Introduction
Traditionally, the Western Atlantic forests and Lower Amazon basin in Brazil have been recognized as a rich source of oleaginous crops, mostly used as foods or as a source of medicine and cosmetic products by the locals. The recent drive to promote biofuel in Brazil has started to threaten the native oil yielding crops, and research is being undertaken to explore the contents of essential fats and minerals rationalizing the applicability of seeds from diverse regions as a source of food or fuel.
Lecythis pisonis Camb. (Sapucaia), locally known as ‘cumbuca-de-macaco’, thrive in forests in the State of Pernambuco through São Paulo and the Amazon region. The new phylogenetic taxonomic scheme of Arthur Cronquist, updated from the classical Bentham and Hooker’s scheme, has categorized L. prisons within family Lecythidaceae, Order Lecythidales, Subclass Rosidae, and Class Magnoliopsida of dicots. The molecular phylogenetic NCBI taxonomic scheme has placed L. pisonis under Suborder Lecythidaceae, Order Ericales, Subclass Aasterids, Core Eudicotyledons, Eudicotyledons, Magnoliophyta, Spermatophyta, Euphyllophyta, Tracheophyta, Embryophyta, Streptophytina (all unranked), Phylum Streptophyta, and Kingdom Viridiplantae.
In the present biodiversity investigation, Vallilo and co-workers have analyzed the fatty acid and mineral composition of L. prisons Camb. seeds from four locations of São Paulo State and evaluated the nutritive properties.
Background: Mori & Prance illustrated the identifying keys for the family Lecythidaceae and subtaxa of the lower hierarchy up to species (321-330). This tropical family comprises 20 genera and ca. 285 species, mostly shrubs and trees. The flowers are large with 4-6 sepals and petals. The most characteristic feature is the fused stamens, which form an asymmetric ring projected in to a flat ligule and extended over an inferiorly placed gynoecium as a hood. There are two floral types related to androecium structures – radially symmetrical actinomorphic and bilaterally symmetrical zygomorphic. The androecium characters are highly genera specific. For actinomorphic flowers the basal androecium is fused and the stamens are free. In the zygomorphic flowers, either the prominent hood stays open keeping a distance from the ovarian summit or remain closed and tightly encircling the ovaries. The genus Lecythis belongs to the later category. The pollens are identical and without nectars for actinomorphic species, and specialized or fodder pollen with nectars are seen in zygomorphic hood areas.
The pollen colour is highly characteristic of Lecythis species; for e.g. fodder pollens of L. pisonis in the hood region turn black within a day but in the staminal ring they remain yellow. Herbarium identification is difficult because flower parts get carbonated and distorted. Seed dispersal is another criterion to differentiate the genera in the Lecythidaceae family. Lecythis species for e.g. lack well organized cotyledons or any other dispersal appendages. Lecythis are mostly small to large trees with species specific characteristics of the basal trunk. L. pisonis exhibit swollen trunks while the other species are cylindrical throughout the length. The colour of the bark is another feature and most Lecythis species have bright yellow inner bark.
Montagnini and co-workers worked on ecological aspects and found that among many forest species tested, L. pisonis enhanced soil fertility by increasing the soil pH and basic cations and moderately supporting overall biomass of litter and soil nitrogen and phosphorus contents (841-856). In another report from Denadai and co-workers on L. pisonis, the high nutritive value of the seeds was advocated from the fact the oil was found rich in unsaturated fatty acids and certain minerals, especially Cu and Mn and to some extent K, and, moreover, the seed proteins were highly digestible with surplus essential amino acids (538).
Considering the importance and diversity of L. pisonis and relatively less information on the nutritional value of the seeds collected from different locations, the present paper was envisaged to provide data on characterization of the seed oil in plants collected from four locations, in particular the lipid, and overall and individual fatty acid composition, and cation abundance in relation to health impetus. It was expected that due to soil and climatic differences of locations, the aforementioned parameters may vary, and consequently some analogy can be established between the soil conditions and seed chemistry.
Data Analysis
In the paper of Vallilo and co-workers, L. pisonis Camb. Nuts were collected from Tupi (T), Santa Rita do Passa Quatro (STdPQ), Piracicaba (P) and Nova Europa (NE) regions in São Paulo State (197-200). The approach was to extract and quantify the overall and individual fatty acids (Palmitic acid and Stearic acid as saturated and Oleic acid and Linoleic acid as unsaturated) and associated indexes (percentage saturated and unsaturated acids, iodine value, refractive index and acid value). The quantities of Ca, Mg, P, Mn, Sn, Cu, Zn, As, Cd and Pb were also measured. Typically, seeds were sorted from five plants at each location and lipids were extracted by the hot Soxhlet or cold Stansby method. The free fatty acids were derivatized to their methyl esters, and were separated on a gas chromatograph for identification and quantification using the reference fatty acid methyl esters. Their refractive index at 40oC, acid values and iodine values, which determine the proportion of unsaturated fatty acids, were also determined by standard methods. The macro- and micronutrient contents in acid digested and peroxide treated samples were determined by Atomic Emission Spectrometry using metal standards. The appropriate replicate analysis and statistical treatments were included in the analysis. The values were tabulated and the mean and standard deviations are presented.
I am presenting Table 3 in order to explain the fatty acid composition of the seeds. The highest lipid content of 61%, close to recommended nutritive level, was found in samples of NE. While the total and individual saturated fatty acid content did not vary much from the other samples, despite high Oleic acid, the Linoleic acid and overall unsaturated fatty acid level and iodine number in NE samples remained low. The proportion of Linoleic acid to Oleic acid for the other samples was opposite, i.e. towards higher side, and correspondingly the iodine values were also higher than the NE samples. The seeds obtained from STdPQ exhibited the maximum iodine value indicating the highest fatty acid unsaturation index, presumably due to the high Linoleic acid component. Strikingly, the composition of saturated fatty acids, in particular the Palmitic acid, was also quite high in these samples. Notwithstanding, the maximum content of unsaturated fatty acids came from P samples.
There was not much variation in the refractive indexes of the samples except in the P sample, where low Palmitic acid contributed to slight decrease in refractive index. There was significant variation in acid values within the samples, and T and NE samples presented considerably higher values than the other two. These values were above the edible vegetable oils, indicating somewhat higher acid content.
The authors clearly indicated that high unsaturation of fatty acids, especially the essential fatty acid Linoleic acid, and high lipid content in the seed samples collected from the P locale is the most suitable for edible purposes. However, here authors have also apprehended that high acid value and divalent cations like Zn and Mn often found in L. pisonis Camb. may lead to uncontrolled oxidation of unsaturated fatty acids and this may generate erroneous results. Besides, two different methods of lipid extraction (hot and cold) may also give improper results. Within these experimental limitations, the authors concluded that lipid content and fatty acid unsaturation suggest high nutritive values of L. pisonis Camb. The other parameters like values and refractive indexes were equivalent to corn or peanut oil standards.
Collectively, it was concluded that L. pisonis Camb. exhibits better nutritive properties than most vegetable or seed-based oils. Notwithstanding, high content of toxicants Pb and Cu as also the micronutrients Zn and Mn above the recommended values in T samples, and high acidity in some samples may be a concern for applicability of L. pisonis Camb. for edible purposes.
Conclusion
Consistent to other findings, L. pisonis Camb. seeds display higher unsaturation of fatty acids though lower lipid content than most common edible vegetative oils. The chemodiversity of the species is apparent from a limited survey, and diverse region, especially the Lower Amazon and Western Atlantic coast of Brazil, needs to be explored for a more suitable population of L. pisonis Camb. to be used for edible purpose.
So far as the question of applicability of L. pisonis Camb. for biodiesel production is concerned, it should be noted that free fatty acid content is high, lipid content is low, and the metal content is high, and this may affect the trans-esterification reaction, necessary as the first step in production. Such seeds should be promoted for edible purposes and as food supplements only, rather than for exploitation for biofuel production.
Table
Lipid content and main fatty acid composition of L. pisonis nuts from various regions of São Paulo State expressed in P/P (%) in methyl esters:
Bibliography
Denadai, Sandra Maria Silveira, “In vitro digestibility of globulins from sapucaia (Lecythis pisonis Camb.) nuts by mammalian digestive proteinases.” Ciência e Tecnologia de Alimentos 27.3 (2007): 535-543.
Montagnini, Florencia, Anna Fanzeres, and Sergio Guimaraes Da Vinha, “The potentials of 20 indigenous tree species for soil rehabilitation in the Atlantic forest region of Bahia, Brazil.” Journal of Applied Ecology 32 (1995): 841-856.
Mori, Scott A., and Ghillean T. Prance, “” A guide to collecting Lecythidaceae. “ Annals of the Missouri Botanical Garden 74 (1987): 321-330.
Vallilo, M.I., et al. “Lecythis pisonis Camb. nuts: oil characterization, fatty acids and minerals.” Food Chemistry 66 (1999): 197-200.