SAN JOSE -- The American Medical Association recommends that people apply a sunscreen with an SPF of at least 15 to reduce their risk of developing skin cancer. Those doctors, not surprisingly, don't mention anything about skin protection for apples or walnuts, tomatoes or peppers.
But solar radiation also harms fruits and vegetables, destroying 20 percent to 40 percent of some crops each season. Damage from the sun can reduce a fruit from a top-quality, eat-it-fresh product into something that's only suitable for making juice. That hurts the bottom line for farmers. Sun-stressed fruits and vegetables need more water, too.
In response, a Fremont company called Purfresh has created a sunscreen that's applied to fruits and vegetables to protect the harvest. Called Purshade, it's made of multicrystalline calcium carbonate crystals, which ward off the sun's harmful rays, but still allow the photosynthesis that lets fruits and vegetables to grow.
The product, which has an SPF of 45, has been field-tested in California, Australia and Chile, and is now on sale. Purshade isn't available as a consumer product.
"We saw a perfect storm developing," said David Cope, Purfresh's chief executive officer.
Experts say climate change is leading to higher temperatures and water shortages; they worry about food shortages and escalating food prices. And food safety, including the recent scares in the United States surrounding E. coli in spinach, or salmonella in tomatoes and jalapeño peppers, remains a concern.
Purshade can be sprayed on with other pre-harvest sprays, Cope said. Once crops are picked, the substance washes off easily with water. Farmers testing the product have seen higher yields of higher-quality fruits and an increase in the number of harvests during a year, Cope said.
The company is developing an organic version of Purshade.
Purshade follows Eclipse, an earlier sunscreen product from Purfresh specifically designed to protect apples from too much sun exposure.
Over the years, farmers have tried everything from nets to spray-on clay products to protect their crops from solar damage.
Farmers are more satisfied with Purshade than other options, said Mark Frisbie, an agri-chemical distributor in Florida.
"Growers in South Florida can experience severe sunburn or sun-scald on watermelons, peppers and tomatoes," said Frisbie, who works for Howard Fertilizer and Chemical. "The higher SPF factor found in Purshade offers better sun protection on exposed fruit." Purshade is applied three to six times during a season, and typically costs about $100 to $250 per acre per season.
Purfresh was founded as Novazone in 1996, and was renamed Purfresh in 2007 as its product line expanded. In May, it moved its headquarters from Livermore to Fremont. The company sells products that purify and disinfect water, clean fruits and vegetables with ozone, and keep produce fresh during transport. Safeway, Sunkist and Procter & Gamble are among its 320 customers.
The 50-person company closed $25 million in third-round venture funding in February from Foundation Capital of Menlo Park as well as other investors. Cope said Purfresh is bringing a Silicon Valley approach to agriculture, a $32 billion industry in California.