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Please note this is a comparison between Version 1 by Agnieszka Najda and Version 3 by Jason Zhu.
Taro (Colocasia esculenta) ijes an important source of carbohydrates as ant ważnym źródłem węglowodanów jako źródło energy source and is used as a staple food throughout the world. It is rich in mucilageii i jest używany jako podstawowe pożywienie na całym świecie. and Jestarch bogaty w śluz i granules, making it a highly digestible ingredientki skrobi, dzięki czemu jest składnikiem wysoce przyswajalnym. MŚlucilage can act as a matrix and a thickening, bindingz może działać jako matryca i środek zagęszczający, wiążący, emulsifying, or foaming agent in food, pharmaceutical, and several other fields of researchgujący lub spieniający w żywności, farmacji i kilku innych dziedzinach badań. MCoreover, mucilage can be extracted from several living więcej, śluz może być ekstrahowany z kilku żywych organisms and has excellent functional properties, such as water-holding, oil-holding, and swelling capacitieszmów i ma doskonałe właściwości funkcjonalne, takie jak zdolność zatrzymywania wody, zatrzymywania oleju i pęcznienia. ThDlaterefore, these remarkable functional properties make mucilage a promisinggo te niezwykłe właściwości funkcjonalne sprawiają, że śluz jest obiecującym składnikiem o możliwych zastosowaniach przemysłowych. iPongredient with possible industrial applications. Furthermore, several extraction techniques, including enzyme-assistedadto kilka technik ekstrakcji, w tym metody ekstrakcji wspomaganej enzymami, ultrasonication, microwave-assisted, aquatic, and solvent extraction methodsdźwiękowej, wspomaganej mikrofalami, wodnej i rozpuszczalnikowej, aresłużą used to obtain quantitative amounts of tarodo uzyskania ilościowych ilości śluzu taro. muEkstrakcilage. Coldwater extraction with ethanol precipitation can be considered an effective and cost-effective technique to obtain high-quality mucilage with suitable industrial applications, whereas the ultrasonication method is more expensive but results in a higher amount of mucilage than other emerging techniques. Mucilage can also be used as a fat replacer or reducer, dye remover, coating agent, and antioxidating agentję zimną wodą z wytrącaniem etanolem można uznać za skuteczną i opłacalną technikę uzyskiwania wysokiej jakości śluzu przy odpowiednich zastosowaniach przemysłowych, podczas gdy metoda ultradźwiękowa jest droższa, ale skutkuje większą ilością śluzu niż inne nowe techniki.
- mucilage
- biopolymer
- polysaccharide
1. Extraction Process and Compositional Properties of Taro Mucilage
M
1. Proces ekstrakcji i właściwości składowe śluzu Taro
Śluz wyekstrahowany z różnych części roślin ma różnorodne zastosowania i właściwości w oparciu o ich odpowiednie elementy funkcjonalne i strukturalne. Ponadto do uzyskania ilościowych ilości śluzu stosuje się kilka technik ekstrakcji, w tym metody ekstrakcji wspomaganej enzymami, ultradźwiękami, wspomaganej mikrofalami, wodnej i rozpuszczalnikowej [ 23 ]. Jednak bardzo niewiele technik zostało przyjętych do ekstrakcji śluzu taro. W celu uzyskania wysuszonego proszku lub oczyszczonego śluzu stosowano techniki wirowania i suszenia [ 24 ]. Dodatkowo doniesiono, że technika suszenia w piecu jest bardziej efektywna niż suszarka rozpyłowa, ponieważ działa w wysokiej temperaturze przez krótki czas [ 25]. Skrobię obecną w śluzie taro można uznać za główne zanieczyszczenie, które wpływa na jej jakość i nie sprzyja emulgowaniu [ 26 ]. Oprócz metod ekstrakcji, na właściwości funkcjonalne śluzu taro wpływają również różne czynniki, takie jak stopień dojrzałości, rozmieszczenie, wielkość cząsteczkowa, stopień rozgałęzienia, wiązania strukturalne, obecność składników hydrofobowych oraz skład monomerów [ 27 , 28 ]. Podobnie, stadia fizjologiczne kłączy pącza wykazywały zróżnicowanie w wydajności śluzu, jak zaobserwowali Tavares i in. [ 21]. Wyższą zawartość skrobi stwierdzono 6 miesięcy po posadzeniu i obniżono w ósmym miesiącu, natomiast dużą zawartość suchej masy stwierdzono w fazie dojrzałości fizjologicznej taro, a wysoką zawartość białka przed osiągnięciem dojrzałości. Ultradźwięki w połączeniu z siłami hydrodynamicznymi są szeroko stosowane w celu zwiększenia potencjału mechanicznego ośrodka o wysokiej lepkości [ 29 ]. W konsekwencji Lin i Huang [ 30] wyekstrahowano śluz o wysokiej czystości (98%) z bulw taro metodą niskotemperaturową. W tym badaniu do analizy kwaśnych hydrolizatów śluzu zastosowano wysokosprawną chromatografię cieczową (HPLC) i określono D-galaktozę (61,6%) jako główny składnik, a następnie D-glukozę (19,7%) i D- arabinoza (16,2%). Podobnie w badaniu Andrade i wsp., śluz taro ekstrahowano w pięciu różnych warunkach, tj. (a) w temperaturze pokojowej, (b) w temperaturze pokojowej z wytrącaniem etanolem, (c) w wysokiej temperaturze, (d) w wysoka temperatura z wytrącaniem etanolem oraz (e) w niskiej temperaturze z wytrącaniem etanolem [ 31]. Wyższą wydajność (8,05%) uzyskano w temperaturze pokojowej, a najwyższą aktywność emulgującą i stabilność stwierdzono w warunku (b), śluz ekstrahowany w temperaturze pokojowej z wytrącaniem etanolem. Z drugiej strony, stan (d) w wysokiej temperaturze z wytrącaniem etanolem i stan (e) w niskiej temperaturze z wytrącaniem etanolem był silnie odzwierciedlony w wytrącaniu śluzu etanolem ze względu na solubilizację nieskrobiowych krótkołańcuchowych węglowodanów i innych składniki. W związku z tym ekstrakcję śluzu w niskiej temperaturze z wytrącaniem etanolem wyjaśniono na rysunku 1. W tym procesie po oczyszczeniu, obraniu i zmiażdżeniu kłącza są filtrowane przez dodanie wody destylowanej. Następnie przesączony roztwór odwirowuje się, zbiera się supernatant i wytrąca śluz alkoholem etylowym. Ponadto śluz ekstrahowany kwasami i zasadami wykazywał mniejszą lepkość i wyższą wydajność w porównaniu ze śluzem ekstrahowanym wodą ze względu na różnice w składzie monosacharydów w strukturze śluzu [ 3 ].
Rysunek 1. Schematyczny diagram przedstawiający ekstrakcję śluzu taro w niskiej temperaturze z wytrącaniem etanolem.
Fucilage extracted from different plant parts has diverse applications and characteristics based on their respective functional and structural components. In addthermore, the chemical composition, several extraction techniques, incincluding enzyme-assisted, ultrasonication, microwave-assisted, aquatic, and solvent extraction methods, are used to obtain quantitative amounts of monosaccharide units and amino acids, and proximate composition of taro mucilage [1]. Howevear, very few techniques have been adopted for also dependent upon the extraction of taro mucilage. Centrifugation and drying tetechniques have been used in order to obtain dried powder or purifiedof mucilage [2]. AdditionTally, it has been reported that the oven-drying technique is more effective than the spray dryer because it operates at a high temperature for a short timero mucilage consists of carbohydrates (arabinose, [3]. Starch present in taro mucilage can be considered a major impurity that affects its quality and is not beneficial for emulsification [4]. Aparamnose, arabinose, fructose, mannose, galactose, fructose, and glucose) and also cont from extraction methods,ins various factors such as maturity stage, distribution, molecular size, degree of branching,amino acids, as shown in structuralFigure 2. linkages, prThesence of hydrophobic components, and monomeric compositions also affect the functional properties of high glucose content present in taro mucilage [5][6].is due Similarly,to the physiological stages of taro rhizomes showed variation in the yield ofresence of starch during the extraction. In addition, taro mucilage, as observed by Tavares et al. [7]. H is a righer starch content was noted six months after planting and was reduced at the eighth month, whereas a hsource of high amount of dry matter was found at the physiological maturity stage of taro, and high protein content was found before the maturity stage. Ultrasonication in combination with hydrodynamic forces is widely adopted in order to increase the mechanical potentials of arabinogalactan-protein (AGP) (93–98%) and provides a high amount of AGP, which is responsible for the improvement of the highly viscous medium [8]. Conseqemuently, Lin and Huansifying [9] propextracted high-purity (98%) ties of mucilage from taro corms using a low-temperature method. High-performance liquid chromatography (HPLC) was used to analyze the acidue to the presence of hydrophilic and hydrolysates of mucilage, and D-galactose (61.6%) was determined to be a major component, followed by D-glucose (19.7%) and D-arabinose (16.2%). Similarly, in a studyphobic amino acids, as stated by Andrade et al., taro [32] mucilage was extracted in five different conditions, i.e., (a) atnd Njintang et al. [33]. room tSemperature, (b) at room temperature with ethanol precipitation, (c) at high temperature, (d) at high temperature with ethanol precipitation, and (e) at low temperature with ethanol precipitation [10]. Hiveral phenolic compounds present in taro mucilagher yield (8.05%) was obtained at room temperature, and the highest emulsifying activity and stability were found in condition (b), mucilage extracted at room temperature with ethanol precipitation. On the other hand, condition (d) at high temperature with ethanol precipitation and condition (e) at low temperature with ethanol precipitation was highly reflected in the precipitation of mucilage with ethanol due to the solubilization of non-starch short-chain carbohydrates and other component are esterified (bound phenolic compounds), which are interconnected to arabinose residues or carboxyl groups via ester bonds. The extraction of mucilage at low temperature with ethanol precipitation is explained in Figure 1. In the pse esterified compounds have grocess, after cleaning, peeling, and crushing, rhizomes are filtered by adding distilled water. Afterward, the filtered solution is centrifuged, the supernatant is collected, and mucilage is precipitated by ethyl alcohol. Moreover, acid- and alkali-extracted mucilage showed less viscosity and higher yield as compared to water-extracted mucilage due to composiat potential to inhibit enzymatic activity by polyphenol oxidases (PPO) such as laccase, which results in the improvement of functional differences in monosaccharides in the mucilage structure [11]properties.
Figure 1. Schematic representation diagram of the extraction of taro mucilage at low temperature with ethanol precipitation.
Furthermore, the chemical composition, including monosaccharide units and amino acids, and proximate composition of taro mucilage are also dependent upon the extraction techniques of mucilage. Taro mucilage consists of carbohydrates (arabinose, rhamnose, arabinose, fructose, mannose, galactose, fructose, and glucose) and also contains various amino acids, as shown in Figure 2. The high glucose content present in taro mucilage is due to the presence of starch during the extraction. In addition, taro mucilage is a rich source of high amounts of arabinogalactan-protein (AGP) (93–98%) and provides a high amount of AGP, which is responsible for the improvement of the emulsifying properties of mucilage due to the presence of hydrophilic and hydrophobic amino acids, as stated by Andrade et al. [12] and Njintang et al. [13]. Several phenolic compounds present in taro mucilage are esterified (bound phenolic compounds), which are interconnected to arabinose residues or carboxyl groups via ester bonds. These esterified compounds have great potential to inhibit enzymatic activity by polyphenol oxidases (PPO) such as laccase, which results in the improvement of functional properties.
Figure 2. Chemical structures of different amino acids present in taro mucilage.
Consequently, Njintang et al. [13][33] extracted mucilage from five different taro varieties by solvent extraction treatment. In their work, the protein content of mucilage was found to be higher (30–51%) due to the use of saline buffer during the extraction. Therefore, different growth conditions of taro can affect the protein content, carbohydrate proportion, and yield of mucilage. Similarly, taro mucilage also contains acidic glycoproteins, acidic glycans, and natural glycans. These fractions of glycans are considered effective viscosity modifiers and gelling agents according to Manhivi et al. [14][34]. Carbohydrates, ash, fiber, moisture, lipids, and proteins are major components constituting the proximate compositions of foods. However, several researcheuthors have obtained different results for the proximate compositions of taro mucilage [15][35]. For example, the chemical composition of mucilage extracted at low temperature with ethanol precipitation showed an average ash content, a lower amount of crude fiber and ethereal extract, and a higher amount of the glycosidic fraction and protein content in the inorganic fraction of mucilage [10][31], whereas mucilage extracted at room temperature without precipitation showed a decreasing trend of glycosidic fractions from 91% to 38%, and protein content was increased from 3% to 47%. These findings were caused by the elimination of carbohydrates, including starch components, after centrifugation in the cold treatment [12][32]. Moreover, several reports have revealed that bonding between proteins and carbohydrates is responsible for the emulsifying properties of mucilage [16][36].
2. Techno-Functional Property of Taro Mucilage
Hydrocolloid polymers (high-molecular-weight biopolymers) are extensively used in the food and pharmaceutical industries. A hydroxyl group in a biopolymer causes viscous dispersions, which increases water attraction [17][18][16,47]. Hydrocolloids are also commonly used as stabilizers, thickening agents, dietary fiber, whipping agents, and fat substitutes. However, mucilage is water-soluble and often has remarkable functional properties, including water-holding capacity, oil-holding or binding capacity, and emulsifying, foaming, antioxidant, and antimicrobial properties [19][48]. Moreover, they also have diverse industrial applications in edible films and coatings, crystallization inhibition, and flavor encapsulation. High water-holding capacity is attributed to the presence of hydroxyl groups and protein substituents in the gum and mucilage structure [20][49]. The moist polymer or sample can hold water when exposed to an external centrifugal gravity force or compression. Water-holding capacity comprises the sum of linked water, physically trapped water, and hydrodynamic water, the latter of which contributes most to this capacity. Conversely, the inability to form a gel is due to the high solubility of mucilage, even at high concentrations, which results in a low water-holding capacity [21][22][50,51]. Furthermore, the elastic structure of mucilage is linked to good foaming properties. Foaming properties are influenced by a variety of parameters, including the presence of various chemicals in carbohydrates, structure, protein content, and molecular weight. The flexible structure of mucilage, which can minimize surface tension, is closely linked to its excellent foaming capacity [23][52].
3. Application of Taro Mucilage
Plant-derived additives or polymers can be used as natural thickeners or emulsifiers in the human diet and thus act as alternatives to synthetic polymers or additives [24][53]. Mucilage derived from plants can form a large number of network molecules due to their elasticity and thus can be widely used for edible films or edible coating in food packaging applications, thickening, encapsulation, inhibition of syneresis, control of crystallization, suspension of particulates, and stabilization of emulsions in the food industry, while it can act as disintegrators in tablets, tablet binders, and a variety of other pharmaceutical applications [25][26][54,55]. Additionally, mucilage is highly capable of swelling or solubilizing in aqueous systems, providing viscous material, similarly to the characteristics provided by fats. However, excessive intake of fats and oils can cause obesity, several types of cancer, cardiovascular diseases, and hypercholesterolemia [27][56]. Therefore, several researcheuthors have stated that mucilage should be considered as a potential ingredient in food industry applications, including fat replacers, emulsifiers, and dye removers [28][57].
3.1. Application of Mucilage as an Emulsifying Agent
The emulsifying capacity of mucilage is an important function and has a wide range of applications in several industries. An emulsion is a homogeneous mixture of two immiscible liquids in which one phase is dispersed and distinct from the other [29][58]. Emulsifiers aid in the formation of fine dispersions, whereas stabilizers improve the stability of the dispersion of two or more ordinarily immiscible phases. A few mucilages and gums (e.g., gum arabic) can act as stabilizers and emulsifiers at the same time [30][59]. Furthermore, emulsifiers are amphiphilic compounds with a water-soluble polar component (hydrophilic) and a non-polar water-insoluble component (lipophilic or hydrophobic), and they are extensively employed in the food industry [31][60]. Monoglycerides, propylene glycol monoesters, lactylate esters, acetylated monoglycerides, and ethoxylated esters are the most common synthetic commercial emulsifiers. Natural emulsifiers include lecithin and gum arabic, as well as guar, xanthan, locust bean, and carrageenan gums. It can be utilized as a natural emulsifier in baking to produce sensory characteristics comparable to bread with additional commercial synthetic emulsifiers in the food industry [32][61]. However, it has been reported that taro mucilage has lower lipid content than other commercial emulsifiers [33][62]. In Tthis context, the emulsifying properties of taro mucilage were evaluated by Andrande et al. [12][32]. The presence of a methyl group, which was observed in the infrared spectra, and the presence of low amounts of lipids may also contribute to the emulsifying power by providing a hydrophobic moiety. The hydrophilic portion of this emulsifier mainly consists of hydroxyl-containing carbohydrates. Therefore, it can be concluded that the protein content of taro mucilage, as well as weakly polar amino acids found in gums, is primarily responsible for its emulsifying capacity [34][35][63,64].
3.2. Application of Taro Mucilage as a Fat Replacer
In recent years, consumers have become more health-conscious. As a result, demand for low and reduced-fat foods is increasing, as customers need to change their food intake in order to lose weight [36][65]. Taro mucilage is an edible polysaccharide also known for its excellent functional properties (especially water-holding capacity) due to its several free hydroxyl groups and fiber-rich fractions, which may form bonds with water molecules [37][66]. Therefore, taro mucilage can mimic the properties of fats by increasing the viscosity of a system and promoting moisture retention in low-fat food products. This has a positive impact on the rheological aspects of foods (baked goods, meats, and dairy products) and is also correlated with softness and cooking loss [38][67]. Fat is important in baked products because it promotes dough lubrication and air incorporation and prevents gas-bubble coalescence during mixing. Moreover, the gelatinization of starch also reduces the presence of fat because the retardation of water is transferred to the starch granules [39][68]. In a study by Nagata et al. [40][69], physical, chemical, and sensory analyses of bread slices were carried out after the addition of taro mucilage. It was observed that bread containing taro mucilage showed excellent softness and sensorial properties. Additionally, it is believed that fat replacers have different mechanisms in common food products. In the case of bakery products, the interaction between fat and protein reduces the growth of the protein matrix during the process of dough formation, which is responsible for the short structures and softness of the bread. In this case, protein interaction with lipids can have an impact on the bread volume, the firmness of the crumbs, and the destabilization of the gas cell. Moreover, water activity can be reduced with the addition of mucilage to bakery products due to its good water-holding or absorbing properties [7][21]. In general, hydrogen bonding, steric interactions, electrostatic interactions, and covalent bonding are responsible for the techno-functional properties and applications of mucilage as fat replacers. The self-interactions of mucilage without competing with starchy polysaccharides and gluten proteins for available water in the system led to an increase in moisture content in some bakery products (e.g., eggless cake) [31][60].
3.3. Antioxidant Activity of Taro Mucilage
The hydroxyl radical is a potential oxidant that may react with all biological components, including proteins, lipids, and carbohydrates, and oxidative stress is known to have a role in a range of degenerative processes and diseases [41][70]. The damaging power of OH radicals is very strong, and the oxidation of fatty acids in biological membranes leads to the eventual destruction of the membrane, rearrangement of double bonds in unsaturated lipids, uptake of oxygen, and propagation of lipid radicals [42][71]. Therefore, research on antioxidants, especially plant-based polymer extracts, has become an important branch of science. Additionally, mucilage has a wide range of therapeutic properties, has become well known, and is widely used due to its ability to prevent oxidation [43][72]. The majority of plant-derived mucilages showed the ability to scavenge different free radicals produced and generated by various biological and chemical reactions. As a result, mucilage’s antioxidant function assists in the control of oxidative stress in the circulatory system [44][73]. Electron donor or hydrogen donor functional groups attached to polysaccharide chains provide polysaccharides with their antioxidant properties. These properties differ from one functional group to another and can be easily measured using in vitro antioxidant assays. However, very little literature is available on the antioxidant activity of taro mucilage [45][74]. For example, Nguimbou et al. [46][75] measured the antioxidant activity of mucilage from yellow and white giant swamp taro tubers. YIn this study, yellow taro mucilage showed higher antioxidant activity than white, while the chelating ability and the reducing power of taro increased with mucilage content. Moreover, the antioxidant activity of phenolic compounds is due to their redox characteristics, which allow them to act as singlet oxygen quenchers, hydrogen donors, and reducing agents. They also have metal-chelating potential. Therefore, they have excellent antioxidant properties [47][76].
3.4. Application of Taro Mucilage as Dye Remover
Dye wastewater primarily consists of residual dyes and auxiliary chemicals and can be one of the most significant contributors to water pollution in several industries, including textile effluent and food industries [48][77]. Over 50,000 tonnes of dye are discharged into wastewater each year, with the percentage varying depending on the dye type, fiber application, and degree of dye fixation. The proportion of dye that is lost to effluent varies among dye–fiber application systems [49][78]. Several methods for removing color from dyehouse effluent have been developed, with varying degrees of effectiveness, costs, and environmental impacts. However, it has been proven that color removal by sorbing dye molecules onto a substrate (adsorbent) can be a very successful and low-cost approach. Adsorption is used in numerous procedures that change or destroy the dye chromophore to remove color, but residual moieties are not always removed from the effluent and may cause environmental issues [50][79]. In addition, naturally, polysaccharides (gums, mucilage, and chitin) are superior to polymers for the adsorption of heavy metals and dyes due to the higher number of sites for possible chelation. Likewise, Mijinyawa et al. [41] udowodnił, że śluz taro może usuwać błękit metylenowy przy zasadowym pH pod wpływem ultradźwięków.
