PASSION FRUIT JAM SMALL-SCALE PRODUCTION
Introduction
Passion fruit (Passiflora edulis) is the edible fruit of a plant that is native to South America but which is widely grown in many tropical or sub-tropical areas. Other common names for passion fruit are Maracuya, Parcha (Spanish) and Maracuja (Portuguese). The passion fruit is round to oval, and either yellow or dark purple at maturity. It has a soft to firm, juicy interior filled with numerous seeds. The fruit can be grown to eat or for its juic e, which has a strong exotic flavour and bright orange colour and is often added to other fruit juices to enhance the flavour. The fruits vary in size, but on average there are 25 -35 fruits per kg. The bigger fruits (heavier than 30g) are more suitable for food processing as they have a higher percentage of juice to rind. The juice has a pH between 2.6 and 3.0 and an unusually high starch content. There are two important commercial varieties, purple passion fruit (Passiflora edulis), and yellow passion fruit (Passiflora edulis flavicarpa). The latter has larger fruits, more acidic juice and a less preferred flavour. The fruits are most suitable for processing when all greenness has disappeared and the outer skin has a smooth or slightly crinkled surf ace. The fresh whole fruit can only be stored for a few days at ambient tem perature before it deteriorates. If the storage temperature is reduced to 6.5°C, they can be stored for 3-4 weeks before any major deterioration. The pulp can be stored for long p eriods in bulk with 1000-1500ppm of sulphur dioxide or benzoic acid or a mixture of both, but there is a reduction in the quality of the flavour. During heat preservation the main problem to overcome is the loss of the extremely heat sensitive flavour, which is susceptible to quick oxidation. The seeds are not suitable for stock feeding due to their very high crude fibre content. However, they can be refined and used in the manufacture of soap, paint, varnish and cooking oils. The skin of passion fruit is a good source of pectin, and makes a good manure. This technical brief should be read together with the brief on jams and marmalades, where there is an overview of the principles of jam making and a general introduction to quality assurance and control.
Recipe
Sugar Fruit juice Skin pulp Water Sodium bicarbonate
49% 20% 20% 11% 0.015%
(starting recipe before boiling)
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Jam, jellies & marmalade
Practical Action
In most countries, preservative cannot be added to the jam. Only a residue of preservative is allowed in jam which has been made from fruit pulp which has been stored with chemical preservatives (100ppm sulphur dioxide or 500ppm benzoic acid). Sodium bi carbonate is not a preservative. It is added to adjust the pH of the jam if the juice is too acidic. Jams give a gel when there is the correct ratio of pectin to water and the pH is between 2.5 -3.45pH. The optimum pH to give a good gel is pH 3.0. Therefore, sodium bicarbonate is generally added to passion fruit juice to decrease the acidity.
Method
Wash whole fruits in clean water and discard any bad fruits. Cut fruits in half with a stainless steel knife and scoop out the pulp with a stainless steel spoon. Stainless steel equipment is preferred for fruit as it does not stain the flesh and does not react with the acidity of the juice. If stainless steel is not available, make sure the knives and spoons are not rusted. Use a plastic spoon to scoop out the flesh. Extract the juice from the pulp by liquidising the pulp at a very low speed for about a minute. It is important to use a low speed to prevent the seeds from chipping. Chipped seeds appear as black specks in the jam. They are very difficult to remove and give the product a bad appearance. Tip the contents into a muslin cloth and squeeze out the juice leaving t he seeds behind. This method will give a yield of raw juice from whole fruit of between 30 to 35%. Measure the amount of juice extracted and use this to calculate how much skin pulp is required. Skin pulp is added to the jam as it contains natural pectin and so saves adding artificial pectin which is expensive. To make skin pulp take the same quantity of skins, as skin pulp required . Boil the skins for approximately 30 minutes, until the flesh of the skin is soft and translucent. Then remove the skins from the water and scoop out the flesh from the outer cuticle. Liquidise this softened flesh with water (2 parts softened flesh to 1 part water) until it forms a smooth cream. Use the water in which the skins were boiled as this will contain pectin washed out during the boiling. Squeeze the mixture through a muslin cloth to remove hard pieces of pith. Mix the raw juice with sodium bicarbonate (NaHCO3) before boiling (if the NaHCO3 is added during boiling the jam will bubble-up over the top of the saucepan). Add the sugar and water and heat gently at first to ensure the sugar has dissolved. Then boil rapidly to evaporate the water and continue until the jam thickens. Keep stirring during boiling to make sure the jam does not stick to the base of the pan. Jam should not be boiled for more than 12 -15 minutes as this can give rise to caramel flavours, over sweetness and discolouration, apart from being a waste of energy. By reducing the amount of water in the starting recipe, the boiling time can be reduced.
Boiling to reach the final sugar concentration
The aim of boiling is to reduce the water content of the mixture and concentrate the fruit and sugar in as short a time as possible. The final Total Soluble Solids (TSS) content of a jam (also known as the “Degrees Brix” or “end-point of the jam”) should be 65 to 68% (the TSS is a measure of the amount of material that is soluble in water. It is expressed as a percentage -a product with 100% soluble solids, has no water and one with 0% soluble solids is all water). The correct sugar content is critical for proper gel formation and for preservation of the jam or jelly. If the final TSS of jam is lower than 65 -68% the shelf life will be reduced. The jam will have a runny consistency and bacteria and moulds will be able to grow in the product. If the TSS is higher than 68%, the jam will be very stiff and the sugar might start to form crystals in the jam.
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Jam, jellies & marmalade
Practical Action
The end-point of boiling is measured in different ways. The most accurate method is to use a refractometer to measure the total sugar concentration. Remove the pan from the heat during testing as the jam will continue to cook and may become over -cooked. It is always possible to cook the jam a little bit more, but once it is over-cooked (and too thick) it cannot be reversed. Cool the sample before it is measured by smearing it on a cold dry plate or saucepan lid. All implements used to take the sample must be dry otherwise the reading will be reduced. It is important to stir the jam at all times durin g heating, otherwise it may burn at the bottom of the saucepan, causing off flavours and discoloration. This method is not really suitable for home-use as a refractometer costs about US$ 150. It is only when making jam for sale that a refractometer is necessary, to ensure consistency between different batches of the jam. When making jam for home consumption, other methods can be used to determine the end point: these include the drop test, the skin wrinkle test, or the use of a jam thermometer to test the temperature (68% sugar corresponds to a jam temperature of 105°C). When the jam starts to thicken, it is important to test for the end point at frequent intervals. Remember to remove the pan from the heat source while you test or it will continue to th icken and may burn.
Filling into jars, cooling and labelling
Wash and sterilise the glass jars and lids by placing in a pan of water and boiling for 10 minutes. Remove the jars from the water with a pair of tongs and stand upside down to drain. Do not dry with a towel as this could contaminate the jars. If glass jars are not available, use plastic jars. These cannot be sterilised with boiling water as they will melt. They should be thoroughly cleaned in warm soapy water and rinsed with a weak solution of sodium metabisulphite. Sterilising tablets (made of sodium metabisulphite) can be bought for this purpose. Allow the jam to cool slightly (to about 80°C for glass jars and 60°C for plastic jars) and then pour it into clean, sterilised jars. The jars should still be warm to prevent them from cracking when the hot jam is poured in. If the jam is cooled too much it will be difficult to pour. Place the clean lids on top and fasten. Invert the jars to form a seal. The filled jars can be placed in water to cool down the jam so that it does not keep cooking in the jar. The water should not be too cold or the glass may crack. Also, the water level must be kept below the lid of the jar. The gel starts to form as the temperature of the jam reduces (about 55°C) and continues until it is cold. The jars should not be moved or shaken while they are cooling or the gel will not form and the jam will not set.
Storage
Jam that is hygienically prepared, boiled until it reaches the correct final total soluble solids (68%) and which is packaged in sterilised glass jars can be stored for up to a year so long as it is kept in a cool place away from direct sunlight. Jam that is packaged in plastic containers has a shorter shelf life – up to 4 months.
Equipment list
Glass jars, Omnia lids and labels Omnia capper Cooking facilities, gas ring, electric ring, etc Stainless steel saucepan Thermometer in protective jacket Stainless steel cutting knife and spoon Wooden spoon for stirring Refractometer Cutting board Scales Liquidiser or mashing tool
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Jam, jellies & marmalade
Practical Action
Equipment suppliers
Note: This is a selective list of suppliers and does not imply endorsement by Practical Action
Cutting and slicing equipment
A range of manual and powered cutting and slicing machinery is available. Eastend Engineering Company 173/1 Gopal Lal Thakur Road Calcutta 700 035 India Tel: +91 33 2553 6397 Gardners Corporation 158 Golf Links New Delhi 110003 India Tel: +91 11 2334 4287/2336 3640 Fax: +91 11 2371 7179
Narangs Corporation P-25 Connaught Place New Delhi 110001 India Tel: +91 11 2336 3547 Fax: +91 11 2374 6705
Juice filters, strainers and sieves
A range of filtering and straining equipment can be used. The simplest is the filter bag (or jelly bag) made of terylene or muslin cloth. More sophisticated are the filter presses and strainers which may be mechanised. Gauthier Parc Scientifique Agropolis 34397 Montpellier Cedex 5 France Tel: +33 4 67 61 11 56 Fax: +33 4 67 54 73 90 Lakeland Mail order kitchenware 38 Alexandra Buildings Windermere LA23 1BQ United Kingdom Tel: +44 (0)15394 88100 Website: www.lakeland.co.uk Alvan Blanch Chelworth Malmesbury Wiltshire SN16 9SG United Kingdom Tel: +44 (0) 666 577333 Fax: +44 (0) 666 577339 E-mail: info@alvanblanch.co.uk Website: http://www.alvanblanch.co.uk Gardners Corporation India (see above)
Weighing machines
It is important to have accurate weighing machines. Quite often more than one machine is required - -a large one to weigh the fruit and a small one for weighing out the dry ingredients such as pectin and spices. Fisher Scientific Bishop Meadow Road Loughborough LE11 5RG UK Tel: +44 1509 231166 Fax: +44 1509 231893 Email: fisher@fisher.co.uk Web: www.fisher.co.uk
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Jam, jellies & marmalade
Practical Action
Alvan Blanch UK (see above) Lakeland UK (see above) Gardners Corporation India (see above)
Essae-Teraoka Ltd 377/22 6th Cross Wilson Garden Bangalore 560027 India Tel: =91 80 2216185/2241165 Narangs Corporation India (see above)
Juice extractors and pulpers
A variety of juice extractors and pulpers is available from a wide range of suppliers. They are available in different capacities and either manual or powered (either electric or diesel). Kenwood Limited New Lane Havant Hampshire PO9 2NH United Kingdom Tel: +44 (0) 23 9247 6000 Fax: +44 (0) 23 9239 2400 Website: http://www.kenwood.co.uk Alvan Blanch UK (see above) Lehman Hardware and Appliances Inc. P.O. Box 41 Kidron Ohio 44636 USA Tel orders: +1 877 438 5346 Tel enquiries: +1 888 438 5346 E-mail: info@lehmans.com Website: http://www.lehmans.com Robot Coupe 12 Avenue Cal Leclerc BP 134 71303 Montceau-les-Mines France Tel: +33 3 85 58 80 80 DISEG (Diseno Industrial y Servicios Generales) Av Jose Carlos Mariategui 1256 Villa Maria del Triunfo Lima Peru Tel: +51 14 283 1417 Servifabri SA JR Alberto Aberd No. 400 Urb Miguel Grau (ex Pinote) San Martin de Porres Lima Peru Tel: +51 14 481 1967 Bajaj Machine Private Limited 7/20, 7/27, Jai Lakshmi Industrial Estate, Side-IV Sahibabad Industrial Area Ghaziabad-201301 U.P India Tel: +91 120 22775119/22775137 Fax: +91 120 22775137 Website: www.indiamart.com/bajajmachine Buhler (India) Pvt Ltd 13-D, K A I D B Industrial Area, Attibele Bangalore Karnataka 562107 India Tel: +91 80- 27820000 Fax: +91 80-7820001 Website: www.buhlergroup.com Delhi Industries 4 Paharganj Lane, New Delhi 110055 India Tel: +91 11 2529720, 27525200, 27536888 Fax: +91 11 25791291
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