The pomegranate has rich medicinal properties that cure numerous health problems and health issues. Its exports earn a handsome foreign exchange for our country and thus India stands first in the cultivation and production of Pomegranate. P. N. Kale and S. J. Kale review research activities by food scientists and various scholars have created interest in pomegranate fruit and have developed technologies for its value addition.
The pomegranate (Punicagranatum L.), a native of Iran, has been grown since ancient times as a wonder fruit. It belongs to the Punicaceae family. It is also known as the Chinese apple or Apple of Carthage or Apple with many seeds. This red delicious fruit is grown extensively in Iran, Spain, India, and USA as well as in most Near and Far East countries (Borgese and Massini, 2007, Schubert et al., 1999). The main pomegranate growing states in India are Maharashtra, Karnataka, Gujarat, Rajasthan, Uttar Pradesh, Andhra Pradesh, and Tamil Nadu. Some of the wild-growing varieties of pomegranate are found in the hills Himalayas, covering Jammu and Kashmir, Himachal Pradesh and parts of Uttar Pradesh.
India ranks first in the pomegranate production (8.07 lakh tones) in the world, on an area of 1.09 lakh hectares with the productivity of 7.40 t/ha. Maharashtra, a pomegranate basket of India, covers 0.82 lakh ha area (75 percent) with the production of 5.50 lakh tones (68per cent of the total pomegranate production in the country). More than 90 percent of the fresh produce is utilized for domestic fresh consumption and export. Spain (45per cent) and Iran (15 percent) competes in India in the International market (NHBMA, 2010).
It is also grown as an ornamental garden plant for its red, orange or occasionally, creamy yellow flowers. Pomegranate plant is able to withstand different soil and climate stresses hence is a crop of arid and semi-arid regions. Owing to its better keeping quality and high nutritional and nutraceutical value its popularity is increasing among the growers and consumers worldwide.
Nutritional Composition of Pomegranate
Pomegranate is a promising source of polyphenols and ellagitannins (Negi and Jayaprakasha 2003) as represented in Table 1. These phenolic compounds have the ability to scavenge reactive oxygen intermediates, thus preventing oxidation reactions (Ainsworth and Gillespie 2007). The pomegranate peels make up about 60per cent of the fruit, and they are rich in many compounds such as phenolics, flavonoids, ellagitannins, complex polysaccharides and many minerals including potassium, nitrogen, calcium, magnesium, phosphorus and sodium (Viuda-Martos et al., 2010). The peel is the part of the fruit with the highest antioxidant activity, which corresponds to its high content of polyphenols (Guo et al., 2003). Moreover, pomegranate peels also show higher antioxidant activity in vitro when compared with other fruits such as mangos, bananas and coconuts (Okonogiet al., 2007).
Pomegranate juice is also a rich source of anthocyanins, vitamin C, vitamin E, coenzyme Q10 and lipoic acid (Vroegrijk et al., 2011). Arils of pomegranate are rich in sugars, vitamins, polysaccharides, polyphenols, minerals, and its seeds are good in polyunsaturated (n-3) fatty acids. Although pomegranate seeds, which represent about 3% of the fruit weight, have a low polyphenol content and in vitro antioxidant capacity, they contain other components that may contribute to pomegranate’s health benefits (Guo et al., 2003). Other minor components are sterols, steroids and cerebrosides in seed oil (Gil et al., 2000). The beneficial qualities of pomegranate for human health are attributed to the exceptionally high antioxidant capacity that strongly correlates with high content and unique composition of phenolic compounds(Fischer et al., 2011; Gil et al., 2000).
Therapeutic Importance of Pomegranate
Pomegranate is a promising and emerging crop for its refreshing arils, juice, and its chemopreventive properties having medicinal value (Hertog et al., 1997). The pomegranate has been regarded as a food medicine of great importance for therapeutic purposes like colic, colitis-diarrhea, dysentery, leucorrhea, paralysis and headache (Sedeghi et al., 2009; Schubert et al., 1999). It finds wide application in the traditional Asian medicines both in Ayurvedic and Unani medicine systems. The therapeutic properties are reported to be due to the presence of betulic and urosolic acids along with different alkaloids such as pseudo pelletierine, pelletierine and some other basic compounds (Singh et al., 1990). There has been a remarkable increase in the commercial farming of the pomegranates globally, due to the potential health benefits of the fruit including its high antioxidant, anti-mutagenic, anti-hypertension activities and the ability to reduce liver injury (Lansky et al., 1998; Gil et al., 1996a; Tsuda et al., 1994; Du et al., 1975).
Pomegranate fruit is also known for its anti-inflammatory and anti-atherosclerotic effect activity against osteoarthritis, prostate cancer, heart disease and HIV-I (Malik et al., 2005, Summer et al., 2005). The juice from the pomegranates is one of the natures most powerful antioxidants. Gil et al. (2000) reported the antioxidant activity of pomegranate and compared to those of red wine and a green tea infusion showing that the commercial pomegranate juices had three times higher antioxidant activity than those of red wine and green tea.
Pomegranate juice also increases the body’s resistance against infections, acts as a cooling beverage and tones up the function of kidney, liver and heart. All the parts of the tree, the roots, the reddish-brown bark, leaves, flowers, rinds and seeds have featured in medicine for thousands of years as they are a rich source of different chemical constituents (Table 2). The sweet varieties of pomegranate are considered a good laxative while those which are intermediate between sweet and sour are regarded as valuable in stomach inflammations and heart pain. The pomegranates have recently been found to boost the activity of an enzyme which protects the cardiovascular risks.
Pomegranate Processing and Value Addition
The excellent flavour, nutritive quality and medicinal value of pomegranate fruit indicate its potential for processing into food products have extended shelf life. In India, in spite of the known nutraceutical benefits and great global demand for potential pomegranate derived products; its processing industry is underdeveloped due to a lack of technological developments for commercialization, resource personnel and scientific research database. Thus the post-harvest losses are very quite high.
About 10-15 percent of fresh produce loses its market value and consumer acceptability due to improper post-harvest management. Minimizing these losses can increase their supply without bringing additional land under cultivation.
A number of processed products can be manufactured and preserved for future time satisfying the consumer perception of a high nutritional quality and convenience produce. These could also help to have good returns and make the availability of the fruit throughout the year increasing the shelf life of the pomegranate fruits as such for a considerable period.
The ongoing global drive for a healthier diet has led to a rise in demand for convenient and fresh food produce, with high nutritional value and free of chemical additives (James et al., 2011). Pomegranate holds great scope for processing into value-added products have extended shelf life and wide viability (Table 3). The aim of processing is to use undersize fruits of low quality that cannot be commercialized and are not meant for table purposes. The fruit disorders such as sunburnt husks, splits and cracks and husk scald on whole fruit reduce marketability and consumer acceptance. Despite of great potential for pomegranate derived products, the industrial processing of pomegranate is a niche market due to the peeling difficulties and lack of technological development for industrial processing (Lopez-Rubiraet al., 2005).
Production of juice from the pomegranate arils proved to be one of the important methods of value addition. The edible portion of pomegranate i.e. arils constitutes around 48 to 52 percent of the edible portion on the whole fruit basis, thereby comprising of 78 percent juice and 22 percent seeds. Juice forms the basic material for processing into other value-added products such as., squash, syrup, nectar, jelly, concentrate and such other products.
Pomegranate juice can be extracted from whole fruit or only from arils as represented in Fig 2. Juice from whole fruit tastes bitter due to the high content of tannins responsible for bitterness. Juice from arils is less bitter in taste. Arils when crushed into juicer yields fresh juice with attractive color, nutritive value and taste. Pomegranate juice is a rich source of polyphenols, flavonoids and non-flavonoid compounds responsible for antioxidant properties, astringency and bitterness in the juice. Tannins from the juice can be precipitated by adding gelatin or it may be clarified by pectinase enzyme or by heating the juice at 79 to 82 °C followed by cooling and filtration. Sodium benzoate may be added as a preservative to prolong its shelf life while the use of potassium metabisulphite is not recommended due to the bleaching action of sulphur dioxide.
Pomegranate RTS, Squash and Juice Concentrate
Ready to serve (RTS) is a type of fruit beverage that contains at least 10 percent fruit juice and 10 percent total soluble solids besides about 0.3 percent acid. It may be plain (as such non-aerated) or aerated by carbonation which improves its stability. It should contain good body, uniform colour and possess pleasing flavour and an aroma characteristic of the fruit. RTS beverages are thought to be a convenient and economical alternative for utilization of these fruits. It is not diluted before serving, hence it is known as ready to serve (RTS) (Srivastava and Kumar, 2009). They are meant for direct consumption, without any dilution, thus offering the advantage of convenience to the consumers.
Whereas, squash is a concentrated liquid with 40per cent juice and acidity of 1.5per cent. Squash isready to serve in the ratio of 1:4 (one part of squash with 4 parts of water). Squash tastes best when served chilled and is a thirst quencher in summers. Pomegranate juice can also be converted into pomegranate juice concentrate containing around 65-70 percent total solids and pH 2.7 to 3.1. It is generally free from any added sugar or preservative hence is also being popularized as a health drink with known antioxidant activity.
Pomegranate syrup is commercially known as “grenadine” and is used as a flavoring ingredient in alcoholic drinks, soft drinks and confections. Grenadine is light pomegranate syrup prepared by mixing juice and sugar in the ration 60:40. A syrup of about 60° Brix with an added acidity of 1.5 per cent as citric acid has a bright purplish red colour and a delightful taste and flavor. It can be preserved by pasteurization or by addition of sodium benzoate.
Anardana and Anardana Powder
The conventional utilization of this fruit lies in drying the seeds along with pulp i.e. aril, which constitutes the product “Anardana” (Pruthi and Saxena, 1984). Anardana comprises the dried seeds of wild pomegranate which grows abundantly in the lower Himalayas parts of Jammu & Kashmir and Himachal Pradesh. Wild pomegranate is subjected to different types of unit operations for obtaining dried Anardana as the final product. The improved processing technique consists of pre-cleaning, mechanized extraction of arils, solar/sun drying, and packaging. After treating with sodium benzoate (600 ppm) for 10 minutes, arils are dehydrated in a drier at 45°C for 48 hours to 10-12 percent moisture content.
Traditionally the anardana is made by separating arils manually followed by sun-drying in open. The drying process takes around 10 to 15 days to dry completely followed by its packing in gunny bags. Traditionally processed anardana was found to be contaminated with microbes and was overall inferior in quality. Anardana is a highly acidic product with acidity varying from 7.8 to 15 percent. It has attractive brown colour and can be stored for a long time in glass jars (Artes et al., 2000). About 800 tonnes of anardana is produced annually valued at Rs. 10 crores at current market price. Anardana when converted into powder is called anardana powder.
Applications of Anardana
- It is a valuable commodity used as a condiment in the acidification of chutneys and certain curries particularly in the northern part of India.
- It is mainly used as acidulent in place of tamarind of dried green mango (Amchur) in North India in Indian styled curries, chutney and other culinary preparations.
- It is also used in the preparation of digestive candies and by the traditional system of Ayurvedic and Unnani medicine.
Unique Selling Points of Anardana
- Good source of vitamin C and minerals
- Attractive color and flavor
- Digestive properties and help improving mouthfeel
High Sugar Products from Pomegranate
Jams: Pomegranate jam commonly known as anar rub is a shelf-stable product with fairly good nutritional composition. The product is made by heating pomegranate juice with a sufficient quantity of sugar and pectin followed by for a good time to convert it into a thick consistency. The finished product contains 70-75per cent TSS with a shelf life of one year.
Jellies: An attractive jelly can be prepared from pomegranate juice (Phadnis et al., 1974). Chavan et al., (1995) prepared good pomegranate jelly on a small scale from Ganesh cultivar of pomegranate. While making jellies, approximately 50 percent of the anthocyanins present in pomegranate juice was lost. Maestre, et al. (2000) investigated that the acidification of juice produced a noteworthy improvement in the colour of the jelly, both initially and during storage. During storage, certain colour differences were observed, which indicates that the pH was not only the parameter responsible for this characteristic.
Pomegranate Waste Utilization: Rind and Seed Powder
All parts of the pomegranate tree i.e. roots; bark, leaves, flowers, rind and seeds can be processed for value addition into different value-added products as mentioned above. The developed products find use in medicines, pigment industries and cosmeceutical industries. Pomegranate rinds which form the major byproduct of the pomegranate processing industry can be converted into rind powder for consumption (Fig. 3).
The recovery of rind powder has been found to be 15.5 percent on whole fruit basis and 34 percent on a rind weight basis. Similarly, seeds left after juice extraction can be utilized in converting them into powder after drying to the moisture content of around 8 to 10 percent. Both rinds as well as seed powder are used as medicines for combating many stress-related disorders and lifestyle diseases.
Pomegranate is a wonder fruit because of its high antioxidant content and other therapeutic health benefits. There has been a rapid increase in its production and consumption in the form of value-added products especially in the form of “Juice”. The fruits of pomegranate are excellent in flavor and taste thereby becoming suitable for value addition and processing into various products. It is referred to as a “Wonder Fruit” due to its high nutritional value and unique antioxidant activity followed by great consumer appeal. But in spite of its high nutraceutical value and various health benefits its consumption for table purpose is not widespread due to time-consuming peeling. The pomegranate processing and product diversification has played an important role in the increased consumption and utilization of pomegranate.
Research activities by food scientists and various scholars have created interest in pomegranate fruit and have developed technologies for its value addition. The pomegranate can also be processed into products like minimally processed fresh arils and frozen arils besides juice, squash, beverage, juice concentrates, jam, jelly, grenadine, pomegranate rind powder, anardana, etc. These products are not yet popularized in a large scale due to lack of the commercially viable processing technologies. The keen and immediate attention is required in meeting the research and developmental gaps for the commercialization and popularization of pomegranate processing technology and pomegranate products.