Melicoccus Bijugatus (guinep): Phytochemical Properties, Associated Health Benefits and Commercial Applications

ABSTRACT

Melicoccus bijugatus Jacq. (guinep) is a member of the Sapindaceae family. It is native to South America but grows in the Caribbean and parts of Central and North America. It is a small round fruit with a thick green rind covering a peach colored pulp which has a jelly like consistency with taste ranging from sweet to sour. Recent studies posit the presence of various phytochemicals in guinep with health benefits which may be useful in the creation of value-added products that are beneficial to both the international and local food manufacturing industries and their consumers. This paper discusses the associated health benefits, phytochemical properties and commercial applications of Melicoccus bijugatus (guinep).

KEYWORDS:

• Melicoccus bijugatus
• guinep
• bioactives
• commercial applications

Introduction

Melicoccus bijugatus Jacq. is a woody slow-growing tree that belongs to the Sapindaceae/soapberry family (Bystrom, 2012). It is known by various names in different countries and cultures around the world. The most popular names include guinep (Jamaica), genip, Spanish lime, mamoncillo, mamon (Spanish), anoncillo, honeyberry, ackee (Barbados), quenepa, chennette, kenep, quenette (French) and limoncello. The tree is originally from the Orinoco basin, which refers to the Latin America countries of Columbia and Venezuela. Explorers carried the fruits from the Orinoco basin, northwards. The fruit can now be found growing throughout the Caribbean and as far north as Florida. It is said that the Jamaican species of guinep was brought from Surinam. The tree has also been naturalized in Puerto Rico (Francis and Liogier, 1991) and West Africa (Adeyemi and Ogundipe, 2012). The fruit is small and round with a thick green rind covering a peach colored pulp/mesocarp which is attached to the seed coat (Figure 1). Typically there is one seed per fruit and on rare occasions there may be two seeds in which case it is colloquially referred to as a “twin”. The pulp also referred to as the aril, has a jelly like consistency ranging in taste from sweet to tart with an underlying starchiness. The sweetness of the pulp is due to the presence of carbohydrates while astringency is due to polyphenolic compounds (Bystrom et al., 2008). When the pulp is fully mature and sweet, it has a total soluble solids content of approximately 19 °Brix (Campbell, 1976). Sucrose, a dissacharide, is the main carbohydrate present in the fruit followed by the monosaccharides glucose and fructose (Bystrom et al., 2008). The glucose to fructose ratio in the pulp is 1:1 while in the embryo they occur in a ratio of 0.1:1 (Bystrom et al., 2008). The guinep is primarily consumed fresh by removing the skin and eating the pulp from the seed. The skin and seeds of the fruit are normally discarded. The pulp comprises approximately 51% of the whole fruit (Campbell, 1976). In Latin America, the fruit is also processed to make jams, jellies, preserves, juices, sauces and fillings. The seeds may also be roasted and eaten similarly to chestnuts (Morton, 1987).

Figure 1. Melicoccus bijugatus (guinep) fruit.

Growth Conditions and Tree Propagation

The guinep is seasonal typically bearing in the months of July through to September/October (Khan, 2018). Flower blooms which are greenish white in color, occur in April. The tree is generally polygamous producing both bisexual and unisexual flowers. No viable pollen is however present on tress having bisexual flowers. Pollination is necessary for fruit set to occur with fruits only developing when cross pollination occurs. The tree is slow growing taking between five to ten years before fruiting begins (Francis, 1992). Tree heights of 30 m and trunk diameters of 1.7 m have been attained. The tree grows best in tropical climates and is highly susceptible to low temperatures (Campbell, 1976). It is able to grow in a variety of soil conditions and is adaptable to dry and rocky conditions. The tree may be propagated from the seeds or by grafting and air layering (Campbell, 1976). Seeds take approximately 27 days to germinate (Francis and Rodriguez, 1993). In Puerto Rico there have been reported incidences of pest infestation with Eulepidotis merricki which are larvae and pupae belonging to the genus Eulepidotis hubner (Pogue and Aiello, 1998). Trees in Hawaii have also been host to the black twig borer Xylosandrus compactus (Hara and Beardsley, 1979). The fruits are eaten on a small scale by the Jamaican fruit bat (Artibeus jamaicensis) (Fabianek, 2014).

The Guinep Fruit

The fruit grows in clusters of twelve or more from a single stem and is ovoid in shape. It has a slight resemblance to limes with a small protrusion at the tip. Fruits are typically 1 inch in length but in some cases may be larger. The leathery skin allows for the fruits to have a long shelf life. Postharvest studies have revealed that fruits harvested from the top of the tree and stored at 10°C had a shelf life of 14 days (Pérez et al., 2009). The pulp ranges in color from salmon with an orange tinge to yellow and is gelatinous in texture. Guinep contains many nutrients and possesses various health benefits. The fruit is a source of fiber, vitamin A, vitamin B, vitamin C, calcium, iron and the amino acid tryptophan (Francis, 1992; Khan, 2018) (Tables 1 and 2). Care should be taken when eating the fruit as the large seed is slippery and may accidently lodge in the throat and can cause choking or suffocation especially in young children (Khan, 2018).

Table 1. Nutritional composition of the mesocarp, (the edible portion) of guinep.

Nutrient	^1Composition
Water	77%
Carbohydrate	19%
Fiber	2%
Protein	1%
Fat	0.2%
Calcium	0.4%
Energy	73 kcal/100 g

¹Francis 1992

Table 2. Vitamin and mineral composition of guinep per 100 g of pulp.

Nutrient	^1Composition/mg
Phosphorus	50
Ascorbic acid	10
Niacin	0.8
Carotene	0.2
Thiamine	0.02

¹Francis 1992

Phytochemical Components

The chemistry of M. bijugatus fruits differs from that of other fruits belonging to the Sapindaceae family (Bystrom, 2012). Recent research has provided more information on its chemical components. The pulp, seed tissue (the embryo) and seed coat tissue of the guinep consists of different phytochemicals. The seeds are reported as possessing more phenolics, antioxidants and antimicrobial properties compared to the pulp of the fruit (Bystrom et al., 2009). Chemical analysis utilizing High Performance Liquid Chromatography (HPLC) and Mass Spectrometry (MS) analysis showed that the fruit is a source of various phenolics, flavonoids and their associated sugar derivatives (Bystrom et al., 2008). These compounds contribute to the characteristic smell and taste of guinep. The embryo contains flavonoids which include epicatechin, catechin, epigallocatechin, B-type procyanidins naringenin, naringenin derivatives, phloretin, phloridzin, quercetin, myricetin and resveratrol (Bystrom et al., 2008). Hydroxycinnamic acid and sinapic acid were also identified in embryo extracts (Bystrom et al., 2008). The seed coat is not edible but has high levels of phenolic compounds (Bystrom, 2012). The most prevalent flavonoids were procyanidins (Bystrom et al., 2008). Both A-type and B-type procyanidins were identified (Bystrom et al., 2008). A-type procyanidins differ from B-type procyanidins in chemical structure by one ether bond (Bystrom et al., 2008). A-type procyanidins are taught to contribute to the medicinal properties of seed extracts (Foo et al., 2000; Kondo et al., 2000). In addition to these flavonoids, coumaric acid derivatives were also identified in the seed coat (Bystrom et al., 2008). Coumaric acid and derivatives of ferulic acid, resveratrol and benzyl alcohol were identified in the pulp, as well as in the embryo and seed coat tissues (Bystrom et al., 2008). The carbohydrates sucrose, glucose and fructose were identified in the fruit with higher quantities being present in the pulp compared to the embryo tissue (Bystrom et al., 2008, 2009). Further analysis of the active components and medicinal properties of the fruit may lead to their application in the nutraceutical industry (Bystrom, 2012).

Associated Health Benefits

Phenolic compounds are associated with several health benefits which include the prevention of diabetes (Ortmeyer et al., 1995) and cardiovascular disease (Jiang and Dusting, 2003) as well as mitigating symptoms of gastrointestinal disorders (Hyams et al., 1988). Laxative properties exhibited by the fruit have been attributed to the fruit pulp and may be due to the presence of ferulic acid derivatives (Badary et al., 2006; Mitra et al., 2002). The phenolics p-coumaric acid and caffeic acid detected in pulp extracts may explain the use of M. bijugatus fruits for the treatment of hypertension (Luceri et al., 2007). p-Coumaric acid provides anti-platelet activity (Luceri et al., 2007). In a study conducted by Li et al. (2005) using stroke-prone hypertensive rats as the test subjects, it was concluded that caffeic acid is able to inhibit vascular smooth muscle cell proliferation induced by angiotensin II. Luceri et al. (2007) ascertained that the aglycone p-coumaric acid is a systemic antioxidant with anti-platelet activity in humans at doses that can be obtained from dietary sources. Sugars such as mannose derivatives, promote immune function (Campbell et al., 1997). The equal ratio of glucose-to-fructose in the pulp tissue may assist with alleviating certain gastrointestinal problems such as irritable bowel syndrome (Goldstein et al., 2000; Hyams et al., 1988). Pulp extracts exhibited antimicrobial activity whereas pulp and embryo extracts were reported as displaying antifungal activity (Bystrom et al., 2009).

Roasted seeds macerated and mixed with honey are used in the treatment of diarrhea (Morton, 1987). The mixture may also be consumed as a tea. This concoction is mainly consumed in the Latin America countries of Venezuela and Columbia. In Nicaragua, seed extracts are utilized for the treatment of parasites (Bystrom, 2012). Anti-parasitic activity may be related to the presence of naringenin (Mead and McNair, 2006). Sugar derivatives found in some types of seeds reportedly have anti-diabetic potential (Ortmeyer et al., 1995). Particular ratios of sugars have been reported to mitigate symptoms of gastrointestinal disorder (Goldstein et al., 2000; Hyams et al., 1988). Catechins present in embryo extracts could substantiate the use of seeds to treat diarrhea. Specific catechins inhibit over-active chloride transportation, which is associated with bacterial infection that leads to diarrhea. The catechins are able to block the cystic fibrosis transmembrane conductance regulator in colon epithelial cells (Schuier et al., 2005). Epicatechin is believed to act by preventing dehydration and nutrient losses that is typically associated with diarrhea.

Fruit peels often contain more bioactive components relative to the edible portion of a fruit.

Flavonoids, anthraquinones, and triterpenoids were detected in methanolic extracts of the skin of the fruit (Chel-Guerrero et al., 2018). The skin contains the carbohydrates, fructose, glucose, and sucrose. Skin extracts also have the ability to modulate acetylcholinesterase activity (Chel-Guerrero et al., 2018). Fruit peel powders may therefore be considered for use as a source of functional ingredients (Can-Cauich et al., 2017).

Commercial Applications

M. bijugatus fruits while related to other internationally recognized species, namely longan (Dimocarpus longan Lam.), lychee (Litchi chinensis L.), ackee (Blighia sapida) and rambutan (Nephelium lappaceum L.) (Zomlefer, 1994), have been of little horticultural or economic importance historically (Morton, 1987). This may be due to the fruits being mainly popular in native regions of South and Central America where they have minimal monetary value with limited availability throughout the year. Additionally, the physical characteristics of the fruit may contribute to their limited commercial success in international and local markets. The removal of the pulp from the seeds can be challenging and low yielding (Bystrom, 2012).

In the Caribbean, the fruits are mainly sold in their original unprocessed form by street vendors, at local markets, as well as being exported to markets in the United States of America (Bystrom, 2007). Other reported utilization of the fruit include its use in the manufacture of jams, jellies, preserves, pie fillings, roasted guinep seed, starch/staple food like cassava, cold drinks, alcoholic beverages including wines and a native liquor called ‘Bili’ and various medicinal preparations (Morton, 1987). The seeds may be cooked and used as a cassava substitute as well as being ground to make flour for baking (Bystrom, 2012). Additionally a dye may be made from the juice. The flowers are rich in nectar and results in a honey that has a dark color but appealing flavor (Khan, 2018). The wood of the tree may be used to make furniture (Khan, 2018).

Conclusion

M. bijugatus (guinep) is an untapped and underutilized natural resource that has the potential of creating value added products with functional benefits. The fruit provides several health benefits and contains a variety of nutrients and bioactive components that make the creation of commercially manufactured products from the fruit commercially viable. Lucrative value-added products such as preserves and wines can be made on a large scale utilizing this fruit. The fruit contains phenolics, flavonoids and sugars that may be associated with medicinal and health-promoting properties that make it a viable option for the food processing industry. The peel of the fruit is also a promising source of bioactive components. Potential applications include its use as a functional food, food additive and natural preservative.