J. Hortl. Sci. Vol. 12(2) : 124-132, 2017 Seasonal influence on volatile aroma constituents of two banana cultivars (Grand Naine and Nendran) under Kerala conditions K.S. Shivashankara*1, K.C. Pavithra1, G.A. Geetha1, T.K. Roy1, Prakash Patil2 and Rema Menon3 1Division of Plant Physiology and Biochemistry, ICAR-Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bengaluru - 560 089, Karnataka, India 2Project Coordinator (Fruits), ICAR-Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bengaluru - 560 089, Karnataka, India 3ICAR-AICRP (Fruits), Banana Research Station, Kerala Agricultural University, Marakkal, Thrissur - 680 652, Kerala, India *E-mail: shiva@iihr.res.in, shivaiihr@yahoo.com ABSTRACT Banana is a tropical fruit with a pleasant flavour, widely consumed throughout the world. Volatile aroma compounds are responsible for olfactory flavor of banana. However, the development of aroma flavors is affected by the atmospheric temperatures during fruit growth period. In order to get good quality fruits in terms of aroma it is essential to understand the optimum temperature for maximum aroma production. The approach used in this study was to alter the dates of harvest to understand the optimum temperature required for maximum production of volatile compounds under Kerala conditions. The results revealed that with increased temperature volatile aroma compounds decreased in cvs. Grand Naine and Nendran. Total volatile compounds were higher in cv. Grand Naine compared to cv. Nendran. Cultivar Nendran recorded increased concentrations of esters, alcohols and decreased aldehydes, ketones, hydrocarbons and acids at high temperatures. Phenols and other constituents did not show much variation with respect to the temperature variation in both the cultivars. Among esters, Isoamyl butanoate and 3-Methylbutyl-3-methylbutyrate esters were the most abundant in both the cultivars. Ketones, especially 4-Methyl-1-penten-3-one was higher in cv. Nendran whereas esters were lower compared to cv. Grand Naine. Total area of aroma constituents in cultivars Grand Naine and Nendran were high in October followed by February with mean atmospheric temperature of 30.5ºC and 32.6ºC respectively. In case of cv. Nendran, total area of esters and alcohols were maximum at high temperature (34.5ºC) but in cv. Grand Naine, esters and alcohols decreased with high temperature. Results indicated that fruits harvested in October were better in terms of volatile aroma quantity in both the cultivars due to lower atmospheric temperature. Seasonal variations affected the two cultivars differentially in terms of percentage of groups of volatile compounds. Key words: Banana, volatile compounds, atmospheric temperature, SPME, GC-MS INTRODUCTION Banana (Musa spp.) is one of the most widely distributed and consumed fruits in the world. It is grown extensively in tropical and subtropical regions and is an economically important fruit crop (Selli et al, 2012). The fruit aroma is one of the most important factors, which determines the consumer acceptability and the quality of bananas. More than 350 aroma compounds ha ve been identified in ba na na s. Most of the components a re ester s, alcohols, and ca rbonyl compounds (Berger, 1991). The biosynthetic pathways for production of aroma compounds involved β- oxidation, hydroxyacid cleavage (leading to lactones), and lipoxygenase to form aldehydes, ketones, acids, alcohols, lactones, and esters from lipids (Heath and Original Research Paper 124 125 Reineccius, 1986; Dixon and Hewett, 2000). Esters of acetate and butyrate have been reported to play an important role in the aroma of fully ripe banana fruit; however, isoamyl acetate and isobutyl acetate have generally been regarded as the key characteristic compound in the aroma of banana fruit (Marriot, 1980; El Hadi et al, 2013). Other researchers have also investigated a roma compounds of banana. T he concentrations of acetates and butanoates increased during ripening of banana fruit (Jayanty et al, 2002). In addition, isoamyl alcohol, isoamyl acetate, butyl acetate, and elemicine were detected by olfactometric analyses as characteristics of banana odor (Boudhrioua et al, 2003). Volatile esters, such as 3-methylbutyl- acetate and 2-methylbutyl-acetate, also contribute to the characteristic banana flavor of the fruits. Fatty acids are major precursors of aroma volatiles in most fruit (Sanz et al, 1997). Aroma volatiles are affected by abiotic factors such as temperature and humidity (Takabayashi et al, 1994; Gouinguene a nd Tur lings, 2002). High temperatures influence the biosynthesis of volatiles in banana fruit at the transcriptional level and confirm the findings that high temperatures cause stress in bana na fr uit dur ing ripening. In ba nana , high temperature resulted in elevated levels of ethanol, ethyl acetate and other acetate esters. Higher expression level of Ban BCAT was found in pulp which correlated well to volatile production in banana fruit, indicating the role of Ban BCAT in regulating the formation of branched aroma compounds during banana fruit ripening (Yang et al, 2011). Wills and McGlasson (1971) concluded that volatile concentrations increase as temperature increases, although production rate is reduced above 32°C. High temperature can cause a dramatic increase in the production of off-flavour aroma compounds during the storage of fruits (Liu and Yang, 2002; Petracek et al, 2002). T he main objective of this study was to investigate the effect of seasonal temperature during fruit growth period on the volatile aroma quality of banana fruits of cvs. Grand Naine and Nendran under Kerala conditions. MATERIAL AND METHODS Effect of seasonal temperature on volatile aroma constituents in banana varieties [cv. Grand Naine (GN), and Nendran] grown in Kerala region were studied. Fruit samples were collected at full maturity stage at quarterly intervals during the period October 2013 to February 2015 from Kerala region along with the data on temperature from shooting to harvest period (Table 1). Harvested fruits were ripened at room temperature. The room temperature during fruit ripening period was recorded and is given in Table 2. Volatile aroma constituents were analyzed in the Fruit Biochemistry laboratory of ICAR-IIHR, Bengaluru, by headspace-solid phase micro-extraction (HS- SPME) technique using capillary GC and GC-MS/MS. Seasonal influence on banana volatiles in Kerala Months of Harvest Region Varieties 2013-Oct 2014-Feb 2014-Jun 2014-Oct 2015-Feb Kerala Grand Naine 33.3 34.5 33.8 30.5 32.6 Nendran 33.3 34.5 33.8 30.5 32.6 Table 1. Mean maximum temperature (°C) from shooting to harvest period Table 2. Mean room temperature (°C) from harvest to ripe period Months of Harvest Region Varieties 2013-Oct 2014-Feb 2014-Jun 2014-Oct 2015-Feb Kerala Grand Naine 28.0 27.2 30.5 29.5 29.4 Nendran 28.0 27.2 30.5 29.5 30.0 J. Hortl. Sci. Vol. 12(2) : 124-132, 2017 126 Shivashankara et al SPME Extraction of Volatiles Earlier studies have reported the extraction and analysis of head space volatiles of banana fruits by using SPME fiber (Facundo et al, 2012; Pino and Febles, 2013). SPME fiber device coated with DVB/ CAR/PDMS (50/30 μm, highly crossed linked) was first conditioned at 250°C for 2 hours. The extraction process for head space volatiles from fresh banana fruit pulp was followed as described by (Facundo et al, 2013) with slight modification. A known quantity (50 g) of fresh cut ripe banana fruits was macerated to slurry by using a pre-chilled homogenizer, the slurry was transferred with 100 ml of double distilled water and 0.5 g of solid NaCl to the 250 mL flasks with silicon rubber caps. The flasks with slurry were kept on a magnetic stirrer after an incubation period of 20 minutes. The solid phase micro-extraction fibre was inserted into the flask through the silicon rubber stopper and was allowed to adsorb all the volatiles for 2 hrs with continuous stirring. Later the fibre was removed a nd injected into a ga s chroma togr a phy-ma ss spectrometry for separation and identification of compounds. Gas Chromatography and Gas Chromatography-Mass Spectrometry analysis Subsequently, The SPME device was injected into the injector port for GC analysis and was remained in the inlet for 15 min. The GC/MS analysis was carried out using a Varian-3800 Gas Chromatograph coupled to a Varian-4000 Ion-Trap mass spectrometer. The MS column VF-5MS (Factor four) (Varian, USA) fused- silica capillary column of 30 m x 0.25 mm id, 0.25 mm film thickness was used for the analysis. The injector temperature was set at 250ºC and all injections were made initially in split (1:20) mode for 0.5 min followed by split-less. The detector temperature was 270°C, and the temperature programmes for column was as follows: 40°C for 3 min at an increment 3°C/min to 190°C, hold for 1 min, then 5°C/min to 220°C and maintaining the constant temperature for 5 min. The mass spectrometer was operated in the external electron ionization mode with the carrier gas helium 1 ml/min; injector temperature, 250°C; trap temperature 180°C, ion source-heating at 190°C, transfer line temperature 260°C, EI-mode was 70 eV, with full scan-range 50-350 amu was used. The total volatile production was estimated by the sum of all GC peak areas in the chromatogram and individual compounds was quantified as relative percent area and the compounds were identified by comparing the retention index which was determined by using homologous series of n-alkanes (C5 to C32) as standard (Kovats, 1965) and comparing the spectra using two spectral libraries available as Wiley and NIST-2007. RESULTS AND DISCUSSION More than 50 major volatile compounds were identified in both the cultivars irrespective of the seasons (Table 3). The results revealed that with increased temperature, the quantity of volatile aroma compounds decreased in cvs. Grand Na ine and Nendran. Total area of aroma constituents in cultivars Grand Naine and Nendran were high in October month followed by Febr uar y with mea n a tmospher ic temperature of 30.5ºC and 32.6ºC respectively (Table 4). The various groups of aroma compounds found in banana cultivars were esters, alcohols, aldehydes, ketones, acids, phenols, hydrocarbons and few others (Table 3). J. Hortl. Sci. Vol. 12(2) : 124-132, 2017 Table 3. Volatile components identified in banana cvs. Grand Naine and Nendran by gas chromatography–mass spectrometry analysis 2013-October 2014-February 2014-June 2014-October 2015-February Volatile components KI Grand Grand Grand Grand Grand Naine Nendran Naine Nendran Naine Nendran Naine Nendran Naine Nendran (%)* (%) (%) (%) (%) (%) (%) (%) (%) (%) Esters Ethyl Acetate 614 0.17 0.52 0.07 0.68 0.18 0.51 0.18 0.22 0.04 0.22 Ethyl butanoate 799 0.06 - 0.08 - 0.06 - 0.11 - 0.14 - Methyl 2-propenoate 812 - 7.45 - 8.53 - 7.99 - 4.45 - 4.92 1-Butyl acetate 813 0.05 - 0.02 - 0.27 - 0.12 - 0.03 - 127 Seasonal influence on banana volatiles in Kerala J. Hortl. Sci. Vol. 12(2) : 124-132, 2017 2013-October 2014-February 2014-June 2014-October 2015-February Volatile components KI Grand Grand Grand Grand Grand Naine Nendran Naine Nendran Naine Nendran Naine Nendran Naine Nendran (%)* (%) (%) (%) (%) (%) (%) (%) (%) (%)3- Methyl-2-butenyl formate 867 - 0.12 - 0.26 - 0.22 - 0.32 - 0.13 Isoamyl acetate 876 0.09 0.05 0.09 0.24 0.04 0.07 0.13 4.54 0.04 0.92 Propyl butanoate 897 0.63 0.13 0.91 1.21 0.68 0.79 1.46 0.26 1.65 0.43 Propyl pivalate 899 0.29 2.82 0.12 3.80 0.11 3.52 0.03 0.83 0.08 0.74 Isopentyl acrylate 910 0.89 1.82 1.73 2.56 0.93 0.76 0.30 0.84 0.39 1.78 Propyl isovalerate 949 - 0.15 - 0.71 - 0.54 - 0.19 - 0.32 1-Butyl butyrate 994 1.22 0.55 2.94 1.62 1.27 0.51 1.14 0.40 0.06 1.06 2-Methylpropyl 3-methylbutyrate 1003 0.51 0.25 0.91 1.41 0.46 1.02 0.67 0.99 0.24 0.11 1-Butyl isovalerate 1010 0.92 0.84 1.96 1.39 0.80 0.76 0.54 0.76 0.15 0.78 Isoamylbutanoate 1056 20.39 9.64 23.02 9.57 22.60 8.47 18.71 5.03 18.90 5.74 1-Pentyl butyrate 1094 2.21 1.96 2.26 0.28 2.11 0.59 4.81 0.18 4.47 0.93 3-Methylbutyl 3-methylbutyrate 1094 17.74 10.34 18.02 8.97 16.98 9.20 11.58 2.12 10.57 3.75 iso-Amyl 2-methyl butyrate 1102 0.53 9.34 0.63 10.32 0.53 9.66 0.50 3.75 0.46 4.15 1-Methylbutyl pentanoate 1118 0.06 - 0.10 - 0.06 - 0.08 - 0.23 - Amyl valerate 1183 - 0.37 - 1.43 - 0.39 - 0.50 - 0.41 Butyl hexanoate 1186 1.03 0.50 0.16 0.15 0.95 0.76 1.22 0.06 0.38 0.34 Hexyl butyrate 1190 0.13 - 0.15 - 0.14 - 4.71 - 4.85 - Butyl sorbate 1199 0.12 0.36 0.06 0.80 0.13 0.41 0.40 0.19 0.14 0.05 Isopentylhexanoate 1208 0.77 - 0.44 - 0.02 - 0.01 - 0.01 - HeptyIisobutyrate 1218 1.79 0.15 0.83 0.53 1.80 0.13 1.63 0.12 3.32 0.12 cis-3-Hexenyl-α-methylbutyrate 1226 5.80 1.24 6.38 1.21 5.77 1.36 2.20 1.01 1.38 0.96 Cyclopentylpentanoate 1226 - 0.17 - 0.81 - 0.09 - 0.17 - 0.21 Hexyl 3-methylbutanoate 1245 5.56 1.80 5.99 1.37 5.81 1.37 2.03 0.83 1.18 0.28 Linalyl acetate 1256 0.12 0.35 0.02 0.38 0.10 0.16 0.13 0.16 0.27 0.17 4-Pentenyl hexanoate 1272 3.49 - 1.01 - 3.50 - 2.75 - 3.50 - Heptylbutanoate 1282 3.17 0.17 1.78 0.13 3.13 0.44 7.28 0.12 9.52 0.15 1-Cyclohexyl pentanoate 1345 0.78 - 0.51 - 0.88 - 0.10 - 0.21 - Isobutyl decanoate 1545 - 0.46 - 0.43 - 0.30 - 0.26 - 0.43 Ethyl dodecanoate 1597 - 0.53 - 0.67 - 0.34 - 0.26 - 0.72 Isoamyllaurate 1844 - 2.30 - 0.86 - 0.89 - 0.74 - 0.93 Acetic acid,1,4-dimethylpent-4 -enyl esters 0.17 0.20 0.36 0.94 0.14 0.17 0.62 0.37 0.23 0.34 n-Hexyl-trans-hexen-2-oate 0.16 0.34 0.01 0.41 0.15 0.48 0.01 0.37 0.04 0.29 Alcohols Hexynol 778 - 0.12 - 0.16 - 0.29 - 0.14 - 0.12 2,3-Dimethyl-1-pentanol 832 0.02 - 0.02 - 0.02 - 0.03 - 0.03 - 1-Hexanol 841 0.09 1.85 0.15 2.74 0.07 1.74 0.04 0.61 0.04 0.50 1-Methyl-2-cyclohexen-1-ol 913 - 0.63 - 0.78 - 0.84 - 0.18 - 0.21 (3E,6E)-3,6-Nonadien-1-ol 1175 - 0.38 - 0.24 - 0.25 - 0.47 - 0.82 Citronellol 1223 0.47 - 0.22 - 0.45 - 0.29 - 0.41 - 10-Undecyn-1-ol 1355 1.00 - 0.16 - 0.83 - 0.66 - 0.22 - (8E,10E)-8,10-Dodecadien-1-ol 1473 0.95 - 1.28 - 2.01 - 7.14 - 3.45 - 1-Dodecanol 1473 - 0.15 - 1.22 - 0.40 - 0.42 - 0.72 128 Shivashankara et al J. Hortl. Sci. Vol. 12(2) : 124-132, 2017 2013-October 2014-February 2014-June 2014-October 2015-February Volatile components KI Grand Grand Grand Grand Grand Naine Nendran Naine Nendran Naine Nendran Naine Nendran Naine Nendran (%)* (%) (%) (%) (%) (%) (%) (%) (%) (%)1- Tridecanol 1569 0.14 - 0.15 - 0.22 - 0.03 - 0.13 - (3Z,6Z)-Dodeca-3,6-dien-1-ol 0.46 - 0.17 - 0.44 - 0.95 - 0.65 - (E)-5-Decen-2-ol - 0.89 - 1.78 - 1.15 - 0.25 - 0.35 Aldehydes and Ketones 3-Methylbutanal 654 0.25 1.12 0.34 1.40 0.26 1.31 0.11 1.67 0.06 2.06 4-Methyl-1-penten-3-one 680 0.18 11.82 0.24 6.15 0.20 12.31 1.31 22.57 0.76 15.47 (E)-2-Hexenal 848 0.55 - 0.05 - 0.65 - 0.16 - 1.02 - 2-Heptanone 891 0.12 - 0.11 - 0.11 - 0.09 - 0.03 - Pulegone 1176 1.24 0.27 1.21 1.43 1.32 0.94 1.16 0.03 0.94 0.08 1-(3-Cyclohexen-1-yl)- 2,2-dimethyl-1-propanone 1212 0.84 0.07 0.67 0.04 0.86 0.06 1.45 1.57 1.48 1.14 6-Dodecanone 1350 - 0.15 - 1.45 - 1.54 - 2.20 - 1.80 Dodecanal 1409 0.44 - 0.33 - 0.44 - 0.33 - 0.29 - 7-Tridecanone 1449 0.41 0.24 0.02 0.27 0.13 0.51 0.02 1.15 0.16 1.54 trans-β-Ionone 1482 - 1.02 - 0.68 - 0.66 - 0.81 - 1.45 2-Tetradecanone 1597 - 0.80 - 0.53 - 1.01 - 2.20 - 2.42 (9Z)-9,17-Octadecadienal 1997 0.09 5.35 0.03 0.61 0.03 3.07 0.03 1.00 0.02 1.36 Acids 4-Butoxybutanoic acid 1249 0.53 0.41 0.47 0.17 0.47 0.30 0.43 0.45 0.45 1.72 8-Nonenoic acid 1262 2.14 0.34 1.37 0.54 1.77 0.55 5.41 0.54 5.03 1.09 Phenols Eugenol 1356 0.22 0.35 0.68 0.41 1.19 0.91 0.49 0.20 2.18 0.25 Hydrocarbons Decane 1015 0.02 2.97 0.02 2.30 0.04 3.29 0.05 6.19 0.01 6.29 cis-1,2-Dichlorocyclohexane 1052 0.99 0.66 0.25 0.40 0.28 0.21 0.54 0.30 0.75 0.12 (±)-Dictyopterene A 1076 1.41 - 1.11 - 1.08 - 3.76 - 3.61 - 3-Hexyl-1-cyclopentene 1140 0.54 - 0.60 - 0.58 - 0.69 - 1.04 - Naphthalene 1179 0.51 - 0.04 - 0.04 - 0.08 - 0.06 - Tetradecane 1214 - 0.80 - 2.43 - 2.19 - 1.53 - 1.07 (5E,7E)-5,7-Dodecadiene 1230 3.39 0.32 4.10 0.22 3.10 1.10 1.32 0.41 2.92 0.29 (2E,4Z)-2,4-Dodecadiene 1230 0.42 - 0.27 - 0.29 - 0.09 - 0.26 - (2Z)-2-Dodecen-4-yne 1239 0.36 - 0.33 - 0.18 - 0.05 - 0.90 - (3Z)-3-Tetradecen-5-yne 1438 1.00 - 1.05 - 0.98 - 0.28 - 0.99 - α-Selinene 1478 - 1.15 - 0.61 - 0.61 - 0.46 - 0.69 Pentadecane 1512 - 1.44 - 1.75 - 1.28 - 14.92 - 14.78 δ-Selinene 1532 - 0.79 - 0.78 - 0.69 - 0.90 - 1.27 C16 Hydrocarbon - 1.02 - 1.75 - 0.76 - 0.86 - 1.10 Others 2-Amyl furan 989 - 0.99 - 0.24 - 0.53 - 0.74 - 0.81 Isoelemicin 1568 0.35 2.60 0.36 1.46 0.39 3.11 0.08 1.52 0.15 1.06 2,2-Diisopropyltetrahydrofuran 2.59 0.71 1.60 0.18 1.46 0.56 2.29 0.13 2.05 1.62 cis-epoxy ocimeme 4.45 0.66 7.03 0.58 5.51 0.90 2.16 0.52 2.43 1.43 Is the relative percentage of compounds 129 Seasonal influence on banana volatiles in Kerala J. Hortl. Sci. Vol. 12(2) : 124-132, 2017 Esters were the most abundant volatile aroma constituents in both the cultivars compared to other group of volatiles (Table 4). Among esters, Isoamyl butanoate and 3-Methylbutyl-3-methylbutyrate esters were found most abundant in both the cultivars. Similarly, esters were quantitatively the dominant group of volatiles in ripe banana fruits (Wyllie and Fellman, 2000). Esters account for about 70% of the volatile compounds and acetates and butyrates predominate (Seymour, 1993). Esters were produced from the enzymatic actions on alcohols and acyl CoA’s derived from both fatty acid and amino acid metabolism (Wyllie and Fellman, 2000). Berger (1991) reported that 3- Methylbutyl acetate was considered to be the dominate 2013-October 2014-February 2014-June 2014-October 2015-February Volatile components Grand Grand Grand Grand Grand Naine Nendran Naine Nendran Naine Nendran Naine Nendran Naine Nendran (%)* (%) (%) (%) (%) (%) (%) (%) (%) (%) Esters 6511854 471 511 6275480 503 442 6456552 444 040 12559920 391 141 11799107 333 602 (-48.2) (+20.5) (-50.0) (+28.7) (-48.6) (+13.5) (-6.1) (-14.7) Alcohols 295 804 345 34 191 349 565 61 376 514 399 58 1808978 270 13 932 449 288 87 (-83.6) (+27.8) (-89.4) (+109.4) (-79.2) (+47.9) (-48.5) (+6.9) Aldehydes and Ketones 389 894 178 910 264 420 102 606 371 524 183 175 923 857 432 140 897 960 290 595 (-57.8) (-58.6) (-71.4) (-76.3) (-59.8) (-57.6) (-2.8) (-32.8) Acids 251 960 64 78 163 553 58 33 208 115 72 62 1155835 129 45 1034967 299 24 (-78.2) (-50.0) (-85.8) (-54.9) (-82.0) (-43.9) (-10.5) (+131.2) Phenol s 208 36 30 12 601 84 33 47 110 434 78 21 963 73 25 43 411 324 26 54 (-78.4) (+18.4) (-37.6) (+31.6) (-14.6) (+207.6) (+326.8) (+4.4) Hydrocarbons 818 419 784 54 691 594 835 93 609 114 867 07 1358478 332 830 1989832 272 279 (-39.8) (-76.4) (-49.1) (-74.9) (-55.2) (-73.9) (+46.5) (-18.2) Others 698 792 425 68 798 430 201 68 683 019 436 23 895 284 379 15 874 552 523 58 (-21.9) (+12.3) (-10.8) (-46.8) (-23.7) (+15.1) (-2.3) (+38.1) Total Area 8987559 815 467 8445010 775 550 8815272 812 586 18798725 1236527 17940191 1010299 (-52.2) (-34.1) (-55.1) (-37.3) (-53.1) (-34.3) (-4.6) (-18.3) *Values mentioned in the parenthesis are percent reduction in volatile components over October 2014 - indicates the decrease in volatiles + indicated the increase in volatiles Table 4. Percent change in area under curve of volatile components when compared to fruits (cvs. Grand Naine and Nendran) harvested during October 2014 which showed maximum area under curve. banana flavor and it was the key odor-impact volatile in ba nana fr uit followed by buta noa te a nd 3- methylbutanoate. In our study, with increased seasonal temperature, total area of volatile aroma compounds decr ea sed in cvs. Gr a nd Na ine a nd Nendr a n. Isoamylbutanoate (23.02%) and 3-Methylbutyl-3- methylbutyrate (18.02%) esters were the major esters found high at high temperature (34.5ºC) in cv. Grand Naine. Hexyl butyrate and Heptyl butanoate esters were found high at low temperature of 30.5ºC and 32.6ºC where as least was observed during low temperature in both the cultivars. Cultivar Nendran recorded increased concentrations of esters at high temperatures. Wills and McGlasson (1971) concluded that volatile concentrations increase as temperature increases, although production rate is reduced above 32°C. Ester concentrations and rates of production of ‘Jonathan’ apples increased as temperature increased. The biosynthetic pathway for the formation of volatile esters in ripening climacteric fruits is well-established (Arvanitoyannis and Mavromatis, 2009). Nogueira et al (2003) investigated that the ester (57.2-89.8 mg/ kg) a ppear ed to pla y an importa nt r ole in the characteristics of the composition of volatiles of Dwarf Cavendish, Giant Cavendish and Robusta banana cultivars. Methyl-2-propenoate (8.53%) and iso-Amyl- 2-methyl butyrate (10.32%) were recorded highest in cv. Nendran whereas least in cv. Grand Naine at high 130 Shivashankara et al J. Hortl. Sci. Vol. 12(2) : 124-132, 2017 temperatures. In case of cv. Nendran, esters were maximum at high temperature (34.5ºC) but in cv. Grand Naine, esters decreased with high temperature. Results indicated that fruits harvested during October month followed by February were better in terms of esters volatile aroma quantity in both the cultivars due to lower growth temperature. Guactagni et al (1971) concluded that the ‘Red Delicious’ apples had maximum ester production at low temperature; it decreased at 32°C and was inhibited at 46°C indicating that temperature inhibit or inactivate enzymes responsible for producing volatiles. Cultiva r Nendr a n r ecor ded incr ea sed concentrations of alcohols at high temperatures (34.5ºC) whereas least in cv. Grand Naine. Nogueira et al (2003) recorded that the alcoholic fractions (19.0- 47.7 mg/kg) appeared to play a significant role in the sensorial characteristics of banana fruit. Variation in volatiles was affected by abiotic factors such as temperature and humidity (Vallat et al, 2005). In our study, 1-Hexanol followed by (E)-5-Decen-2-ol were found maximum in cv. Nendran; similarly, (8E,10E)- 8,10-Dodecadien-1-ol was higher in cv. Grand Naine irrespective of the seasons (Table 3). Results indicated that fruits harvested at February month followed by October were better in terms of alcohols volatile aroma quantity in both the cultivars due to lower growth temperature. Alcohol concentrations and rates of pr oduction of ‘Jona tha n’ a pples incr ea sed a s temperature increased (Wills and McGlasson, 1971). Volatile production is considered to be proportional to temperature, the higher the temperature, the greater the production of volatiles (Fallik et al, 1997). However, the volatile aroma production seems to increase only up to a certain temperature beyond that the production decreases. Fatty acids serve as the precursor for alcohols which could be generated through lipoxygenase pathway of unsaturated linoleic and linolenic acids (Perez et al, 1999). In many types of fruits, through the action of lipoxygenase isozymes, linoleic and linolenic acids are degraded and produce fatty acid hydroperoxides. Hydroperoxide lyase converts these fatty acid hydroperoxides to aldehydes and oxoacids, while alcohol dehydrogenase acts on them to produce the corresponding alcohols (Sanz et al, 1997). Increased temperature resulted in decreased aldehydes and ketones in cvs. Grand Naine and Nendran. Total concentrations of aldehydes and ketones were maximum in cv. Nendran (Table 4). Ketones, especially 4-Methyl-1-penten-3-one followed by (9Z)-9,17-Octadecadienal and 3-Methylbutanal were higher in cv. Nendran whereas these compounds were lower in cv. Grand Naine. Total concentrations of aldehydes and ketones in cultivars Grand Naine and Nendran were high in October followed by February with mean growth temperature of 30.5ºC and 32.6ºC respectively (Table 4). Hexanal concentrations of ‘Cortland’ and ‘Mclntosh’ apples had the same pattern of change, irrespective of temperature (Yahia et al, 1990b; Yahia et al, 1991). A few hydrocarbons were also identified in the present study (Table 4). Hydrocarbons were present in high proportions in cv. Nendran compared to cv. Grand Naine. Varieties of hydrocarbons have been detected in banana cultivars (Shiota, 1991). Total concentration of hydrocarbons especially, pentadecane was high in October month (14.92%) followed by February (14.78%) in cv. Nendran with mean growth temperature of 30.5ºC and 32.6ºC respectively. But in cv. Grand Naine, pentadecane was totally absent. Decane and tetradecane were also present in high proportions in cv. Nendran. Similarly, in cv. Grand Naine, hydrocarbons were high in October with mean growth temperature of 30.5ºC. The concentrations of (5E, 7E)-5, 7-Dodeca diene followed by (±)- Dictyopterene were maximum in cv. Grand Naine. Temperature may also affect production of specific volatiles with some compounds only being produced at certain temperatures by affecting rates of substrate supply and volatile biosynthesis. If this is so then the different biosynthetic pathways producing volatiles may be active at different rates according to temperature (Dixon and Hewett, 2000). There were two kinds of acids namely; 4- butoxybutanoic acid and 8-nonenoic acid were found in cultivars Grand Naine and Nendran (Table 3). Maximum concentrations of acids were found in cv. Gra nd Naine compar ed to cv. Nendr an a t low temperature where as minimum were recorded at high temperature. Fallik et al (1997) concluded that the high temperature (38°C) reduced volatile production in ‘Golden Delicious’ a pples compa r ed to low temperature. Most of the acids were probably derived from β-oxidation of fatty acids. 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