Rangpur “Kona” Lime

By Ken Love

Family: Rutaceae

Scientific name: Citrus x limonia Osbeck

Origin: Northwest India

Introduction

Often called a mandarin lime or local lemon in Hawaii, the fruit is a naturally occurring hybrid between lemon and mandarin orange (tangerine). A medium sized citrus tree often confused with a tangerine or other citrus on first glance. The fruit is polyembryonic and usually reproduces true to seed. A popular rootstock in many citrus growing locations, the tree evolved in Hawaii as an ornamental, often when the top graft died off. The spreading and drooping branches have dull green foliage with an occasional purple tint on new growth. It can reach a height of 20 feet. Numbers and size of thorns vary from tree to tree with some trees being almost thornless. The fruit rind is orange to reddish orange with minutely pitted moderately loose skin with oil glands and a lime like aroma. Highly acidic and very juicy, the fruit has 8 to 10 segments with numerous seeds and is slightly hollow in the center. Reportedly introduced to Hawaii in the 1880s, the fruit has acclimated to Hawaii’s volcanic well drained soil. Having been used for culinary purposes since the early 1920s, the trees have been maintained for their fruit rather than their use as a rootstock. The juice from the fruit has also been used for cleaning dishes and glass. With the possible exception of India, which exports Rangpur lime marmalade to England, the fruit has found a growing following on the Big Island and arguably deserves to be called Kona lime. Further selection work to determine specific cultivars for Hawaii is recommended.

Varieties

There are few reported cultivars of Rangpur as most trees are produced from seed. There are occasional differences in the color and nature of the rind, numbers of seeds and the amount and size of thorns. There are two other mandarin limes often categorized with Rangpur, the kusaie lime, a yellow colored highly acidic form of the Rangpur and the Otaheite Rangpur, a acidless form of the fruit. ‘Citrolima’, is a cultivar with larger leaves and vigorous growth often used in Brazil as a rootstock for Valencia oranges.

Environment

The Rangpur, as with most citrus prefers well-drained soil. In the Kona district the tree is found from sea level to 3000-foot elevation. It is tolerant of colder areas and should do well at much higher elevations given sufficient rainfall and nutrition. Spacing is consistent with other citrus, usually planted 15 to 20 feet apart or about 100 trees per acre. Seedlings will produce fruit in 4 to 6 years reaching full production in 7 to 10 years. The trees can be grown and will fruit in pots. When root bound in large tubs, they will naturally dwarf. The tree is more tolerant of salt and high pH than many citrus. It is resistant to a number of diseases making it the rootstock of choice in large citrus producing areas in Brazil. The tree requires irrigation in periods of extended drought but will not tolerate being waterlogged.

Culture

Young trees are pruned to establish shape, which facilitates harvesting and increases yields on mature trees. Annual pruning to maintain a desired height of 6 to 8 feet and to thin new growth and remove dead wood is advisable. Increased yields can be obtained by pruning to open the trees interior to light and air circulation. Flowering and fruiting occurs on 2-year growth.

Pests and Diseases

A common problem for most citrus in Hawaii is the citrus leafminer, Phyllocnistis citrella Stainton. Damage to new growth and developing fruit can be extensive with the insect tunneling just under the surface of the leaves or skin of the fruit. Control of the leafminer by a parasitic wasp, also found in Hawaii, Ageniaspis citricola Logvinovskaya, helps minimize damage. Spiders, flower bug, Orius insidiosus, ladybugs, fire ants and the lacewing, Chrysoperla rufilabris also help to keep the leafminer in check. Petroleum sprays help to inhibit egg laying but need to be repeated every 2 weeks when the plant flushes.

Foot rot and root rot from Phytophthora sp can be a problem with Rangpur. Good soil drainage is important to prevent rot from occurring. Over watering and wetting of the trunk will promote the spread of this fungus.

Citrus black fly, Aleurocanthus woglumi Ashby, damage citrus trees by sucking the sap, which removes water and nutrients. The excretion is small droplets of honeydew on which grows the sooty mold fungus. The sooty mold causes a reduction of photosynthesis that causes a general decline of plant health and reduction of fruiting. Parasitic wasps were released in 2000, which have helped to control the pest. Neem oil and other sprays help to limit infestation. Once a tree is infected it is important to make sure it has enough water and additional fertilizer to replenish lost nutrients.

Fruit flies are not a major problem for the Rangpur Kona Lime but it is advisable to follow the Hawaii Areawide Fruit Fly Pest Management Program (HAW-FLYPM).

Citrus tristeza virus is not a major problem for the Rangpur Kona lime as it is naturally resistant. Other resistant root stocks like the mandarin ‘Heen Naran’ or ‘Cleopatra’ can be used for the lime or other citrus.

Propagation

The Rangpur lime tree is generally propagated by seed but can be grafted. Trees with few thorns or those that are especially prolific producers can be grafted onto a rangpur or other citrus rootstock like the rough skinned lemon, ‘Citrus jambhiri’, ‘Heen Naran’ or trifoliate orange, Poncirus trifoliata Raf. Rangpur can co-exist with other citrus on the same rootstock. On a South Kona tree, Rangpur lime, Meyer lemon, and tangelo all produce fruit on the same tree.

Harvesting and Yield

The fruit is harvested when orange colored. A mature 7-foot well-pruned tree can produce 100 fruit or more per season and yield an average of 50 pounds of fruit. Older trees that have not been pruned can yield 300 to 400 fruit but harvesting is difficult and time consuming due the excessive height and numerous thorns.

Postharvest Quality

As with most citrus, Rangpur limes can be stored from 36 to 39 degrees F. for up to 5 months. A wax coating will lengthen the time they can be stored, often up to 10 months. Frozen juice can be stored for future use.

Cost of Production

The two project Rangpur lime trees produced an average annual marketable yield of 83.1 pounds. The average market price was $0.60 per pound, and therefore the trees generated a gross revenue of $99.75 for the year. Growing costs (fertilization, irrigation, pruning and all weed and pest control) amounted to $80.26, and harvesting costs (picking, packing and delivery to market) totaled $23.06. (All labor to grow and harvest the Rangpur limes was assumed to be paid at an hourly wage rate of $16.00, including withholding, FICA and benefits.) Thus, the total annual operating costs, sometimes referred to as “variable costs,” were $103.32. The gross margin (gross revenue minus all operating costs) was a negative $3.57.

The Rangpur lime gross margin is the amount of money available to pay all the ownership costs associated with the Rangpur lime enterprise. Ownership costs, sometimes referred to as “fixed costs,” include the value of land used (rent or rent equivalent or mortgage and property taxes), the value of the capital investment (such as the tree establishment cost and buildings and vehicles), the value of the management, and the value of any unpaid labor. (All paid labor is already included in the gross margin.) Ownership costs, unlike operating costs, will vary substantially from farm to farm and will depend largely on how the farming operation is financed and on economies of scale. Each grower will have to calculate his total farm ownership costs and then allocate an appropriate portion of these costs to each enterprise on the farm. Now the profitability of the Rangpur lime enterprise can be determined by subtracting the Rangpur lime enterprise’s share of the total ownership costs from the gross margin for Rangpur limes.

The cost and return data are what was obtained from the 12 Trees Project site and other locations. Yields and costs were based on optimal growing conditions for one or more trees at various locations; different results will be obtained under different growing conditions. The prices used were actually obtained in 2005 and 2006. There is no guarantee that these prices will continue, especially if production increases significantly. These costs and returns are simply a starting point for growers to make their own estimates.

Packaging, Pricing and Marketing

Fresh fruit sold to markets in South Kona are boxed in 10-pound packages and wholesaled for 50 cents per pound. The markets found that consumers often confused the fruit with tangerines regardless of signage that promoted the unusual locally grown fruit. Packaging of 5 fruit in a vented plastic bag was then used. Hotels and restaurants order the fruit by weight, sometimes as much as 50 pounds at a time. Individual fruit, with an average weight of 7 ounces, are sold at farm stands for 50 cents each. In order to interest other hotel and restaurant chefs in the fruit, samples were sent to 10 Big Island chefs who had not previously ordered the fruit from wholesalers. Sample recipes created by students at the Hawaii Community College West Hawaii Culinary Arts Program as well as nutritional information was sent with the fruit. Seven of the ten chefs have continued to order the fruit for a year after receiving the first samples.

Food Uses and Nutrition

Food Value Per 100 g of Edible Portion

Moisture 88.7-90.86 g

Energy 24-25 kcal

Protein 0.053-0.112 g

Fat 0.01-0.17 g

Fiber 0.1-0.5 g

Carbohydrate 8.33-10g

Ash 0.25-0.40 g

Calcium 4.5-33.3 mg

Phosphorus 9-21.0 mg

Potassium 82 mg

Sodium 4 mg

Iron 0.11-0.33 mg

Vitamin A 0.003-0.040 mg

Thiamine 0.019-0.068 mg

Riboflavin 0.011-0.034 mg

Niacin 0.14-0.25 mg

Ascorbic Acid 25.10-48.7 mg

Health Benefits- All citrus contain healthy amounts of Vitamin C that helps to manufacture the body’s collagen that helps heal cuts or wounds. The zest from limes and other citrus also contains compounds that can block cancerous cell changes. Limonene in the zest can increase the level of liver enzymes that fight cancer-causing chemicals.

Recipes

Rangpur Kona Lime Papaya Cheesecake Yield:6 servings

By Teri Wisdom, Hawaii Community College-

West Hawaii Culinary Arts Program

Ingredients:

6 egg yolks

1 1/2 cups sugar

2 Rangpur Kona limes, juice and zest

1 teaspoon vanilla

1/4 cup water

2 teaspoons unflavored gelatin

2 cups whipping cream

8 ounces cream cheese, softened

1/2 teaspoon salt

Procedure:

Mix egg yolks, sugar, lime juice and lime zest in double boiler to 165*F; remove from heat.

Place mixture in a bowl and beat until it thickens and starts to cool, 4-8 minutes. Set aside.

Combine water and gelatin. Let stand to hydrolyze. Heat heavy cream to a simmer and add gelatin. Stir to dissolve gelatin for one minute. Remove from heat and set aside.

Whip cream cheese and salt till light and fluffy. Scrape bowl to ensure all cream cheese is whipped.

Fold in cooled whipped cream mixture, and then fold in egg mixture. Spoon into cups and freeze overnight or until set.

For the lilikoi sauce and papaya garnish:

Mix 1 cup lilikoi puree with 1 cup sugar and 2 tablespoons lime juice in sauté pan, heat to simmer, reducing until it becomes a thin sauce. Cool.

Peel, seed and slice papayas thinly for garnish.

To serve:

Loosen cups of frozen or set dessert in warm water briefly, plate upside down, garnish with papaya slices and drizzle with lilikoi sauce.

Kona Rangpur Lime Hummus

Chef Paul Heerlein

2 cans chickpeas (garbanzo) drained

1 head roasted garlic

1 clove chopped garlic

Water

Olive oil

Kona Rangpur limejuice

Curry powder

Salt

Puree chickpeas and garlic to desired consistency,

Add remaining ingredients to taste.

Rangpur Kona Lime Hollandaise Sauce

Vince Mott

Yield – 1 quart

2lbs clarified butter, warm but not too hot to the touch.

12 egg yolks

2 oz cold water

3 oz Rangpur Kona limejuice

Cayenne to taste

Salt to taste

1. Place yolks and cold water in a stainless steel bowl and beat well. Beat in a few drops of the juice.

2. Hold the bowl over a hot water bath and continue to beat until yolks are thickened. Draw a figure 8 in the mix to test thickness.

3. Remove bowl from heat. Using a ladle, slowly and gradually beat in the warm butter. Use approximately 2 oz to 2.5 oz per egg yolk. Add the butter drop by drop at first then ladle by ladle. Continually beat during this process. If the sauce becomes to thick to beat before all the butter is added, beat in a little more Rangpur Kona limejuice.

4. When all the butter has been added, beat in the remaining limejuice. If necessary, thin sauce with a few drops of warm water.

5. Hold in bain marie in a warm water bath. Will hold for approx 1.5 hours.

The 12 Trees Project

Is funded by the Western Sustainable Agriculture Research and Education (WSARE) USDA-CSREES competitive grants program. 54 Hawaii Island chefs, fruit buyers and growers were invited to select the types of fruit they would like to see commercially available, based on their desire to utilize the fruit in culinary applications. In selecting the final 12 fruits, considerations were given to seasonality and harvest times so that the availability of harvested fruit and on-farm labor needs were spread out over the year.

Fruit trees were planted and brought into production at a demonstration orchard at the Kona Pacific Farmers Cooperative on Napoopoo Road in the South Kona District. During the course of the three-year project, fruit from this orchard, as well as additional fruit purchased from area farmers, were donated to the West Hawaii Community College culinary school. Culinary student chefs developed recipes to be published on the project web site < http://www.hawaiifruit.net/12trees.html> and in a book in the final year of the project. Members of the cooperative as well as members of the Hawaii Tropical Fruit Growers - West Hawaii association and any other interested growers were encouraged to plant these trees. The goals of this project were to increase profitable agricultural diversification and to develop a consistently high quality, year-around supply of tropical fruit for local markets.

References and Further Reading

Morton, Julia F., 1987. Fruits of Warm Climates

The Citrus Industry

Revised Edition

University of California

Division of Agricultural Sciences

1967

Vol. 1 CHAPTER 4

Horticultural Varieties of Citrus

BY ROBERT WILLARD HODGSON

Internet References:

University of Georgia