- Research Notes -
Evaluation and Characterization of Concord-type Grape Juice Concentrates from the San Joaquin Valley
by
Katherine G. Haight, Barry H. Gump and R. Keith Striegler
CATI Publication #951002
© Copyright October 1995, all rights reserved
INTRODUCTION
Concord (Vitis labruscana Bailey) is the predominant grape cultivar grown in USA viticultural regions outside California. It is used to produce single strength juice, juice concentrate, and wine. Production of Concord grapes has been attempted in the San Joaquin Valley on numerous occasions by both back yard gardeners and commercial growers. Growth, yield, and fruit composition of Concord grapevines is adversely impacted by the hot, dry conditions which occur during the growing season. Therefore the results in the San Joaquin Valley have been uniformly disappointing. Often, fruit will exhibit poor color development and uneven ripening as is seen when Concord is grown in the Southern USA (3,4,12). Consequently, Concord juice and juice concentrate produced from grapes grown in hot climates is not suitable for commercial production. Previous attempts to develop Concord-type cultivars for the San Joaquin Valley resulted in the introduction of Niabell and Early Niabell by H.P. Olmo, Department of Viticulture and Enology, University of California, Davis (9). These cultivars have been used primarily in the home garden.
Grape utilization for juice concentrate production has increased significantly in recent years. With the current emphasis on "healthy foods," consumers are drinking more fruit juices and consuming more foods sweetened with concentrate. Grape juice concentrate is used in a number of processed products, including beverages, fruit spreads, yogurt, and as a replacement for sucrose in cereals and baking products.
The International Trade Centre in 1992 concluded that the fruit juice business would remain a growth industry as foreign consumers become more "health conscious" and change "their eating and drinking habits."(5) The outlook for increased utilization of grape juice concentrate appears to be promising, including exportation to countries such as Japan and Canada(8). However, continued growth of this industry and its maturation from a disposal market for surplus grapes to a primary market for grapes will require additional research and development. Statistics from the U.S. Department of Agriculture reveal that grape juice concentrate consumption in the U.S. rose from 682,000 tons in 1985 to 1.3 million tons in 1992 (1). During that same period California's production of juice concentrate nearly doubled from 350,000 tons to 652,000 tons (1).
Although not currently produced in the San Joaquin Valley, it should be noted that Concord grape juice concentrate is well accepted by consumers. It would enhance grower profitability, if a highly colored Concord-type cultivar were adapted for production in the Valley. Cultural practices and cultivar selection need to be optimized for vineyards in which grapes are grown for juice concentrate production. The major thrust of this work is to develop an experimental "concentrate vineyard" for evaluating [i] common cultivars not currently being used for concentrate production, and [ii] new cultivars especially bred and adapted for concentrate production. While juice concentrate with Concord flavor is currently a fixed market, the demand for products with depth and stability of color expanding.
CULTIVAR SELECTIONS
Following is a brief description of the cultivars selected for use in this study:
Sunbelt: In 1993 this cultivar was released as a new juice grape from the Arkansas Agricultural Experiment Station. Sunbelt may fulfill the need for a juice concentrate grape that can be grown in hot areas where Concord displays uneven fruit ripening (6). This cultivar was derived from open-pollinated seeds collected from Concord grapes in 1968. The vines are vigorous and moderately productive, with small clusters and large berries. Sunbelt's juice characteristics are similar or better than commercially produced Concord grape juice (6).
Cloeta: [America X R. W. Munson] Grapes ripen just after Concord. Juice quality is far better than Concord. The vine is very vigorous and prolific. Cluster and berries are large and black. The skin is thin, while the pulp juicy. (2)
R. W. Munson: [Big Berry X Triumph] The characteristics of this cultivar include strong healthy growth; clusters medium to large, cylindrical, often shouldered, peduncle medium; skin never cracks; tender, juicy pulp. The juice is of very good quality [better than Concord or Beacon]. Ripens just before Concord. (9)
Bailey: [Big Berry X Triumph] The characteristics of Bailey include strong growth, clusters large to very large, cylindrical or often branching, and generally compact. The berries are large; with a thin, tough skin; never cracking. The pulp is meaty and juicy, but not tough. The juice is of very good quality, considerably above Concord. (9)
Extra: [Big Berry X Triumph] The characteristics of Extra include strong growth, clusters sometimes shouldered and moderately compact. The berries are medium to large, dark purple to black, with moderate bloom, skin thin, tough, and never cracks. The pulp is tender, juicy, sweet, and agreeable. (9)
MATERIALS AND METHODS
Grape Cultivars
Grape cultivars utilized in this study were selected for their potential to produce high quality grape juice concentrate, high yields of optimum quality fruit, and to have low maintenance requirements in the vineyard. Cultivars developed by T. V. Munson (9,12) and a new release 'Sunbelt' (6) were included in the study. Grapes used in this project were grown in the San Joaquin Valley of California.
Processing
In 1993, Sunbelt, R. W. Munson, and Bailey were harvested at commercial maturity and transported to the CSUF winery. Grapes from these cultivars were processed separately into concentrate. All samples were frozen and thawed before crushing. Lots of grapes varying between 16 and 22 Kg were crushed manually. GENENCOR PCL5 [pectinase] was diluted to a 10% solution added to the crushed berries at an enzyme dosage rate of 20 ppm. All lots were pressed at 30 psi for 10 minutes, then the pressure was released, the must was mixed and repressed at 30 psi for another 10 minutes in an Enorossi laboratory scale bladder press. Juice samples were stabilized with 1,000 ppm of Velcorin Cold Beverage Sterilant [DMDC]. Juices were racked off gross lees. A portion of these juices were concentrated using a laboratory rotary evaporator.
In 1994, the cultivars; Sunbelt, R. W. Munson, Bailey, Cloeta, and Extra were harvested at commercial maturity and transported to the CSUF winery. This year various processing methods were used. Sunbelt procedures included: [i] hot, [ii] cold, and [iii] freezing processing. The grapes used for hot and cold processing were crushed via garolla style crusher-steamer in three separate batches. Three batches of crushed berries, approximately 76 liters each, were heated to 58-59° C for 12 minutes in a steam kettle with constant stirring. The must was then transferred to a 60 gallon drum while still hot. A macerating enzyme, GIST-BROCADES CYTOLASE M219 was diluted to a 10% solution and added at a dosage rate of 50 ppm. The drum was then stored closed for approximately four hours before pressing the must. This lot [313 Kg] was then pressed in a Wilmes TP-6 bladder press. The procedure for pressing included increments of 10, 20, and 30 psi at 10 minutes duration each. The remaining cake was rearranged and slowly pressed for an additional 10 minute cycle at increasing pressures from 10 to 30 psi.
The cold processed Sunbelt were crushed in three separate lots and then pressed together [320 Kg] on the same day as the hot pressed Sunbelt. The process was similar to that used with the hot pressed Sunbelt except there was no heating of the crushed grapes. The must of the Sunbelt grapes was noted as very fragrant and flavorful with a Concord-like aroma and taste. These juices were racked off gross lees. A portion of each juice was concentrated using a centrifugal flow thin film vacuum evaporator.
Various cultivars were stored frozen. The R. W. Munson grapes were frozen for both 3 days [short term freezing] and four months [long term freezing]. While Bailey, Cloeta, Extra, and a portion of Sunbelt, were frozen for four months and processed separately into concentrate. All samples were frozen and thawed before crushing. Lots of grapes varying between 20 and 31 Kg were crushed via garolla style crusher-steamer. All lots were pressed at 30 psi for 10 minutes, then the pressure was released, the must was mixed and repressed at 30 psi for another 10 minutes in an Enorossi laboratory scale bladder press. Juice samples were stabilized with 1,000 ppm of Velcorin Cold Beverage Sterilant [DMDC]. Juices were racked off gross lees. A portion of these juices were concentrated using a laboratory rotary evaporator. All samples were the analyzed as part of our ongoing grape juice characterization program (3,4).
RESULTS & DISCUSSION
In 1993 samples of Sunbelt, R. W. Munson, and Bailey were evaluated. In 1994 two additional cultivars, Cloeta and Extra, were added to this project. All samples were harvested at commercial maturity and processed separately into juice concentrate.
Various processing methods were used during 1994 [hot press, cold press, & frozen]. These samples were analyzed along with commercial Concord juice concentrate samples from various years produced in New York and Washington states. Even when compared to some Concord grape juice concentrate, hot pressed Sunbelt produced the most intense color to date [Table 1]. The stability of this color is still being evaluated. Phenolic levels in hot pressed Sunbelt and Concord cultivars were fairly similar [Table 2].
It was noted during both 1993 and 1994 processing that Sunbelt had good flavor and aroma characteristics during pressing. During 1993 processing, Bailey was also noted for its good quality aroma during pressing. Nothing was noted during processing of the other cultivars.
"Concord type" experimental cultivars have potential in vineyards, as high color, high sugar, low maintenance grapes. Work is currently underway to develop optimum cultivar and processing practices and better evaluation techniques for determining juice concentrate quality. For maximum color extraction, all cultivars will be hot pressed during the 1995 season.
ACKNOWLEDGEMENTS
We would like to thank the California Agricultural Technology Institute [CATI] for the financial support for this research. The "concentrate vineyard" in the CSU, Fresno Campus Vineyards has also been supported by industry donations of trellis materials, trellis installation, and grafted grapevines.
LITERATURE CITED
1. Anonymous. New cultivars tested for concentrate. Update CSU Fresno California Agricultural Technology Institute. Fall 1994. p. 5 & 7.
2. Anonymous. "Thomas Volney Munson Grape Varieties."
3. Cawthon D. L. , and J.R. Morris. Relationship of seed number and maturity to berry development, fruit maturation, hormonal changes, and uneven ripening of 'Concord' (Vitis labrusca L.) grapes. J. Amer. Soc. Hort. Sci. 107(6): 1097-1104 (1982).
4. Cross, F. B., and J. E. Webster. Physiological studies of uneven ripening of 'Concord' grapes. Proc. Amer. Soc. Hort. Sci. 12: 361-364 (1935).
5. Haight, K. G., and B. H. Gump. "Red and White Grape Juice Concentrate Component Ranges". J. Food Comp. & Anal. 8:71-77 (1995).
6. Haight, K. G., and B. H. Gump. "Characteristics of Components in Red and White Grape Juice Concentrate." Proceedings of California State University, Fresno's Grape Day 1992. August 11, 1992. CATI Publication #920801.
7. Kortbech-Oleson, R. "The World Market for Grape Juice." International Trade Centre UNCTAD/GATT. Prepared for: Food and Agriculture Organization of the United Nations. March 1992.
8. Moore, J. N., J. R. Morris, and J. R. Clark. "Sunbelt, a new juice grape for the South-Central United States." Hort. Sci. 28:859-860. (1993).
9. Munson, T. V. Foundations of American Grape Culture. T. V. Munson & Son. Denison, Texas. 1909.
10. Olmo, H. P. and A. Koyama. 'Niabell' and 'Early Niabell.' Ca. Agr. Expt. Sta. Bul. #790 (1962).
11. "Popularity of Grape Juice Concentrate Helps Growers." American Vineyard. Vol. 2, No. 1, January 1993.
12. Tarara J. M. and E. W. Hellman. The Munson grapes - A rich germplasm legacy. Fruit Cultivars Journal. 44(3): 127-130 (1990).
13. Webster, J. E. and F. B. Cross. The uneven ripening of 'Concord' grapes: Chemical and physiological studies. Okla. Agr. Expt. Sta. Tech. Bul. T-13 (1942).
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CALIFORNIA AGRICULTURAL TECHNOLOGY INSTITUTE - CATI
College of Agricultural Sciences and Technology
California State University, Fresno
