MEDICINAL PLANTS

Plant-derived phytochemicals protect against diseases and in maintaining well-being [90]. Plants having medicinal properties are provided for cure of different ailments in various indigenous healthcare systems viz., Allopathy (30), Siddha (600), Amchi (600), Ayurveda (700) and Unani (700) [63]. In India, around 20,000 plants with medicinal activities have been documented [9, 21]. However, the data suggests that traditional communities are using only about 7,000-7,500 plants for medicinal purposes [67]. Ayurvedic system of medicine is well-established in developed countries including Europe, America, and Asia [84].

IMPORTANCE AND SCOPE OF HERBAL MEDICINES

Majority of the population in the developing countries depends upon herbal medicines to cure diseases. Utilization of herbal medicines is interestingly rising in developed and developing countries. For instance in France and Germany, many herbal extracts are considered and prescribed as drugs; and their sales in the European Union was estimated to be>$20 billion in 2014. In India, the herbal drug market is approximately S3.89 billion in the domestic market and $145 billion for export [77]. Herbal medicines as nutraceuticals (health foods) have an estimated market of about $ 80-250 billion in the Western counties [36].

DELIVERY SYSTEM FOR HERBAL BIOACTIVE COMPOUNDS

Daily products are increasingly being used as a delivery vehicle for different bioactive ingredients [34, 78] including the herbal extracts [30]. When herbs are added directly into milk, organoleptic, and physicochemical attributes are prone to be affected severely, which tends to limit their application. Encapsulation of herbal extracts has been used as a successful tool to restrict their implications on sensory quality thereby enabling the use of food products as a vehicle for delivery of bioactive ingredients and for their higher bioavailability [47].

The European legislation describes the delivery system as modification in the extent or location at which the active component is to be released. Such an alternation is done by employing appropriate materials possessing well-defined protective attributes to manipulate the release of the active compound. Encapsulation can act as an effective method to deliver the herbal bioactive compounds through aqueous food systems. Microcapsules, developed in the encapsulation system, comprises of two phases: (i) an imier phase, which carries the active compound of interest; and (ii) an outer phase, which acts a carrier material and encapsulates the inner phase. Different kinds of encapsulation techniques have been developed, such as [17]:

  • • Phase separation (coacervation);
  • • Solvent dispersion/evaporation;
  • • Co-crystallization;
  • • Diying polymerization;
  • • Interfacial polymerization to suitably encapsulate different compounds: minerals, vitamins, antioxidants, polyphenols, amino acids, and enzymes.

From the perspective of food processing, encapsulation not only limits the chemical and enzymatic degradations [95] but also enhances the miscibility of active component in food products without affecting the inherent organoleptic attributes [19].

Literature highlights some materials for encapsulation of active components, such as [92]: synthetic polymers, acacia gums, semi-synthetic cellulose derivatives, and maltodextrin. Soluble polysaccharides (maltodextrin) have been reported as potential encapsulating ingredient; however, its main drawback is its inferior emulsification activity, specifically for volatile compounds that tend to escape rapidly after encapsulation using maltodextrin. Thus, there is urgent need for more efficient and stable encapsulating ingredient for delivering bio-functional agents through different food systems. Gelatin and gum acacia are also considered as efficient encapsulating ingredients for their lower viscosity and high solubility in aqueous solutions and ability to form stable O/W emulsions. Combination of maltodextrin and gum acacia is reported to yield an emulsion with higher encapsulation efficiency and recovery of bioactive component [92].

United States Food and Drug Administration (US-FDA) has defined Maltodextrin as sensorially bland tasting (non-sweet) polysaccharide of a-1, 4-linked D-glucose monomeric units with <20 dextrose equivalent (DE) value [64]. It has also been suggested that low-DE maltodextrins can be potentially used as fat replacers in different fat-rich products [46]. DE value has great relevance with viscosity and Maillard browning ability of maltodextrins [4]. Maltodextrins are utilized in our body and give calories like starch (viz., 4 kcal/g), however when they are used as fat alternatives, their actual concentration is very low and hence their net calorie contribution in the food product is approximately 1 kcal/g [25]. Encapsulates formed by maltodextrins showed very less stability of encapsulated bioactive compounds, which may be due to its poor emulsification ability and stability.

Desobiy et al. reported that drum and freeze-dried (3-carotene encapsulation from maltodextrin had higher encapsulation efficiency as compared to spray dried encapsulation [20]. Buffo and Reineccius [15] compared spray, tray, freeze, and drum diying techniques for encapsulating orange oil. They reported that highest encapsulation efficiency was obtained with freezedrying technique. Zheng et al. [41] encapsulated blueberry polyphenols using ethyl cellulose added with lecithin. Finotelli et al. [24] reported complete encapsulation of ascorbic acid (AC) using maltodextrin as coating agent and spray diying as technique for encapsulation.

Gum Arabic is often considered as a suitable ingredient for encapsulation purposes due to its lower viscosity, high solubility, and superior emulsification capacity. It has shown to retain volatile compounds in the capsules, which was not observed for maltodextrin. Also, literature confirms it’s functioning as a surface-active agent. However, gum Arabic is used at a very limited level by food companies due its higher cost than maltodextrin, which is further subjected to fluctuations [44, 79, 69].

Encapsulation using a mix of coating ingredients has also been applied to efficiently deliver the bioactive components. Recent report suggests of increased encapsulation efficiency of maltodextrin and gum Arabic with addition of gelatin along with them [43, 45, 93]. Karaca et al. [37] reported higher encapsulation efficiency of a mix of lentil protein isolate and malto- dextrin for encapsulating flaxseed oil.

 
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