Harvesting by Peel Color to Reduce Bruising of Golden Delicious Apples

Transcription

1 International Journal of Fruit Science, 10: , 2010 Copyright Taylor & Franci Group, LLC ISSN: print/ online DOI: / Harveting by Peel Color to Reduce Bruiing of Golden Deliciou Apple WSFR International Journal of Fruit Science, Vol. 10, No. 2, May 2010: pp. 0 0 Harveting K. Mituhahi-Gonzalez by Peel Coloret al. KAY MITSUHASHI-GONZALEZ, ERIC A. CURRY, JOHN K. FELLMAN, MARVIN J. PITTS, and CARTER D. CLARY Department of Horticulture and Landcape Architecture, Wahington State Univerity, Pullman, Wahington, USA Golden Deliciou apple were harveted at three peel color tage and equilibrated at 22 C for 2 day before inducing bruiing to a contant depth uing an artificial ilicon finger attached to an Intron univeral material teting intrument. After 48 hr, bruied tiue wa liced equentially from the fruit urface in a plane perpendicular to the direction of the applied force until dicoloration wa no longer evident. Thickne and dicolored area of each tiue lice wa meaured uing a digital caliper and total volume of bruied tiue wa etimated. Analyi howed that there wa a ignificant difference in bruie volume between green and yellow peel tage. Suceptibility to bruiing of fruit at the white (intermediary) tage appeared to vary with environmental condition (year to year). Compared with the previou year, the 2008 growing eaon wa cooler and horter and bruie volume at all tage wa greater. Analyi of fruit maturity uggeted bruie volume wa influenced by ripening-induced change in cell tructure, ize, and integrity. Where fruit peel color changed but fleh firmne did not, bruie volume increaed. We conclude that peel color i a better indicator of bruie uceptibility than fruit fleh firmne. KEYWORDS bruiing, bruie volume, kin color, firmne, Malu Addre correpondence to Carter D. Clary, Department of Horticulture and Landcape Architecture, Wahington State Univerity, P.O. Box , Pullman, WA , USA. cclary@wu.edu 166

2 Harveting by Peel Color 167 INTRODUCTION Golden Deliciou apple are often harveted in a ingle pick depending on peel ground color, compared to other cultivar, uch a Gala, that are harveted more than once baed on both red pigmentation and changing ground color. Golden Deliciou apple are harveted approximately 130 day after full bloom (DAFB) (Jackon, 2003) at which time, depending on the eaon, peel color may vary from green (le mature) to yellow (more mature). Roth et al. (2005) reported that bruiing occur more in firmer apple. Hertog et al. (2003) found that fleh firmne meaured by a Magne-Taylor fruit penetrometer (Stable Micro Sytem Ltd., Godalming, Surrey, UK) i affected by the mechanical trength of the tiue. Other have reported that apple fruit fleh firmne i determined by the phyical anatomy of the tiue, including uch component a cell ize, cell hape, and tiue arrangement (Toivonen and Brummell, 2008). Moreover, cell wall thickne and trength, cell to cell adheion, and turgor may influence bruie volume (Harker et al., 1997). Development of internal fruit tructure i influenced by eaonal temperature, which may alter the number of cell in the cortex (Lako et al., 1995). Small cell tend to have greater cell to cell contact, a lower amount of intercellular air pace, and le cell ap (cytoplam and vacuole), making the tiue firmer and le juicy (Harker et al., 1997). During ripening, fruit fleh undergoe degradation reulting in reduced cell wall thickne and leened intercellular adheion (Toivonen and Brummell, 2008). Fruit parenchyma cell often have relatively thin and weak primary cell wall compared to thoe from more vegetative (tructural) tiue, which have a higher proportion of cell with thickened and lignified cell wall, thereby conferring greater trength (Kay, 1997; Toivonen and Brummell, 2008). Roth et al. (2005) alo reported that ofter fruit are le enitive to damage by impact than firmer fruit and, therefore, are le uceptible to impact damage. They howed that reduction in firmne of ripened fruit wa attributable, in part, to increaed enzymatic activity leading to cell wall breakdown. Specifically, polygalacturonae activity increaed exponentially during the firt 30 day after harvet. Cortex tiue from ripe apple ha more intercellular pace and i not a dene a younger, le mature tiue (Glenn and Poovaiah, 1987; Roth et al., 2005). According to Alvarez et al. (2000a, 2000b), the dener the cell, the maller the intercellular airpace are, and the le damage occur when a force i applied. Indeed, Knee (1993) ha uggeted an increae in the number and ize of individual air pace during ripening may partially account for the decline in fleh firmne. Previou reearch on bruiing of Golden Deliciou focued on comparing peel color tage green v. yellow for bruiing uceptibility. Hyde and Ingle (1968), Kvaale et al. (1968), Diener et al. (1979), and Saltveit

3 168 K. Mituhahi-Gonzalez et al. (1984) all concluded, to reduce bruiing of Golden Deliciou apple at harvet, it i advantageou to pick the fruit while the peel i green. Preliminary obervation of bruiing at harvet within everal commercial Golden Deliciou orchard in central Wahington (Mituhahi, unpublihed) indicated a tranitory white peel color, which occur between green and yellow, and may alo be related to bruie uceptibility. The objective of thi reearch wa to determine if bruiing of Golden Deliciou apple at harvet could be reduced by evaluating difference in bruie uceptibility (volume) of fruit harveted at the white peel ground color compared with that of fruit harveted with green or yellow peel color. MATERIALS AND METHODS Experimental Deign and Treatment Thi tudy wa completed over two harvet eaon ( ) in a commercial apple (Malu dometica Borkh cv. Golden Deliciou ) orchard located in Orondo, WA. The experiment wa laid out a a completely randomized deign with three treatment (peel color) each coniting of three fruit harveted from each of 20 tree. Sixty green, white, or yellow apple were harveted at 143, 150, and 158 day after full bloom (DAFB), repectively, in 2007, and 132, 139, and 146 DAFB, repectively, in 2008, a previouly decribed by Mitcham et al. (2006). The orchard wa managed organically and all tree were treated imilarly. Bruie Evaluation and Fruit Quality Analyi Apple were harveted individually into tri-layered European-tyle (Euro) apple boxe and neted in cylindrical hole cut in low-denity foam. An additional foam heet lined the bottom of the box to protect the apple from damage due to handling after harvet (not the focu of thi work). Fruit were tranported to the laboratory, weighed individually, and kept at 22 C for 48 hr to etablih temperature equilibrium. To imulate bruiing by a picker, a ilicon finger wa attached to an Intron Model 1350 (Intron Indutrial Product, Grove City, PA, USA) and diplaced 10 mm in 23 ec into the ide of the apple at approximately the widet equatorial diameter (houlder). Rate of diplacement of the ilicon finger wa the ame for all apple. Fruit were then placed back into the Euro foam boxe, bruied ide up, and kept at 22 C and 68% relative humidity for 48 hr prior to evaluation. Bruie volume wa meaured by removing erial 1 mm tangential ection through each bruied area, perpendicular to the direction of the applied force, uing a tainle teel blade, until dicoloration (brown) wa no longer evident. The bruied (brown) region of each lice wa meaured

4 Harveting by Peel Color 169 at the widet diameter and again at 90 to the widet diameter uing a digital caliper (Model CD67-6, Mitutoyo Corporation, Kawaaki, Japan) and averaged to provide the mean diameter of a circular (aumed) area. Bruie volume per tiue lice wa etimated to be the area thickne (depth). Total bruie depth wa calculated a the um of the depth of affected lice. Total bruie volume wa calculated in cubic millimeter uing the um of bruie volume of individual lice. Apple Quality Evaluation After fruit were bruied, but before licing for bruie volume determination, fleh firmne wa meaured uing a Texture Analyzer (FTA, Gü Manufacturing (Pty) Ltd., Strand, SA) on oppoite ide of each apple after removing about 1 mm of peel tiue. Average value per fruit were ued in tatitical analyi. After fruit were proceed and bruie volume determined, oluble olid content wa meaured from the juice of the apple uing an ABBE Refractometer (American Optical, Model Mark II, Digital Refractometer, Southbridge, MA) and recorded a Brix. To meaure the tarch clearing index, each fruit wa cut tranverely through the equatorial line and the cut urface dipped in 2% iodine/potaium iodide olution (1:4) for 10 ec and left to equilibrate for about 1 min. The tained area of each fruit wa compared to a tandard cale of 1 to 6 (1 = maximum tarch content, 6 = no tarch content) and the value recorded. Acid content expreed in percent malic acid equivalent wa meaured by a titration method uing the Model TIM 850 titration worktation (Radiometer Analytical SAS, Lyon, France). Peel ground color wa meaured uing a Konica Minolta Croma Meter CR 300 (Konica Minolta Sening, Inc., Tokyo, Japan). Value were expreed uing the Commiion Internationale de l Eclairage color ytem with the L*a*b axi repreenting lightne, green-red and blue-yellow, repectively, and tranformed to degree ( ) hue according to Mclellan et al., Internal ethylene concentration (IEC) in each fruit wa evaluated by firt inerting an 18-gauge needle equipped with a rubber eptum through the fruit calyx into the central cavity and withdrawing 1 ml of core ga. Ethylene in the withdrawn ga ample wa meaured by injecting 0.5 ml of the ga into an HP 5880A ga chromatograph with flame ionization detector (GC-FID, Hewlett Packard, Avondale, PA, USA) equipped with a 1 m 3.2 mm i.d. gla column packed with meh Porapak Q (Water Corporation, Milford, MA, USA) in an oven at 40 C according to tandard method. Statitical Analyi Data collected from the two-year trial were combined and analyzed for tatitical ignificance uing the general linear model (GLM) procedure of

5 170 K. Mituhahi-Gonzalez et al. SAS v.9.1 oftware (SAS Intitute, Cary, NC, USA). Difference among treatment were identified uing the Duncan New Multiple Range Tet at P Data within variable were ditributed normally. RESULTS Fruit Quality 2007 v In 2008, anthei wa delayed by about 2 week due to cooler than normal ambient temperature (data not hown). Becaue fruit were harveted at about the ame calendar date a the previou year, the 2008 growing eaon wa, however, about day horter. Although peel color at the time of ampling wa imilar in the two year, comparion of fleh firmne, tarch index, oluble olid, and titratable acidity among year illutrate effect of eaonal temperature difference on fruit quality (Table 1). In 2007, fruit fleh firmne in apple at green and yellow peel color tage wa le than that of fruit ampled at the white tage, wherea in 2008, firmne of green apple wa tatitically different than that of white and yellow apple (Table 1). In 2007 and 2008, firmne wa higher in white apple compared to green and yellow apple. Starch content differed ignificantly among the three color tage and decreaed with ucceive harvet in both year (Table 1). IEC alo increaed with each ubequent ampling, however, only the yellow peel tage howed IEC greater than 1.0 μl l 1. In 2007, although green apple had the lowet titratable acidity, there wa no ignificant difference between white and yellow apple, wherea, in 2008, green and yellow apple howed no ignificant difference, yet both differed ignificantly from white apple. Meaurement of oluble olid content in both 2007 and 2008 howed all tage were ignificantly different, although in 2008 there wa an unexplained increae during the white peel tage (Table 1). Alo in 2008, titratable acidity in white apple wa lower than that of green or yellow apple. Though uncommon, thi pattern occur occaionally (Curry, unpublihed), but i inconitent with typical progreive ripening. Although peel color wa correlated with tarch content, we did not find ignificant correlation among tarch, titratable acidity, and oluble olid content in either year (data not hown). Bruie Volume The relationhip between peel color and bruie volume wa imilar in both year howing a general trend toward greater bruie volume with increaing fruit maturity (Fig. 1). In contrat, the degree to which bruie volume occurred at both green and white peel tage wa ignificantly different among year. Bruie volume of apple harveted at the white color tage

6 TABLE 1 Mean Value of Typical Fruit Quality Parameter for Golden Deliciou Apple Harveted at Three Peel Color Stage in 2007 and 2008 Year Harvet (DAFB) Peel color (viual) Peel color ( hue) Weight (g) Fleh firmne (lb) Starch index(1 6) Soluble olid ( Brix) Titratable acidity (% malic acid) Internal ethylene (μl l 1 ) Green c b a 3.23 a a a 0.28 a 150 White b a b 3.54 b b b 0.74 a 158 Yellow a b a 4.62 c c b 7.47 b Green c a b 3.49 a a b 0.02 a 139 White b b c 4.47 b c a 0.12 a 146 Yellow a b a 4.97 c b b 5.74 b Column value within a year followed by the ame letter are not ignificantly different a determined by Duncan New Multiple Range tet (P 0.05). DAFB = Day after full bloom. 171

7 172 K. Mituhahi-Gonzalez et al Bruie volume (mm 3 ) G W Y G W Peel viual color Y FIGURE 1 Bruie volume (impoed) at harvet a a function of year and peel color: green (G), white (W), and yellow (Y). Bar indicate ± tandard error of the mean. wa imilar to that of fruit at green tage in 2007 and of the yellow tage in In other word, apple at the white peel tage had a tendency to behave a green apple one year and yellow apple the next. Thu, white peel color tage may not be ueful for predicting bruie volume unle pecific environmental and fruit quality parameter are evaluated a well. DISCUSSION Uing tarch index and IEC a criteria, yellow apple in 2007 and 2008 were at imilar tage of phyiological maturity and howed imilar value for bruie volume, even though fruit firmne differed by more than 2 lb (Table 1, Fig. 1). Thi ugget that fruit firmne i not correlated with bruiing. Indeed, Pearon correlation coefficient for bruie volume v. fleh firmne for 2007 and 2008 are quite low (Fig. 2). Further analyi indicate that at none of the peel color tage wa fruit firmne, a meaured uing the FTA, correlated with impoed bruie volume (Table 2). In thi tudy, we choe to evaluate apple fleh characteritic (firmne) uing the FTA rather than a handheld Magne-Taylor fruit firmne teter to: (1) reduce operator and intrument variability and thereby improving accuracy of the meaured value, (2) permit thee experiment to be reproduced more preciely elewhere, and (3) correlate with a previou tudy (Mituhahi et al., 2010). Although, thee data may imply indicate an FTA i not the intrument of choice to predict cell to cell attachment and bruiing uceptibility, other invetigator (Lidter and Tung, 1980; Klein, 1987; Ericon and Tahir, 1996) alo failed to find ignificant correlation between firmne, a meaured

8 Harveting by Peel Color 173 Bruie volume (mm 3 ) r = r = FIRM Fruit fleh firmne (lb) FIGURE 2 Linear regreion and Pearon correlation coefficient (r) for fruit fleh firmne v. impoed bruie volume for Golden Deliciou in 2007 ( ) and 2008 ( ). TABLE 2 Pearon Correlation Coefficient for Fruit Fleh Firmne v. Impoed Bruie Volume at Three Peel Color Maturity Stage for Golden Deliciou in 2007 and 2008 Year Harvet (DAFB) Peel color (viual) Correlation coefficient (r) Green White Yellow Green White Yellow DAFB = Day after full bloom. with a Magne Taylor penetrometer and cortex tiue denity, peel color, or bruiing uceptibility. Ericon and Tahir (1996) bruied apple by dropping them from a pecified height, and determined that maller fruit were le prone to bruiing from high impact energy (dropping) than were larger fruit. Moreover, they reported no difference in bruiing uceptibility with harvet date. Viljoen et al. (1996) and Ericon and Tahir (1996) harveted fruit baed on DAFB and found no ignificant relationhip between bruie volume and peel color. In the preent tudy, apple were approximately the ame weight, but till exhibited different level of bruiing. In fruit uch a apple, oftening involve degradation of large pectin molecule in the middle lamella that bind cell wall together (Kay, 1997). During ripening, enzymatic degradation of cell wall reult in a textural alteration (Kay, 1997). Fruit cell firmne decreae during torage while oluble pectin increae and detachment of cell occur (Glenn and Poovaiah, 1987). We found the number of damaged cell alo increae with ripening, a doe the ize of intercellular pace (Fig. 3).

9 174 K. Mituhahi-Gonzalez et al. A B C FIGURE 3 Graycale light micrograph of Golden Deliciou apple peel cro ection at progreive harvet in 2007: green (A), white (B), and yellow (C) peel color. Note thickening parenchyma and difference in ize of intercellular airpace () a apple ripen. Individual image view field = 1.0 mm. Bar repreent 500 μm.

10 Harveting by Peel Color 175 In thi tudy, there wa a ignificant difference in bruie volume with peel color. Among year, variation of bruie volume with peel color ignificant, epecially at the green and white peel tage. Thi may have been due to environmentally-induced difference in tiue characteritic, ince cell diviion and cell number influence fruit tiue characteritic. Lako et al. (1995) reported Golden Deliciou apple exhibited a poitive curvilinear growth pattern of growth from 32 to 74 day. Moreover, cultivar and environment contributed to the number of cell in the cortex. Smith (1940, 1950) found that cultivar difference in apple ize were due to difference in cell number and cell ize. Such difference could explain, in part, why ome apple cultivar are more bruie reitant than other. In many traditional apple and pear growing area, fruit tend to be maller during cooler eaon or when grown under cooler climate by reaon of latitude or altitude. Perhap, by developing model of fruit growth uing multiple environmental variable, we might be able to predict tiue propertie and bruiing enitivity of apple. CONCLUSIONS Our data ugget everity of bruiing in Golden Deliciou might be reduced by harveting apple while they are green. On the other hand, becaue green apple are normally more firmly attached to the tree than riper fruit, a greater force i uually required to remove them, which could, potentially, increae bruiing incidence. Thu, teaching proper technique in harveting apple remain key to minimizing picker-induced bruiing. LITERATURE CITED Alvarez, M.D., D.E.J. Saunder, and J.F.V. Vincent. 2000a. An engineering method to evaluate the crip texture of fruit and vegetable. J. Texture Studie 31: Alvarez, M.D., D.E.J. Saunder, and J.F.V. Vincent. 2000b. Fracture propertie of tored freh and omotically manipulated apple tiue. Eur. Food Re. Technol. 211: Diener, R.G., K.C. Elliot, P.E. Neelroad, M. Ingle, R.E. Adam, and S.H. Blizzard Bruie energy of peache and apple. Tran. ASAE 22: Ericon, N.A. and I.I. Tahir Studie on apple bruiing. II. The effect of fruit characteritic, harvet date and precooling on bruie uceptibility of three apple cultivar. Acta Agric. Scand. Sec. B. Soil Plant Sci. 46: Glenn, G.M. and B.W. Poovaiah Role of calcium in delaying oftening of apple and cherrie. Potharvet Pomology Nwl. 5: Harker, F.R., R.J. Redgwell, I.C. Hallett, S.H. Murray, and G. Carter Texture of freh fruit. Hort. Rev. 20:

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