Tomato, one of the most popular vegetables in the American diet (Chun et al., 2005), is an excellent source of antioxidants, and has scientifically been proven to be an anticancer agent (Guil-Guerrero and Rebolloso-Fuentes, 2009). Aroma, which is produced by a complex mixture of volatile compounds, plays an important role in the perception and acceptability of tomato products by consumers (El Hadi et al., 2013). Although more than 400 volatiles have been identified in the ripening tomato fruit, only 16 are reported to have positive log odor units, which is calculated from the ratio of the concentration of a component in a food to its odor threshold, and substantially contribute to tomato aroma, including cis-3-hexenal, β-ionone, hexanal, β-damascenone, 1-penten-3-one, 3-methylbutanal, trans-2-hexenal, 2-isobutylthiazole, 1-nitro-2-phenylethane, trans-2-heptenal, 2-phenylacetaldehyde, 6-methyl-5-hepten-2-one, cis-3-hexenol, 2-phenylethanol, 3-methylbutanol, and methyl salicylate (Buttery, 1993). However, volatile compounds with negative odor units also may contribute to tomato aroma as background notes (Baldwin et al., 2000). Therefore, aroma models, based on concentrations and odor thresholds of individual volatiles, do not account for synergistic and antagonistic interactions that may occur in tomato fruit (Tieman et al., 2012).
Over the past 50 years, a significant drop-off in tomato aroma has been noticed by consumers, which is a major source of consumer complaints (Klee, 2010). In addition, breeding programs, which have made cheaper and year-round produce available, and have done so at the expense of aroma quality (Maul et al., 2000). Furthermore, inappropriate pre- or postharvest practices such as harvest maturity, application of plant growth regulators, and storage temperature/atmosphere have been shown to cause aroma loss in tomato fruit as well (Wang et al., 2015a). Like many other tropical and subtropical horticultural crops, tomato is sensitive to low temperature stress (McDonald et al., 1999). Under the current marketing system, fruit usually are harvested at the mature green stage and shipped at low temperature to slow ripening and prevent fruit losses due to bruising and decay, thereby extending storage life. When mature green tomatoes are stored at 13 °C for longer than 2 weeks or at 5 °C for longer than 7 d before ripening at 20 °C, a series of physiological/biochemical responses are activated that impair the fruit, including failure to develop full color and flavor, water-soaking, surface pitting, and susceptibility to Alternaria rot and other decay (Ding et al., 2002; Gross et al., 2004; Luengwilai and Beckles, 2010; Saltveit and Morris, 1990). Internal chilling injury (CI) in the form of aroma loss usually takes place in advance of visual CI symptoms (Maul et al., 2000). Our previous research showed impacts of chilling on flavor loss of mature green tomatoes: exposure of ‘FL 47’ tomato to 5 °C for 4 d did not cause any visual chilling symptoms following ripening at 20 °C. However, a 51% reduction in aroma volatiles occurred, with the highest reduction in terpene volatiles followed by aldehydes, alcohols, esters, ketones, and acids (Wang et al., 2015b). Meanwhile, the production of seven key volatile compounds suggested by Klee (2010) was downregulated after the chilling exposure, including 6-methyl-5-hepten-2-one, β-ionone, trans-2-hexenal, hexanal, 2-phenylethanol, and 2-methylbutanal (Wang et al., 2015a). Furthermore, Bai et al. (2011) found that chilling-induced inhibition of tomato C6 volatile production may be due to downregulation of gene expression, and subsequent reduction of human pancreatic lipase (HPL) and alcohol dehydrogenases (ADH) enzyme activities in the oxylipin pathway.
Heat treatment has been shown to be an effective method to sanitize the tomato and other fruit surfaces by reducing microbes. In addition, heat treatments can disinfect insects, delay ripening, and alleviate pathological and physiological disorders (Bai et al., 2004; Lurie, 1998; Plotto et al., 2003). However, a detrimental effect of heat treatment is aroma loss evidenced in many fruits including tomatoes (Bai et al., 2004, 2011; Lurie, 1998). Immersion of red tomato fruits (‘Tasti-Lee’ and ‘Sanibel’) in 52 °C hot water for 15 min inhibited C6 volatile production, possibly owning to the suppressed HPL and ADH activities (Bai et al., 2011). On the other hand, pretreatment with heat is a postharvest handling tool used to reduce CI in tomatoes. Tomatoes, pretreated at the mature green stage with either hot water (42 °C for 1 h) or hot air (38 °C for 48 h), did not suffer external CI after exposure to cold temperature (McDonald et al., 1996), and had less volatile flavor loss at 2 °C storage than those treated without prechilling heat treatment (McDonald et al., 1999). Previously, we reported that 52 °C hot water treatment for 5 min greatly alleviated chilling-induced volatile losses; however, the heat treatment itself inhibited the production of alcohols and acids in mature green ‘FL 47’ tomatoes along with lower levels of β-ionone, 2-methylbutanal, 3-methylbutanol, and 2-phenylethanol (Wang et al., 2015b). Nevertheless, the fate of tomatoes at the end of the journey from farm to fork is the consumer, and how the consumer handling of tomatoes at home affects tomato flavor has not been well studied.
Refrigeration of tomatoes is a common consumer practice in home kitchens and blanching of fruit including tomatoes is common for Japanese consumers and in some food service operations. Refrigeration has been thought to slow fruit ripening and senescence, reduce microbial growth, and extend the storage time of tomato fruits (de Castro et al., 2006). The use of 50 °C or higher temperature for a few minutes (blanching) has been used in food service companies and kitchens to reduce microbial loads and inactivate deleterious enzymes (Castro et al., 2008). In Japan, a 50 °C dipping for up to 30 min has been suggested for fruits, vegetables, meat, and fish washing, which is believed to improve food flavor, but there is a lack of scientific evidence (Hirayama, 2012). Little is reported on the impact of such practices on tomato aroma quality. In this research, ‘FL 47’ tomatoes at full red stage were dipped in 50 °C hot water for 5 min or exposed to 5 °C for 4 d to simulate home kitchen practices. A combination of biochemical and physiochemical analysis was conducted to determine the impact of food service or kitchen practices on tomato aroma quality.
This article is one in a series of articles on postharvest flavor loss in tomato fruit. The previous two publications addressed how hot water pretreatment alleviates chilling-induced volatile loss (Wang et al., 2015a), and how methyl salicylate pretreatment alleviates chilling-induced volatile loss (Wang et al., 2015b). Mature green tomatoes were used for both experiments, and they were subjected to simulate the industrial storage and transportation conditions. In this article, we focused on the consumer-end temperature control—the fruit were treated after reaching edible maturity and right before serving. The objective was to provide consumers with information on how their kitchen practices influence tomato flavor quality.
We thank the financial support to the experiment from China Scholarship Council (201306850049), Postgraduate Program in Jiangsu Province (CXLX13ˍ267), and the Big Red Tomato Packers, Fort Pierce, FL.
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Acree, T. & Arn, H. 2010 Flavornet and human odor space. Gas chromatography–olfactometry (GCO) of natural products. Cornell University, Ithaca, NY. 18 May 2015. <http://www.flavornet.org/flavornet.html>
Bai, J., Baldwin, E.A., Imahori, Y., Kostenyuk, I., Burns, J. & Brecht, J.K. 2011 Chilling and heating may regulate C6 volatile aroma production by different mechanisms in tomato (Solanum lycopersicum) fruit Postharvest Biol. Technol. 60 111 120
Bai, J., Baldwin, E.A., Soliva Fortuny, R.C., Mattheis, J.P., Stanley, R., Perera, C. & Brecht, J.K. 2004 Effect of pretreatment of intact ‘Gala’ apple with ethanol vapor, heat, or 1-methylcyclopropene on quality and shelf life of fresh-cut slices J. Amer. Soc. Hort. Sci. 129 583 593
Baldwin, E.A., Bai, J., Plotto, A., Cameron, R., Luzio, G., Narciso, J., Manthey, J., Widmer, W. & Ford, B.L. 2012 Effect of extraction method on quality of orange juice: Hand-squeezed, commercial-fresh squeezed and processed J. Sci. Food Agr. 92 2029 2042
Baldwin, E.A., Bai, J., Plotto, A. & Dea, S. 2011 Electronic noses and tongues: Applications for the food and pharmaceutical industries Sensors (Basel Switzerland) 11 4744 4766
Baldwin, E.A., Plotto, A., Manthey, J., McCollum, G., Bai, J. & Irey, M. 2009 Effect of Liberibacter infection (Huanglongbing disease) of citrus on orange fruit physiology and fruit/fruit juice quality: Chemical and physical analyses J. Agr. Food Chem. 58 1247 1262
Baldwin, E.A., Scott, J.W., Shewmaker, C.K. & Schuch, W. 2000 Flavor trivia and tomato aroma: Biochemistry and possible mechanisms for control of important aroma components HortScience 35 1013 1022
Bradford, M.M. 1976 A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding Anal. Biochem. 72 248 254
Buttery, R. 1993 Quantitative and sensory aspects of flavor of tomato and other vegetables and fruits, p. 259–286. In: T. Acree and R. Teranishi (eds.). Flavor science: Sensible principles and techniques. ACS, Washington, DC
Castro, S.M., Saraiva, J.A., Lopes-da-Silva, J.A., Delgadillo, I., Van Loey, A., Smout, C. & Hendrickx, M. 2008 Effect of thermal blanching and of high pressure treatments on sweet green and red bell pepper fruits (Capsicum annuum L.) Food Chem. 107 1436 1449
Chun, O.K., Kim, D.O., Smith, N., Schroeder, D., Han, J.T. & Lee, C.Y. 2005 Daily consumption of phenolics and total antioxidant capacity from fruit and vegetables in the American diet J. Sci. Food Agr. 85 1715 1724
de Castro, L.R., Cortez, L.A. & Vigneault, C. 2006 Effect of sorting, refrigeration and packaging on tomato shelf life J. Food Agr. Environ. 4 70–74
Ding, C-K., Wang, C., Gross, K.C. & Smith, D.L. 2002 Jasmonate and salicylate induce the expression of pathogenesis-related-protein genes and increase resistance to chilling injury in tomato fruit Planta 214 895 901
Froehlich, J.E., Itoh, A. & Howe, G.A. 2001 Tomato allene oxide synthase and fatty acid hydroperoxide lyase, two cytochrome P450s involved in oxylipin metabolism, are targeted to different membranes of chloroplast envelope Plant Physiol. 125 306 317
Fung, R.W., Wang, C.Y., Smith, D.L., Gross, K.C. & Tian, M. 2004 MeSA and MeJA increase steady-state transcript levels of alternative oxidase and resistance against chilling injury in sweet peppers (Capsicum annuum L.) Plant Sci. 166 711 719
Gross, K.C., Wang, C.Y. & Saltveit, M. 2004 The commercial storage of fruits, vegetables, and florist and nursery stocks. An Adobe Acrobat pdf of a draft version of the forthcoming revision to U.S. Department of Agriculture, Agriculture Handbook 66 on the website of the USDA, Agricultural Research Service, Beltsville, MD. 18 May 2015. <http://www.ba.ars.usda.gov/hb66/>
Guil-Guerrero, J. & Rebolloso-Fuentes, M. 2009 Nutrient composition and antioxidant activity of eight tomato (Lycopersicon esculentum) varieties J. Food Compos. Anal. 22 123 129
Hirayama, K. 2012 50 °C waching and dipping. 1st ed. Shufunotomo, Tokyo, Japan
Kochevenko, A., Araújo, W.L., Maloney, G.S., Tieman, D.M., Do, P.T., Taylor, M.G., Klee, H.J. & Fernie, A.R. 2012 Catabolism of branched chain amino acids supports respiration but not volatile synthesis in tomato fruits Mol. Plant 5 366 375
Lewinsohn, E., Sitrit, Y., Bar, E., Azulay, Y., Meir, A., Zamir, D. & Tadmor, Y. 2005 Carotenoid pigmentation affects the volatile composition of tomato and watermelon fruits, as revealed by comparative genetic analyses J. Agr. Food Chem. 53 3142 3148
Luengwilai, K. & Beckles, D.M. 2010 Climacteric ethylene is not essential for initiating chilling injury in tomato (Solanum lycopersicum) cv Ailsa Craig. J. Stored Prod. Postharvest Res. 1 1 8
Maul, F., Sargent, S., Sims, C., Baldwin, E., Balaban, M. & Huber, D. 2000 Tomato flavor and aroma quality as affected by storage temperature J. Food Sci. 65 1228 1237
McDonald, R., McCollum, T. & Baldwin, E. 1996 Prestorage heat treatments influence free sterols and flavor volatiles of tomatoes stored at chilling temperature J. Amer. Soc. Hort. Sci. 121 531 536
McDonald, R., McCollum, T. & Baldwin, E. 1999 Temperature of water heat treatments influences tomato fruit quality following low-temperature storage Postharvest Biol. Technol. 16 147 155
McLachlan, G. 2004 Discriminant analysis and statistical pattern recognition. 2nd ed. John Wiley & Sons, Inc., Hoboken, NJ
Plotto, A., Bai, J., Baldwin, E.A. & Brecht, J.K. 2003 Effect of pretreatment of intact ‘Kent’ and ‘Tommy Atkins’ mangoes with ethanol vapor, heat or 1-methylcyclopropene on quality and shelf life of fresh-cut slices Proc. Fla. State Hort. Soc. 116 394 400
Raithore, S., Dea, S., Plotto, A., Bai, J., Manthey, J., Narciso, J., Irey, M. & Baldwin, E. 2014 Effect of blending Huanglongbing (HLB) disease affected orange juice with juice from healthy orange on flavor quality Lwt-Food Sci. Technol. 62 868 874
Rambla, J.L., Tikunov, Y.M., Monforte, A.J., Bovy, A.G. & Granell, A. 2014 The expanded tomato fruit volatile landscape J. Expt. Bot. 65 4613 4623
Renard, C.M., Ginies, C., Gouble, B., Bureau, S. & Causse, M. 2013 Home conservation strategies for tomato (Solanum lycopersicum): Storage temperature vs. duration—Is there a compromise for better aroma preservation? Food Chem. 139 825 836
Rhodes, M.J. & Wooltorton, L.S. 1977 Changes in the activity of enzymes of phenylpropanoid metabolism in tomatoes stored at low temperatures Phytochemistry 16 655 659
Rivero, R.M., Ruiz, J.M., Garcıa, P.C., Lopez-Lefebre, L.R., Sánchez, E. & Romero, L. 2001 Resistance to cold and heat stress: Accumulation of phenolic compounds in tomato and watermelon plants Plant Sci. 160 315 321
Rugkong, A., McQuinn, R., Giovannoni, J.J., Rose, J.K. & Watkins, C.B. 2011 Expression of ripening-related genes in cold-stored tomato fruit Postharvest Biol. Technol. 61 1 14
Saltveit, M. & Morris, L. 1990 Overview on chilling injury of horticultural crops, p. 3–15. In: C.Y. Wang (ed.). Chilling injury in horticultural crops. CRC Press, Boca Raton, FL
Shen, J., Tieman, D., Jones, J.B., Taylor, M.G., Schmelz, E., Huffaker, A., Bies, D., Chen, K. & Klee, H.J. 2014 A 13-lipoxygenase, TomloxC, is essential for synthesis of C5 flavour volatiles in tomato J. Expt. Bot. 65 419 428
Tandon, K.S., Jordan, M., Goodner, K.L. & Baldwin, E.A. 2001 Characterization of fresh tomato aroma volatiles using GC-olfactometry Proc. Fla. State Hort. Soc. 114 142 144
Tieman, D., Bliss, P., McIntyre, L.M., Blandon-Ubeda, A., Bies, D., Odabasi, A.Z., Rodríguez, G.R., van der Knaap, E., Taylor, M.G. & Goulet, C. 2012 The chemical interactions underlying tomato flavor preferences Curr. Biol. 22 1035 1039
USDA 1997 United States standards for grades of fresh tomatoes. 18 May 2015. <http://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELPRDC5050331>
van Gemert, L. 2003 Odour thresholds-compilations of odour thresholds in air, water and other media, 1st ed. Oliemans Punter & Partners BV, Utrecht, The Netherlands
Viljanen, K., Lille, M., Heiniö, R-L. & Buchert, J. 2011 Effect of high-pressure processing on volatile composition and odour of cherry tomato purée Food Chem. 129 1759 1765
Wang, L., Baldwin, E.A., Plotto, A., Luo, W., Raithore, S., Yu, Z. & Bai, J. 2015a Effect of methyl salicylate and methyl jasmonate pre-treatment on the volatile profile in tomato fruit subjected to chilling temperature Postharvest Biol. Technol. 108 28 38
Wang, L., Baldwin, E.A., Zhao, W., Plotto, A., Sun, X., Wang, Z., Brecht, J.K., Bai, J. & Yu, Z. 2015b Suppression of volatile production in tomato fruit exposed to chilling temperature and alleviation of chilling injury by a pre-chilling heat treatment Lwt-Food Sci. Technol. 62 115 121
Yang, X., Song, J., Fillmore, S., Pang, X. & Zhang, Z. 2011 Effect of high temperature on color, chlorophyll fluorescence and volatile biosynthesis in green-ripe banana fruit Postharvest Biol. Technol. 62 246 257