A Change in Positions
Soluble Solids (^OBRIX) Determinations by Hydrometers and Refractometers
Pest Insects to Consider as We Approach Harvest
Observations from Oregon
Enzymes
Upcoming Events

For the past several seasons, we have received questions about differences in soluble solids (^oBrix) readings as measured with hydrometers and refractometers. An interesting article by Cooke (2) may offer an explanation for the discrepancies between the two methods. The study was made to determine the effect of solids upon the accuracy of hydrometer and refractometer readings of soluble solids in grape juice. Of course, measuring soluble solids is the common method in determining the sugar content in grape musts. At least, 90% of the soluble solids in grapes are sugars.

Cooke (2) presented the results of 245 readings from both hydrometer and refractometer techniques for several grape varieties. For the hydrometer method, all readings were corrected for temperature. Since the refractometer was equipped with a temperature-compensated prism, no correction was necessary. However, an invert sugar "correction factor" (0.022) was added to each percent soluble solids reading. For example, 0.4% (0.022 x 20) was added to a refractometer reading of 20%. According to AOAC (1), this correction is necessary for the refractometer index of glucose and fructose (major sugars in grapes) is much less than sucrose. The refractometer scale is based on sucrose solutions.

Cooke (2) compared hydrometer and refractometer Brix determinations of filtered and unfiltered juices. Results from the unfiltered juices indicated that the hydrometer readings were considerably higher than the refractometer values. The mean differences for three grape varieties (Thompson Seedless, Carignane, and Tokay) were 0.7, 0.6 and 0.4^oBrix, respectively, and were highly significant. However, Brix readings obtained on filtered juices showed no real differences between the two methods, less than 0.1^oBrix. On the basis of these results, it is strongly suggested that suspended solids (pulp) have a significant influence upon the accuracy of hydrometer measurements. Moreover, using a refractometer was found to be more accurate in measuring soluble solids in unfiltered juices. Also, refractometers are simple and rapid to operate.

1. Association of Official Agriculture Chemists. 1960. Official and Tentative methods of Analysis. 9th ed., Washington, D.C.

2. Cooke, G.M. 1964. Effect of grape pulp from soluble solids determinations. Am. J. Enol. Vitic. 15:11-16.

Having just returned from the recent southern Ohio vineyard tour, and visiting two new vineyards, it’s important to note that the grape root borers are very evident in that area. We’ve found that after handling the pheromone for root borers, the insects will be attracted to those people even weeks later! Even though the plantings of vinifera were young at the first two vineyards, there were quite a few adult root borers seen flying about. They were highly attracted to one particular person that had been handling the pheromone.

It was good to see little or no Japanese beetle damage at these southern vineyards as compared to the damage done to our experimental vineyard at the OARDC Snyder farm in Wooster. They have also caused major damage to the blueberry planting at the Snyder Farm.

During the upcoming harvest, keep in mind to watch for yellow jackets, fruit flies and bees. Congratulations to the growers in Southern Ohio on putting on a great tour.

Observations from Oregon by Roland Riesen

Mid-June, temperatures in the low 50's, rain the last few days, a break today, more rain in the forecast for the next few days. The wind is relatively calm, but there is a lot of "smell" in the air: Chemical sprays! The sound of tractors is ubiquitous: everybody is out there taking care of their "darling": the dear and precious Pinot Noir vineyards. Of course there are other cultivars, but Pinot Noir is what is closest to their hearts (and purses!). In the last few years Oregon has gained more and more believers as a prime Pinot Noir growing area challenging the best sites and producers certainly in the New World, but also reaching out to the most famous Pinot Noir region in the Old World - Burgundy. Or maybe it was the other way round: The Old World it extending its reach to Oregon - by investing money and - more important - knowledge and experience in new ventures here. Research at Oregon State University has supported these efforts for several years, recently the 2^nd Joint Burgundy-California-Oregon Winemaking Symposium was held at UC Davis (with the 4^th in 2001 being planned in Oregon), the International Pinot Noir Celebration has been a fixture in every Pinot Noir lover’s agenda for nearly a decade. What is behind this success? What’s the current status of the vineyards and wineries? Is there a lesson to learned for Ohio?

The basis for a successful industry - terroir - is well known for Oregon: Cool, rainy, moderate climate subject to big yearly variations with good sites exhibiting excellent meso- and microclimates and soils. The biggest challenge: Exactly these huge yearly fluctuations classically demonstrated in the recent vintages 1994-1998. My observations confirmed that the best growers have learned to do everything in their power to master the vagaries of the weather: By adjusting the planting and maintenance of the vineyards, by being very meticulous about the spray program, by working closely with the winemaker enabling him to adjust the winemaking techniques, by applying the newest research and developments worldwide and establishing their own trials to test the validity. The newest plantings have all reduced the spacing to 3-4 ft between vines and 6-8 ft between rows (mostly 6 ft, depending on equipment). Close attention is payed to each particular site to adjust for vigor and optimum sun exposure. The training systems used are variations of Guyot. Practices to provide adequate fruit exposure are standard, timing and type of which again depend heavily on site and vigor of the vines. Two main clones have been planted in the past: Pommard (FPMS 4) and Wädenswil (FPMS 2A), all vines own-rooted. Newer clones have been added in the last few years: Dijon 113, 114, 115, 667, 777, some of them grafted to mostly 3309 and 101-14, either as prevention or because the vineyard has already been affected by phylloxera (to visit one of the sites I had to wear special shoes in order the prevent further spread; it was sad to see these dying vines . . . Thanks to a less favorable climate and the separation of the vineyards phylloxera is spreading much slower than in California). Other clones and rootstock are included to complement each others strengths and weaknesses. Yields are "Burgundian": 1.5 - 2 t/a (20-30 hl/ha). In years like 1998 (poor bloom and fruitset) nature can even reduce it more (0.75-1.5 t/a!). The reward thanks to a late but lasting burst of nice weather without rain: An outstanding quality with excellent fruit concentration. The wines (barrel samples) are so rich that they are almost atypical for Pinot Noir and Oregon in particular (which was a complaint by one of the winemakers).

Oregon provides a textbook example to study the influence of terroir (which in the narrowest definition includes the winemaker) and winemaking techniques (clones, must preparation, yeast strain, fermentation [temperature, duration], post-fermentation treatment [maceration, clarification], age and type of oak, fining and filtration) on wine type and style. Point in case: Fruit from the same vineyard is shared by several wineries, single-vineyard wines from the same soil type are made by the same winery, wines from different areas with radically different soils are made by the same winery, clones are vinified separately and aged in different types of oak. A paradise for a curious and inquisitive mind (with stressable and durable taste buds)! Common to all wineries in addition to the yield limitation is the extreme care devoted to the fruit once it is in the winery. Pre-sorting of the fruit - with the help of additional lamps for "dark" days - on a conveyer belt is standard. From then on: as gentle and little handling of the fruit and wine as possible, both are as fragile as glass: Little if any pumping, gravity rules, minimal racking, filtration and fining - if at all. Religious topping of the barrels (barrel from which we sampled were marked with little stones or marbles on top of the bungs - even though not more than 30-40 ml were taken out!) and finally lengthy and judicious blending trials, evaluated blind usually by a group of people. Archery Summit Winery has even installed an elevator in order to lift the bottling tank above the bottling line after it has been filled from the barrels - by gravity of course!

Each winery has set up their own experiments, based on their particular interests, and the newest research and information gathered at conferences and meetings which are generally very well attended. The winemakers were very open in sharing these experiments and the corresponding wines with me. After tasting dozens of barrel samples (at almost all wineries in an elegant Pinot Noir glass) I slowly developed a feeling for the differences between the "Willa Kenzie soil" and the "Yamhill area", the Pommard and the Wädenswil clone, and the "winemaker’s" stamp on the wines. As a summary the Pommard clone was a favorite at most wineries with more depth, blue and black fruit, balance and complexity than Wädenswil, which is more the "work horse", a steady and reliable producer with a crisper acid, red fruit and simpler structure. In blends both complement each other very well! From the newer Burgundian clones early indications in Oregon as well as in California seem to favor Dijon 115 (over 113 and 114) and 777 (over 667). Because of the youth of the vines it is too early to draw conclusions about their vineyard performance. RC 212 was one of the most often (and favorite) yeasts used. Other newer Burgundian strains were also evaluated, but PDM (Prise de Mousse) was nearly absent. Enzymes to extract and stabilize color, added prior to the 4-5 days standard cold-soak period, (and to help with clarification since many wineries don’t fine and filter) are common. Fermentation temperatures are in the mid- to upper 80's. The must is pressed depending on the condition of the fruit and extraction of color and tannins, quite often before dryness. Extended macerations are rarely used. After gentle pressing (if at all! If so, press wines are kept separate.), some settling and completion of the malolactic fermentation the wines are bunged up, sealed and left alone as much as possible - until blending, a lengthy and laborious process but considered of utmost importance, and bottling. The marketing crew contributes to the success of the wines with elegantly shaped bottles and an attractive overall package. Because of the shape and size (and weight) of the bottles special boxes had to be created!

How does 1999 look like? On June 21, bloom hadn’t started yet - with temperatures in the 50's and more rain for several more days - at least - in the forecast! The conclusion for Ohio? Even though we are also subject to climatic variations, our weather offers much more stability (excluding the winters, of course) and a warmer and longer growing season which should enable us to ripen Pinot Noir adequately at the appropriate sites in most years. Our climate is comparable to the Finger Lakes where Pinot Noir already has a strong foothold. In cooperation with the industry we have decided a couple of years ago to evaluate the potential of Pinot Noir for Ohio. The setup of the vineyard at Kingsville confirms that we are on the right track to include the experiences from Oregon, New York and other Pinot Noir growing areas.

ENZYMES by Linda King

Many of us use enzymes in our winemaking practices. All of us should.

Since grapes contain substances such as colloids and insoluble solids in the structure of the cell wall, it is very desirable to add enzymes to the must or crushed grapes. The result is a breaking down of the pectin and mucous substances found in these cell walls. Enzymes can even have some benefits in finished wine, although they generally don’t work as well since enzymes are alcohol and SO₂ intolerant to a point.

Some of the reasons enzymes are used include easier filtration, higher juice extraction, ease in pressing, better clarification, and color extraction.

There are some very important facts to remember when you are making your plans to add enzymes. Here are a few do’s and don’ts:

1. Do not add enzymes at the same time as you add SO₂. The SO₂ should be thoroughly mixed into the must. Then it is OK to add the enzyme.

2. Never add an enzyme in the presence of bentonite. The bentonite will remove the enzyme and render it useless.

3. Manufacturers tell us enzymes would love a temperature of 130°F. Of course, that is completely infeasible. Realistically, 68°F is a good temperature to get the enzyme working properly. If the must or grapes are too cold, the enzyme will not begin it’s work very well until the product warms up. The bottom line-as far as enzymes are concerned, the warmer the better.

4. Since enzymes have a more difficult time working in the presence of alcohol, you need to use more of it. Consult the manufacturer for the recommended amount.

5. Don’t expect miracles when it comes to color extraction. One enzyme manufacturer who touts their color extraction enzymes highly has now put a caveat in their printed materials stating that the product only facilitates the extraction and, if the grapes are lacking some compounds, the product won’t work as well. You can read into this what you will.

I highly recommend the use of enzymes, particularly in the high pectin grapes derived from Vitis labrusca. The results speak for themselves, particularly in the aspect of clarification and filtration. There are many products on the market. Each has its own rate of addition and recommended usage. Therefore, it is necessary to consult your manufacturer for this information.

August 12, 1999 (10:00am – 3:00pm) – Winemaker’s Meeting: Tasting of OARDC Experiments in Gourley Hall Conference Room, Dept. of Horticulture & Crop Science, OARDC, 1680 Madison Ave., Wooster, OH 44691. We need your help and expertise! Contact Roland Riesen (phone: 330-263-3814; e-mail: riesen.1@osu.edu) for information and reservation.

August 19, 1999 – TriCounty Grape Growers Twilight Tour. Contact Dave Marrison at phone: 440-576-9008 or e-mail: marrison.2@osu.edu for details.

January 16-20, 2000 - 5^th International Symposium on Cool Climate Viticulture and Enology, Melbourne, Australia. Contact the symposium secretary at ICMS Pty. Ltd., 84 Queensbridge St., Southbank, VIC 3006 Australia, and phone 61 3 9682 0244 or fax: 61 3 9682 0288 or web site: http://www.icms.com.au/coolclimate for details.

Any information provided in this newsletter regarding procedures, products or equipment are provided solely for informational purposes and are not intended for advertisement and endorsement of any procedures, products or equipment, nor criticism of procedures, products or equipment not mentioned. The authors, The Ohio State University, Ohio State University Extension, and Ohio Agricultural Research and Development Center assume no responsibility for the implementation of procedures, products or equipment mentioned in this publication. Readers should follow manufacturers label for specified directions and recommendations.