Changes in Pectin Content of Cabernet Sauvignon Grape Berries During Maturation

Transcription

1 Changes in Pectin Cntent f Cabernet Sauvignn Grape Berries During Maturatin MICHAEL W. SILACCI ~ and JANICE C. MRRISN 2. The ttal pectin cntent f Cabernet Sauvignn grapes increased during the perid f rapid berry grwth fllwing veraisn frm 6.8 t.3 mg urnic acid per berry in samples frm Napa and frm 4.7 t 8.1 mg per berry in fruit frm Ldi. Because the increase in pectin was slwer than the berry grwth rate, the cncentratin f pectins decreased during ripening. Mre than 85% f the ttal pectin was extracted frm the cell wall with EDTA. The prprtin f cell wall bund pectin decreased, and water sluble pectin increased during ripening. Althugh the ttal pectin cntent was higher in grapes frm Napa, water sluble pectin was higher in grapes frm Ldi. These differences suggest that vineyard lcatin has an effect n pectin metablism during grape berry grwth and maturatin. KEY WRDS: Vitis vinifera, ripening, pectin Like mst fruit species, grape berries sften during ripening. The degree t which they sften affects press yield, ease f filtratin and clarificatin (9,15), as well as the extractin f anthcyanins (19) and ther cmpunds frm the fruit during wine making. In sme cases, grape maturity and quality fr wine making have been crrelated with textural changes during ripening (9). Crrelatins between fruit sftening and the slubilizatin f pectins have been reprted in many fruit species, including pear (5), bysenberry (11), apple, and strawberry (4). In thse species, increases in the cncentratin f sluble pectins during fruit ripening are assciated with decreases in cell wall bund pectin. The cell walls f grape berries cntain less pectin than thse f many ther fruits. At cmmercial harvest, the ttal pectin cntent f Cncrd (Vitis labrusca) was.29% f berry fresh weight (8). Fr wine grapes (Vitis vinifera), values frm.2% (3) t as high as.6% (reviewed in 1) have been reprted amng different cultivars. Variability in the pectin cntent f grapes als has been attributed t seasnal differences (12), cultural practices (18), and variability within r amng vineyard lcatins (15). As reprted fr ther fruits, a decrease in pectin cncentratin is assciated with grape berry ripening (8,15, 18). Althugh Mrgues (12) reprted a substantial increase in the prprtin f water sluble pectin t ttal pectins in Carignane grapes during ripening, Rbertsn (15) fund n increase in water sluble pectins during the ripening f three ther grape cultivars. The experiments reprted here were designed t study changes in pectin cntent and pectin slubility during ripening f Cabernet Sauvignn grapes. Samples were taken frm tw vineyards f similar age and viticultural practices, ne frm a relatively warm lcatin in the central valley f Califrnia, and the ther frm a relatively cl castal regin, t determine if 1,2Department f Viticulture and Enlgy, University f Califrnia, Davis, CA *Authr t whm crrespndence shuld be addressed. Acknwledgement: The authrs wish t thank Jhn Kautz Farms and Rbert Mndavi Winery. Manuscript submitted fr publicatin: 6 December Cpyright 199 by the American Sciety fr Enlgy and Viticulture. All rights reserved. vineyard lcatin influences the relatinship between fruit ripening and pectin cntent. Materials and Methds Grape berries (Vitis vinifera L. cv. Cabernet Sauvignn) were sampled weekly during ripening frm tw cmmercial vineyards, ne in the Napa Valley and the ther in Ldi, Califrnia. The tw vineyards were chsen fr similarity in age, vigr, and viticultural practices. Bth vineyards were 17 years ld, grafted t A X R#1, spaced 2.4 X 3.7 m, cane pruned and trained t a 4-wire trellis with 6-cm crssarms. Bth are vigrus vineyards planted n deep, fertile sils, and neither vineyard was irrigated during the grwing seasn. The Napa vineyard is in an area classified as regin II (25 t 3 degree days), whereas the Ldi area was classifled as regin IV (35 t 4 degree days) by Amerine and Winkler (2). Weather data were nt cllected at the vineyard lcatins, but during the perid f sample cllectin the mean daily maximum temperature was 28 C in the Napa Valley, and 32 C in Ldi (IMPACT, University f Califrnia Divisin f Agriculture and Natural Resurces). In each vineyard, frty vines f apprximately equal vigr were selected and divided int fur replicates f vines each. Weekly samples were taken frm the nset f ripening (veraisn) until cmmercial harvest in the Ldi vineyard, and until tw weeks after cmmercial harvest in the Napa vineyard. Samples f ten berries were taken randmly frm the shulder area f each f tw clusters per vine, fr a ttal f 2 berries per replicate. Each sample was hmgenized fr minutes in a Waring cmmercial blender, which thrughly hmgenized bth the pulp and skin tissues. The hmgenate was centrifuged at X g fr 15. minutes, then vacuum filtered (Whatman N. 1). Brix levels f the supernatant were determined by refractmeter. The water sluble plysaccharides were precipitated frm the supernatant by adding five vlumes f 95% ethanl and refrigerating vernight. The precipitate was cllected by filtratin, washed with additinal ethanl, and ven-dried at 45 C. 111

2 1 12- PECTIN CNTENT F BERRIES The residue frm the hmgenizatin was biled three times in 95% ethanl fr minutes t remve simple sugars and phenlic cmpunds, which interfere with the m- phenyl phenl assay. Chelatr sluble pectins were extracted frm the residue by biling three times in 2 mm disdium ethylenediaminetetraacetic acid (EDTA), ph 8., with stirring fr minutes, using 5 ml/ g. The samples were vacuum-illtered, and the filtrates cmbined. Hydrxide sluble plysaccharides were extracted frm the EDTA residue by stirring in 5 mm NaH (5 ml/g) fr 15 minutes at rm temperature and filtering. Aliquts f the three pectin-cntaining fractins were diluted apprpriately and analyzed clrimetrically fr urnic acid cntent (6). Ttal pectin cntent was calculated as the sum f the water-, chelatr-, and base-sluble fractins. The data were analyzed by tw-way analysis f variance and by regressin analysis (SAS, Cary, NC). Results A "z=, = rjr~ The ripening perid f the grapes sampled frm the Ldi vineyard extended ver a nine-week perid frm veraisn until cmmercial harvest, when the fruit had reached 22.5 Brix. In the Napa vineyard, cmmercial harvest was eight weeks after veraisn, at 22.9 Brix, but sampling cntinued fr an additinal tw weeks, until the fruit had reached 24.4 Brix ( weeks pst-veraisn). "~.~ Berry grwth and sugar accumulatin during the ripening perid are shwn in Figure 1. Althugh berry.,~ size was similar in the tw vineyards at veraisn, the grwth rate after veraisn and final fruit size were greater in the Napa samples than in.~ thse frm Ldi. The rate f sugar accumulatin was similar in the tw vineyards. The cncentratin f ttal pectic plysaccharides in the fruit decreased after veraisn (Fig. 2). The urnic acid cntent decreased frm.9% t abut.7% f berry fresh weight in samples frm Ldi and in samples frm Napa frm 1.% t abut.8% f berry fresh weight at cmmercial harvest. The cncentra ~. Napa ~. Ldl Weeks After Veraisn m Fig. 1. Change in sluble slids (circles) and berry weight (squares) during ripening. pen symbls represent Napa samples, clsed symbls represent Ldi samples. Errr bars dente p < Napa. Lcii I " l " I " I ' I i Weeks After Veraisn Fig. 2. Changes in cncentratin f ttal acidic plysaccharides during ripening. Errr bars dente p <.5.

3 PECTIN CNTENT F BERRIES Table 1. Urnic acid cntent f Cabernet Sauvignn grapes at the nset f ripening (veraisn) and harvest at tw sampling lcatins. Ttal plyurnide Chelatrsluble Base sluble Water sluble Napa Veraisn Harvest Ldi Late Harvest Veraisn Harvest < tin cntinued t decrease after harvest. The decrease in urnic acid cncentratin crrespnded t the perid f rapid berry grwth immediately after veraisn; the rate f decrease slwed during the latter part f the ripening perid. Unlike cncentratin, ttal plyurnide per berry increased with berry grwth between veraisn and harvest (Table 1). Bth the cntent per berry and cncentratin f ttal pectic plysaccharides were higher in fruit frm Napa than frm Ldi thrughut ripening. In additin t changes in ttal pectin, the distributin amng the three fractins als changed during fruit maturatin. The majrity f the pectic plysaccharides were in the chelatr sluble fractin, which cntained frm 87% t 96% f the ttal plyurnide (Table 2). In samples frm bth vineyards there was an increase in chelatr-sluble plyurnide per berry assciated with pst-veraisn fruit grwth (Table 1). Hwever, the rate f berry grwth was greater than the rate f pectin increase, re- "~ sulting in a decrease in the cncen- "~ tratin f chelatr-sluble plyurnide with ripening (Fig. 3, 4). The prprtin f the ttal pectin in this.- fractin als decreased during ripen-,~ ing in fruit frm bth vineyards (Table 2). The cncentratin f base-sl- ~, uble pectin als decreased during the perid f rapid berry grwth (Fig. 3, 4). Hwever, there was a marked increase in base-sluble pectin per berry during the later stages f ripening (Table 1), resulting in an verall increase in the prprtin f ttal pectin in this fractin during ripening (Table 2). The cncentratin f water-sluble pectic plysaccharides increased during grape berry ripening (Fig. 3, 4), and the increase ver time Table 2. Percentage distributin f urnic acid amng the water-, chelatr-, and base-sluble pectin fractins in grapes frm tw sampling lcatins. Chelatr sluble Base sluble Water sluble Napa Veraisn Harvest Ldi Late Harvest Veraisn Harvest < was highly significant in samples frm bth lcatins (p <.1). The increase in water-sluble pectin per berry was highly crrelated with sugar accumulatin in grapes frm bth the Napa (P=.93) and the Ldi (P-.88) vineyards (Fig. 5). The prprtin f the ttal plyurnide that was in the water-sluble fractin increased frm 2.3% t 7.8% frm veraisn t harvest in the fruit frm Ldi and frm.6% t 4.3% in fruit frm Napa (Table 2). Water sluble pectin cntinued t increase after the fruit had reached cmmercial maturity and accunted fr 7% f the ttal n the final sampling date in the Napa vineyard, tw weeks after cmmercial harvest. Discussin At veraisn, grapes frm the Napa and Ldi vine- I '1 = Chelatr Sluble / -- Ba=MI Sluble I Weeks After Veraisn 1Z "8 Fig. 3. Changes in the cncentratins f chelatr-sluble (in mg/g), and water- and base-sluble (in #g/ g) acidic plysaccharides in fruit frm the Napa vineyard. Errr bars dente p < A

4 114- PECTIN CNTENT F BERRIES tm -w, dl,/ r~ ~. Chelatr Sluble Base Sluble! "! " 1 " "! '~ Weeks After Veraisn 12 I - 8 "6 " 4-2 Fig. 4. Changes in the cncentratins f chelatr-sluble (in mg/g), and water- and base-sluble (in ~g/ g) acidic plysaccharides in fruit frm the Ldi vineyard. Errr bars dente p <.5. J ::L ) P.. r~ l-i aj 7 t n Nape s -! Ldi / ! s Brix Fig. 5. The relatinship between water sluble pectin and sluble slids cntent in fruit frm the Napa and Ldi vineyards. yards had reached nly 53% and 62% f their final size, respectively. The increase in ttal pectic plysaccharides per berry during the ripening perid was therefre prbably due t cell wall synthesis related t fruit grwth. The increase in ttal pectin cntent is in agreement with the results f Sait and Kasai (16). Fruit "~ =L grwth after veraisn is due t cell ~" expansin, and the rati f cell wall t.~, cell vlume decreases, in effect diluting the cncentratin f cell wall cmpnents (). Because the in- " crease in pectin was less than the increase in berry size, the cncentratin f urnic acid decreased, which als has been reprted fr ther grape cultivars (8,12,15,18). The increase in the prprtin f water sluble pectin t ttal pectin during ripening is in agreement with Mrgues (12), wh similarly reprted a substantial increase in sluble pectin in Carignane, but nt with Rbertsn (15), wh fund n ripening related pattern. The clse crrelatin seen here between sugar cncentratin and water-sluble pectin per berry was als reprted fr Cncrd grapes (18). The cncentratins f water-sluble pectins in Cabernet Sauvignn are similar t thse reprted fr Carignane (12). Hwever, the sluble fractin represented abut 23% f the ttal pectin extracted frm Carignane at maturity, but nly abut 7% f the ttal extracted frm Cabernet. The lwer prprtin f pectin in this fractin despite the similar cncentratin can be attributed t the higher cncentratins f cell wall bund pectins detected in the current study. The ttal pectin extracted frm Cabernet Sauvignn was mre than twice that reprted at harvest in Carignane (13,17) and Riesling Silvaner (14). The previus studies, which used xalate t extract pectins frm the cell wall, extracted nly a small percentage f the ttal urnic acid with this chelatr (14,15,17,18). In the current study, EDTA was used t extract cell wall bund pectins, and the vast majrity f the pectin was fund in this fractin. This suggests that EDTA is mre effective than xalate in extracting pectins frm the hmgenized grapes, which may

5 PECTIN CNTENT F BERRIES- 115 cntribute t the higher values fr ttal pectic plysaccharides reprted here. The high pectin cntent may als be partially due t varietal differences. Mre than tw-fld differences in ttal pectin (2), and up t six-fld differences in the cncentratin f water-sluble pectins (7, 9) were reprted amng cultivars. Cabernet Sauvignn may be a high pectin cultivar, with a relatively high prprtin f cell wall bund pectin. Althugh changes in pectin cntent during ripening fllwed similar patterns in fruit frm the tw sampling lcatins, quantitative differences were seen between the tw sets f samples. Cncentratins f ttal pectin and chelatr-sluble pectin were cnsistently higher in grapes frm Napa than thse frm Ldi, despite the larger size f the Napa fruit which might be expected t reduce pectin cncentratin (). Hwever, cncentratins f water-sluble pectins were higher in the Ldi samples, and this trend became mre prnunced with increasing maturity. These differences in the amunt and slubility f pectic plysaccharides indicate an effect f lcatin n pectin metablism in grape berries, which was als suggested by Rbertsn (15). The tw vineyards sampled in this study were similar in age, vigr, and viticultural practices, but the Napa vineyard is in a relatively cl (regin II, 25 t 3 degree days), and the Ldi vineyard in a relatively warm (regin IV, 35 t 4 degree days) area f Califrnia (2). Frm the data reprted here it cannt be determined if the differences in pectin slubility were due t dissimilarities in daily temperature regime r t ther surces f variability between the tw vineyards. Hwever, differences in ther ripening-related metablic prcesses are well knwn between the warmer and cler grwing regins f Califrnia (2). Mthugh bth the cncentratin f ttal pectin and the prprtin f the ttal that was slubilized during ripening were lwer than thse reprted fr many ther fruit species, the general patterns seen here in Cabernet Sauvignn grapes were similar t changes reprted in pear (5), bysenberry (11), apple, and strawberry (4), amng thers. Unlike mst ther temperature fruit species, grape berries cntinue t grw during the ripening perid. Changes in pectin cntent f grapes during ripening are therefre the result f cell wall metablism related t fruit sftening, grwth-related cell wall metablism, and the effect f berry expansin in lwering the cncentratin f pectins by dilutin. Simultaneus fruit grwth and sftening make this a cmplex ripening system, and interpretatins f the bserved changes in grape berry pectin cntent must take int accunt bth f these prcesses. Literature Cited 1. Amerine, M. A., H. W. Berg, R. E. Kunkee, C.S. ugh, V.L. Singletn,and A. D. Webb. The Technlgy f Wine Making (4th ed.). AVI, Westprt, Cnnecticut (198). 2 Amerine, M. A., and A. J. Winkler. Cmpsitin and quality f musts and wines f Califrnia grapes. Hilgardia 15: (1944). 3. Baltaga, S. V., and L. V. Yartskaya. Pectic substances f table wine in cnnectin with grwth cnditins and strage. Abstract frm: Isz. Akad. Nauk. Mld. SSR. 1:7-12 (1975). 4. Bartley, I. M., and M. Knee. The chemistry f textural changes in fruit during strage. Fd Chem. 9:47-58 (1982). 5. Bartley, I. M., M. Knee, and M. A. Casimir. Fruit sftening I. Changes in cell wall cmpsitin and end-plygalacturnase in ripening pears. J. Exp. Bt. 33: (1982). 6. Blumenkrantz, N. and G. Asbe-Hansen. New methd fr quantitative determinatin f urnic acids. Anal. Bichem. 54:484-9 (1973). 7. Brilluet, J.-M. A study f pectic plysaccharides in musts frm varius mature grapes grwn in the Pech Ruge experimental vineyards. Bichimie 69: (1987). 8. Carter, G. H. Pectic substances in 'Cncrd' grapes with relatin t maturatin in Prc. Am. Sc. Hrtic. Sci. 92: (1968). 9. Duburdieu, D., D. Hadjiniclau, and P. Rib6reau-Gayn. Les plysaccharides slubles du mt: methde simple d'appreciatin; evlutin au curs de la maturatin; incidence sur les peratins prefermentaires. Cnnaiss. Vigne Vin 15:29-4 (1981 ).. Jna, R., R. Vallania, and C. Rsa. Cell wall develpment in the berries f tw grapevines. Sci. Hrtic. 2: (1983). 11. Mnr, J. A., and J. Lee. Changes in elements, pectic substances and rganic acids during develpment f bysenberry fruit. J. Sci. Fd Agric. 38: (1987). 12. Mrgues, J. Evlutin au curs de la maturatin des substances pectiques et des plysides neutres nn cellulsiques dans les baies de raisin 'Carignan' et dans les mt3ts. Sci. Aliments 1: (1981). 13. Murgues, J., C. Flanzy, and M. Burzeix. Evlutin des plysides nn cellulsiques au curs du metablisme anaerbie de la baie de raisin. Sci. Aliments 4: (1984). 14. Rbertsn, G. L. The fractinal extractin and quantitative determinatin f pectic substances in grapes and musts. Am. J. Enl. Vitic. 3:182-6(1979). 15. Rbertsn, G. L., R. Eschenbruch, and K. J. Cresswell. Seasnal changes in the pectic substances f grapes and their implicatin in juice extractin. Am. J. Enl. Vitic. 31:162-4 (198). 16. Sait, K., and Z. Kasai. Cnversin f labeled substrates t sugars, cell wall plysaccharides, and tartaric acid in grape berries. Plant Physil. 62:215-19(1978). 17. Saulnier, L., and J.-F. Thibault. Extractin and characterizatin f pectic substances frm pulp f grape berries. Carbhydr. Plymers 7:329-43(1987). 18. Smit, S.J.B., and G. A. Cuvilln. The effect f the Mdified Munsn and 4-arm Kniffen training systems n changes in pectic substances f 'Cncrd' grapes. J. Am. Sc. Hrt. Sci. 96:547-9 (1971 ). 19. Urlaub, R. Pectinl D in the wine industry. Prc. Bichem. 13:14 (1978). 2. Ussegli-Tmasset, L. Le pectine dell'uva Ir evluzine nella vinificazine. Ann. Acad. Agric. Trin 118: (1976).