New Approaches to Industrialization of Algarrobo (Prosopis pallida) Pods in Peru Nora Grados and Gastón Cruz University of Piura Faculty of Engineering - Laboratory of Chemistry Aptdo. 353, Piura, Peru e-mail: [email protected] ABSTRACT Peruvian "algarrobo" (Prosopis pallida and Prosopis juliflora) and its fruits are described and some new ways for its industrialization are suggested on the basis of the research done at the University of Piura since 1984. The processing alternatives of Prosopis pods developed at the University of Piura are focused especially on the different uses for each part of the fruit [exocarp, mesocarp (pulp), endocarp], and the episperm, endos- perm and cotyledon from the seed. Each of these components has specific industrial applications. Several specific components have been determined. Sucrose is the main sugar (46% in weight) in the pulp. In the endosperm the polysaccharide is a galactomannan, with a 1:1.36 galactose/mannose ratio. Among the important amino acids in the seed cotyledon are: glutamic acid, arginine, aspartic acid, leucine, proline and serine. In the pulp, vitamin C, nicotinic acid, and calcium pantothenate have also been found. In the seed the content of vitamin C and E are significant. The dietary fiber of the pulp and endocarp hulls is basically insoluble dietary fiber. The results of the research show the feasibility of industrialization of Prosopis in Peru. The basic equipment for a pilot plant is being installed at the University of Piura to demonstrate this fact. Introduction Piura is on the northwestern coast of Peru (Figure 1), an arid zone where the annual rainfall is below 100 mm. The average annual temperature is 24EC and the relative humidity is 74%. Algarrobo (Prosopis pallida and Prosopis juliflora) [1] is one of the few arboreal species that occur natu- rally in these desertic areas (Figure 2). It has, therefore, an enormous importance in the protection of this fragile environment. Some trees can be 15 meters tall. Prosopis forests cover about 85 000 ha of land in northern Peru [2]. Algarrobo is the name the Spaniards gave the tree when they arrived in Peru in the 16th century, due to the similarity of its fruits to those of the mediterranean carob. The Peruvian native names for Prosopis were Thacco or Guarango, which are not often used today [3]. Thanks to its wood and fruits, Prosopis plays an important role in the daily life of impoverished local farmers in northern Peru. They use Prosopis wood in constructing their rustic houses and cattle fences, and as fuel for cooking; fallen Prosopis leaves, as an organic fertilizer (called puño); and their fruits, with a high sugar content, are used as forage and food (mainly as algarrobina syrup). Since Prosopis is one of the few trees growing in this area, the people and the animals can also enjoy the shade of the tree, which is a very important benefit. 3-25 Figure 1. Location of Piura in Peru Figure 2. Tree of Prosopis pallida in Piura, Peru 3-26 Figure 3. Desertification Areas Nevertheless, fuelwood is not only used for cooking but is also commercialized as fuel for brick baking furnaces, bakery ovens, and making charcoal for grills in chicken restaurants. The excessive extraction of Prosopis fuelwood has caused a reduction of the availability of this resource (Figure 3). It is estimated that from the 1950s to the 1980s, 200 000 ha were deforested [4]. In 1983, as a result of the El Niño phenomenon, rainfall reached 2 411 mm [5], resulting in new areas of land being recovered by Prosopis trees. The University of Piura has been developing a project for conservation and propagation of Prosopis since 1984. The success of this project is based on showing that Prosopis has many other rational uses. One part of this project includes the characterization of the fruit and the studies of new products and processes; another part includes agroeconomical aspects for forestation of these arid areas. There are 80 ha of Prosopis at the campus of the University for these studies (Figure 4). Prosopis Pods Production And Storage Since Prosopis trees are not cultivated but grow wild in desertic areas, the fruits are not harvested but collected by those who need them. Prosopis pallida and Prosopis juliflora are varieties with especially large and sweet fruits (Figure 5). The fruits are yellow pods of up to 30 cm long, with an average weight of 12 g. The sugar content of its pulp is 46% [6, 7]. The tree produces twice every year: the main pod production is between December and March. The second, minor production season, is between June and July. The productivity depends mainly on the age of the tree and on the soil quality. Some trees produce up to 300 kg of fruits per year. 3-27 Figure 4. Experimental Plantation at the Campus of the University of Piura Figure 5. Pods of Prosopis pallida 3-28 The pods fall to the ground when they are ripe, and remain there for a long time until they are collected or eaten by animals, such as goats, sheep, or donkeys. During the production period, the fruit has a very low price because of its abundance. A metric ton of pods costs US$27. The collecting is done by very poor children and women as an activity parallel to their agricultural tasks (Figure 6). One person can collect about 150 kg of pods in a day, which is equivalent to less than US$5. The quantities of comercialized Prosopis pods are not officially recorded. An estimation based on measurements done on representative parcels of land [2] would give an approximate production of 300 000 metric tons per year in the northern region of Peru. However, not all of it is used. More than 50% is lost because it is not collected, 15% is used as animal food and the remaining 35% is bought by dealers who sell it in feed stores in other cities (Figure 7). In fact, the main use of Prosopis pods in Peru is still the feeding of animals, which eat the pods without any previous processing. Some factories produce feed mixtures for livestock. It is interesting to point out that Prosopis is prefered by ranchers because they believe it has some special properties in addition to its recognized nutritional value, that make it irreplaceable. It is enough to say that a large part of the production is fed to racehorses. Prosopis pods are attacked by insects which eat the pulp and the seeds. The most numerous are insects of family Bruchidae, but Tribolium castaneum (fam. Tenebrionidae), Laspeyresia leguminis and Cryptophebia sp. (fam. Olethreutidae) and Plodia interpunctella (fam. Pyralidae) are also known to eat the seeds [8]. Rain also damages the fruits. When the fruits lying on the ground get wet, they become rotten (Figure 8). To reduce the damage, the pods are usually stored in rustic storage rooms, on the ground, or underground. Once a room is full it is sealed with clay. A typical storage room made from adobe is showed in Figure 9. Chemicals are not often used to control insects during storage, but natural- repellent plants are used. PhostoxinTM has proved to be efficient in avoiding proliferation of insects in the storage rooms, but a considerable number of pods are damaged in the tree or on the ground and no control methods for the damage is known. Because of the seasonal production of Prosopis, storage is necessary to supply seeds throughout the year. Between August and October, the price rises up to 5 times. Traditional Human Food Products From Prosopis Pods For many years, inhabitants of northern Peru have prepared and consumed algarrobina, a concentrated sugary extract of the pods. The concentrated syrup has a brilliant, dark brown color and is thicker than honey. Algarrobina is used in different ways: it is taken by spoon as a medicine or is added to juices and milk as both sweetener and a natural flavoring. We must say that a delicious drink is algarrobina cocktail, a mixture of a small quantity of algarrobina, pisco brandy, and milk. Algarrobina is produced now in very simple plants and is sold in reusable glass bottles (Figure 10). Ancient people talk about another product, yupisin, a beverage obtained in the same way as algarrobina, but is not concentrated. It is consumed directly or used to prepare desserts with sweet- potato flour or corn flour. Yupisin is consumed in rural areas only; it is not bottled. 3-29 Figure 6. Children Collecting Prosopis Pods 3-30 Figure 7. Loading a Truck With Prosopis Pods Figure 8. Typical Damage in Prosopis Pods 3-31 Figure 9. An Algarrobera (Rustic Storage Room for Prosopis Pods) Figure 10. Bottles of Algarrobina from Local Producers 3-32 Figure 11. Potential Uses of Prosopis Pods 3-33 Potential Uses of Prosopis Pods The two traditional food products from Prosopis described above use only the soluble sugars in its pulp, which, in fact, is the main constituent and the other components, i.e., the endocarp, fiber, and seeds are discarded. For this reason we have studied each of the fractions of the fruit separately to develop a more complete utilization of the entire fruit. For the industrial processing of Prosopis we have carried out many studies to fractionate the fruit into exocarp and mesocarp (pulp), endocarp, and seed, based on an ambitious proposal for North American Prosopis species [9]. The seed can then be separated in episperm, endosperm, and cotyledon. The scheme in Figure 11 shows the variety of products that can be obtained in a process which uses all the components of Prosopis pods.