J. Sci.Fd Agric. 1978, 29, 737-738
The Component Fatty Acids of Psidium guajava Seed Fats Fred Idiem’ Opute Department of Biological Sciences, University of Benin, Benin City, Nigeria (Manuscript received 13 October 1976)
The seed fat of Psidium guujavu has been analysed by thin-layer and gas-liquid chromatographic methods. The lipids, made up exclusively of neutral lipids, mostly triglycerides, accounted for 9.4% of the dry weight of the seeds. G.1.c. revealed that the seed fat is linoleic acid-rich (79 %); palmitic, oleic and stearic acids being the other minor acids present. There are neither percentage nor compositional differences in the fatty acids at different stages of development of the seeds. 1. Introduction
Psidium guajava, originally derived from tropical America, is commonly found growing in villages and towns in most parts of West Africa. The fruit, a globular or pear-shaped berry contains numerous small seeds (2-3 mm in diameter and length) embedded in the white or pink edible flesh. The fruit which is an excellent source of vitamins A and C, iron, calcium and phosphorus is eaten fresh or made into guava jelly. ‘Guava juice’ is also extracted from the fruit and is sold commercially as a beverage. The seeds hitherto have been discarded as serving no useful purpose. Like cotton seeds,l the seeds of Psidium guujuva have been shown to be rich in fat c ~ n t e n t . ~This - ~ short communication which is a reinvestigation of the subject, uses the modern sensitive tools of thin-layer and gasliquid chromatography which in the past decade have contributed in no small measure to our understanding of the chemical nature of lipids and fatty acids synthesised by plants.
2. Experimental The seeds of P. guujuvu used in this study were either bought (ripe fruits) locally from the market or plucked (immature fruits) from the trees. Seeds were removed quantitatively from the flesh and sun-dried. The seeds were ground to a fine powder and extracted for total lipids using a cold mixture of chloroform-methanol (2: 1, v/v). Thin-layer chromatography was carried out on 250 nm prekotes with silica gel HF as adsorbent and developed with petroleum ether-ether-formic acid (70: 30: 1, v/v/v) as solvent system. Lipids were transmethylated according to the methods of Feldman, Johnson, Culp and G ~ w a n The . ~ fatty acid methyl esters were analysed by g.1.c. as described previously.6
3. Results and discussion The lipid weight of 9.4% (dry weight) found in this study is comparable with 10.1 % reported by Subrahmanyam and Achaya.3 T.1.c. of the lipid extract showed no presence of polar lipids (phospholipids, sulpholipids and glycolipids) but instead was made up mainly of fats (triglycerides) with traces of phytosterols. G.1.c. analysis of the fatty acids of the ripe seed fat revealed that linoleic acid predominated (79.1 %). Palmitic acid (9.7%), oleic acid (7.8%) and stearic acid (3.4%)completed the fatty acid spectrum (Table 1). The results obtained here show that P . guujuvu seed fat is linoleic acid-rich in contrast with the findings of Varma et ul. and Subrahmanyam and Achaya, that Psidium seed fat is oleic acid-rich 0022-5142/78/0800737 $02.00
01978 Society of Chemical Industry 137
F. I. Opute
738 Table 1. Psidium guujuvu oil characteristics
Present work
% Fat in seed Iodine value Sap. equiv. of fat Fatty acid Composition (% weight) Myristic Palmitic Stearic Oleic Linoleic Linolenic
9.4
-
t
9.7 3.4 7.8 79.1
-
Subrahmanyam and Achayo
10.1 98.7 291.3
1.2 8.9 4.8 53.9 29.2 1.1
Varma, Godble and Srivastava
96.4 282.4
Kafuku, Hata and Fujikawa
140.7 292.1
16.0 55.8 27.8 0.4
(Table I). These authors found oleic acid to account for 55.8 and 53.9% and linoleic acid 27.8 and 29.2% respectively of their total fatty acid composition. The differences in these results could be due either to the technique employed (lead salt separation method followed by ester fractionation) or the geographical location which could account for differences in chemical composition of the same plant species. This fact has been widely shown by Hilditch and Williams7 for the fats of many plants. Kafuku, Hata and Fujikawa,* working with a Japanese strain of P. guajava reported an iodine value of 140 for the seed oil as against 96-98.7 found for the Indian straim2,3 The iodine value reported by the Japanese workers, which is an indication of higher unsaturation, supports the findings in this study. So far only very few species of plants, Chaetacme microcarpa,s Cordyline australis, C. banksii, C. indivisu, C. Kaspar and Phormidium colensig possess fats with higher contents of linoleic acid than has been found for P. guujuvu. Lipid extracts made from seeds of 3- and 6-month-old immature fruits showed no significant variation in the fatty acid composition with age. The fatty acid pattern is thus established in the early stages of seed formation. In the past, difficulties of seed collection, mainly occasioned by scattered plant growth had rendered impracticable the utilisation of many otherwise useful minor seed fats. In the case of P. guajava, this difficulty is now largely overcomewith the growth of trees in orchards. In the commercial production of juice from the fruits, a reasonable quantity of seeds is produced. These seeds which were previously discarded could be usefully employed either in the production of linoleic acid or as a supplement in animal feeds.
References 1. 2. 3.
4. 5. 6. 7. 8. 9.
Jamieson, G . S . ; Baughman, W. F. J . Am. chem. Suc. 1920,42, 1197. Varma, P. S.; Godble, N. N.; Srivastava, P. D. Fettchem. Umsch. 1936, 43, 8. Subrahmanyam, V. V. R.; Achaya, K. T. J. Sci. Fd Agric. 1957, 8, 657. Kafuku, K.; Hata, C.; Fujikawa, M. J. Chem Soc. Jupnn 1934, 55, 369. Feldman, G. L.; Johnson, H. T.; Culp, T. W.; Gowan, R. H . Poulfry Science 1962, 41, 418. Opute, F. I. Phytochemistry 1975, 14, 1023. Hilditch, T. P.; Williams, P. N. The Chemicnl Composition of Natural Furs 4th edn, Chapman and Hall, London, 1964. Grindley, D. N. J. SOC.Chem. Ind. (London) 1948, 67,230. Morice, I. M. J. Sci. Fd Agric. 1962, 13, 666.
The Component Fatty Acids of Psidium guajava Seed Fats Fred Idiem’ Opute Department of Biological Sciences, University of Benin, Benin City, Nigeria (Manuscript received 13 October 1976)
The seed fat of Psidium guujavu has been analysed by thin-layer and gas-liquid chromatographic methods. The lipids, made up exclusively of neutral lipids, mostly triglycerides, accounted for 9.4% of the dry weight of the seeds. G.1.c. revealed that the seed fat is linoleic acid-rich (79 %); palmitic, oleic and stearic acids being the other minor acids present. There are neither percentage nor compositional differences in the fatty acids at different stages of development of the seeds. 1. Introduction
Psidium guajava, originally derived from tropical America, is commonly found growing in villages and towns in most parts of West Africa. The fruit, a globular or pear-shaped berry contains numerous small seeds (2-3 mm in diameter and length) embedded in the white or pink edible flesh. The fruit which is an excellent source of vitamins A and C, iron, calcium and phosphorus is eaten fresh or made into guava jelly. ‘Guava juice’ is also extracted from the fruit and is sold commercially as a beverage. The seeds hitherto have been discarded as serving no useful purpose. Like cotton seeds,l the seeds of Psidium guujuva have been shown to be rich in fat c ~ n t e n t . ~This - ~ short communication which is a reinvestigation of the subject, uses the modern sensitive tools of thin-layer and gasliquid chromatography which in the past decade have contributed in no small measure to our understanding of the chemical nature of lipids and fatty acids synthesised by plants.
2. Experimental The seeds of P. guujuvu used in this study were either bought (ripe fruits) locally from the market or plucked (immature fruits) from the trees. Seeds were removed quantitatively from the flesh and sun-dried. The seeds were ground to a fine powder and extracted for total lipids using a cold mixture of chloroform-methanol (2: 1, v/v). Thin-layer chromatography was carried out on 250 nm prekotes with silica gel HF as adsorbent and developed with petroleum ether-ether-formic acid (70: 30: 1, v/v/v) as solvent system. Lipids were transmethylated according to the methods of Feldman, Johnson, Culp and G ~ w a n The . ~ fatty acid methyl esters were analysed by g.1.c. as described previously.6
3. Results and discussion The lipid weight of 9.4% (dry weight) found in this study is comparable with 10.1 % reported by Subrahmanyam and Achaya.3 T.1.c. of the lipid extract showed no presence of polar lipids (phospholipids, sulpholipids and glycolipids) but instead was made up mainly of fats (triglycerides) with traces of phytosterols. G.1.c. analysis of the fatty acids of the ripe seed fat revealed that linoleic acid predominated (79.1 %). Palmitic acid (9.7%), oleic acid (7.8%) and stearic acid (3.4%)completed the fatty acid spectrum (Table 1). The results obtained here show that P . guujuvu seed fat is linoleic acid-rich in contrast with the findings of Varma et ul. and Subrahmanyam and Achaya, that Psidium seed fat is oleic acid-rich 0022-5142/78/0800737 $02.00
01978 Society of Chemical Industry 137
F. I. Opute
738 Table 1. Psidium guujuvu oil characteristics
Present work
% Fat in seed Iodine value Sap. equiv. of fat Fatty acid Composition (% weight) Myristic Palmitic Stearic Oleic Linoleic Linolenic
9.4
-
t
9.7 3.4 7.8 79.1
-
Subrahmanyam and Achayo
10.1 98.7 291.3
1.2 8.9 4.8 53.9 29.2 1.1
Varma, Godble and Srivastava
96.4 282.4
Kafuku, Hata and Fujikawa
140.7 292.1
16.0 55.8 27.8 0.4
(Table I). These authors found oleic acid to account for 55.8 and 53.9% and linoleic acid 27.8 and 29.2% respectively of their total fatty acid composition. The differences in these results could be due either to the technique employed (lead salt separation method followed by ester fractionation) or the geographical location which could account for differences in chemical composition of the same plant species. This fact has been widely shown by Hilditch and Williams7 for the fats of many plants. Kafuku, Hata and Fujikawa,* working with a Japanese strain of P. guajava reported an iodine value of 140 for the seed oil as against 96-98.7 found for the Indian straim2,3 The iodine value reported by the Japanese workers, which is an indication of higher unsaturation, supports the findings in this study. So far only very few species of plants, Chaetacme microcarpa,s Cordyline australis, C. banksii, C. indivisu, C. Kaspar and Phormidium colensig possess fats with higher contents of linoleic acid than has been found for P. guujuvu. Lipid extracts made from seeds of 3- and 6-month-old immature fruits showed no significant variation in the fatty acid composition with age. The fatty acid pattern is thus established in the early stages of seed formation. In the past, difficulties of seed collection, mainly occasioned by scattered plant growth had rendered impracticable the utilisation of many otherwise useful minor seed fats. In the case of P. guajava, this difficulty is now largely overcomewith the growth of trees in orchards. In the commercial production of juice from the fruits, a reasonable quantity of seeds is produced. These seeds which were previously discarded could be usefully employed either in the production of linoleic acid or as a supplement in animal feeds.
References 1. 2. 3.
4. 5. 6. 7. 8. 9.
Jamieson, G . S . ; Baughman, W. F. J . Am. chem. Suc. 1920,42, 1197. Varma, P. S.; Godble, N. N.; Srivastava, P. D. Fettchem. Umsch. 1936, 43, 8. Subrahmanyam, V. V. R.; Achaya, K. T. J. Sci. Fd Agric. 1957, 8, 657. Kafuku, K.; Hata, C.; Fujikawa, M. J. Chem Soc. Jupnn 1934, 55, 369. Feldman, G. L.; Johnson, H. T.; Culp, T. W.; Gowan, R. H . Poulfry Science 1962, 41, 418. Opute, F. I. Phytochemistry 1975, 14, 1023. Hilditch, T. P.; Williams, P. N. The Chemicnl Composition of Natural Furs 4th edn, Chapman and Hall, London, 1964. Grindley, D. N. J. SOC.Chem. Ind. (London) 1948, 67,230. Morice, I. M. J. Sci. Fd Agric. 1962, 13, 666.
