Pertanika 10(3), 277-282 (1987) The Physico-chemical Changes in Ciku (Achras sapota L.) of Jantung Variety MOHAMAD NORDIN BIN ABDUL KARIM, SAPII AHMAD TARMIZI l and ABDULLAH ABU BAKAR 2 Department of Food Science, Faculty of Food Science and Biotechnology, Universiti Pertanian Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia. Key words: Ciku; sapota; physico-chemical changes; respiration; maturity. ABSTRAK Ciku jenis jantung mencapai kematangan enam bulan selepas masa pembentukan buah. Berat, panjang, garispusat dan isipadu buah meningkat sehingga dituai. Kadar peningkatan sangat perlahan iaitu di antara enam dan tujuh bulan. Kadar tumbesaran yang perlahan adalah sejajar dengan perubahan warna isi buah dan biji. Kekerasan buah berkurangan semasa hampir matang. Kandungan kelembapan dan tanin mencapai tahap maksimum apabila buah berada di dalam bulan kelima dan keenam, Pada masa yang sama, jumlah keasidan tertitrat mula menurun dengan perlahan. Jumlah pepejal larut, jumlah gula dan gula penurunan meningkat di sepanjang masa tumbesaran buah. Peningkatan pesat berlaku dalam bulan ketujuh dan kelapan. Corak pernafasan buah ciku didapati sama dengan buah-buahan klimaterik. Buah yang dituai selepas enam bulan mempunyai kadar pernafasan yang rendah. Ukuran panjang dan garispusat amatlah dipengaruhi oleh faktor umur dan boleh digunakan sebagaisatu petunjuk kematangan. ABSTRACT Ciku of jantung variety attains maturity after six months from fruit set. The weight, length, width and volume of the fruit increases until harvest but slows between six to seven months. The slow rate of growth coincides with the colour changes of the pulp and pip. The firmness of the fruit decreases towards maturity. Moisture and tannin content reach maximum level between the fifth and the six month. At the same time, total titratable acidity starts to decrease gradually. Total soluble solid, total sugar and reducing sugar increase throughout fruit development, being particularly rapid between the seventh and eighth month. Starch- content decreases as growth increases. Respiratory pattern of ciku is similar to that of a climat eric fruit. Fruit harvested after six months have a low rate of respiration. The length of width of the fruit are greatly influenced by age and can be used as an index of maturity. INTRODUCTION Ciku (Achras sapota L.) is a popular fruit in Malaysia. Total acrage planted with this tree increased from 443 hectares in 1976 to 863 hectares in 1981 (Kementerian Pertanian, 1981). The quality of ciku is influenced by several factors such as its maturity when harvested and post-harvest treatments including transportation and storage (Lakshminarayana, 1980). The stage of maturity of the fruit affects flavour, Fruit Research Division, MARDI, 43400 Serdang, Selangor Darul Ehsan, Malaysia. 2 Department of Food Technology, UPM.
MOHAMAD NORDIN BIN ABDUL-KARIM, SAPII AHMAD TARMIZI AND ABDULLAH ABU BAKAR aroma and storage quality which collectively affect its commercial value. There is no published data on the suitable maturity stage for the harvesting of the sapota variety in Malaysia. Such information that is available is of the Indian varieties only. (Lakshminarayana and Subramanyam, 1966; Sastry, 1970). The objective of this study was to observe the physical and chemical changes during development and growth of ciku. In this study, the growth pattern of the fruit was followed through to enable prediction for suitable maturity stage for harvesting. MATERIALS AND METHODS Four ciku trees of jantung variety at the Experimental Farm, Universiti Pertanian Malaysia were adopted for this study. Nearly 700 blossoms were tagged between April and September 1983. The tagged fruits were randomly collected at age three to eight months for analysis. Ten fruits of every developmental stage were studied for weight, length, width, volume and firmness. Weight was obtained using an electrical balance. Size was measured using a vernier calipher whilst volume through the water displacement method. Firmness was determined using Instron Universal Testing Machine, Model 1140 with a nine mm Magnus Taylor probe. The drive and chart speed were at 100mm per min. The same fruits used for weight, volume, length, width and firmness determination were then pooled and homogenized for chemical analysis. Moisture, total soluble solid and titratable acidity were measured according to AOAC methods (AOAC, 1975). Starch and total sugar content were measured by Somogyi-Nelson colorimetric method (Southgate, 1976) using alcohol extraction (AOAC, 1965). Total tannin was determined spectrophotometrically (Price and Butler, 1977). The rate of respiration of ciku was measured after a four hour stabilization period in a respiratory chamber at 20 + l C using the colorimetric method (Claypool and Reefer, 1942). In cases where the fruit was considered large, only two fruits were used for the respiration study. A large sample (up to ten) was adopted for smaller and younger fruits. Changes in colour of the skin, pulp and pips of the fruit, at different developmental stages, were observed visually. Regression analysis was carried out to determine the correlation coefficient (r) among weight, volume, length, width and firmness according to the method described by Steel and Torrie (1960). The coefficient of determination (T 2 ) between the physical characteristics and age was also determined. RESULTS AND DISCUSSION The changes in the physical characteristics of ciku is shown in Table 1. Increases in weight, volume, length and width were rapid at the earlier stage of growth ie. until the sixth month. Growth slowed down from six to seven months TABLE 1 Changes in the physical characteristics of ciku Age month Weight g Volume cm 5 Length cm Width cm Firmness kg force 3.0 1.34±0.27 1.30±0.27 1.22±0.10 1.41 ±0.15 n.d. 3.9 7.88±2.39 7.30 ±2.80 2.56±0.27 2.37 ±0.27 21.08 ±2.23 4.6 19.23 ±4.95 18.75 ±6.09 3.64±0.38 3.14 ±0.25 25.30 ±1.55 5.3 23.25 ±5.30 22.00 ±4.20 3.88±0.19 3.35 ±0.37 20.85 ±2.42 6.0 44.16± 10.70 42.94 ±10.29 4.72 ±0.66 4.12±0.35 20.25 ±3.80 6.9 47.72 ±7.58 46.87 ±6.09 4.97 ±0.42 4.18±0.21 17.21 ±3.00 7.6 101.52±22.00 98.33 ±23.17 6.49 ±0.43 5.37 ±0.52 13.40 ±2.07 n.d. Not determined 278 PERTANIKA VOL. 10 NO. 3, 1987
THE PHYSICO-CHEMICAL CHANGES IN CIKU (ACHRAS SAPOTA L.) OF JANTUNG VARIETY after which the increase was rapid again. The slow stage of growth at six to seven months was due to the embryo having reached maximum developmental state; the increase in growth observed after this period was due to the enlargement of the cells and the extracellular space (Bollard, 1970). The firmness of the fruit progressed with age reaching a maximum level at 4.6 months and decreased as the fruit became older. Rapid decrease in the firmness was observed after the sixth month. This is due to the breakdown of polymeric carbohydrates, especially pectic substances and hemicelluloses (Wills et al., 1981). Table 2 shows the correlation coefficient (r) amongst the physical characteristics of ciku. The weight, volume, length, width and firmness are correlated with each other especially between weight and volume (r = 0.99) and that of length and width (r = 0.99). Firmness exhibited negative correlation with the rest of the parameters studied. Coefficient of determination (r z ) shows that length and width (r 2 = 0.99 respectively) are the better indicators of the age of the fruit rather than weight and volume (r 2 = 0.84 respectively). Firmness of the fruit is a poor indicator of the fruit development (r 2 = 0.73) because texture of fruit obtained from different areas, seasons and years was known to vary considerably (Harman and Hewett, 1981). The changes in chemical characteristics of ciku is shown in Table 3. Moisture content of the fruit increased with age reaching maximum level at 5.3 months. This was followed by a gradual decrease in the moisture content. Lakshminarayana et al. (1969), reported that the moisture content of sapota reached maximum level at the sixth month and decreased a little at TABLE 2 Correlation coefficient (r) amongst the physical characteristics of ciku Weight Volume Length Width Firmness Weight Volume Length Width Firmness 0.99-0.96 0.97 0.96 0.97 0.99-0.86-0.86-0.80-0.80 TABLE 3 Changes in selected chemical characteristics of ciku Age month Moisture % Total soluble solid Brix Titratable acidity mlo.ln NaOH Total tannin mg catechin/loog 3.0 3.9 4.6 5.3 6.0 6.9 7.6 58.06 70.12 72.87 75.55 75.09 73.83 72.65 n.d. 5.0 8.0 8.0 10.0 12.0 18.0 2.10 6.25 4.23 3.63 2.25 2.12 2.00 1.98 3.93 5.58 7.16 3.22 2.14 1.07 n.d.: not determined PERTANIKA VOL. 10 NO. 3, 1987 279
MOHAMAD NORDIN BIN ABDUL KARIM, SAPII AHMAD TARMIZI AND ABDULLAH ABU BAKAR seven to eight months. a The pattern in the changes of titratable acidity was similar to that of moisture content. Maximum level was reached at 3.9 months. A, rapid decrease in the value was observed from 3.9 to 6 months after which the fall was gradual. Ingle et al. (1981) also found the acidity of u sapota to decrease as the fruit got older. Total soluble solid content of ciku increased with age reaching maximum level (18 Brix) at J* 7.6 months. This observation was consistent with the results obtained by other researchers who. noted that total soluble solid content of mature sapota reached values between 13 and 25 "Brix, depending on variety and area where the trees ( were grown (Lakshminarayana and Subramanyam, 1966; Shanmugavelu and Srinivasan, 1973). The tannin content of the fruit increased as the fruit developed reaching a maximum level at 5.3 months. The level of tannin decreased thereafter untir the fruit was harvested. A similar trend in the changes of tannin content was observed by other researchers (Lakshminarayana Fig. 1: Ag«(mmnff» > The changes in starch content (O), total and Mathews, 1967; Lakshminarayana et al., 1969). Changes in the starch, total sugar and reducing sugar of ciku is shown in Figure 1. Starch content decreased as the fruit developed. Mature sapota contained a small amount of starch (Lakshminarayana and Moreno-Rivers, 1979). Total sugar and reducing sugar, on the _c sugar (*) and reducing sugar (&) of ciku other hand, increased with age. The rise was j? gradual until 6.9 months when the change was g* rapid. A great increase in reducing sugar was "g 1t0 mostly due to glucose and fructose (Lakshmi- 0 narayana, 1980). As maturity increased, the 2 sucrose content decreased due to its reduction to glucose and fructose (Lakshminarayana and Subramanyam, 1966). Rate of respiration increased with age of the fruit, reaching maximum level at 4.4 months (Figure 2). This was followed by a rapid decrease which then stabilized after 6.2 months. The pattern of respiration follows that of climateric fruits. A similar observation was also made by Broughton and Wong (1979). Table 4 shows the changes in the colour of J 2 'a 'he skin, pulp and pip of the ciku. Eventhough Fig. 2. the skin was still greenish at six months, 60% of 280 PERTANIKA VOL. 10 NO. 3, 1987 1J0 Ag«(month) Respiration rate of ciku at different stages of development
THE PHYSICO-CHEMICAL CHANGES IN CIKU {ACHRAS SAPOTA L.) OF JANTUNG VARIETY TABLE 4 Changes in the skin, pulp and pip of ciku Age month Colour of skin when scratched Colour of pulp Colour and texture of pip 3.9 dark green yellowish white and soft 4.6 dark green yellowish white and soft 5.3 dark green yellowish white and soft 6.0 6.9 7.6 light green light green yellowish green yellowish-brown slightly brownish brownish partly white and black; slightly hard black and hard black and hard the pip was already black and slightly hard in texture. The pulp at this time had already turned yellowish brown. Comparatively, the pulp was yellowish with white and soft pip at 5.3 months. At 6.9 months, the pulp was brownish and the seeds were hard and dark. Lakshminarayana (1980) observed that mature sapota had soft pulp, brownish or red in colour with a dark slimy pip. CONCLUSION The observations made showed that ciku of jantung variety attains physiological maturity after six months. However, ciku harvested after seven months was bigger and sweeter. Lakshminarayana and Subramanyam (1966) and Sastry (1970) reported that sapota matured at eight and four months respectively. The differences observed were due to variety, climate and soil conditions. Sporadic flowering and fruiting behaviour of this plant and the height attainable by older trees make harvesting a problem. Therefore, it is possible to utilise the length or/ and width of the fruit to design a suitable gadget for successful harvesting. ACKNOWLEDGEMENTS This study was made possible by a research grant from Universiti Pertanian Malaysia No. 1718 1-488. REFERENCE AOAC (1965): Official method of analysis. 10th edition. Washington DC: The Association of Official Agricultural Chemists. AOAC. (1975): Official method of analysis. 12th edition. Washington DC: The Association of Official Analytical Chemists. BOLLARD, E.C. (1970): Physiology and nutrition of developing fruit. Hulme, A.C., ed. The biochemistry of fruits and their product. Vol. 1. London: Academic Press, 387-425. BROUGHTON, W.J. and H.G. WONG. (1979): Storage conditions and ripening of ciku (Achras sapota L.). Scientia Hortic. 10: 377-385. CLAYPOOL. L.L. and R.M. KEEFER. (!942): A colorimetric method for CO determination in respiration studies. Proc. of the Amer. Soc. for Hortic. ScL 40:177-186. HARMAN, J.F. and E.W. HEWETT. (1981): Maturity and storage of kiwi fruit. Proceedings of postharvest and horticulture workshop. Sydney: Standing Committee on Agriculture, Horticulture & Post harvest 74-84. INGLE, C.S., D.M. KHEDKAR and R.S. DABHADE. (1981): Ripening studies in sapota fruit (Achras sapota L.). Ind. Food Packer. 35: 42-45. KEMENTERIAN PERTANIAN. (1981): Keluasan pelbagai tanaman di Semenanjung Malaysia. Kuala Lumpur: Government Printer. LAKSHMINARAYANA, S. and H. SUBRAMANYAM. (1966): Physical, chemical and physiocological changes in sapota fruit (Achras sapota L.) during development and ripening./. Food Sci. TechnoL 31:151-154. LAKSHMINARAYANA, S. and A.G. MATHEW. (1967): Leucoanthocyanidins of sapota fruit. J. Food Sci. 32:451-45. LAKSHMINARAYANA, S., A.G. MATHEW and H.A.B. PARPIA. (1969): Changes in polyphenols of sapota fruit (Achras sapota L.) during maturation. /. Sci. Food Agric. 92: 303-305. PERTANIKA VOL. 10 NO. 3, 1987 281
MOHAMAD NORDIN BIN ABDUL-KARIM, SAPII AHMAD TARMIZI AND ABDULLAH ABU BAKAR LAKSHMINARAYANA, S. and M.A. MORENO-RIVERS (1979): Proximate characteristics and composition of sapodilla fruits grown in Mexico. Proc. Florida State Hortic. Soc. 92: 303-305. LAKSHMINARAYANA, S. (1980): Sapodilla and prickly pear. Nagy, S. & Shaw, P.E., (eds.) Tropical and subtropical fruits. Composition, properties and uses. Westport, CT: AVI: 415-441. PRICE, M.L. and L.G. BUTLER. (1977): Rapid visual estimation and spectrophotometric determination of tannin content in sorghum grain. J. Agric. Food Chem. 25: 1268-1273. SASTRY. M.V. (1970): Biochemical studies in the physiology of sapota IV. Ripening and storage studies, Ind. Food Packer: 24-26. SHANMUGAVELU, K.G. and G. SRINIVASAN. (1973): Proximate composition of fruit of sapota cultivar (Achras sapota L.)- South Ind. Hortic. 21: 107-108. SOUTHGATE, D.A.T. (1976): Determination of food carbohydrate. London: Applied Science Publishers, STEEL, R.G.D. and J.H. TORRIE. (1960): Principle and procedure of statistics. New York: Me Graw Hill Book Co. WILLS, R.B.H., T.H. LEE, D. GRAHAM, W.B. Me GLASSON and E.G. HALL. (1981): Post harvest: An introduction to the physiology and handling of fruit and vegetables. Kensington: New South Wales University Press Limited: 33-35. (Received 11 May, 1987) 282 PERTANIKA VOL. 10 NO. 3, 1987