Manilkara zapota (Naseberry): Medicinal Properties and Food Applications

ABSTRACT

Manilkara zapota L (naseberry) is popular in the food and nutraceutical industries in many parts of the world. The plant is however underutilized in Jamaica where the fruit is mainly eaten fresh. The fruit and leaves of the plant are rich in phytochemicals and antioxidant compounds. Naseberry has many potential agro-processing applications and may be utilized in the preparation of various food products such as flavored water, iced tea, freeze-dried naseberry snacks and antibacterial packaging for meat. This paper serves as a review of the various health benefits that may be afforded from this plant.

KEYWORDS:

• Manilkara zapota
• naseberry
• bioactives
• postharvest
• commercial applications

Introduction

Manilkara zapota L, a tropical fruit (Figure 1) belonging to the Sapotaceae family, is native to Central and South America (Morton, 1987). The tree is grown commercially in India, the Philippines, Sri Lanka, Malaysia, Mexico, Venezuela, Guatemala and in Central America. The largest producer of this fruit is India (Morton, 1987). The tree also grows in the West Indies and the State of Florida in the United States of America. In Jamaica, the fruit is often sold by vendors and can be purchased throughout the year at various places such as Flat Bridge, St. Catherine. M. zapota is of great economic importance globally but is underutilized in Jamaica.

Figure 1. Naseberry fruit

The fruit goes by various names viz. naseberry (British West Indies), chicku (India), chicopote, chickozapote (Mexico), dilly (Bahamas), kauki (Southeast Asia), mispu, mispel, mispelboon (Suriname), muyozapot (El Salvador), nispero (Puerto Rico), sapitija, sapodilla plum, sapodilla (Dutch West Indies), sapota, sapote (Cuba), sapoti or sapotilha (Brazil), sapotille and sapotillier (French West Indies) (Mickelbart, 1996). Sapodilla is one of the more popular names in America. The origin of the name sapodilla is from the Latin word zapotilla which means small sapote.

The plant is well adapted to grow in a wide range of climatic conditions ranging from dry cool subtropical to wet tropical climatic conditions growing to heights of 30 m (Mickelbart, 1996). It is also able to thrive under dry conditions, in the presence of poor soil and in low rainfall areas as the roots are located within 75 cm of the depth of soil. Pruning is not necessary for the first ten years. Young trees require irrigation for the first four years. Fertilizers rich in potassium in conjunction with phosphorous is beneficial to the crop. The propagation of the tree is mostly vegetative (Mickelbart, 1996).

The fruit is round or egg shaped ranging from 5 to 9 cm in diameter and weighing 75 to 200 g. The pulp, the inner fleshy part of the fruit, is soft and easily digestible. It is light brown in color with a gritty texture and typically contains 12 black, flat seeds. The flesh of superior varieties is seedless and has a smoother texture (Mickelbart, 1996). The skin has a rough texture and is brown in color. The sweet taste of the fruit is due to the presence of simple sugars such as glucose, fructose and sucrose. The fruit can be stored for up to three weeks at 12 to 16°C maintaining a relative humidity of 85–90%. The storage life of the fruit may be extended if the fruit is held at 4°C before storing at 20°C. The fruit is however subject to chill injury if stored at 4°C for more than 10 days (Siddiqui et al., 2014).

Medicinal Properties and Bioactive Components

M. zapota is world renowned and is well appreciated for its nutritional values and medicinal properties. Plants rich in phytochemicals and antioxidants have stroked the interest of medical researchers (Lobo et al., 2010). The fruit as well as various parts of the tree have been used traditionally for the treatment of various ailments. The fruit is rich in vitamins, carbohydrate, minerals, is a good source of energy and contains flavonoid and bioactive polyphenolic compounds. Methyl 4 -O- galloylcholorogenate and 4 -O- galloylchlorogenic acid, two novel antioxidants, were isolated from methanolic extracts of the fruit. Eight other known polyphenolic antioxidants were also identified, namely methyl chlorogenate, di hydromyricitin, quercitrin, myricitrin, (+) catechin, (-) epicatechin, (+) gallocatechin and gallic acid (Ma et al., 2003). Catechin also present in teas is a well-known antioxidant (Nile and Park, 2014). Natural antioxidants can assist in the protection of human cells against the effects of free radicals that may contribute to cancer forming cells among other diseases (Widsten et al., 2014).

Tannin is one of the major chemical compounds found in the pulp of the fruit. Tannins belong to a family of complex natural polyphenols that participates in chemical reactions neutralizing acids by precipitating proteins. Tannins and phenolics extracted from the leaf of the naseberry act as secondary metabolites assisting in protecting the plant against preying animals and microorganisms. Tannin extracts can be considered for use as an antimicrobial agent to extend the shelf life of food (Hintz et al., 2015).

The leaves of the plant exhibit antihyperglycemic, hypocholesterolemic and antioxidant activities (Fayek et al., 2012). Sravani et al. (2015) demonstrated that leaf ethanoic extracts possess anti-inflammatory activity. Leaf ethanolic extracts also exhibit anti-arthritic activity (Singh et al., 2011). Phenolic compounds are the dominant phytochemical component in the leaves (Fayek et al., 2012). Lupeol acetate, oleanolic acid, apigenin-7-O-α-L-rhamnoside, myricetin-3-O-α-L-rhamnoside, and caffeic acid were the major compounds isolated from the leaves of the plant (Fayek et al., 2012). Another study conducted on the leaves of the Jamaican naseberry plant revealed that they contain high levels of tannins as well as a small portion of flavonoid and polyphenols (Bryan-Thomas, 2016). The antioxidant properties of the leaves are as a result of its free radical scavenging activity (Islam et al., 2012). Kaneria and Chanda (2012) evaluated the leaves of the plant for antioxidant and antibacterial properties and concluded that acetone extracts of the leaves exhibit strong antioxidant and antibacterial properties which may be of therapeutic value (Kaneria and Chanda, 2012).

Research conducted by Mohanapriya et al. (2014) revealed that acetone extracts of the seeds contained alkaloids, steroids, flavonoids, tannins, phenols, glycosides and saponins. The presence of various phytochemical compounds was confirmed by Shanmugapriya et al. (2011). Silver nano particles synthesized from aqueous extracts of the seed were effective against Candida species (Otari et al., 2014). Animal studies showed that leaf extracts and the juice from the fruit are effective in the prevention of diabetes, dyslipidemia and obesity as well as complications that may arise due to these diseases (Barbalho et al., 2015). The juice of unripe fruit is used to treat diarrhea (Mohiddin et al., 1992). The decoction of the tree bark is used as a tonic and peludism (Nair and Chanda, 2008). Flavonoid and bioactive polyphenolics have applications in the beverage industry (Shafii et al., 2017).

Food Applications

The naseberry fruit has many food applications. Due to its sweet taste, the fruit is often consumed fresh as a dessert, used to make sherbets, ice cream, jam and dehydrated fruits snacks. The pulp of the fruit is also used to make vinegar and powder for juices. The juice may be extracted to make syrup and vinegar. A milky latex that exudes from the stem and bark of the plant is used to make the base of chewing gum (Peiris, 2007). M. zapota can also be combined with pectin to formulate shelf-stable fruit bars that are a good source of vitamins, carbohydrates and fibers (Salleh et al., 2017).

Freeze Drying

Natural M. zapota pulp is not shelf stable and it is therefore best to consume within a few days before spoilage occurs. Scientists have explored various methods to improve the shelf stability of the fruit such as freeze drying and spray drying. Freeze drying was utilized to extract tannins (proanthocyanidins) from the M. zapota fruit. Extracts were freeze dried to a powder form (Aliah, 2015). The freeze-dried fruit was found to have high levels of proanthocyanidin. It was observed that the concentration of tannin decreased as the fruit ripened (Aliah, 2015). As the tannin concentration decreased, the concentration of gallic acid increased (Aliah, 2015). Freeze drying is a good way of extending the shelf life of tropical fruits while causing minimal loss to it phytochemical and antioxidant properties (Shofian et al., 2011).

Spray Drying

M. zapota fruit puree was spray dried producing a powder that can be used in juice formulations (Yee Chong and Wong, 2015). It was observed that at 180°C powder recovery was most efficient. The viscous liquid from the puree is however prone to sticking to the walls of the cyclone resulting in a reduction in powder recovery. Through the addition of maltodextrin, this stickiness may be reduced contributing to an improvement in fruit powder recovery. Stickiness is frequently encountered during spray drying due to the presence of low molecular weight sugars (glucose, fructose) and organic acids (citric, malic and tartaric acid) (Yee Chong and Wong, 2015).

Potential Applications of Naseberry

Sugary foods have become increasingly available in developing countries. Sugary fast foods, juice and sodas are a major cause of non-communicable diseases such as cancer and diabetes (Lin et al., 2018). In response to this global phenomenon, the government of Jamaica has implemented a ban on sugary drinks in public schools. Sugary drinks, as defined in the context of the ban, refers to beverages that contain added sugar and syrup by the manufacturer and do not include 100 percent juice. The ban to be imposed on “sugary drinks” is an opportunity for agro-processors to utilize locally available fruits to produce more healthy products in the market.

The naseberry plant is underutilized in Jamaica and may be processed to produce various value added products. These include the production of freeze dried naseberry powder packaged in aluminum laminated packaging for making juice (instant powder packets “mix-and-drink”) and freeze dried naseberry snacks. Extracts can be used to make flavored water and iced tea to replace carbonated beverages. Freeze dried extracts that are rich in tannins may also be able to extend the shelf life of fresh fish and meat on the local market by utilizing them as antibacterial packaging in active packaging (Widsten et al., 2014).

Conclusion

The M. zapota plant is underutilized in Jamaica. It contains phytochemical compounds such as flavonoids and bioactive phenolic compounds. The fruit is a good source of nutrients and also exhibits antioxidant and antimicrobial activities. This paper has highlighted various potential food and nutraceutical applications of the fruit. Freeze drying is an effective way of extending the shelf life of the fruit and may be further explored.