Organization: Instituto Tecnologico de Veracruz (http://www.itver.edu.mx)
Authors: J. De La Cruz Medina and H.S. García
Edited by: Danilo Mejía, PhD - Agricultural and Food Engineering Technologies Service (AGST)
CHAPTER XXXIII: Pineapple post-harvest operations
2.0 Harvesting and Post-production operations
2.1 Harvesting
2.1.1 Yield
2.1.2 Transportation
2.1.3 Grading :
2.1.4 Packing.
2.3 Packinghouse operations
2.4 Packing
2.5 Cooling system
2.6 Storage of fruits and vegetables
2.7 Transportation system
2.8 Processing
2.0 Harvesting and Post-production operations
Traditional and improved picking operations (Fig 22)
Fig. 22 Basket picking operation (SARH,1994)
2.1 Harvesting
Location of the crops, internal ways and access to the main roads leading to the packing site must be considered so that pineapples can be transported in the minimum time under controlled conditions. Transporting pineapples from the production field to the packing location is made by tows, trucks or specially-designed vehicles. Availability of a double roof, thermal insulation and sliding curtains help keep the storage temperature of the fruit during loading and unloading. The equipment must be kept clean and disinfected and fitted with good suspension, low-pressure tires and even and smooth floor surface, such that the packing units can be easily handled. Bulk transportation the use of vegetative material is placed on the vehicle platform to avoid extreme temperatures and to act as cushion against mechanical collisions during transport (Colfruits, 2004).
2.1.1 Yield
In order to reach crop yields of 100 tons a minimum of 60,000 plants per hectare need to be planted, using the arrangement of 30 cm between plants, 40 cm between lines and 70 cm from the aisle or between the double lines. If density needs to be increased the distance between plants can be varied and the rest may remain unchanged.
To estimate the density the following formula:
100/distance between plants+ aisle width = a
100/distance between plants = b
D = (a ) (b) (2)
2.1.2 Transportation
Export logistics for pineapple
The harvested fruit is deposited in drawers and transported to the packing plant, where it is submerged in disinfectant in trays. Another alternative process consists on submerging the fruit completely in similar solution (with Triadimefon), this process is used especially to export to United States and Europe. The boxes used in the packing are revised to detect the presence of insects. The fruit is placed in boxes of 10 - 20 kg and, finally, put in pallets. The pallets, properly maintained in refrigeration chambers are loaded in the refrigerated containers. Each container has a capacity of 1500 boxes of 20 kg and/or 3000 approximately boxes of 10 kg. The refrigerated container is maintained at 7.5 - 8° C previous to export. Each container has a thermograph for the control and registration of the temperature while traveling as well as with the respective filters for the control of the ethylene. Is important to offer and use an appropiate packing for the pineapple, for the cultivation and preparation of the fruit, because just with a safe and functional protection it can keep the quality of the product until arrival to the final market. The packing also helps to promote the fruit's sales because of the presentation, as well as the description of content and origin. The appropriate packing use for the product fulfills the following functions: To avoid the loss of aroma, to protect the product against the admission of flavors and disgusting scents, to offer a good period of conservation, to avoid the accumulation or loss of humidity, to protect the product against damages, to offer a space to print the relative necessary information about the product. A careful crop handling and postharvest contributes to the maintenance of the quality of the products. The gathered pineapples should be packed in clean plastic boxes (Fig. 23) and be stowed. An important characteristic in this stage is that the boxes should have holes with lengthened form in all sides for the ventilation, because it allows a quick exit of the heat of the fruit. The packing measures for the pineapple are not standardized, but are guided with the international packing norm for agricultural products according to the size. The product should be kept at temperature packing from 7 - 10° C, with a relative humidity of 90%. The pineapples should be fixed inside the box, in order to avoid wounds in the shell and/or the crown (Isabellefruits,2004).
Fig..23 Packing of pineapple fruits
2.1.3 Grading :
After pre-grading, washing, waxing, and fungicide treatment, the pineapples are left to dry and then are graded for packing. Graders remove any fruit that shows signs of fresh mechanical damage or any of the conditions that qualify the fruit for rejection in the pre-grading stage. Remaining pineapples are classified for packing based on size, stage of ripeness, and, if applicable, shape. Fruits of different shape may not be mixed in the same carton.
2.1.4 Packing.
The preferred method of packing is to place the fruit vertically on the base, and then to place dividers between the fruits to prevent rubbing and movement. With some cartons, this is not possible and fruit are laid horizontally in alternating directions; where two layers of fruit are packed, a layer of card is required between the layers : 6 count - 1.75 kg fruit (3.8 lb) ,12 count - 1.25 kg fruit (2.7 lb) ,12 count - 1.00 kg fruit (2.2 lb) and 20 count - 0.75 kg fruit (1.6 lb)
Fruits are normally packed to a net weight of 10 to 15 kg (22 to 33 lb) depending on the carton and the market. High value small pineapples may be shipped in some instances at 6 kg (13 lb), whereas the large fruit in some cases may be packed up to 20 kg (45 lb).
Packaging:
A full-telescopic two-piece fiberboard carton with internal dividers between the fruit; bursting strength 275 lb/in2. Top and bottom ventilation, in addition to side vents are required, particularly where sea-shipments in break bulk are used. Where staples are used in carton construction, care should be taken to ensure complete staples closure to prevent fruit damage.
Storage and Transportation:
Where sea-shipment is to be used, the fruit should be harvested on the day prior to shipment. Green fruit should be stored at 10ºC, 85 to 95% relative humidity, and under these conditions, should have a storage life of two to three weeks (Fig. 24). This will be dependent on the sugar content and the agronomic conditions during production, in addition to the handling and storage procedures. Where exports are made by air with fruit harvested at more advanced stages of maturity, pre-export storage can be used and the suitable storage temperature decreases to 7.5ºC, 85 to 95% relative humidity.
Potential Post-harvest Losses: Losses in pineapples during air-transport are minimal if careful handling is employed. On sea-shipments and long term storage however, the fruit are more susceptible to post-harvest losses as a result of increased handling, control of temperature and disease incidence
Mechanical damage: Bruising or puncturing caused by poor handling, dropping or abrasion, will result in localized areas of softening and development of secondary microbial infection (Foodmarketexchange, 2004).
Fig. 24 Pineapple refrigeration
For canned pineapple can sizes used are: 608X700 (108 oz), with a net weight of 3030 oz, 6 cans per box and a total weight of 20 kg per box; size 401X411 (30 oz), with a net weight per can of 820 oz, 24 cans per box and a total weight 24 kg per box; size 307X409 (20 oz), with a net weight of 560 oz, 24 cans per box and a total weight of 16 kg per box; size 307X309 (15 oz), with a net weight of 425 oz, 24 cans per box and a total weight of 13 kg per box; and size 307X201 (8 oz), with a net weight of 227 oz, 24 cans per box and a weight of 7 kg per box. The packing is in corrugated cardboard carton to prevent dents during transportation. The packing in tray of 12 cans for retail can size is available with and without shrink wrapping. Products can also be palletized on wooden pallet or slip sheet for the convenience of handling. For industrial use, product of 108 oz. can be palletized without cartons. Pineapple juice is extracted from selected fruits where pulp is controlled to the requirement. NFC (not from concentrate) pineapple juice is single strength at 12 ± 1 °Bx. It is aseptically processed, while some juice will be processed through evaporators to the desired °Bx. All juice and concentrate will be stored in cold storage to preserve the quality. Frozen concentrate is stored at the temperature of -20°C. Aseptic product can be stored at the ambient temperature but it is recommended to stored at 5 °C in order to preserve the quality and to prolong the storage life and packed in steel drum or wooden bin. The canned pineapples are packed in accordance with the US FDA, and are available in different sizes to serve both retail and institutional purposes. The cuts include slice, chunk, tidbit and crushed packed in either natural juice or syrup. Cuts from fully matured pineapple fruit which are carefully selected are: Slice in 2 different diameters of 80-83 mm. and 90-97 mm., chunk that is a segment of pineapple good for barbeque, salad or full-bite snack, tidbit/pieces in various sizes from small pieces for pizza topping to large piece as natural snack and crushed/chopped pineapple that can be used as desert topping and pie filling (tpc-canning.com 2004)
Pineapples are also separated according to degree of ripeness. Average weight of the fruit is ca. 2.5 kg, pulp color must be in the range of pale to gold yellow, with 13 % of soluble solids and 0.6 % acidity as citric acid. These attributes are an important part of the overall qualities of a widely accepted pineapple flavor for either fresh or canned product.
Inspection
Mechanical damage: Many factors contribute to pineapples skin damage, including the harvesting tool used, dropping of fruit into crates, overfilling of crates, and jostling of fruit during field transportation. Similar problems can result from poor handling during washing, grading, and packing.
Pineapples handlers can minimize fruit damage by taking protective measures throughout all handling stages. Staff should be trained in proper harvesting techniques. In addition, transporters should drive slowly and carefully when taking fruit from the field to the packing house.
At the packing house, crates should include foam in their base and contain only one layer of fruit. In automated operations, all machinery should be padded where possible. Palletized systems are preferable for moving produce in both field crates and final packages.
2.3 Packinghouse operations
The fruit is harvested and delivered to the packinghouse. Field Managers are in contact with growers to schedule deliveries of fruit to meet market demands. Growers who want their fruit picked up in the groves will schedule transportation with the Field Manager. Many Growers elect to deliver the fruit to the packinghouse themselves.
The fruit is gradually pre-cooled before packing. This allows the fruit to cool down over a 12 hour period from the ambient temperature at delivery time.
Packers have a built in system that allows full bins to be weighed before packing. Empty bins are then weighed so that the grower is given credit for every pound of fruit delivered to the packinghouse.
The fruit is placed on the packing line and graded (Fig 25). The fruit is then placed into tight fill cartons by a sizer machine. The fruit is labeled during the process. The sizer insures not only that the correct number of fruit is packed into the cartons by size, but also that the weight of the carton is correct.
2.4 Packing
All cartons of fruit are checked once more by quality control personnel before the carton is sealed and placed in a cooler until shipment time. The cartons of fruit are stacked on pallets and these pallets are placed in a shipping cooler, where temperature is maintained between 8-10 °C (Calavo Products, 2002).
Fig. 25 Pineapple selection and inspection line
2.5 Cooling system
Pineapples are placed in an insulated room equipped with refrigeration units and forced air-cooling where fans pull cool air through pineapple packages. After storage the pineapple pallets are placed in refrigerated containers with fresh air supply or controlled atmosphere.
2.6 Storage of fruits and vegetables
Chilling damage arises in the varieties "Queen" and "Smooth Cayenne" when they are stored for 14 days at temperatures of < 7°C. Signs of chilling damage are: loss of skin gloss, formation of brown to black stripes under the skin and around the woody central cylinder (endogenous brown spot), watery flesh, insipid taste, susceptibility to rotting and loose crown leaves. At temperatures > 10°C, the crown leaves have an increased tendency to bolt. Bolted crown leaves impart a tired appearance to the fruit and diminishes its value. In addition, the tendency to fruit rot (black rot) also increases, often occurring as butt rot above the stem but also arising in the crown. Susceptibility to chilling damage reduces as ripeness increases.
The cargo and holds/containers must be cooled before loading starts, to ensure that the cold chain is unbroken and the quality of the fruit is not reduced.
Pineapples require particular temperature, humidity/moisture and ventilation conditions. Recommended ventilation conditions: air exchange rate 40 - 60 times per hour with constant supply of fresh air, so as constantly to remove the ripening gases arising and to keep the CO2 content of the hold air low. Spoilage may occur as a result both of inadequate ventilation (danger of rotting) and of excessive ventilation (drying-out, weight loss. Pineapples display 2nd order biotic activity. They are living organs in which respiration processes predominate, because their supply of new nutrients has been cut off by separation from the parent plant. Care of the cargo during the voyage must be aimed at controlling respiration processes (release of CO2, water vapor, ethylene and heat) in such a way that the cargo is at the desired stage of ripeness
( tis-gdv,2004)
Compatibility groups for storage of fruits
The best storage environment for an individual fruit or vegetable depends on its unique requirements for temperature, relative humidity, and ethylene exposure. Most compatibility charts for mixing products during postharvest handling divide fruits and vegetables into eight groups. In practice it is very difficult to separate products into this many groups-very few wholesale or retail handling facilities, if any, have eight temperature-controlled rooms.
Researchers of UC Davis (Thompson, Kader and Sylva, 1999), have developed a three-group chart that is easier to use and still provides good product shelf life (Table 4).
Table 4 Compatible Fresh Fruits During 7 Day Storage
http://rics.ucdavis.edu/postharvest2/Pubs/postchrt2.shtml
avocado olive
babaco orange
tuna pepino
carambola pummelo
feijoa Sugar apple
granadilla tamarind
Grape fruit watermelon
guava cranberry
lemon pineapple
mandarin Ugli fruit
*Source: (UC Davis, 2004)
Group 3- Fruits
code thermometer
45-50 °F, 7-10 °C & 85-95% RH
2.7 Transportation system
Marketing and physical distribution of fresh produce inherently means moving the produce. The commodities are handled, either manually or mechanically, many times from harvest and through the distribution process before the consumer buys and prepares them to eat.
For domestic transportation the use of road vehicles offers substantial advantages of convenience, availability, flexibility permitting door-to-door delivery, and reasonable cost of transport. The use of road transportation for fresh produce is increasing and likely to increase in countries all over the world. Produce may be transported by pick-up, enclosed truck, open truck or refrigerated vehicle (Harris, 1988).
For perishable products, however, the increased speed of handling and reduced transport costs that came with containerization were not enough. Ocean transport of cooled and frozen cargo received a substantial boost with development of mobile refrigerated cargo ships that lack this flexibility. Controlled atmosphere (CA) technologies allow operators to lower the respiration rate of produce by monitoring oxygen, carbon dioxide and nitrogen levels within a reefer. In this way, CA can slow ripening, retard discoloration, and maintain freshness of pineapple. Although it is likely that container ships will dominate the perishable trade between North America, East Asia and Europe, conventional refrigerated vessels can serve many smaller ports, especially in the developing world, that are unable to handle large container vessels. Thus, in north-south trade and in certain niche markets, conventional refrigerated ships may have a brighter future, but even here, competition from container vessels is bound to increase as cost decline (Agricultural Outlook, 1999)
2.8 Processing
There is a series of physical properties of pineapples that play important roles during processing. Leverington (1970) described research works on the relationship between translucency and other quality characteristics. It was found that in addition to be considered as a maturity index, translucency is a quality attribute of the fruit. Translucent or semi-translucent slices are generally considered as desirable and associated with better flavor. Fully translucent pulp have an overripe flavor, while those not translucent are too sour. As pulp becomes more translucent air cavities decrease in size and therefore in porosity. Internal color affects the appearance and acceptance of the fruit; yellow-gold color has been regarded as best.
Traditionally pineapple is consumed fresh or canned (Fig. 26). Diversification of pineapple products is a good strategy to increase consumption in the main markets of the world. Thus, pineapple is now consumed in the form of single strength or concentrated juice, dehydrated and/or sugared, canned in slices or bits. The variety traditionally employed to develop these products has been Cayena lisa. Among the newer developments are dried chips, cocktail-type drinks, dried powdered, isotonic mixtures and wine; there are also new canned forms as whole fruit, bars, flakes and cubes. For fresh consumption, new varieties have been introduced: MD2, Josapine, LR41 and Gandul (Coveca, 2002).
Fig. 26 Canned pineapple
Essentially a prime table fruit, pineapple pulp (Table 5) is perfectly suited for conversion to frozen juices (Fig. 27 ), nectars, drinks, jams, fruit cheese, concentrates (Fig. 28) or to be had by itself or with cream as a superb dessert. It can also be used in puddings, bakery fillings, and fruit meals for children, flavors for food industry, and also to make the most delicious ice cream and yoghurt. While the raw fruits are utilized for products like chutney, pickle, sauce. pineapple beverage, etc. ripe ones are used in making pulp, juice, nectar (Table 6), squash, leather, slices, etc. Major export products include dried and preserved vegetables, jams, fruit jellies, canned fruits and vegetables, dehydrated vegetables, frozen fruits, vegetables and pulps (Table 7) and freeze dried products.
Ripe pineapple may be frozen whole or peeled, sliced and packed in sugar (1 part sugar to 10 parts pineapple by weight) and quick-frozen in moisture-proof containers. The diced flesh of ripe pineapple, bathed in sweetened or unsweetened limejuice, to prevent discoloration, can be quick-frozen. Half-ripe or green pineapples are peeled and sliced as filling for pie, used for jelly, or made into sauce.
Table 5 Industrial processing possibilities
pinapple pulp Glazings
Fruit cocktails Dried pineapple slices
Juice Pineapple wine
Nectar Flavored yoghurt
Fruit sauces Ice cream
Fig.. 27 Processing of frozen Pineapple juice
a) Fresh consumption and processing
Processed pineapples shall meet standards of quality to assure market acceptance. Processing plants reject fruit with bruises, with defective heart, or multiple crowns. Porosity should be minimal and the °Bx to acidity ratio should be near 20. Acidity should be kept close to 0.75%.
In average the yield in processing ranges from 45% to 55%. End products include packed pineapple, which includes pulp from the cuts made to the base, crown and peel. This product may be done in small slices, chunks or bits. The pieces are placed in cans containing syrup. It is important to maintain a good control of the °Bx of the syrup in order to reach an equilibrium between the fruit and the syrup. The thermal treatment and final pH value of the product are key factors to assure product quality. Either cans or glass jars can be employed for packing purposes. Pineapple pieces can be mixed with other fruits to prepare fruit cocktails, which entails another commercial alternative (Coveca, 2002).
In the process for preparation of pineapple products, fruit are unloaded from trailer trucks to conveyor bands where crowns are taken off and fruit are placed in a washing vat, then through an elevator the pineapples go to a roller sorter, and then separated in two different sizes and two slides take the fruit to different packing lines. The Guinaka brand peeler(Fig 28) removes the peel and forms a cylinder with the peeled fruit, by a circular blade that spins at high speed. The cylinder is sent by another slide where they are placed manually in another machine that removed the core. The coreless cylinder is then moved to the dicer and the product is then ready to be packed in buckets holding 10 to 15 kg. The product is frozen in a chamber set at -20°C, for further transfer to distribution points or processing. Pineapple cylinders are sliced and canned with syrup, then passed through an exhauster with steam at 3 bar and 120 °C to eliminate air and create vacuum (Fig 29). Cans are sealed and sent to the autoclave. After the thermal treatment the cans are placed in a cooling vat for 10 minutes; this produces a thermal shock that inactivates bacteria. Finally, cans are labeled and boxed and ready for distribution.
Fig. 28 Guinaka peeler
Fig. 29 Exhauster
Other different products of pineapple processing are:
Dried pineapple:
In this product, most of the free water of the fruit is eliminated. Usually, chunks or slices are prepared for better presentation and make handling easier. Final moisture is near 5%, and this allows the dried fruit to have a long shelf life as long as proper packing is provided and storage is done in a fresh place. (Fig. 30)
Juice:
Pineapple juice is obtained from crushing fruit pieces and proper pysical separation of the solids (Fig. 31). Juice must be pasteurized and packed to extend its shelf life and a preservative or refrigerated storage may be used as additional barriers to microbial spoilage. No juice should reach the market if it becomes fermented or mixed with water. Packing may be plastic bottles or bags, coated cans, multilaminate (plastic, paper, metal foil) or any newer materials. The pH values of the product must be controlled so it remains agreeable for human consumption. It is a common practice to blend batches of juices to attain proper acidity and sensory qualities. Juices from other fruits can be blended with pineapple's and interesting mixtures make novel products.
Nectar:
It is the product of blending juice with a certain amount of solids from the pulp containing the same amount of °Bx as the original fruit. Normally, nectars are prepared by diluting fruit pulp to 30 °Bx. Methods of preservation and packing are similar to those described for juice.
Pulp:
It is the product of the basic processing of peeled pineapple pulp by crushing. Pulp may be preserved by thermal treatment, by preservatives addition and proper handling in either small packages, or in bulk packages for further industrial processing and formulations as ice cream mixes, jellies, jams, sodas, etc.
Concentrated frozen pulp:
It is the product from thermal treatment of the pulp to remove at least 50% of the initial water content. Concentration and freezing are applied to preserve the pulp for extended periods of time. The concentrated pulp is stable without the addition of chemicals as long as it is kept frozen. Upon reconstitution (by replenishing the previously eliminated water) the pulp should have the same qualities as the original pulp.
Aseptic pulp:
It is the pulp that was heat-sterilized and packed aseptically; no chemicals are added and has a long shelf life. There is very specific equipment to perform this process and it is considered to be at the cutting edge of technology.
Concentrated Frozen Juice:
This product is prepared by direct application of heat to pineapple juice to reduce its water content. Preservation methods are similar as described for concentrated pulp in which no chemical additives are used.
Jelly:
Jellies fall in the group of fruit preserves, which are defined as semisolid products prepared by mixing 45 parts of fruit and 55 parts of sugar. This mixture is cooked until the final solids contents reach 65 to 68%. It is hot-filled for better stability. Usually, jellies are prepared from fruit juice and a gel-type product is obtained; it may or may not contain fruit pieces. Final textural firmness is dependent of the type of gel-forming agent as pectin which is added under controlled acidity and solids content to assure the proper texture of the product. To assure proper shelf life at ambient temperature, preservatives may be added. These chemicals are mainly used to control mold growth; but once the jar is open, it shall be stored under refrigeration.
Marmalades:
This is also considered as a fruit preserve using the same proportions of fruit and sugar, and cooked until the same solids content as jellies. Consistency is semi-fluid and not a gel as jellies. Preservation criteria and shelf life considerations are similar as for jellies.
Fillings:
Pineapple pieces mixed with bakery cream may be used as cake fillings for institutional service and large-scale production of bakery goods. Stability of the product depends on the cleanliness and hygiene of the manufacturing process. Product may be packed in plastic bags, plastic containers or metal bins. If no additives are used, the fillings must be kept refrigerated. Due to its elevated nutrient and water content, shelf life is not very long.
Vinegar:
Vinegar is prepared by an acetic fermentation of alcohol solutions derived from sugar or starchy materials (fermentable sugar content of 8-20%). This is done by strains isolated from the raw materials. Peel and other pineapple by-products from processing can be used as raw materials to prepare natural vinegar and thus make a proper use of residuals. Vinegar must be pasteurized once it is prepared and bottled. It is stable at ambient temperature (Coveca, 2002).
Fig. 30 Dried pineapple chunks
Fig. 31 Traditional extraction of pineapple juice
Sauce
Concentrate 1 kg strained pulp containing 20 g sugar to 1/3 of its original volume in the presence of suspended spice bag containing 50 g chopped onion, 5 g garlic and 50 g ginger, 10 g powdered spices and 5 g red chillies. Press out spice bag occasionally and squeeze it out finally to obtain maximum spice extract. Add 15 g salt and remaining 40 g sugar and cook to thick consistency. Add 450 ml vinegar and cook again to end point. Add and mix preservative after dissolving in minimum quantity of water. Heat to boiling and hot pack.
Jam
Boil 1 kg pulp of ripe firm peeled fruit with 100 ml water 3 g citric acid and 10 g of pectin. Add 750 g sugar and cook to thick consistency. End point is confirmed by sheet test. Boiling mass is allowed to fall after cooking from a laddle which will flow in the form of a sheet. Pack hot in clean dry glass jars.
Jelly
Mix 1 kg grated pulp of fully mature peeled but somewhat raw fruits with ripe pineapple pulp (1 kg), 2.5 litre water 10 g citric acid and 2 g of pectin. Boil for 30 min, cool and allow to settle for 2 hours. Separate the supernatant (upper layer) and filter. Test for pectin quality. Formation of single clot with small quantity of ethyl alcohol added to test samples indicates high pectin content. Concentrate further if necessary to obtain single clot. Cook gently the extract with equal quantity of sugar to obtain the end point indicated by the formation of sheet. Pack hot. Cover with a layer of melted wax and close the lid.
Preserve and candy
Cut rectangular slices (4x1 cm) or suitable sized cubes from the fully mature ripe washed peeled fruits after removing seeds. Keep in 1.5 % limewater for 3-4 hours. Drain and wash 3-4 times in plain water. Dissolve 400 g sugar in 600 ml hot water and filter. Boil pieces in sugar syrup and keep overnight. Next day drain the syrup, raise its Brix to 50. Add slices, boil and keep again. Repeat this process every day, untill Brix reaches 70-75°. Keep for a week. Drain the syrup, fill the pieces in dry jars and cover slices with freshly prepared sugar syrup of 70°Bx.
For the preparation of candy, raise the Brix of syrup to 75°, and keep it for a week. Drain and dry the pieces under shade. Dip pieces in boiling water to remove adhering sugars. Drain, dry and pack.
Toffee
Concentrate 1 kg sieved pulp to 1/3 volume and cook with added sugar (600 g), glucose (100 g) and hydrogenated fat (100 g) till a speck of the product put into water forms compact solid mass. Make thick paste of 100 g skim milk powder in minimum quantity of water and mix with the boiling mass. Spread 1-2 cm thick layer of the cooked mass over /SS trays smeared with fat. Add flavoring material at this stage, if necessary. Allow to cool. Cut and wrap in butter paper (Indiaagronet.com, 2000).
Authors: J. De La Cruz Medina and H.S. García
Edited by: Danilo Mejía, PhD - Agricultural and Food Engineering Technologies Service (AGST)
CHAPTER XXXIII: Pineapple post-harvest operations
2.0 Harvesting and Post-production operations
2.1 Harvesting
2.1.1 Yield
2.1.2 Transportation
2.1.3 Grading :
2.1.4 Packing.
2.3 Packinghouse operations
2.4 Packing
2.5 Cooling system
2.6 Storage of fruits and vegetables
2.7 Transportation system
2.8 Processing
2.0 Harvesting and Post-production operations
Traditional and improved picking operations (Fig 22)
Fig. 22 Basket picking operation (SARH,1994)
2.1 Harvesting
Location of the crops, internal ways and access to the main roads leading to the packing site must be considered so that pineapples can be transported in the minimum time under controlled conditions. Transporting pineapples from the production field to the packing location is made by tows, trucks or specially-designed vehicles. Availability of a double roof, thermal insulation and sliding curtains help keep the storage temperature of the fruit during loading and unloading. The equipment must be kept clean and disinfected and fitted with good suspension, low-pressure tires and even and smooth floor surface, such that the packing units can be easily handled. Bulk transportation the use of vegetative material is placed on the vehicle platform to avoid extreme temperatures and to act as cushion against mechanical collisions during transport (Colfruits, 2004).
2.1.1 Yield
In order to reach crop yields of 100 tons a minimum of 60,000 plants per hectare need to be planted, using the arrangement of 30 cm between plants, 40 cm between lines and 70 cm from the aisle or between the double lines. If density needs to be increased the distance between plants can be varied and the rest may remain unchanged.
To estimate the density the following formula:
100/distance between plants+ aisle width = a
100/distance between plants = b
D = (a ) (b) (2)
2.1.2 Transportation
Export logistics for pineapple
The harvested fruit is deposited in drawers and transported to the packing plant, where it is submerged in disinfectant in trays. Another alternative process consists on submerging the fruit completely in similar solution (with Triadimefon), this process is used especially to export to United States and Europe. The boxes used in the packing are revised to detect the presence of insects. The fruit is placed in boxes of 10 - 20 kg and, finally, put in pallets. The pallets, properly maintained in refrigeration chambers are loaded in the refrigerated containers. Each container has a capacity of 1500 boxes of 20 kg and/or 3000 approximately boxes of 10 kg. The refrigerated container is maintained at 7.5 - 8° C previous to export. Each container has a thermograph for the control and registration of the temperature while traveling as well as with the respective filters for the control of the ethylene. Is important to offer and use an appropiate packing for the pineapple, for the cultivation and preparation of the fruit, because just with a safe and functional protection it can keep the quality of the product until arrival to the final market. The packing also helps to promote the fruit's sales because of the presentation, as well as the description of content and origin. The appropriate packing use for the product fulfills the following functions: To avoid the loss of aroma, to protect the product against the admission of flavors and disgusting scents, to offer a good period of conservation, to avoid the accumulation or loss of humidity, to protect the product against damages, to offer a space to print the relative necessary information about the product. A careful crop handling and postharvest contributes to the maintenance of the quality of the products. The gathered pineapples should be packed in clean plastic boxes (Fig. 23) and be stowed. An important characteristic in this stage is that the boxes should have holes with lengthened form in all sides for the ventilation, because it allows a quick exit of the heat of the fruit. The packing measures for the pineapple are not standardized, but are guided with the international packing norm for agricultural products according to the size. The product should be kept at temperature packing from 7 - 10° C, with a relative humidity of 90%. The pineapples should be fixed inside the box, in order to avoid wounds in the shell and/or the crown (Isabellefruits,2004).
Fig..23 Packing of pineapple fruits
2.1.3 Grading :
After pre-grading, washing, waxing, and fungicide treatment, the pineapples are left to dry and then are graded for packing. Graders remove any fruit that shows signs of fresh mechanical damage or any of the conditions that qualify the fruit for rejection in the pre-grading stage. Remaining pineapples are classified for packing based on size, stage of ripeness, and, if applicable, shape. Fruits of different shape may not be mixed in the same carton.
2.1.4 Packing.
The preferred method of packing is to place the fruit vertically on the base, and then to place dividers between the fruits to prevent rubbing and movement. With some cartons, this is not possible and fruit are laid horizontally in alternating directions; where two layers of fruit are packed, a layer of card is required between the layers : 6 count - 1.75 kg fruit (3.8 lb) ,12 count - 1.25 kg fruit (2.7 lb) ,12 count - 1.00 kg fruit (2.2 lb) and 20 count - 0.75 kg fruit (1.6 lb)
Fruits are normally packed to a net weight of 10 to 15 kg (22 to 33 lb) depending on the carton and the market. High value small pineapples may be shipped in some instances at 6 kg (13 lb), whereas the large fruit in some cases may be packed up to 20 kg (45 lb).
Packaging:
A full-telescopic two-piece fiberboard carton with internal dividers between the fruit; bursting strength 275 lb/in2. Top and bottom ventilation, in addition to side vents are required, particularly where sea-shipments in break bulk are used. Where staples are used in carton construction, care should be taken to ensure complete staples closure to prevent fruit damage.
Storage and Transportation:
Where sea-shipment is to be used, the fruit should be harvested on the day prior to shipment. Green fruit should be stored at 10ºC, 85 to 95% relative humidity, and under these conditions, should have a storage life of two to three weeks (Fig. 24). This will be dependent on the sugar content and the agronomic conditions during production, in addition to the handling and storage procedures. Where exports are made by air with fruit harvested at more advanced stages of maturity, pre-export storage can be used and the suitable storage temperature decreases to 7.5ºC, 85 to 95% relative humidity.
Potential Post-harvest Losses: Losses in pineapples during air-transport are minimal if careful handling is employed. On sea-shipments and long term storage however, the fruit are more susceptible to post-harvest losses as a result of increased handling, control of temperature and disease incidence
Mechanical damage: Bruising or puncturing caused by poor handling, dropping or abrasion, will result in localized areas of softening and development of secondary microbial infection (Foodmarketexchange, 2004).
Fig. 24 Pineapple refrigeration
For canned pineapple can sizes used are: 608X700 (108 oz), with a net weight of 3030 oz, 6 cans per box and a total weight of 20 kg per box; size 401X411 (30 oz), with a net weight per can of 820 oz, 24 cans per box and a total weight 24 kg per box; size 307X409 (20 oz), with a net weight of 560 oz, 24 cans per box and a total weight of 16 kg per box; size 307X309 (15 oz), with a net weight of 425 oz, 24 cans per box and a total weight of 13 kg per box; and size 307X201 (8 oz), with a net weight of 227 oz, 24 cans per box and a weight of 7 kg per box. The packing is in corrugated cardboard carton to prevent dents during transportation. The packing in tray of 12 cans for retail can size is available with and without shrink wrapping. Products can also be palletized on wooden pallet or slip sheet for the convenience of handling. For industrial use, product of 108 oz. can be palletized without cartons. Pineapple juice is extracted from selected fruits where pulp is controlled to the requirement. NFC (not from concentrate) pineapple juice is single strength at 12 ± 1 °Bx. It is aseptically processed, while some juice will be processed through evaporators to the desired °Bx. All juice and concentrate will be stored in cold storage to preserve the quality. Frozen concentrate is stored at the temperature of -20°C. Aseptic product can be stored at the ambient temperature but it is recommended to stored at 5 °C in order to preserve the quality and to prolong the storage life and packed in steel drum or wooden bin. The canned pineapples are packed in accordance with the US FDA, and are available in different sizes to serve both retail and institutional purposes. The cuts include slice, chunk, tidbit and crushed packed in either natural juice or syrup. Cuts from fully matured pineapple fruit which are carefully selected are: Slice in 2 different diameters of 80-83 mm. and 90-97 mm., chunk that is a segment of pineapple good for barbeque, salad or full-bite snack, tidbit/pieces in various sizes from small pieces for pizza topping to large piece as natural snack and crushed/chopped pineapple that can be used as desert topping and pie filling (tpc-canning.com 2004)
Pineapples are also separated according to degree of ripeness. Average weight of the fruit is ca. 2.5 kg, pulp color must be in the range of pale to gold yellow, with 13 % of soluble solids and 0.6 % acidity as citric acid. These attributes are an important part of the overall qualities of a widely accepted pineapple flavor for either fresh or canned product.
Inspection
Mechanical damage: Many factors contribute to pineapples skin damage, including the harvesting tool used, dropping of fruit into crates, overfilling of crates, and jostling of fruit during field transportation. Similar problems can result from poor handling during washing, grading, and packing.
Pineapples handlers can minimize fruit damage by taking protective measures throughout all handling stages. Staff should be trained in proper harvesting techniques. In addition, transporters should drive slowly and carefully when taking fruit from the field to the packing house.
At the packing house, crates should include foam in their base and contain only one layer of fruit. In automated operations, all machinery should be padded where possible. Palletized systems are preferable for moving produce in both field crates and final packages.
2.3 Packinghouse operations
The fruit is harvested and delivered to the packinghouse. Field Managers are in contact with growers to schedule deliveries of fruit to meet market demands. Growers who want their fruit picked up in the groves will schedule transportation with the Field Manager. Many Growers elect to deliver the fruit to the packinghouse themselves.
The fruit is gradually pre-cooled before packing. This allows the fruit to cool down over a 12 hour period from the ambient temperature at delivery time.
Packers have a built in system that allows full bins to be weighed before packing. Empty bins are then weighed so that the grower is given credit for every pound of fruit delivered to the packinghouse.
The fruit is placed on the packing line and graded (Fig 25). The fruit is then placed into tight fill cartons by a sizer machine. The fruit is labeled during the process. The sizer insures not only that the correct number of fruit is packed into the cartons by size, but also that the weight of the carton is correct.
2.4 Packing
All cartons of fruit are checked once more by quality control personnel before the carton is sealed and placed in a cooler until shipment time. The cartons of fruit are stacked on pallets and these pallets are placed in a shipping cooler, where temperature is maintained between 8-10 °C (Calavo Products, 2002).
Fig. 25 Pineapple selection and inspection line
2.5 Cooling system
Pineapples are placed in an insulated room equipped with refrigeration units and forced air-cooling where fans pull cool air through pineapple packages. After storage the pineapple pallets are placed in refrigerated containers with fresh air supply or controlled atmosphere.
2.6 Storage of fruits and vegetables
Chilling damage arises in the varieties "Queen" and "Smooth Cayenne" when they are stored for 14 days at temperatures of < 7°C. Signs of chilling damage are: loss of skin gloss, formation of brown to black stripes under the skin and around the woody central cylinder (endogenous brown spot), watery flesh, insipid taste, susceptibility to rotting and loose crown leaves. At temperatures > 10°C, the crown leaves have an increased tendency to bolt. Bolted crown leaves impart a tired appearance to the fruit and diminishes its value. In addition, the tendency to fruit rot (black rot) also increases, often occurring as butt rot above the stem but also arising in the crown. Susceptibility to chilling damage reduces as ripeness increases.
The cargo and holds/containers must be cooled before loading starts, to ensure that the cold chain is unbroken and the quality of the fruit is not reduced.
Pineapples require particular temperature, humidity/moisture and ventilation conditions. Recommended ventilation conditions: air exchange rate 40 - 60 times per hour with constant supply of fresh air, so as constantly to remove the ripening gases arising and to keep the CO2 content of the hold air low. Spoilage may occur as a result both of inadequate ventilation (danger of rotting) and of excessive ventilation (drying-out, weight loss. Pineapples display 2nd order biotic activity. They are living organs in which respiration processes predominate, because their supply of new nutrients has been cut off by separation from the parent plant. Care of the cargo during the voyage must be aimed at controlling respiration processes (release of CO2, water vapor, ethylene and heat) in such a way that the cargo is at the desired stage of ripeness
( tis-gdv,2004)
Compatibility groups for storage of fruits
The best storage environment for an individual fruit or vegetable depends on its unique requirements for temperature, relative humidity, and ethylene exposure. Most compatibility charts for mixing products during postharvest handling divide fruits and vegetables into eight groups. In practice it is very difficult to separate products into this many groups-very few wholesale or retail handling facilities, if any, have eight temperature-controlled rooms.
Researchers of UC Davis (Thompson, Kader and Sylva, 1999), have developed a three-group chart that is easier to use and still provides good product shelf life (Table 4).
Table 4 Compatible Fresh Fruits During 7 Day Storage
http://rics.ucdavis.edu/postharvest2/Pubs/postchrt2.shtml
avocado olive
babaco orange
tuna pepino
carambola pummelo
feijoa Sugar apple
granadilla tamarind
Grape fruit watermelon
guava cranberry
lemon pineapple
mandarin Ugli fruit
*Source: (UC Davis, 2004)
Group 3- Fruits
code thermometer
45-50 °F, 7-10 °C & 85-95% RH
2.7 Transportation system
Marketing and physical distribution of fresh produce inherently means moving the produce. The commodities are handled, either manually or mechanically, many times from harvest and through the distribution process before the consumer buys and prepares them to eat.
For domestic transportation the use of road vehicles offers substantial advantages of convenience, availability, flexibility permitting door-to-door delivery, and reasonable cost of transport. The use of road transportation for fresh produce is increasing and likely to increase in countries all over the world. Produce may be transported by pick-up, enclosed truck, open truck or refrigerated vehicle (Harris, 1988).
For perishable products, however, the increased speed of handling and reduced transport costs that came with containerization were not enough. Ocean transport of cooled and frozen cargo received a substantial boost with development of mobile refrigerated cargo ships that lack this flexibility. Controlled atmosphere (CA) technologies allow operators to lower the respiration rate of produce by monitoring oxygen, carbon dioxide and nitrogen levels within a reefer. In this way, CA can slow ripening, retard discoloration, and maintain freshness of pineapple. Although it is likely that container ships will dominate the perishable trade between North America, East Asia and Europe, conventional refrigerated vessels can serve many smaller ports, especially in the developing world, that are unable to handle large container vessels. Thus, in north-south trade and in certain niche markets, conventional refrigerated ships may have a brighter future, but even here, competition from container vessels is bound to increase as cost decline (Agricultural Outlook, 1999)
2.8 Processing
There is a series of physical properties of pineapples that play important roles during processing. Leverington (1970) described research works on the relationship between translucency and other quality characteristics. It was found that in addition to be considered as a maturity index, translucency is a quality attribute of the fruit. Translucent or semi-translucent slices are generally considered as desirable and associated with better flavor. Fully translucent pulp have an overripe flavor, while those not translucent are too sour. As pulp becomes more translucent air cavities decrease in size and therefore in porosity. Internal color affects the appearance and acceptance of the fruit; yellow-gold color has been regarded as best.
Traditionally pineapple is consumed fresh or canned (Fig. 26). Diversification of pineapple products is a good strategy to increase consumption in the main markets of the world. Thus, pineapple is now consumed in the form of single strength or concentrated juice, dehydrated and/or sugared, canned in slices or bits. The variety traditionally employed to develop these products has been Cayena lisa. Among the newer developments are dried chips, cocktail-type drinks, dried powdered, isotonic mixtures and wine; there are also new canned forms as whole fruit, bars, flakes and cubes. For fresh consumption, new varieties have been introduced: MD2, Josapine, LR41 and Gandul (Coveca, 2002).
Fig. 26 Canned pineapple
Essentially a prime table fruit, pineapple pulp (Table 5) is perfectly suited for conversion to frozen juices (Fig. 27 ), nectars, drinks, jams, fruit cheese, concentrates (Fig. 28) or to be had by itself or with cream as a superb dessert. It can also be used in puddings, bakery fillings, and fruit meals for children, flavors for food industry, and also to make the most delicious ice cream and yoghurt. While the raw fruits are utilized for products like chutney, pickle, sauce. pineapple beverage, etc. ripe ones are used in making pulp, juice, nectar (Table 6), squash, leather, slices, etc. Major export products include dried and preserved vegetables, jams, fruit jellies, canned fruits and vegetables, dehydrated vegetables, frozen fruits, vegetables and pulps (Table 7) and freeze dried products.
Ripe pineapple may be frozen whole or peeled, sliced and packed in sugar (1 part sugar to 10 parts pineapple by weight) and quick-frozen in moisture-proof containers. The diced flesh of ripe pineapple, bathed in sweetened or unsweetened limejuice, to prevent discoloration, can be quick-frozen. Half-ripe or green pineapples are peeled and sliced as filling for pie, used for jelly, or made into sauce.
Table 5 Industrial processing possibilities
pinapple pulp Glazings
Fruit cocktails Dried pineapple slices
Juice Pineapple wine
Nectar Flavored yoghurt
Fruit sauces Ice cream
Fig.. 27 Processing of frozen Pineapple juice
a) Fresh consumption and processing
Processed pineapples shall meet standards of quality to assure market acceptance. Processing plants reject fruit with bruises, with defective heart, or multiple crowns. Porosity should be minimal and the °Bx to acidity ratio should be near 20. Acidity should be kept close to 0.75%.
In average the yield in processing ranges from 45% to 55%. End products include packed pineapple, which includes pulp from the cuts made to the base, crown and peel. This product may be done in small slices, chunks or bits. The pieces are placed in cans containing syrup. It is important to maintain a good control of the °Bx of the syrup in order to reach an equilibrium between the fruit and the syrup. The thermal treatment and final pH value of the product are key factors to assure product quality. Either cans or glass jars can be employed for packing purposes. Pineapple pieces can be mixed with other fruits to prepare fruit cocktails, which entails another commercial alternative (Coveca, 2002).
In the process for preparation of pineapple products, fruit are unloaded from trailer trucks to conveyor bands where crowns are taken off and fruit are placed in a washing vat, then through an elevator the pineapples go to a roller sorter, and then separated in two different sizes and two slides take the fruit to different packing lines. The Guinaka brand peeler(Fig 28) removes the peel and forms a cylinder with the peeled fruit, by a circular blade that spins at high speed. The cylinder is sent by another slide where they are placed manually in another machine that removed the core. The coreless cylinder is then moved to the dicer and the product is then ready to be packed in buckets holding 10 to 15 kg. The product is frozen in a chamber set at -20°C, for further transfer to distribution points or processing. Pineapple cylinders are sliced and canned with syrup, then passed through an exhauster with steam at 3 bar and 120 °C to eliminate air and create vacuum (Fig 29). Cans are sealed and sent to the autoclave. After the thermal treatment the cans are placed in a cooling vat for 10 minutes; this produces a thermal shock that inactivates bacteria. Finally, cans are labeled and boxed and ready for distribution.
Fig. 28 Guinaka peeler
Fig. 29 Exhauster
Other different products of pineapple processing are:
Dried pineapple:
In this product, most of the free water of the fruit is eliminated. Usually, chunks or slices are prepared for better presentation and make handling easier. Final moisture is near 5%, and this allows the dried fruit to have a long shelf life as long as proper packing is provided and storage is done in a fresh place. (Fig. 30)
Juice:
Pineapple juice is obtained from crushing fruit pieces and proper pysical separation of the solids (Fig. 31). Juice must be pasteurized and packed to extend its shelf life and a preservative or refrigerated storage may be used as additional barriers to microbial spoilage. No juice should reach the market if it becomes fermented or mixed with water. Packing may be plastic bottles or bags, coated cans, multilaminate (plastic, paper, metal foil) or any newer materials. The pH values of the product must be controlled so it remains agreeable for human consumption. It is a common practice to blend batches of juices to attain proper acidity and sensory qualities. Juices from other fruits can be blended with pineapple's and interesting mixtures make novel products.
Nectar:
It is the product of blending juice with a certain amount of solids from the pulp containing the same amount of °Bx as the original fruit. Normally, nectars are prepared by diluting fruit pulp to 30 °Bx. Methods of preservation and packing are similar to those described for juice.
Pulp:
It is the product of the basic processing of peeled pineapple pulp by crushing. Pulp may be preserved by thermal treatment, by preservatives addition and proper handling in either small packages, or in bulk packages for further industrial processing and formulations as ice cream mixes, jellies, jams, sodas, etc.
Concentrated frozen pulp:
It is the product from thermal treatment of the pulp to remove at least 50% of the initial water content. Concentration and freezing are applied to preserve the pulp for extended periods of time. The concentrated pulp is stable without the addition of chemicals as long as it is kept frozen. Upon reconstitution (by replenishing the previously eliminated water) the pulp should have the same qualities as the original pulp.
Aseptic pulp:
It is the pulp that was heat-sterilized and packed aseptically; no chemicals are added and has a long shelf life. There is very specific equipment to perform this process and it is considered to be at the cutting edge of technology.
Concentrated Frozen Juice:
This product is prepared by direct application of heat to pineapple juice to reduce its water content. Preservation methods are similar as described for concentrated pulp in which no chemical additives are used.
Jelly:
Jellies fall in the group of fruit preserves, which are defined as semisolid products prepared by mixing 45 parts of fruit and 55 parts of sugar. This mixture is cooked until the final solids contents reach 65 to 68%. It is hot-filled for better stability. Usually, jellies are prepared from fruit juice and a gel-type product is obtained; it may or may not contain fruit pieces. Final textural firmness is dependent of the type of gel-forming agent as pectin which is added under controlled acidity and solids content to assure the proper texture of the product. To assure proper shelf life at ambient temperature, preservatives may be added. These chemicals are mainly used to control mold growth; but once the jar is open, it shall be stored under refrigeration.
Marmalades:
This is also considered as a fruit preserve using the same proportions of fruit and sugar, and cooked until the same solids content as jellies. Consistency is semi-fluid and not a gel as jellies. Preservation criteria and shelf life considerations are similar as for jellies.
Fillings:
Pineapple pieces mixed with bakery cream may be used as cake fillings for institutional service and large-scale production of bakery goods. Stability of the product depends on the cleanliness and hygiene of the manufacturing process. Product may be packed in plastic bags, plastic containers or metal bins. If no additives are used, the fillings must be kept refrigerated. Due to its elevated nutrient and water content, shelf life is not very long.
Vinegar:
Vinegar is prepared by an acetic fermentation of alcohol solutions derived from sugar or starchy materials (fermentable sugar content of 8-20%). This is done by strains isolated from the raw materials. Peel and other pineapple by-products from processing can be used as raw materials to prepare natural vinegar and thus make a proper use of residuals. Vinegar must be pasteurized once it is prepared and bottled. It is stable at ambient temperature (Coveca, 2002).
Fig. 30 Dried pineapple chunks
Fig. 31 Traditional extraction of pineapple juice
Sauce
Concentrate 1 kg strained pulp containing 20 g sugar to 1/3 of its original volume in the presence of suspended spice bag containing 50 g chopped onion, 5 g garlic and 50 g ginger, 10 g powdered spices and 5 g red chillies. Press out spice bag occasionally and squeeze it out finally to obtain maximum spice extract. Add 15 g salt and remaining 40 g sugar and cook to thick consistency. Add 450 ml vinegar and cook again to end point. Add and mix preservative after dissolving in minimum quantity of water. Heat to boiling and hot pack.
Jam
Boil 1 kg pulp of ripe firm peeled fruit with 100 ml water 3 g citric acid and 10 g of pectin. Add 750 g sugar and cook to thick consistency. End point is confirmed by sheet test. Boiling mass is allowed to fall after cooking from a laddle which will flow in the form of a sheet. Pack hot in clean dry glass jars.
Jelly
Mix 1 kg grated pulp of fully mature peeled but somewhat raw fruits with ripe pineapple pulp (1 kg), 2.5 litre water 10 g citric acid and 2 g of pectin. Boil for 30 min, cool and allow to settle for 2 hours. Separate the supernatant (upper layer) and filter. Test for pectin quality. Formation of single clot with small quantity of ethyl alcohol added to test samples indicates high pectin content. Concentrate further if necessary to obtain single clot. Cook gently the extract with equal quantity of sugar to obtain the end point indicated by the formation of sheet. Pack hot. Cover with a layer of melted wax and close the lid.
Preserve and candy
Cut rectangular slices (4x1 cm) or suitable sized cubes from the fully mature ripe washed peeled fruits after removing seeds. Keep in 1.5 % limewater for 3-4 hours. Drain and wash 3-4 times in plain water. Dissolve 400 g sugar in 600 ml hot water and filter. Boil pieces in sugar syrup and keep overnight. Next day drain the syrup, raise its Brix to 50. Add slices, boil and keep again. Repeat this process every day, untill Brix reaches 70-75°. Keep for a week. Drain the syrup, fill the pieces in dry jars and cover slices with freshly prepared sugar syrup of 70°Bx.
For the preparation of candy, raise the Brix of syrup to 75°, and keep it for a week. Drain and dry the pieces under shade. Dip pieces in boiling water to remove adhering sugars. Drain, dry and pack.
Toffee
Concentrate 1 kg sieved pulp to 1/3 volume and cook with added sugar (600 g), glucose (100 g) and hydrogenated fat (100 g) till a speck of the product put into water forms compact solid mass. Make thick paste of 100 g skim milk powder in minimum quantity of water and mix with the boiling mass. Spread 1-2 cm thick layer of the cooked mass over /SS trays smeared with fat. Add flavoring material at this stage, if necessary. Allow to cool. Cut and wrap in butter paper (Indiaagronet.com, 2000).
