A REFEREED PAPER. Proc. Fla. State Hort. Soc. 116:

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1 Proc. Fla. State Hort. Soc. 116: A REFEREED PAPER 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 ANNE PLOTTO, JINHE BAI AND ELIZABETH A. BALDWIN 1 USDA/ARS Citrus and Subtropical Products Lab. 600 Avenue S, N.W. Winter Haven, FL JEFFREY K. BRECHT University of Florida Horticultural Sciences Department Gainesville, FL Additional index words. Mangifera indica, fruit ripening, postharvest Abstract. Treatments known to inhibit or delay ripening were applied to imported Kent and Tommy Atkins mangoes. Mangoes that were fairly firm, with some ground color development ( Kent ) or hard with slight color blush ( Tommy Atkins ) ripenness stage were treated with 1-methylcyclopropene (1- MCP) at 25 ppm for 24 or 12 hours, respectively, ethanol (5.0 g kg -1 fruit) for 24 or 8 hours, respectively, and heat (38 C, 98% RH) for 24 or 12 hours, respectively. Treated fruit were cut 24 hours after treatment, and stored at 7 C for 12 ( Kent ) and 14 ( Tommy Atkins ) days. For Kent mangoes, 1-MCP and heat treatments decreased fruit firmness, while ethanol treatment maintained firmness similar to control. Similar differences between treatments were observed for cut fruit during storage. Heat treatment resulted in cut fruit with the lowest firmness and titratable acidity. Ethanol treatment significantly decreased the total soluble solids content of cut mangoes compared to all other treatments. After 12 days of storage, cut pieces from ethanol-treated mangoes maintained the best visual quality, and pieces from heat-treated fruit looked overripe. Informal tasting indicated off-flavor in pieces from ethanol-treated Kent mangoes after 8 days in storage. For Tommy Atkins mangoes, ethanol and 1-MCP treatments increased firmness, but only slices from 1-MCP-treated fruit remained firmer in storage. By reducing the duration of ethanol treatment to 8 hours on Tommy Atkins intact mangoes, the off flavor noted for Kent disappeared in stored slices, but other quality parameters were not improved. Heat and 1-MCP treatments resulted in higher L* value of stored cut pieces. Overall, no treatment extended fresh-cut mango shelf life for Tommy Atkins, but for Kent, spoilage was delayed by two days on all treated pieces. Because they require peeling and are juicy, mango fruit are not convenient to eat; additionally, most North American Mention of a trademark or proprietary product is for identification only and does not imply a guarantee or warranty of the product by the U.S. Department of Agriculture. The U.S. Department of Agriculture prohibits discrimination in all its programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or family status. 1 Corresponding author. consumers are unfamiliar with mangoes. Currently, fresh-cut fruit found on supermarket shelves include pineapples, melons, apples, and grapes (Cooperhouse, 2003). Therefore, developing the technology for fresh-cut mangoes would add to the variety of available fresh-cut fruit, and it would offer consumers convenience for an exotic fruit that is both delicious and nutritious. Reports on the physiology and storage of fresh-cut mangoes are limited. Chantanawarangoon (2000) and Tovar et al. (2001) found that cut mangoes produced little CO 2 and ethylene in comparison to whole fruit, indicating that wounding would have a minimal impact on ethylene-induced ripening events. Lower storage temperatures (2 C vs. 5 C, or 5 C vs. 10 C) increased cut mango shelf life (Chantanawarangoon, 2000; Rattanapanone et al., 2001), and a controlled atmosphere with 10 kpa CO 2 extended potential marketability by 2 to 3 d (Chantanawarangoon, 2000; Limbanyen et al., 1998; Rattanapanone et al., 2001). Antibrowning and firming agents may help maintain the visual quality and firmness of mango pieces in storage (Chantanawarangoon, 2000; González-Aguilar et al., 2000). Most of the research and applications to increase shelf life of fresh-cut produce focus on preventing decay and foodborne disease development, and retarding events associated with tissue senescence, including softening and browning (Alzamora et al., 2000). Treatments to prevent these effects are performed on the fresh-cut product. Another concept is to subject the intact fruit to ripening inhibitors before cutting, with the assumption that inhibition has a residual effect on the cut product senescence (Bai et al., 2003; Jiang and Joyce, 2002; Saftner et al., 2001). 1-Methylcyclopropene (1-MCP), a competitive ethylene inhibitor, binds to the ethylene receptors in plant tissue much longer than ethylene (Sisler and Serek, 1997); therefore, it delays senescence of climacteric fruits long after its initial application (Fan et al., 1999; Roh et al., 2001). 1-MCP was recently approved by the Environmental Protection Agency for postharvest use on fruits and vegetables (Federal Register, July 26, 2002), and numerous publications showed its efficacy in retarding ripening events in fruits and vegetables. 1-MCP is therefore a good candidate as a pre-processing treatment for fresh cut products (Bai et al., 2003). Ethanol is another candidate with an inhibitory effect on ethylene production, resulting in delayed ripening in tomatoes (Beaulieu and Saltviet, 1997; Saltviet and Mencarelli, 1988; Yanuriati et al., 1999), avocado, honeydew and muskmelon when injected in the seed cavity (Ritenour et al., 1997), and mangoes (Abdulah and Basiouny, 2000). The mode of action of ethanol in the fruit would be by conversion to acetaldehyde, which in turn acts as an inhibitor of ethylene production (Beaulieu and Saltviet, 1997; Beaulieu et al., 1997). However, in practice, it is safer to use ethanol, less hazardous than acetaldehyde, which is highly volatile and toxic. 394 Proc. Fla. State Hort. Soc. 116: 2003.

2 Heat, primarily used as an alternative to chemicals to disinfect fruit surfaces of insects or fungi, can have positive or negative effects on commodities. In her review of the physiological effects of postharvest heat treatments, Lurie (1998) showed that in most cases, heat treatments (35-40 C) inhibited ethylene synthesis, delayed fruit softening, but sometimes induced higher respiration rates resulting in lower acidity. In some instances, these effects were carried over after treatment (Klein and Lurie, 1990), or stopped as soon as the fruit were removed from heat (Lurie et al., 1996). For mango, however, the effects of heat treatments are variable and depend on cultivar, fruit maturity, preharvest environmental conditions, temperature, and duration of the treatment (Jacobi et al., 2001). Typical treatments of hot water above 45 C tend to increase yellowing of the skin and fruit softening (Jacobi et al., 2001), although in some instances, inhibition of fruit ripening were observed (Mitcham and McDonald, 1997). Imported mangoes are subjected to a quarantine hot water treatment and are the only material available to U.S. freshcut companies during the mango off-season. This study evaluates the residual effects of a second heat treatment on whole mangoes, as well as 1-MCP and ethanol vapors on the subsequent fresh-cut products. Materials and Methods Treatments. Imported Peruvian Kent mango fruit, 360 g to 380 g each, were purchased through a local supermarket. Fruit were placed in a room at 25 C for 24 h, until they reached the RS4 ripenness stage (Miller et al., 1986: fruit fairly firm, with some yellow ground color development). Fruit were then transferred to 15 C (control), or treated. Treatment of whole fruit included ethanol, heat, and 1-MCP. Ethanol-treated fruit were placed in a 30-L sealed glass chamber for 24 h at 23 C, with a beaker containing an initial 5.0 g ethanol (200 proof U.S.P., Millennium Petrochemicals, Inc., Tuscola, Ill.) per kilo of fruit, with a filter paper wick to aid evaporation. After treatment, ethanol remaining in the beaker in the liquid phase was 1.27 g kg -1 fruit. Heat treatment was at 38 C and >98% relative humidity (RH) for 48 h in a Controlled Relative Humidity chamber (Vapor Temp, General Signal, Blue Island, Ill.). Fruit for the 1-MCP treatment were transported to the University of Florida Horticultural Sciences Department facilities, and placed in a 174-L steel chamber at 20 C with 25 ppm 1-MCP (SmartFresh, Agrofresh, Inc., Springhouse, Pa.) vapors for 24 h. After treatment, ethanol- and 1-MCP-treated fruit were returned to 15 C and cut the next day. Imported Mexican Tommy Atkins mangoes, 400 g to 450 g, were obtained through a local supermarket. Fruit at the RS2 ripenness stage (Miller et al., 1986: fruit hard, with slight blush of color), were selected and kept at C for 20 h, then treated with 100 ppm ethylene at 20 C for 24 h to stimulate faster and more uniform ripening (Kader and Mitcham, 1999). Treatments were the same as for Kent mangoes, except that exposure times were reduced by half or more. Ethanol treatment was 5 g kg -1 of fruit for 8 h at 20 C; after treatment, liquid ethanol remaining in the beaker was 3.11 g kg -1 fruit. 1-MCP treatment was 25 ppm for 12 h at 20 C. Heat treatment was 38 C, >98% RH for 24 h. All treated fruit were maintained at 20 C for 24 h post-treatment and before cutting. Control fruit were maintained at 20 C until processed. Processing. Whole fruit were sanitized for 2 min in a solution of 2.7 mm (400 ppm) sodium hypochlorite adjusted to ph 6.5 with citric acid. Before cutting, fruit firmness was measured with a FT-327 fruit pressure tester (Wilson, Yakima, Wash.) mounted on a drill stand and equipped with an 11 mm probe. Each 30 ( Kent ) or 24 ( Tommy Atkins ) fruit were divided into three batches of 10 or eight fruit, respectively, before cutting (i.e., three replications per treatment). Fruit were peeled, halved, and cut into approximately 2.5 cm cubes ( Kent ) or three longitudinal slices ( Tommy Atkins ). Cubes or slices were dipped in a solution of 0.08 mm (5 ppm) chlorine dioxide (ClO 2) (Aquamira, Bellingham, WA) for 30 s, then in a solution of 2% calcium ascorbate (Fluka Biochemika, Buchs, Switzerland) and 1% citric acid (Aldrich Chemical Company, Inc., Milwaukee, Wis.) for 30 s. Chlorine dioxide is an antimicrobial that may be used in wash water of fresh-cut produce (Hodges et al., 2000; Reina et al., 1995; Winniczuk and Parish, 1997; Zhang and Farber, 1996); calcium ascorbate with citric acid was found to have an anti-browning effect on cut mangoes in preliminary trials. After dipping, fruit pieces were drained, then randomly distributed in 970 ml (20 oz) clamshell containers (Pactiv Corp., Lake Forest, Ill.), with 10 pieces ( Kent ) or 5 slices ( Tommy Atkins ) per container (approximately 130 to 360 g, and 100 to 200 g, respectively). Cutting was performed in a 5-7 C cold room, sanitizing and dip treatments were at 5 C, and cut pieces stored at 7-8 C in clamshells. Quality parameters. Cut fruit were evaluated 1, 4, 8, and 12 d ( Kent ), or 0, 3, 7, 10, and 14 d ( Tommy Atkins ) after cutting. Ethylene and CO 2 production were measured by sampling 5-15 ml headspace of 100 to 300 g cut-fruit incubated for 1 h in 1-L sealed mason jars at 8 C. CO 2 production (ml kg -1 h -1 ) was measured on a Perkin Elmer XL (Perkin Elmer Analytical Instruments, Shelton, Conn.) gas chromatograph (GC) equipped with a thermal conductivity detector (TCD) and a CTR 1 column (1.8 m 0.32 cm) packed with porous polymer mixture (Alltech Associates Inc., Deerfield, Ill.). Conditions of the run were isothermal (83 C), helium flow at 80 ml min -1, injection via a 120 µl loop. Ethylene was measured on a HP 5890 Series II GC equipped with a flame ionization detector (FID) and an activated alumina column. Oven, injector, and detector temperatures were 90 C, 70 C, and 250 C, respectively. Surface color of cut fruit was measured with a Minolta CR- 300 Chroma Meter (Minolta, Tokyo, Japan) calibrated to a white plate using the CIE L*, a*, and b* system. Cut fruit firmness was determined using a XT2i texture analyzer (Stable Micro Systems, Surrey, England), calibrated with a 5-kg weight and equipped with a 1-cm diameter probe. The insert distance was 5.0 mm, with a stroke speed of 5.0 mm s -1. For color and firmness, one measurement was taken on each mango cube, and two on each slice. After firmness and color measurements, pieces were homogenized with 1 ml water per g of fruit tissue for 75 s, and frozen. The supernatant of thawed homogenates, centrifuged at g for 15 min, was analyzed for titratable acidity (TA), ph, and soluble solids concentration (SSC). For titratable acidity, a 10-ml sample of the supernatant was titrated with 0.1 N NaOH to a ph 8.1 endpoint using an Orion 950 titrator (Thermo Electron Corporation, Beverly, MA). Soluble solids were determined with a digital ATAGO PR-101 refractometer (Atago Co, Ltd., Tokyo, Japan). Volatile compounds of the homogenate headspace (2 ml homogenate in 6-mL glass vials) were analyzed with a Perkin Elmer 8500 GC equipped with a 0.53 mm 30 m, 1.0 µm film Proc. Fla. State Hort. Soc. 116:

3 thickness, polar Stabilwax column (Restek, Bellefonte, PA) and a FID (Malundo et al., 1997). A sub-sample of each treatment was set aside for daily visual evaluation. Each cube or piece was evaluated by the same person on a 1-5 visual scale, where 5 is excellent, 3 acceptable (lower limit for shelf-life), and 1 unacceptable. Ratings were summed, and divided by the total number of pieces scored at 5 to give a percent quality index. Statistical analyses. Quality parameters were analyzed using the SAS (SAS System Software Version 8, SAS Institute, Cary, N.C.) general linear model procedure (PROC GLM) (SAS, 1999). Separation of means was performed with the Duncan s multiple range procedure. Results and Discussion Before processing, Kent peel color was visually estimated, and measured by colorimetry on Tommy Atkins fruit. Ethanol, 1-MCP, and control intact Kent fruit had a 66% yellow background with some red, and the heat-treated fruit were fully yellow with some red on the fruit surface. For Tommy Atkins, heat-treated fruit were also different from other treatments, with higher L*, a*, and b* values (data not shown), indicating more yellow in the background color. Therefore, for both cultivars, heat treatment (hot vapor) at 38 C for 48 or 24 h seemed to accelerate ripening as measured by skin color. Likewise, skin color yellowing was accelerated with Keitt (Pesis et al., 1997) and Nam Dok Mai (Ketsa et al., 2000) mangoes under similar treatment conditions. In general, hot water dips or vapor heat above 46 C has been reported to induce or accelerate yellowing of treated mangoes (Jacobi et al., 2001). Fruit firmness was lower in 1-MCP and heat-treated Kent fruit compared with control and ethanol treated fruit (Fig. 1A). These results were contrary to results reported for most fruit treated with 1-MCP, which generally maintains firmness after long periods of storage (Bai et al., 2003; Blankenship and Parker, 2001; Fan et al., 1999; Hofman et al., 2001; Jiang and Joyce, 2000). However, when banana ripening was first initiated with ethylene and then the fruit treated with 1-MCP, 1-MCP retarded ripening only when applied 1 d after the ethylene treatment, and had no effect when applied 3 or 5 d later (Jiang et al., 1999). This suggests that the Kent mangoes may have been too ripe to respond to the 1-MCP treatment. Additionally, Kent control fruit remained at 15 C, while 1-MCPand ethanol-treated fruit were in chambers at 20 C and 23 C, respectively, during the duration of the treatment, and 1-MCP-treated fruit were exposed to C during transport to and from Gainesville, possibly explaining why 1-MCPtreated fruit softened faster than control. These differences in firmness were also observed on the cut fruit (Fig. 1B). To avoid this experimental inconsistency in the subsequent experiment with Tommy Atkins, control fruit were maintained at 20 C, as were treated fruit. As a result, 1-MCP-treated Tommy Atkins mangoes were as firm as ethanol-treated and control fruit on the day of processing (Fig. 2A); 1-MCP treatment also maintained higher firmness of cut slices during storage (Fig. 2B). Bai and co-workers (Bai et al., 2003) found a similar response with Gala apple slices pre-treated with 1-MCP before cutting. Overall, firmness of cut mangoes decreased in storage for both cultivars (Figs. 1B and 2B). Heat-treated Kent fruit were softer than other treatments (Fig. 1A), and some fruit were discarded due to anthracnose Fig. 1. Kent mango firmness. A: whole fruit before processing. B: cut fruit. Different letters indicate significant differences between treatments (A), and between treatments and between observation days (B) by Duncan s multiple range test, 5% level. rot. Based on these results, duration of heat treatment was decreased by half for Tommy Atkins. Heat-treated Tommy Atkins were also softer (22 N) than ethanol- and 1-MCP-treated fruits (27 N and 25 N, respectively; Fig. 2A), without, however, reaching the low level of Kent (17 N heat-, vs. 37 N and 25 N for ethanol- and 1-MCP-treated fruit, respectively, Fig. 1A). Ethanol-treated fruit were similar to or firmer than control for both cultivars (Figs. 1A and 2A). Firmness of cut pieces from ethanol-treated Kent mangoes was higher than 1- MCP- and heat-treated pieces during the 12-d experiment (Fig. 1B), but decreased to the levels of control and heattreated fruit for cut Tommy Atkins after 7 d in storage (Fig. 2B). In other experiments, ethanol vapors resulted in higher firmness of intact Tommy Atkins (Abdulah and Basiouny, 2000), but not Keitt mangoes (Burdon et al., 1994). It appears that ethanol vapors have different effects on fruit ripening, depending on the species (Ritenour et al., 1997) and the maturity stage at the time of treatment (Beaulieu and Saltviet, 1997). Ethanol applied to whole Gala apples did not result in firmer slices compared with 1-MCP and heat treatments (Bai et al., 2003). While CO 2 production of Kent cut mangoes increased over time in storage at 7 C (Table 1), there was no difference between treatments (Tables 1 and 2). On the other hand, for Tommy Atkins, cut pieces from heat-treated fruit generally had lower respiration rate during most of the experiment, but there was no increase in respiration during storage (Table 1). Bai and collaborators (Bai et al., 2003) found that heat-treat- 396 Proc. Fla. State Hort. Soc. 116: 2003.

4 Fig. 2. Tommy Atkins mango firmness. A: whole fruit before processing. B: cut fruit. Different letters indicate significant differences between treatments (A), and between treatments and between observation days (B) by Duncan s multiple range test, 5% level. ed intact apples yielded slices that exhibited reduced fruit respiration. Ethylene production was at the lower limit of instrument detection and no differences were discernible (data not shown). By measuring respiration rate and ethylene production of whole and cubed mangoes, Chantanawarangoon (2000) concluded that wounding had a minor effect on the physiology of fresh-cut mango. Soluble solids content was lower in cut Kent fruit treated with ethanol, indicating less starch degradation to soluble sugars (Fig. 3A). Levels of SSC declined for heat pre-treated cut fruit in storage (Fig. 3A). For Tommy Atkins, SSC of ethanol pre-treated fruit was initially higher than control (Fig. 3B); in storage, cut slices from 1-MCP-treated fruit had lower SSC compared to control (5.2% vs. 6.3%, 7 and 14 d in storage). While cut fruit from pre-treated mangoes maintained levels of SSC, SSC of control slices increased during storage for Tommy Atkins (Fig. 3B). Titratable acidity of Kent cut mangoes was lower in heattreated fruit compared with the other treatments (Fig. 4A); 1- MCP-treated fruit showed a decrease in TA over time. While a general decrease in acidity was observed in Tommy Atkins cut fruit during storage (Fig. 4B), there was overall little significant difference between treatments (Table 2). Lower soluble solids and higher TA indicate slower ripening, since soluble sugar levels increase during ripening due to starch degradation, and citric acid is a metabolic substrate in respiration. Burdon et al. (1994) found an enhanced ripening effect from heat treatment on Keitt mangoes (higher SSC and lower TA), and no effect from ethanol treatment. On the other hand, SSC was significantly less and TA higher (ripening delayed) in ethanol-treated Tommy Atkins mangoes (Abdulah and Basiouny, 2000). These conflicting results indicate that the response of mango to these treatments is cultivar, and perhaps maturity dependent. Cut pieces from heat-treated Kent mangoes were darker as indicated by the L* value of the CIE Lab color space (Fig. 5A). The hue angle was also smaller (data not shown), and they appeared more orange or overripe, and had a lower visual appreciation (Fig. 5A insert). Pieces from ethanol-treated and control fruit were lighter at the end of storage than were pieces from heat- or 1-MCP-treated mangoes (Fig. 5A). For Tommy Atkins, there was no difference between treatments for L* value on the day of cutting, but L* value of control and ethanol pre-treated fruit slices decreased on the third day in storage, and remained lower than heat and 1-MCP pretreated slices (Fig. 5B). This indicates that Tommy Atkins responded positively to the 1-MCP and heat treatments for flesh color, but there was no difference in visual quality between treatments. Tommy Atkins cut fruit showed more browning in the vascular tissue than was observed on Kent cut fruit. Additionally, we noticed that spoilage (visual evaluation) was delayed by two days on all pre-treated Kent cut pieces. Ethanol content was significantly higher in ethanol pretreated Kent cut fruit ( µl L -1 for ethanol-treated fruit, vs µl L -1 for control). This imparted a distinct fermented-like flavor to the cut pieces, as indicated by informal tasting. Ethanol content in ethanol pre-treated Tommy Atkins cut fruit was also initially higher than in the control and 1-MCP treatments (84 µl L -1, vs. 28 µl L -1 and 34 µl L -1, respectively), and this was also perceived as an off-flavor. However, it decreased to the levels found in the control and 1-MCP treated fruit after 3 d in storage, and off-flavor was no longer perceived. Also, the level of ethanol in Kent tissue from fruit exposed to ethanol vapor for 24 h was initially 10-fold higher than ethanol in Tommy Atkins tissue from fruit exposed to ethanol vapor for 8 h. Heat treatment resulted in higher ethanol content than control in both cut Kent and Tommy At- Table 1. CO 2 production by Kent and Tommy Atkins cut mangoes pre-treated with ethanol vapors, 1-MCP or vapor heat (38 C) prior to cutting. Days after cutting Control Ethanol 1-MCP Heat Kent bc z 10.4 c 14.7 abc 13.2 bc ab 16.0 abc 18.0 ab 17.2 ab a 17.0 ab 20.8 a 20.5 a Tommy Atkins bcd 10.6 ab 13.8 a 6.5 cd bcd 6.0 d 7.9 bcd 6.1 cd ab 7.5 bcd 11.3 ab 7.8 bcd ab 10.0 abc 10.8 ab 8.4 bcd z Means (n = 3) followed by the same letter are not significantly different by the Duncan s multiple range test at the 5% level. Proc. Fla. State Hort. Soc. 116:

5 Table 2. F-value and significance for physiological and quality parameters of Kent and Tommy Atkins cut mangoes treated with 1-MCP, ethanol or vapor heat prior to cutting and stored for 12 and 14 days, respectively. Source of Variation df CO 2 firmness TA ph SSC L* a* b* a*/b* Kent Treatment *** z 19.6*** 29.8*** 17.4*** 61.6*** 9.7*** 7.4*** 12.8*** Day *** 32.3*** 4.6** 11.7*** 3.2* 17.3*** 29.7*** 37.9*** 33.2*** Trt day Tommy Atkins Treatment 3 8.0*** 11.8*** * 23.8*** 6.0*** 11.0*** 7.4*** Day 4 4.1* 34.2*** 9.0*** *** 54.7*** 21.1*** 44.4*** Trt day ** 1.78* 3.1*** 2.1* z ***: sign. at P < 0.001; **: sign. at P < 0.01; *: sign. at P < 0.05 kins fruit, with no trend during storage ( µl L -1 ). Cut mangoes from heat-treated intact fruit also tasted over-ripe. Acetaldehyde was higher in the tissue of ethanol pre-treated Kent mangoes than in control, heat-, and 1-MCP pre-treated fruit (42-50 µl L -1 vs µl L -1 ); it was also higher in Tommy Atkins ethanol-treated fruit at day 0, and in the tissue of heat pre-treated Tommy Atkins slices 0, 7, 10, and 14 d in storage, in comparison with control and other pre-treated sli ces (14-30 µl L -1 vs. 1-9 µl L -1 ). Acetaldehyde is converted from excess ethanol in plant tissue when ethanol is exogenously applied or resulting from anaerobic environment (Beaulieu et al., 1997). Increased acetaldehyde was found in mango (Burdon et al., 1994) and tomato (Beaulieu and Saltviet, 1997; Beaulieu et al., 1997) tissue exposed to exogenous ethanol vapor, and in mango tissue exposed to high N 2, low O 2 (Burdon et al., 1994). High ethanol from heat treatments, seen in both cultivars, resulted in increased acetaldehyde in Tommy Atkins mangoes only, suggesting the conversion of ethanol to acetaldehyde may be cultivar or maturity dependent. Beaulieu and Saltviet (1997) proposed a mechanism by which acetaldehyde, at low concentration in the tissue, could enhance ripening by stimulating non-enzymatic ethylene production, or at high concentration, denature and inhibit ACC oxidase activity and therefore, retard ethylene synthesis and ripening. In this study, there was a residual ripening inhibition effect (higher firmness, lower SSC, higher L*) of a 24-h ethanol application on Kent pre-treated mango pieces compared with heat and 1-MCP treatments, but the ripening effect of increased acetaldehyde from the heat treatment in Tommy Atkins was only seen as a lower respiration rate (Table 1) and higher L* value (Fig. 5B). These results support Beaulieu and Saltviet s proposed mechanism, and suggest that the effect of acetaldehyde may be concentration dependent. In summary, ethanol vapor applied for 24 h to intact Kent mangoes had some delayed ripening effect on cut pieces (color, firmness, SSC), but induced unacceptable off-flavor. Decreasing the application of ethanol with Tommy Atkins to 8 h resulted in firmer fruit after treatment, without residual effect Fig. 3. Changes in soluble solids concentration (SSC) in Kent (A) and Tommy Atkins (B) cut mangoes. Different letters indicate significant differences between treatments and between observation days by Duncan s multiple range test, 5% level. Fig. 4. Changes in titratable acidity (TA) in Kent (A) and Tommy Atkins (B) cut mangoes. Different letters indicate significant differences between treatments and between observation days by Duncan s multiple range test, 5% level. 398 Proc. Fla. State Hort. Soc. 116: 2003.

6 Fig. 5. Changes in L* value and visual quality index for Kent (A) and Tommy Atkins (B) cut mangoes. Different letters indicate significant differences between treatments and between observation days by Duncan s multiple range test, 5% level. on cut pieces in storage. Off-flavor in slices from ethanol-treated Tommy Atkins fruit was only perceived on the first day. 1- MCP applied to intact fruit was effective at retarding softening of cut fruit for Tommy Atkins but not Kent. Cut slices from 1-MCP-treated whole Tommy Atkins fruit remained firmer and lighter during storage. Heat treatments increased fruit softening in both cultivars, and decreased titratable acidity and visual quality in Kent cut pieces, which appeared overripe, and had a fermented taste. Temperature before and during the treatment, as well as fruit maturity appear to be important factors influencing the effect of ripening inhibitors on mangoes. In future research, it is hoped that 1-MCP and ethanol pre-treatments could be fine-tuned to benefit the shelf life and quality of fresh-cut mangoes. Literature Cited Abdulah, A-S. and F. Basiouny Effect of elevated CO 2 liquid coating and ethylene inhibitors on postharvest storage and quality of mango. Phyton Buenos-Aires. 66: Alzamora, S. M., A. López-Malo, and M. S. Tapia (eds.) Minimally Processed Fruits and Vegetables. Fundamental Aspects and Applications. Aspen Pub., Gaithersburg, MD. Bai, J., E. A. Baldwin, R. C. Soliva Fortuny, J. P. Mattheis, R. Stanley, C. Perera, and J. K. Brecht Effect of pretreatment of intact Gala apple (Malus domestica, Borkh) with ethanol vapor, heat or 1-methylcyclopropene on quality and shelf life of fresh-cut slices. J. Amer. Soc. Hort. Sci. (in press). Beaulieu, J. C. and M. E. Saltveit Inhibition or promotion of tomato fruit ripening by acetaldehyde and ethanol is concentration dependent and varies with initial fruit maturity. J. Amer. Soc. Hort. Sci. 122: Beaulieu, J. C., G. Peiser, and M. E. Saltveit Acetaldehyde is a causal agent responsible for ethanol-induced ripening inhibition in tomato fruit. Plant Physiol. 113: Blankenship, S. M. and M. L. Parker Influence of 1-methylcyclopropene on shelf life of peach and nectarine cultivars. HortScience 36:468 (Abstr.). Burdon, J. N., S. Dori, E. Lomaniec, R. Mariansky, and E. Pesis Effect of pre-storage treatments on mango fruit ripening. Ann. App. Biol. 125: Chantanawarangoon, S Quality maintenance of fresh-cut mango cubes. M.S.Thesis, Univ. of Calif., Davis. Cooperhouse, H. L Innovations in fruit technology. Fresh Cut Magazine, February Fan, X., S. M. Blankenship, and J. P. Mattheis Methylcyclopropene inhibits apple ripening. J. Amer. Soc. Hort. Sci. 124: Federal Register Environmental Protection Agency, 40 CFR Part Methylcyclopropene; Exemption from the Requirement of a Tolerance. Federal Register, July 26, 2002, Volume 67, Number 144, page González-Aguilar, G. A., C. Y. Wang, and J. G. Buta Maintaining quality of fresh-cut mangoes using antibrowning agents and modified atmosphere packaging. J. Agric. Food Chem. 48: Hodges, D. M., C. F. Forney, and W. Wismer Processing line effects on storage attributes of fresh-cut spinach leaves. HortScience 35: Hofman, P. J., M. Jobin-Décor, G. F. Meiburg, A. J. Macnish, and D. C. Joyce Ripening and quality response of avocado, custard apple, mango and papaya fruit to 1-methylcyclopropene. Austral. J. Expt. Agr. 41: Jacobi, K. K., E. A. MacRae, and S. E. Hetherington Postharvest heat disinfestation treatments of mango fruit. Sci. Hort. 89: Jiang, Y., D. C. Joyce, and A. J. Macnish Response of banana fruit to treatment with 1-methylcyclopropene. Plant Growth Regul. 28: Jiang, Y. and D. C. Joyce Effect of 1-methylcyclopropene alone or in combination with polyethylene bags on the postharvest life of mango fruit. Ann. App. Biol. 137: Jiang, Y. and D. C. Joyce Methylcyclopropene treatment effects on intact and fresh-cut apple. J. Hort. Sci. Biotech. 77: Kader, A. A. and E. J. Mitcham Optimum procedure for ripening mangoes, p In: Kader A.A. (ed.). Management of fruit ripening. Postharvest Hort. Series no. 9., Univ. of Calif., Davis. Ketsa, S., S. Chidtragool, and S. Lurie Prestorage heat treatment and poststorage quality of mango fruit. HortScience 35: Klein, J. D. and S. Lurie Prestorage heat treatment as a means of improving poststorage quality of apples. J. Amer. Soc. Hort. Sci. 115: Limbanyen, A., J. K. Brecht, S. A. Sargent, and J. A. Bartz Fresh-cut mango fruit slices. HortScience. 33:457 (Abstr.). Lurie, S Postharvest heat treatments. Postharvest Biol. Technol. 14: Lurie, S., A. Handros, E. Fallik, and R. Shapira Reversible inhibition of tomato fruit gene expression at high temperature. Plant Phyiol. 110: Malundo, T. M. M., E. A. Baldwin, M. G. Moshonas, R. A. Baker, and R. L. Shewfelt Method for the rapid headspace analysis of mango (Mangifera indica L.) homogenate volatile constituents and factors affecting quantitative results. J. Agric. Food Chem. 45: Miller, W. R., D. H. Spalding, and P. W. Hale Film wrapping mangos at advancing stages of post-harvest ripening. Trop. Sci. 26:9-17. Mitcham, E. J. and R. E. McDonald Effects of postharvest heat treatments on inner and outer tissue of mango fruit. Trop. Sci. 37: Pesis, E., M. Faure, and R. Mariansky-Ben Arie Induction of chilling tolerance in mango by temperature conditioning, heat, low O 2 and ethanol vapours. Acta. Hort. 455: Rattanapanone, N., Y. Lee, T. Wu, and A. E. Watada Quality and microbial changes of fresh-cut mango cubes held in controlled atmosphere. HortScience 36: Reina, L. D., H. P. Fleming, and E. G. Humphries Microbiological control of cucumber hydrocooling water with chlorine dioxide. J. Food Protection. 58: Ritenour, M. A., M. E. Mangrich, J. C. Beaulieu, A. Rab, and M. E. Saltveit Ethanol effects on the ripening of climacteric fruit. Postharvest Biol. Technol. 12: Roh, K. A., K. C. Son, Y. H. Lim, E. S. Oh, B. C. In, and E. C. Sisler Effect of 1-MCP and its derivatives on ethylene binding in banana ripening. J. Korean Soc. Hort. Sci. 42: Saftner, R. A., J. H. Bai, and Y. S. Lee A preprocessing vapor treatment of early climacteric honeydew with 1-methylcyclopropene and a postprocessing dip of fresh-cut honeydew in chlorine water supplemented with a calcium chelate maintains quality and extends the shelf-life of fresh-cut honeydew. HortScience 36:526 (Abstr.). Proc. Fla. State Hort. Soc. 116:

7 Saltviet, M. E. and F. Mencarelli Inhibition of ethylene synthesis and action in ripening tomato fruit by ethanol vapors. J. Amer. Soc. Hort. Sci. 113: SAS SAS/Stat User s Guide, Version 8. SAS Institute Inc., Cary, NC. Sisler, E. C. and M. Serek Inhibitors of ethylene responses in plants at the receptor level: Recent developments. Physiol. Plant. 100: Tovar, B., H. S. García, and M. Mata Physiology of pre-cut mango. I. ACC and ACC oxidase activity of slices subjected to osmotic dehydration. Food Res. Intl. 34: Winniczuk, P. P. and M. E. Parish Minimum inhibitory concentrations of antimicrobials against micro-organisms related to citrus juice. Food Micro. 14: Yanuriati, A., G. P. Savage, and R. N. Rowe The effect of ethanol treatment on the metabolism, shelf life and quality of stored tomatoes at different maturities and temperatures. J. Sci. Food Agric. 79: Zhang, S. and J. M. Farber The effects of various disinfectants against Listeria monocytogenes on fresh-cut vegetables. Food Micro. 13: Proc. Fla. State Hort. Soc. 116: A REFEREED PAPER EFFECT OF 1-MCP PRETREATMENT, CA STORAGE AND SUBSEQUENT MARKETING TEMPERATURE ON VOLATILE PROFILE OF GALA APPLE JINHE BAI AND ELIZABETH A. BALDWIN 1 USDA/ARS Citrus & Subtropical Products Lab. 600 Avenue S, N.W. Winter Haven, FL JAMES P. MATTHEIS USDA/ARS, Tree Fruit Research Lab. Wenatchee, WA Additional index words. 1-methycyclopropene, alcohol, aroma, controlled atmosphere, ester, Malus xdomestica Abstract. Gala apples pretreated or non-treated with 1-methylcyclopropene (1-MCP, µl L -1 ) were stored under controlled atmosphere (CA, 2 kpa O kpa CO 2 ) or regular air (RA) for 6 months at 1 C. Aroma compounds (measured by gas chromatograph and electronic nose) were analyzed every month directly and after transferring to 20 C for one week to simulate marketing conditions. The effect of 1-MCP was stronger than CA after transfer of fruit to room temperature. For electronic nose data, canonical discriminant analysis separated the storage treatments (1-MCP + CA, 1-MCP, CA, RA), indicating that the aroma profile was different in apples from each treatment. This was confirmed by GC analysis. Fruit lost most of the esters but not alcohols after transferring apples from 1 C to 20 C for all treatments. 1-MCP + CA inhibition of volatile production was greater, and did not show any benefit for maintaining firmness and acidity, compared to 1-MCP alone. Therefore, 1-MCP alone was the best treatment for storing Gala apples with minimal loss of volatiles, while maintaining firmness and acidity. Mention of a trademark or proprietary product is for identification only and does not imply a guarantee or warranty of the product by the U.S. Department of Agriculture. The U.S. Department of Agriculture prohibits discrimination in all its programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or family status. 1 Corresponding author; ebaldwin@citrus.usda.gov. To whom reprint requests should be addressed. Controlled atmosphere (CA) storage has been used for apple commercial storage for decades, and had been recognized as the second most practical and effective method, in addition to proper temperature management, for extending the shelf life of intact and fresh-cut fruit and vegetables (Schlimme and Rooney, 1994). Recommended CA conditions were given as 0 C with 1-3 kpa O 2 and 1-5 kpa CO 2, with about 50% of U.S. apple production being stored under CA conditions (Kader, 1989). One of the major effects of CA storage for prolonging shelf life of commodities is inhibition of ethylene production and decreased sensitivity when products are exposed to ethylene. Although most of the ethylene inhibitors, such as aminooxyacetic acid (AOA) and aminoethoxyvinylglycine (AVG), have been found effective for prolonging storage life of commodities, but they can be toxic to fruit tissue and expensive. Sisler and coworkers (1996, 1999) have discovered a very effective ethylene action inhibitor 1-methylcyclopropene (1-MCP) during their searches for the ethylene receptor in plants. 1-MCP can be synthesized easily (Magid et al., 1971), and has been recently approved by Environmental Protection Agency (2002) for postharvest use on apples. Researches using 1-MCP on apples showed positive results in inhibiting ripening and senescence through decreased ethylene production, respiration, softening, loss of titratable acidity, color change and other senescence-related metabolic events (Baritelle et al., 2001; Fan and Mattheis, 1999; Rupasinghe et al., 2000; Saftner et al., 2003; Song et al., 1997; Watkins et al., 2000). In this study we report on the effect of 1-MCP on volatile profile of Gala apple in comparison to apples stored in air or CA. Materials and Methods Gala apples (Malus domestica Borkh.) were harvested from a commercial orchards located in Wenatchee, Wash. on 4 Sept Defect-free fruit were randomly divided into two groups, one for 1-MCP treatment and one for a non-treated control. Pretreatment with 1-MCP was immediately per- 400 Proc. Fla. State Hort. Soc. 116: 2003.