IELTS Cue Card Sample 50 - Describe something healthy you enjoy doing
IELTS Speaking Part 2: IELTS Cue Card/ Candidate Task Card.
Describe something healthy you enjoy doing. You should say:
What you do
Where you do it
Who you do it with
and explain why you think doing this is healthy.
Possible Answer: I wake up early in the morning and then walk for an hour every day. After that, I swim in the nearby river for about 30 minutes and then I start my day. Waking up very early and then doing the physical exercise is the healthy habit I have developed from the early stage of my life.
I remember my father insisting us to wake up very early and then took us to the nearby high school ground for exercise. Nowadays, I wake up from bed at around 5:30 am and wear my exercise trousers and the pair of shoes. Then I start walking along with the road that has passed beside the river. The fresh air in the morning is very healthy for health. Sometimes I take my bicycle and instead of walking, I ride my cycle. I started doing this early morning exercise and swimming a few years back but nowadays 2 of my friends and cousins accompany me almost every day. They enjoy doing the exercise very much.
The morning is a time when the air and environment remain fresher than any time of the day. So breathing the fresh air, doing the exercises and finally swimming in the fresh water is definitely a very healthy habit. A sound mind lies on a sound body and this habit that I adopted is pretty helpful for keeping a sound health and sound mind.
Tips for answering this Cue Card Topic: Exercise, visiting open and natural places, good food habit etc. are some of the habits which are related to the health. Exercise can vary from going for walking in the morning & evening, running, swimming, cycling, playing outdoor games, and going to the gymnasium, doing yoga etc. You can talk about any exercise habit that you have for this cue card as exercise is a healthy habit.
Again you can talk about your passion on visiting different places on your vacation as travelling to open spaces gives you mental refreshment as well as help keeping good health.
Finally, a good food habit is something positive we can have to maintain a good health. You can talk about your habit of eating vegetable over fishes and meats. Your habit of drinking fruit juice daily is also something health you do. Gardening is a good habit which involved both the passion and physical exercise and can be described as a healthy habit.
Pick an idea related to exercise, good food habit or travelling and talk about that particular topic.
On the other hand, reading books, cooking, listening to music etc. are good for our mental health and thus keeps us joyful which is a healthy habit. If you want to talk about your habit of listening music, painting, cooking or reading, first mention the mental benefits it offers. Then relate the mental health with the physical health and then continue describing the habit.
The second question: &why you do it& and the fourth question &and explain why you think doing this is healthy& are actually similar. For the later one describe the benefits it offers and for the second question mention that& you have a passion for it, you spend a quality time this way and you really enjoy doing it. Since the cue card asks you to describe something healthy you enjoy doing, do not only mention the health benefit it offers. You should also talk about why you enjoy it, how passionate you feel about doing it and your involvement on the task.
Part 3: Details Discussion:
Q. What sports do you play?
Q. What is the most popular sport in your country?
Q. What is the most popular form of exercise in your country?
Q. Do you think people in your country are less healthy than they used to be?
Q. How can we encourage young people to stay healthy?
Q. Should governments intervene to force people to be healthier?
Your preparation for this cue card would also help you answering the following cue card topics:
1. Describe something you enjoy doing. 2. Describe something you do every day.
3. Describe a habit you have. 4. Describe an outdoor activity you have.
5. Describe a game or sports you enjoy playing. 6. Describe a really good habit you have.
7. Describe something you maintain to keep a good health. 8. Talk about something you often do.
9. Describe a place you often go to. 10. Describe something healthy you would recommend your friends.
11. Describe a healthy food item you eat.
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Effect of high-pressure processing on volatile composition and odour of cherry tomato puree
Food Chemistry 129 (C1765Contents lists available at ScienceDirectFood Chemistryjourna l h o me pa ge : ww w .else vie r . co m/lo c a te / fo o d ch e mEffect of high-pressure processing on volatile composition and odour of cherry tomato puré eKaarina Viljanen ? , Martina Lille, Raija-Liisa Heini? , Johanna BuchertVTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Finlanda r t i c l ei n f oa b s t r a c tThe impact of high-pressure processing on the odour of cherry tomato puré e was evaluated by sensory evaluation and SPMECGC/MS analysis. Two temperatures (20 and 60 ° C) and two pressures (atmospheric and 800 MPa) were used in processing. Higher pressure at ambient temperature decreased the levels of certain volatile aldehydes, ketones and alcohols present in tomato, whereas, the levels of hexanal, heptanal and octanal increased. The higher temperature combined with either ambient or high-pressure, decreased the levels of many volatile compounds and caused a reduction in the intensity of fresh tomato odour. Processing at 800 MPa and 60 ° C resulted in a marked increase in the intensity of cooked tomato and tea-like odour. On the basis of sensory assessment and volatile analysis, high pressure treatment at 800 MPa does not seem to be suitable for preserving fresh tomato odour. ? 2011 Elsevier Ltd. All rights reserved.Article history: Received 14 January 2011 Received in revised form 20 April 2011 Accepted 27 June 2011 Available online 1 July 2011 Keywords: Tomato Flavour High-pressure processing Volatile compounds GC/MS1. Introduction Flavour is one of the most important quality attributes of fresh tomato together with colour and texture. These quality attributes are usually affected by a conventional thermal treatment. Highpressure is assumed to not alter the fresh odour of the fruits and vegetables, since small molecular ?avour compounds are not directly affected by high pressure (Oey, Lille, Van Loey, & Hendrickx, 2008). However, high pressure processing can indirectly alter the content of some odourous compounds by enhancing or retarding enzymatic and chemical reactions, and subsequently result in undesired changes in the overall odour. Tomato odour is also affected by other factors such as tomato variety and the cultivation, ripening and storage conditions (Boukobza & Taylor, 2002; Gray, Prestage, Linforth, & Taylor, 1999; Krumbein, Peters, & Brü ckner, 2004; Langlois, Etié vant, Pierron, & Jorrot, 1996; Tandon, Baldwin, Scott, & Shewfelt, 2003). More than 400 volatile compounds have been identi?ed in tomato fruit. Volatile compounds include, for example, different aldehydes, ketones, alcohols, furans, and terpenes. Buttery (1993) listed volatiles present at concentrations greater than one part per billion (ppb), and further narrowed these compounds down to 30 by odour threshold studies. Baldwin et al. (1998) suggested that 15C20 volatiles in tomato have an impact on human perception. In their study, a sensory panel showed that a mixture of Z-3-hexenal, Z-3-hexanol, hexanal, 1-penten?Corresponding author. Tel.: +358 20 722 7160; fax: +358 30 722 7071. E-mail address: kaarina.viljanen@vtt.? (K. Viljanen).3-one, 3-methylbutanal, E-2-hexenal, 6-methyl-5-hepten-2-one, methyl salicylate, 2-isobutylthiazole, and b-ionone have an aroma very similar to that of sliced fresh tomato. These results were con?rmed in other studies (Baldwin et al., 1998; Boukobza, Dunphy, & Taylor, 2001; Buttery, Teranishi, & Ling, 1987; Krumbein & Auerswald, 1998; Tandon, Jordan, Goodner, & Baldwin, 2001). Besides these compounds, Krumbein and Auerswald (1998) showed that 1-octen-3-ol and methional affected the odour of fresh tomato. On the other hand, the odour is not only directly re?ected by the sum of the volatile and non-volatile components, but also depends on their interactions (Buttery et al., 1987). Therefore, a decrease in the concentration of one volatile odour compound does not necessarily affect the perceived odour. Processing has great impact on the odour of fresh tomato. During processing, the endogenous enzymes of tomato catalyse the formation of characteristic compounds of tomato ?avour. Most effect is seen on saturated and unsaturated C6 and C9 alcohols and aldehydes, which are typical compounds of fresh tomato odour, and are generated by lipoxygenase activity present in tomato (Buttery, Teranishi, Ling, & Turnbaugh, 1990). Servili, Selvaggini, Taticchi, Begliomini, and Montedoro (2000) also showed that a thermal treatment mainly modi?es saturated and unsaturated C6 aldehydes, esters, ketones and carotenoid derivatives. Endogenic tomato glycosidases can liberate terpene and carotenoid derivatives from their odourless glycosidic compounds (Marlatt, Ho, & Chiem, 1992). On the other hand, the concentration of some volatile odour compounds (e.g. Z-3-hexenal and hexanal) decreased ˇ ic during processing (Buttery et al., 1990; Markovic ? , Vahc ?, Kovac ˇ evic ? Ganic ? , & Banovic ? , 2007). In addition, some volatiles/$ - see front matter ? 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.1760K. Viljanen et al. / Food Chemistry 129 (C1765(E-2-hexenal, 2-methylbutyric acid, 1-hexenol, Z-3-hexenol) can not be detected in some of the processed tomato products at all (Markovic ? et al., 2007). The concentration of hexanal, which is a volatile compound associated with the odour of foliage and grass, has been shown to increase due to high-pressure treatment of strawberries and tomatoes (Porretta, Birzi, Ghizzoni, & Vicini, 1995). The increased concentration of hexanal is considered to be a result of the oxidation of free fatty acids, such as linoleic acid. Enzymes lipoxygenase and hydroperoxide lyase are naturally present in many vegetables and fruits, and are partially responsible for the formation of lipid derived volatile odour compounds such as hexanal. Lipoxygenase oxidises free fatty acids to hydroperoxides and hydroperoxide lyase further decomposes the hydroperoxides to volatile compounds, such as hexanal and Z-3-hexenal. The contribution of the reaction products of the lipoxygenase pathway to the overall ?avour is concentration dependent. At a suf?ciently low concentration, the volatile compounds formed by the action of lipoxygenase and hydroperoxide lyase, contribute to the ‘‘fresh’’ and ‘‘green’’ notes in ripe fruits (Baldwin et al., 1998). A more complete understanding of the changes in the sensory characteristics and the levels of volatile compounds after highpressure thermal processing of tomato is needed. The aim of this study was to investigate the effect of high-pressure thermal processing on odour of tomato puré e. In addition to chemical analysis (SPMECGC/MS) of volatile compounds, sensory analysis was used to gain understanding on how high-pressure and temperature affect on the perceived odour. 2. Materials and methods Plant material Ripe cherry tomatoes of Finnish origin were bought from a local farmer. The tomatoes were frozen and stored at ―40 ° C until use. High-pressure processing Tomatoes were thawed for 2 h at room temperature and homogenised as such for 8 s in a Bü chi mixer (type B-400, Bü chi Labortechnik AG, Switzerland). The puré e was packed into small plastic pouches (3.5 cm × 10 cm) for high pressure processing (15 g/pouch). The samples were high pressure processed in a multivessel high-pressure device (HPIU-10000-AT, Resato International, The Netherlands). The maximum working pressure of the unit is 1000 MPa. The six cylindrical vessels of the unit have an internal diameter of 25 mm and a height of about 120 mm. The vessels are surrounded with a jacket, through which a heating liquid (Kryo 51, Lauda, Germany) from a thermostatically controlled bath (Ultra-Kryomat?, RUK 90 W, Lauda, Germany), is circulated. Pressure is created by means of a pressure intensi?er and glycol (Resato PG Fluid) is used as pressure-transmitting medium. The tomato puré e was high pressure-treated at 800 MPa at an initial temperature of 20 or 60 ° C for a holding time of 10 min. The pressure was manually increased with a rate of about 150 MPa/min. The point at which the desired pressure was reached was taken as the starting point of the holding time. In addition, samples were treated in the pressure vessels at atmospheric pressure (0.1 MPa) at the same initial temperature as the pressuretreated samples. The temperature inside the pressure vessel (not in the sample) was measured every 10 s with a thermocouple mounted in the centre of the vessel cap. The tip of the thermocouple was located 8 mm below the cap. In high pressure-treated samples the temperature increased during pressure treatmentabove the initial temperature (20 ° C increased up to 40 ° C; 60 ° C increased up to 80 ° C). The pressure inside the vessels could not be measured. After processing, the samples were immediately cooled in ice, frozen and stored at ―80 ° C until analysis. An unprocessed tomato puré e, without any treatments, was used as reference sample. All processing treatments were done in triplicate. Sensory analysis Descriptive sensory analysis of the odour of the processed tomato puré es was performed in duplicate sessions by a trained sensory panel of 12 assessors. The evaluated odour attributes were: freshness, tea aroma, fresh tomato odour, cooked tomato odour, and other odour. The panel members practiced the evaluation of attribute de?nitions and their intensities during a training session. Each descriptive attribute was verbally described, and model samples of fresh and cooked tomato and tea aroma were served to the assessors in the training session. The de?nitions of the descriptors served as a guide for the subjects during testing to minimise confusion over the meaning of each attribute. in the evaluations the intensity of each odour attribute was rated on a linear graphical scale from 0 to 10 (0 = no odour, 10 = very strong odour). Panellists also had the possibility to verbally describe the samples. The samples were served to the assessors in closed odourless glass trays containing 7C8 g sample. The samples were presented coded and in random order to the panellists. The data were collected by using the software Compusense 5 (Compusense Inc., Guelph, Canada). SPMECGC/MS analysis of volatile odour compounds For SPMECGC/MS analysis, 2 g of tomato mash was weighted into 20 ml headspace vials containing 500 ll 5% NaCl solution. Toluene was used as internal standard (87 ng/sample). Samples were pre-incubated at +35 ° C for 30 min in closed headspace vials. Extraction of volatile compounds was done at +35 ° C for 60 min with a preconditioned (+300 ° C, 1 h) 75 lm Carboxen/PDMS SPME-?bre (Sulpelco, USA). After extraction the analytes were desorbed during 5 min at +260 ° C in the splitless injector (?ow 19.4 ml/min) of the gas chromatograph (Agilent 6890 Series, USA) combined with a MS detector (Agilent, 5973Network MSD, USA) and SPME autosampler (Combipal, Varian Inc., USA). Analytes were separated on an Ultra-2 capillary column (60 m × 0.25 mm ×1 lm) (Agilent Technologies, USA), with a constant ?ow of 1.5 ml/min, using helium as carrier gas. The temperature programme started at 45 ° C with 3 min holding time, then increased 10 ° C/min up to 100 ° C, followed by 5 ° C/min increase up to 150 ° C and ?nally a 10 ° C/min increase up to 300 ° C, where the temperature was kept for 9 min. MSD was operated in electron-impact mode at 70 eV, in the full scan m/z 40C550. The ion source temperature was 230 ° C and the interface was 280 ° C. Compounds were identi?ed with their speci?c ion and comparing the mass spectra on Palisade Complete 600 K Mass Spectral Library (Palisade Mass Spectrometry, USA). Each sample was analysed in duplicate and the mean of these values was used in further calculations. Statistical data analysis The data was analysed using analysis of variance (ANOVA) and Tukey’s Honestly Signi?cant Difference (HSD) test (signi?cance of differences at p & 0.05) by the statistical software SPSS (Version 17.0). Principal component analysis (PCA) was used to describe the pro?les of volatile compounds by using the Unscrambler software package (Unscrambler Ver. 9.8, CAMO ASA, 2008). The PCA was only used for compounds that were found to be signi?cantlyK. Viljanen et al. / Food Chemistry 129 (C17651761different from the reference (untreated cherry tomato puré e) sample. 3. Results and discussion Sensory evaluation of overall tomato odour Sensory evaluation of odour was used as a ?rst step in analysing the effect of high-pressure processing on the odour of fresh tomato. The analysed tomato puré es showed statistically signi?cant differences in intensity of fresh tomato odour, intensity of cooked tomato odour and tea aroma (Table 1). High-pressure processing at the most intense conditions (800 MPa, 60 ° C) increased signi?cantly the intensity of cooked tomato odour and tea aroma. The intensity of fresh tomato odour decreased signi?cantly in tomato puré es treated at 800 MPa at both temperatures (ambient temperature or at 60 ° C). On the contrary, the perceived odour of the reference tomato puré e (no treatment) and tomato puré es treated at 0.1 MPa (20 and 60 ° C) did not have any signi?cant differences. Chemical analysis of volatile odour compounds The high-pressure processed tomato puré es were further analysed by SPMECGC/MS with the aim to identify volatile odour compounds responsible for the changes in perceived odour. The tomato odour consisted mostly of different aldehydes as well as of some ketones, alcohols and other volatile odour compounds (Buttery et al., 1993; Baldwin et al., 1998; Tandon et al., 2001). The identi?ed tomato odour compounds along with their odour description are shown in Table 2. Since tomatoes have many different odour compounds, there seems to be several major compounds whic pungent, malt, butter, fat and on the other hand, fruit, lemon, green and honey odour. The chosen SPMECGC/MS method is suitable for analysing of tomato volatile odour compounds. The advantage of the SPMECGC/ MS method is that no further derivatisation or extraction of analytes is needed, and it is sensitive since it absorbs the analytes effectively. A disadvantage of the method used, is that different extraction phases can absorb different analytes. Therefore the chosen ?bres affect the range of detected compounds (Beltran et al., 2006). In the past, various SPME and headspace methods have been used to analyse different odourous volatile compounds from tomato and tomato products (Baldwin et al., 1998; Beltran et al., 2006; Buttery et al., 1987; Markovic ? et al., 2007; Ortiz-Serrano & Gil, 2010; Serrano, Beltrá n, & Herná ndez, 2009). An example of a GC/MS-chromatogram of unprocessed cherry tomato puré e is presented in Fig. 1. The volatile compounds found in the studied tomato puré e differed slightly from those reported in the literature for tomato (Baldwin et al., 1998; Buttery et al., 1987; Krumbein & Auerswald, 1998; Boukobza et al., 2001; Tandon et al., 2001). The variation is expected to be due to different tomato varieties, ripening and storage or growth place as well as in the methodologies used to analyse the volatiles (Gray et al., 1999;Langlois et al., 1996; Boukobza & Taylor, 2002; Krumbein et al., 2004; Tandon et al., 2003). In addition, the preparation of tomato puré e could have an impact on volatile odour compounds. Homogenisation of tomatoes has been shown to enhance the formation of enzymatic oxidation products. Tangwongchai, Ledward, and Ames (2000) showed that the amount of volatile compounds increased after fruit disruption, indicating that the enzymes come into contact with their substrates. It has been reported that Z-3-hexenal is a key odorant in the fresh tomato odour, however, it is also an unstable compound (Buttery et al., 1987). In these samples, no Z-3-hexenal was identi?ed. Instead its isomer E-2-hexenal was identi?ed in all samples. Therefore, the homogenisation itself has already changed the original tomato odour. Among the most interesting compounds identi?ed in this study were 2-methyl-2-butenal, E-2-pentenal, hexanal, heptanal, E,E-2,4hexadienal, E-2-heptenal, octanal, E,E-2,4-heptadienal, E-2-octenal, nonanal, E,E-2,4-decadienal, 1-penten-3-one, 1-hepten-3-one, 1penten-3-ol, 1-pentanol, 2-pentylfuran, 4-methyl-1,5-heptadiene and Z-citral (Table 3). The levels of these components were found to change due to processing. For sample treated at 0.1 MPa, 20 ° C, no signi?cant effect on volatiles was detected except in the level of E,E-2,4-hexadienal which increased. This was excepted since this sample is very similar the only difference is that control sample was kept at ―80 ° C until analysis was carried out and this sample was also kept at ambient temperature for 10 min. Higher pressure (800 MPa, 20 ° C) caused a loss of tomato volatiles. The levels of E-2-pentenal, E-2-octenal, E,E-2,4decadienal, 1-penten-3-one, 1-penten-3-ol, 1-pentanol and 2pentylfuran decreased. On the contrary, at ambient temperature high pressure (800 MPa) enhanced the levels of hexanal, heptanal and octanal. In a previous study, the amount of hexanal has been shown to increase during high-pressure treatment of tomato juice (500 MPa, 3 min) (Porretta et al., 1995). This may be due to lipid autoxidation and enzymatic oxidation reactions. Different aldehydes, such as hexanal and pentanal are formed from oxidation of linoleic acid. In cherry tomatoes the amount of fatty acids is over 600 mg/kg fresh tomatoes (Gray et al., 1999). Most of these fatty acids are linoleic acid (45%), followed by linolenic acid (12%) and palmitic acid (25%). Cherry tomatoes contain much more linolenic acid in the neutral lipid fraction than standard tomatoes, which may result in higher hexanal and E-2-hexenal concentrations. Lipoxygenases are known to oxidise endogenous tomato lipids, and hydroperoxide lyase decomposes formed fatty acid hydroperoxides to different aldehydes and ketones, such as hexanal, pentanal, octanal, and 1-penten-3-one, depending on the oxidised lipids (Baldwin et al., 1998). At low concentrations these compounds enhance the fresh tomato odour. On the contrary, at high concentrations, these compounds can cause rancid off-?avours (Belitz, Grosch, & Schieberle, 2009). When high-pressure (800 MPa) treatment was combined with heat treatment (60 ° C), a loss in the levels of many volatile compounds was observed. The levels of E-2-pentenal, E,E-2,4-hexadienal, E,E-2,4-heptadienal, E,E-2,4-decadienal, 1-penten-3one, 1-penten-3-ol, 2-pentylfuran, 4-methyl-1,5-heptadiene andTable 1 Results of sensory analysis of perceived odour of differently processed tomato puré e (n = 2 × 12) on a linear intensity scale from 0 to 10 (0 = no odour, 10 = very strong odour). Intensity of fresh tomato odour Reference 0.1 MPa, 20 ° C 800 MPa, 20 ° C 0.1 MPa, 60 ° C 800 MPa, 60 ° Ca,bFreshness 5.6 5.4 4.4 5.0 5.1Intensity of cooked tomato odour 2.6a 2.7a 3.6a,b 3.6a,b 4.3bTea aroma 2.2a 2.1a 2.8a 2.9a 5.0bIntensity of other odour 1.4 1.7 2.1 2.0 1.65.6b 5.2b 3.5a 4.6a,b 3.8aMeans in each column followed by a different letter signify that the samples are statistically signi?cantly different in respect of that attribute (Tukey’s HSD p & 0.05). Means without any letter are not statistically signi?cantly different in respect of that attribute.1762K. Viljanen et al. / Food Chemistry 129 (C1765 Table 2 The identi?cation of volatile odour compounds found in tomato puré e with their odour a descriptions. Peak number Aldehydes 1 2 5 6 9 12 14 17 18 19 20 22 27 28 30 31 33 36 Ketones 8 23 24 25 34 Alcohols 4 7 10 11 15 Furans 3 16 26 32 Terpenes 21 29 Others 35 13a bm/zb 43 43 44 57 44 84 55 41 41 70 81 41 43 81 41 91 57 81 55 43 55 43 109 43 57 55 57 42 82 84 81 69 93 69 69 94Compound 2-Methyl-1-propanal 2-Methyl-2-propanal 3-Methylbutanal 2-Methylbutanal Pentanal 2-Methyl-2-butenal E-2-Pentenal Hexanal E-2-Hexenal Heptanal E,E-2,4-Hexadienal E-2-Heptenal Octanal E,E-2,4-Heptadienal E-2-Octenal 2-Phenylacetaldehyde Nonanal E,E-2,4-Decadienal 1-Penten-3-one 2-Methyl-1-hepten-6-one 1-Hepten-3-one 6-Methyl-5-hepten-2-one 6-Methyl-3,5-heptadien-2-one Isobutylalcohol 1-Penten-3-ol 3-Methyl-1-butanol 2-Methyl-1-butanol 1-Pentanol 2-Methylfuran 2,3-Dihydro-4-methylfuran 2-Pentylfuran PerilleneOdour description? Pungent, malt, green Pungent Malt Cocoa, almond Almond, malt, pungent Green, fruit Strawberry, fruit, tomato Grass, tallow, fat Green, apple Fatty, citrus, rancid Green Soap, fat, almond Soap, lemon, green, fat Nut, fat Green, nut, fat Honey, hawthorn, sweet Fat, citrus, green Fried, wax, fat Fish, pungent Green, fresh, fruity Metal Pepper, mushroom, rubber Spicy Wine, solvent, bitter Butter, pungent Whiskey, malt, burnt Wine, onion Green Chocolate Cooked Green bean, butter Woody Pine, turpentine Spicy Lemon Onion, cabbage, putrida-Pinene4-Methyl-1,5-heptadiene Z-Citral Dimethyl disulphideOdour descriptions adapted from Acree & Arn (2010). m/z = speci?c ion.Fig. 1. Typical GC/MS chromatogram of volatile odour compounds of unprocessed cherry tomato puré e. The numbers of peaks refer to compounds listed in Table 2.Z-citral decreased. The only compound which increased during processing was 2-methyl-2-butenal. The decreased levels of many tomato volatile compounds may be due to their degradation and oxidation. Lipoxygenase and hydroperoxide lyase in tomato are re-ported to be inactivated at the conditions used in this study (800 MPa, 60 ° C) (Rodrigo, Jolie, Van Loey, & Hendrickx, 2007; Tangwongchai et al., 2000). Therefore further production of volatile compounds is most likely limited during high-pressure processing. Similar decreases in the level of tomato volatile compounds were observed in the tomato puré e sample treated at ambient pressure and 60 ° C. In this sample, in addition to 2-methyl-2-butenal, the level of 1-hepten-3-one increased. Rodrigo et al. (2007) showed that tomato juice lipoxygenase was completely inactivated at 60 ° C in 12 min. Hydroperoxide lyase, in contrast, is a relatively heat labile enzyme losing its activity at lower temperatures when compared to lipoxygenase. On the other hand, the activity of tomato lipoxygenase has been shown to increase with increasing pressure (up to 400 MPa) (Rodrigo et al., 2007). This may be due to increased extraction of lipoxygenase from membranes. In addition to high temperature, tomato lipoxygenase is inactivated at higher pressures (550 MPa for 12 min or 600 MPa for 10 min) (Rodrigo et al., 2007; Tangwongchai et al., 2000). However, the hydroperoxide lyase is still active at these conditions (Rodrigo et al., 2007). Therefore combined heat and pressure treatment is needed for hydroperoxide lyase inactivation.K. Viljanen et al. / Food Chemistry 129 (C1765 Table 3 Normalized peak areas (compound area/ISTD area) of volatile aroma compounds of cherry tomato puré e. Reference Aldehydes 2-Methyl-1-propanal 2-Methyl-2-propanal 3-Methylbutanal 2-Methylbutanal Pentanal 2-Methyl-2-butenal E-2-Pentenal Hexanal E-2-Hexenal Heptanal E,E-2,4-Hexadienal E-2-Heptenal Octanal E,E-2,4-Heptadienal E-2-Octenal 2-Phenylacetaldehyde Nonanal E,E-2,4-Decadienal Ketones 1-Penten-3-one 2-Methyl-1-hepten-6-one 1-Hepten-3-one 6-Methyl-5-hepten-2-one 6-Methyl-3,5-heptadien-2-one Alcohols Isobutylalcohol 1-Penten-3-ol 3-Methyl-1-butanol 2-Methyl-1-butanol 1-Pentanol Furans 2-Methylfuran 2,3-Dihydro-4-methylfuran 2-Pentylfuran Perillene Terpenes a-Pinene 4-Methyl-1,5-heptadiene Others Z-Citral Dimethyl disulphideaCd17630.1 MPa, 20 ° C 0.018a,b 0.302a 0.489a 0.348a 0.800b 0.210a,b 0.188b 1.977b,c 0.175a 0.022c,d 0.025b 0.046c 0.015b 0.010c 0.079b 0.025a,b 0.020b,c b 0.004 2.155b 0.016b 0.015a 1.155a 0.013a 0.018a,b 0.096b 0.139a 0.692a 0.044c 0.105a 0.009a 0.170b 0.016a 0.028b 0.030b 0.008b 0.050a800 MPa, 20 ° C 0.009a 0.364a 0.436a 0.314a 0.508a 0.181a 0.021a 2.421c 0.155a 0.026d 0.014a,b 0.020a,b 0.024c 0.010c 0.017a 0.019a 0.027c a 0.000 0.267a 0.007a 0.013a 1.114a 0.012a 0.009a 0.054a 0.122a 0.605a 0.013a 0.114a 0.009a 0.060a 0.014a 0.018a 0.025b 0.007b 0.067a0.1 MPa, 60 ° C 0.027b 0.293a 0.463a 0.367a 0.549a 0.278c 0.023a 0.992a 0.125a 0.006a 0.007a 0.006a 0.008a 0.001a 0.008a 0.030b 0.012a a 0.000 0.219a 0.009a 0.460b 1.153a 0.013a 0.027b 0.048a 0.140a 0.744a 0.024a,b 0.101a 0.009a 0.027a 0.013a 0.027a,b 0.017a 0.006b 0.066a800 MPa, 60 ° C 0.014a 0.309a 0.500a 0.442a 0.610a,b 0.257b,c 0.011a 1.384a,b 0.121a 0.013a,b 0.005a 0.007a 0.013a,b 0.005a,b 0.009a 0.024a,b 0.017a,b a 0.000 0.058a 0.012a,b 0.170a 1.346a 0.017a 0.014a 0.050a 0.120a 0.655a 0.017a,b 0.124a 0.009a 0.025a 0.015a 0.022a,b 0.014a 0.001a 0.061a0.016a,b 0.299a 0.451a 0.344 a 0.691a,b 0.201a 0.163b 1.738b 0.139a 0.019b,c 0.009a 0.037b,c 0.012a,b 0.007b,c 0.064b 0.023a,b 0.015a,b b 0.003 1.769b 0.012a,b 0.010a 1.088a 0.009a 0.016a,b 0.083b 0.121a 0.628a 0.031b,c 0.109a 0.008a 0.129b 0.014a 0.024a,b 0.026b 0.007b 0.042aValues in the same row followed by different letters are statistically signi?cantly different (p & 0.05).Most of the aldehydes and ketones found in tomatoes, are derived from the lipoxygenase pathway. E-2-Pentenal is decomposition product from linolenic acid oxidation, and E-2-heptenal and E-2-octenal from linoleic acid. Both are suitable substrates for lipoxygenase since linoleic acid has one cis,cis-1,4-pentadiene structure and linolenic acid two cis,cis-1,4-pentadiene structures. Hence, the increased level of some aldehydes in tomato samples is likely to be a result of lipoxygenase reaction as well as their further oxidation, degradation and polymerisation reactions. Further oxidations of enal aldehydes produce next lower alkanal, e.g. E-2octenal produce heptanal, E-2-heptenal produce hexanal, and E-2hexenal produce pentanal (Frankel, 2005). Both lipoxygenase and hydroperoxide lyase are inactivated at 60 ° C, which partly explains why the amount of enal aldehydes is decreasing in samples treated at elevated temperature. Z-3-Hexenal was not present in the analysed tomato samples. This was due to being an unstable compound, that was apparently largely isomerised to E-2-hexenal during homogenisation, high-temperature/high-pressure processing and analysis. Similar isomerisation of Z-3-hexenal to E-2hexenal has been reported in the literature (Buttery et al., 1987; Ortiz-Serrano & Gil, 2010). The formation of nonanal and octanal is probably due to lipid autoxidation since they are formed from oleic acid (Frankel, 2005). Oleic acid has only one double bondand therefore it is not a substrate for tomato lipoxygenase. The decrease in concentrations of these aldehydes at elevated temperature is most likely due to thermal decomposition. The level of a carotenoid-derived volatile compound, 6-methyl5-hepten-2-one remained unchanged at all studied processing conditions. This is in accordance with the literature where highpressure treatment had no effect on carotenoids on tomatoes (Butz et al., 2002). The good pressure stability is probably explained by the matrix effect: endogenous carotenoid pigments are often compartmentalised and therefore protected from adverse in?uences. On the other hand, 6-methyl-5-hepten-2-one has been shown to degrade at high temperatures (Rios, Ferná ndez-Garcí a, Mí nguezMosquera, & Pé rez-Gá lvez, 2008). In this study, no signi?cant decrease on the level of 6-methyl-5-hepten-2-one was seen at higher temperature (60 ° C). Most of the alcohols found in fruits and vegetables have resulted from reductase conversions of the corresponding aldehydes formed from the metabolism of fatty acids and amino acids. Alcohol dehydrogenase can further convert C6 aldehydes into corresponding alcohols. The amount of hexanol has been shown to decrease in high-pressure processed tomatoes (Porretta et al., 1995). In these samples no hexanol was measured. This may be due to the used SPMECGC/MS method which may not be suitable1764K. Viljanen et al. / Food Chemistry 129 (C1765for hexanol measurement or due to co-elution of hexanol with other compounds. Thermal treatments clearly modify the sensory quality of tomatoes. Increasing temperature had an effect on tomato vola the levels of 2-methyl-2-butenal and 1-hepten-3-one increased. On the contrary, the levels of E-2-pentenal, hexanal, heptanal, E-2-heptenal, E,E-2,4-hexadienal, E,E-2,4-heptadienal, E2-octenal, E,E-2,4-decadienal, 1-penten-3-one, 1-penten-3-ol, 2pentylfuran and 4-methyl-1,5-heptadiene decreased. These changes will have an impact on fresh tomato odour since, for example, hexanal has been shown to contribute to the fresh odour of tomatoes (Baldwin et al., 1998; Boukobza et al., 2001; Buttery et al., 1987; Tangwongchai et al., 2000; Ortiz-Serrano & Gil, 2010). In previous investigations, processing has been shown to affect tomato volatile odour compounds (Markovic ? et al., 2007; Servili et al., 2000). Usually processing, especially thermal processing, decreases relative concentrations of volatile odour compounds when compared to fresh tomatoes. Typically thermal treatments modify C6 alcohols and aldehydes, ketones and carotenoid derivatives. However, for example, in tomato juice, higher concentrations of volatile compounds have been analysed when compared to whole fresh tomatoes. In tomato products, typical changes are total loss of Z-3-hexenal and the formation of furfural. In this study, no Z-3-hexenal was identi?ed. Instead its isomer E-2-hexenal was found at high levels. However, the level of E-2-hexenal remained unchanged at all processing conditions when compared to the reference sample (unprocessed cherry tomato puré e). This is contradictory with literature where the amount of E-2-hexenal decreased due to lipoxygenase inactivation at high-pressure treatment (600 MPa for 10 min) (Tangwongchai et al., 2000). In addition to autoxidation and enzymatic reactions modifying volatile compounds, temperature may have an effect on the stability of the compounds. Xu and Barringer (2009) showed that hexanal concentration ?rst increased and then decreased when tomato samples were kept at room temperature. The reason for this, is that after tissue disruption, volatiles are generated and accumulated due to lipoxygenase and hydroperoxide lyase activity. Hexanal is thereafter rapidly degraded into other compounds in a few minutes. In addition, hexanal formation by lipoxygenase is end-product (hexanal) inhibited. Tangwongchai et al. (2000) concluded that the amount of 1-penten-3-one decreased due to lipoxygenase inactivation by high-pressure treatment (600 MPa for 10 min). The same trend was seen in this study. In addition to high pressure, heating at 60 ° C also decreased the level of 1-penten-3-one. Principal component analysis (PCA) was carried out to describe relations between different processing conditions and volatile compounds (Fig. 2). Increasing the temperature from 20 ° C to 60 ° C decreased the level of most of the volatiles analysed in tomato puré e. On the contrary, a treatment at ambient temperature and ambient pressure increased or did not have any effect on the level of tomato volatile odour compounds. This data supports the data shown in Table 3. Octanal, hexanal, and heptanal, nonanal, E,E2,4-heptadienal are related to sample treated at 800 MPa and 20 ° C, while the increased temperature is related to decreased level of E-2-heptenal, E-2-octenal, E-2-pentenal, 1-penten-3-one and 1-pentanol. Most of the volatile odour compounds are related to reference sample and samples treated at ambient temperature. Octanal and nonanal are strongly related to tomato puré e sample treated at ambient temperature and 800 MPa. 1-Hepten-3-one and 2-methyl-2-butenal are related to thermal processing at ambient pressure. Comparison of sensory and volatile analysis Processing at the studied conditions (0.1 or 800 MPa at 20 or 60 ° C) changed the composition of volatile compounds of tomato puré e. This alone does not explain how the perceived ?avour is1.0 PC2 1.0 PC2 1.0Bi -plot Bi -plot 800MPa, 800 80 82 00 M 7 27 0 M Pa, Pa P20C a, , 20 20C C 33 27 2 7 33 3 3 17 17 17 19 19 19 280.5 0.50 080 800 0MPa Pa, , 60 60C C 800MPa, 60C 800MPa, 60C29 29 29 20 2 0
2 2 22 Ref R Ref26 ef26 Ref 0.1MPa, .1MP 20 26 0.1M 0 . 1MPa, 2 0C 3 0 730 7 30 86 8 36 8 14 1 3 4 14
15 15 15 PC1 PC1 1.0-0.5 0.50.1M 0.1MPa, .1MP P 60C a0 ,C 624 0 C 24 24 0.10 M Pa, 6 12 12 12-1.0 1.0 -1.0 -0.8 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 X expl : 67%,26%Fig. 2. Principal component analysis (PCA) plot of the key volatile compounds of the ?ve tomato puré e at different processing conditions. The ?rst principal component (PC) explained 67% and the second PC 26%, altogether 93% of the variation among the samples. The numbers of the plot refer to compounds listed in Table 2.changed. Odour evaluation was used to understand better the relationship between changes in volatile composition and perceived ?avour. Taste evaluation would have been even more useful, but it was not possible to carry out in our case due to limitations set by the high-pressure equipment. If the data obtained from the sensory analysis is combined with the data of the volatile composition, it can be seen that the increased tea aroma and increased cooked tomato odour seen in sample treated at 800 MPa and 60 ° C is most likely due to a loss of almost all volatile compounds found in tomatoes. However, the origin of tea aroma and cooked tomato odour remains unsolved. The amount of dimethyl disulphide has been shown to increase during thermal treatment and being responsible of cooked tomato odour together with linalool (Buttery, Seifert, Guadagni, & Ling, 1971). However, in this study such correlation between dimethyl disulphide and cooked tomato odour was not found. On the contrary, the loss of fresh tomato odour seen in tomato puré es treated at 800 MPa (20 and 60 ° C) is most likely due to decreased levels of aldehydes, 1-penten-3-one, 1-penten-3-ol, 1-pentanol, and 2-pentylfuran. According to literature Z-3-hexenal, Z-3-hexanol, hexanal, 1-penten-3-one and E-2-hexenal are some of the compounds responsible of fresh tomato odour (Baldwin et al., 1998; Buttery et al., 1987; Krumbein & Auerswald, 1998). In addition, Krumbein and Auerswald (1998) found out, that E-2-hexenal, 1-octen-3-one, E,Z-2,4-heptadienal and E,E-2,4-hexadienal were responsible of tomato odour. Hexanal, E-2-hexenal, 6-methyl-5-hepten-2-one and 2-isobutylthiazole have been shown to be responsible for mouldy odour (Krumbein et al., 2004). On the other hand, Tandon et al. (2003) found a negative correlation between green aroma and E-2heptenal. 4. Conclusions The high-pressure treatment, as well as the high temperature had an effect on the amount of volatile odour compounds. The level of most aldehydes decreased as the temperature increased (20 ° C vs. 60 ° C). Most signi?cant changes were seen in hexanal, E-2-hexenal and 1-penten-3-one, which are according to literature, important volatiles of fresh tomatoes (Baldwin et al., 1998; Buttery et al., 1987; Krumbein & Auerswald, 1998). When comparing the resultsK. Viljanen et al. / Food Chemistry 129 (C17651765of the sensory analysis with the volatile composition, it was seen that the odour intensity of fresh tomato and the level of aldehydes, 1-penten-3-one, 1-penten-3-ol, 1-pentanol, and 2-pentylfuran decreased in tomato puré es treated at 800 MPa (20 and 60 ° C). Concomitantly with the loss of fresh tomato odour in samples treated at 800 MPa and 60 ° C, the intensity of cooked tomato odour and tea aroma was increased. On the basis of these results, highpressure treatment at 800 MPa, 20 ° C or 800 MPa, 60 ° C does not seem to be suitable for preserving the ?avour of fresh tomatoes. 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