By Blake Jackson
Researchers at Cornell AgriTech have introduced an innovative microwave-vacuum drying technique that turns grape pomace the skins, seeds, and pulp left after juice production into a nutrient-rich, shelf-stable ingredient in just 20 minutes. Traditionally, this process takes more than six hours using standard drying methods.
Grape pomace, known for its high levels of antioxidants such as anthocyanins and phenolic compounds, holds potential as a natural food coloring or as an ingredient in health-oriented foods and supplements. The key challenge has been drying it fast enough to prevent spoilage.
“Conventional drying takes a very long time,” said Viral Shukla, a postdoctoral researcher at Cornell AgriTech. “You have to use forced air, and it can often degrade the nutrients you're looking for.”
Working alongside food scientists Chang Chen and Olga Padilla-Zakour, Shukla explored this new process for Concord grape pomace, of which around 105,000 tons are produced annually in the U.S.
The study revealed that the microwave-vacuum method dries pomace in 20 minutes compared to 400 minutes with traditional heat-based drying while preserving and even enhancing antioxidants. “We also found that the antioxidant, anthocyanin, actually increased because it was protected by the vacuum and through electroporation effects of the microwave,” Shukla said.
Chen added that microwave drying is already a commercialized technology used for products like dried pineapple and Moon Cheese snacks due to its superior texture results.
One promising application for grape pomace is as a red food coloring, particularly as synthetic dyes are phased out by 2026. However, more research is needed to ensure stability under heat and acidity. “When you’re using them in products that receive a lot of heating, or other harsh conditions like acidity, then a lot of the natural colorings may not work very well,” Chen said.
Beyond food coloring, dried pomace could enhance nutritional products such as health bars or smoothie powders. Repurposing this byproduct also offers environmental benefits reducing landfill waste and providing wineries with a new revenue stream.
Photo Credit: istock-jimfeng
Categories: New York, Crops, Fruits and Vegetables, Education