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09.15.2006

Sunscreen For Grapes

Before I go shooting my mouth off about how silly an idea this is, I'd like to seriously ask if anyone is aware of any scientific studies that exist, or any precedents that exist in general agriculture about the use of chemical sunscreen on food.

Quintessa, a relatively large and well known Napa winery, has decided to create a concoction of Aloe Vera and Yucca extracts to spray on its grapes to protect them from the late summer sun. Is this a rational move driven by evidence showing such treatments actually work, or yet another example of the pseudo-science that plagues Biodynamic farming -- a regimen of farming which contain a set of practices and proscriptions that range from the highly rational to the just downright stupid?

Or maybe it's just one winery's experiments to see whether something actually works or not? I do hope they'll tell us. For now, I'm rolling my eyes with a chuckle.

Read the full story.

Comments (10)

Tyler T wrote:
09.16.06 at 2:30 PM

Wow, what to say? There has been some studies that looked into the impact of blocking UV-A and UV-B radiation to the fruiting zone of Riesling. The authors wanted to see what increases in UV radiation (due to climate change) may do to grapes. It is well known that UV radiation influences gene expression in plants. From my reading of the study, it would seem to me that sunblocking grapes, particularly red grapes, would be a BAD idea! For starters, removing UV-radiation decreased the amount of carotenoids which are well known precursors to desirable flavor compounds. Additionally, disease resistance and phenolics may be reduced. Finally (this wasn't mentioned by the study) it could impact the transpiration of the berry which may increase the berry's temperature. This can cause problems with phenolic production and flavor compounds (this is an inference from what can happen with sunburn/heat damage to grapes).

Hmmmm...very odd and not very well thought through in my opinion.

Kenny Kahn wrote:
09.17.06 at 5:47 PM

A major quality issues that we face in our North Coast vineyards is heat stress and sunburn. Heat damage, in particular, is a problem for vineyards that have a North/ South aspect; the west side of the fruit zone seems to get fried. You can see and taste a dramatic difference between the fruit on the cooler east side and the fruit from the west.
Among other things, we are experimenting with an organic kaolin clay, Surround, that we spray onto the fruit zone. You have probably noticed and wondered why so many vineyards are white. The clay is white and reflects the sun which reduces thew heat. Thus far, we are pleased with the results and have produced some of our best vintages since using Surround in the last 3 vintages. The clay falls out during fermentation and does not by itself affect the wine's flavor. However, the fruit is superior and we are getting some great results.
Cheers,Kenny

haydn wrote:
09.18.06 at 4:59 AM

There's growing evidence that global waraming is adding to the stress on grapes and the unpredictability of harvests

Mithrandir wrote:
09.18.06 at 11:33 AM

Aren't there canopy management strategies designed to shade the fruit? That seems like the best way to prevent sunburn.

Johnny wrote:
09.19.06 at 1:31 AM

How bad is it already you think?

Kenny Kahn wrote:
09.20.06 at 8:56 AM

yes, there are canopy management strategies that we are trying and with success. When we first planted Blue Rock in 1987,we wanted to be just like the Bordelaise. We adopted their VSP system of trellising which looked great but was improperly suited to our warmer climate. We have modified the canopy by reverting back to a modified T Top which allows for much more even light penetration and heat reduction on the west side. None- the- less, the Surround applications seem to help reduce stress and burn

Sondra wrote:
09.20.06 at 9:07 AM

When I originally read about Quintessa's sunscreen I thought it was very weird, but then seeing the reality of 'fried grapes' on the west side of a vineyard it makes a lot of sense. What I do wonder about is how the clay or aloe vera are really removed before the grapes get to the vat, are they hosed off first?

Kenny Kahn wrote:
09.20.06 at 9:11 AM

can't comment on the Aloe vera. However, the clay is fermented and drops out. It is tastless, oderless, and doesn't have any effect on the fermentation.

Alder wrote:
09.20.06 at 9:58 AM

Sondra,

Thanks for the comments. My understanding (as a non winemaker) is that hosing off grapes is usually a bad idea, as it removes the yeast and pollen that help with fermentation. Usually any dust on the berries will settle out during the barrel aging process and is removed by racking (pouring the wine slowly into a new barrel before cleaning out the sediment) or by filtering before bottling.

paolo wrote:
02.16.07 at 8:04 PM

Yet another chemical going into the wine (sigh). More headaches. More chemical soup and less grape and skill.

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