisms, particularly bacteria, as demonstrated through in vitro studies.However, further research is necessary to evaluate the practical application of the rhizome essential oil, as the primary component of curcumin has not been approved as a therapeutic agent due to incomplete knowledge of its pharmacokinetic and physicochemical properties.Therefore, it is not considered a safe substance (19,95,96) and strong conclusions cannot be drawn without further investigation.Other research that must also be carried out is to analyze organoleptic changes in food products that are combined or added to food formulations including their impact on taste, smell and color.When it comes to using rhizome essential oil as an antimicrobial in food or food processing, the biggest concern is likely the cost, which could be high due to the operational expenses involved in processing the oil.Nevertheless, despite the cost, consumers are likely to embrace rhizome essential oil as a natural alternative to conventional food preservatives, as it can help reduce the use of chemicals.
Essential oils can be used as flavorings and have been approved as safe by both the European Commission and the United States.The European Commission policy No 1334/2008 (96) and the Federal Food, Drug, and Cosmetic Act (The Act) and FDA regulations in 21 CFR 182.20 (97) have recognized essential oils as Generally Recognized As Safe (GRAS).In Indonesia, there are already several regulations related to the processing of essential oils, including SNI 8028-1:2014 concerning Essential Oil Distillers, SNI 8744:2019 concerning bioditives based on essential oils for diesel fuel, and several quality standards for essential oil products which are summarized in BSN RI Regulation Number 7 of 2019 concerning Conformity Assessment Scheme for Indonesian National Standards for the Chemical Sector.The rhizome essential oil that already has SNI is ginger oil with SNI number 06-1312-1998 (98).Essential oils used in medicine and food must meet safety regulations, with Regulation of The Agency Of Drug And Food Control (BPOM) No. 29 of 2017 Concerning Control of The Import of Medicine and Food Materials into The Territory of Indonesia.

Conclusion
Plants that possess phytochemical, medicinal, and aromatic properties, such as the rhizomes from the Zingiberceae family, are valuable resources for agroforestry products that can be used to treat various illnesses.To make herbal plants more accessible, they must be cultivated on a large scale in agroforestry systems.However, conventional mass cultivation and conservation methods in forests face several challenges, including rapid depletion of fertile land, declining soil quality, and unpredictable weather conditions.Nanoformulations research is needed to prepare various containing active components from essential oils which can increase water solubility, increase dispersibility, higher cell membrane penetration and therefore increase the therapeutic efficiency of compounds.Considering the various phytochemicals and their bioactivities, plants can be explored to find future drug leads that can help cure various diseases.

Figure
Figure 1.Representative role that Zingiberaceae rhizome oil in sustainable food industry

Table 1 .
The major component of the essential oil extracted from the Zingiberaceae rhizomes 1.Representative role that Zingiberaceae rhizome oil in sustainable food industry