For some cider makers, tannins are the holy grail of the cider business. Without tannins and fermentation, hard cider is merely sweet cider, a confection, and not the beverage whose demand continues to grow significantly.

They are the chemicals in apples that, once they survive fermentation, impart mouth feel and body to cider. And it’s bittersharps and bittersweets that have the highest levels.

In the Mid-Atlantic region of the United States, most of the cider apples grown don’t have elevated levels of tannins, according to Edwin Winzeler, a project assistant at Penn State’s Fruit Research and Extension Center in Biglerville,

Pennsylvania.

The center has a number of ongoing research projects aimed at helping growers successfully grow cider varieties, including those with high tannins.

Properties

Tannins, also known as polyphenols, are the compounds in apples that give cider its bitterness and astringency, Winzeler said.

“Tolerance for bitter flavors varies widely among people. Ciders with excessive bitterness may be either unacceptable or require aging with or without micro-oxygenation,” he said.

From a practical standpoint, there are a number of food and drinks whose popularity is based, in good measure, on their bitterness. “Hops, coffee, dark chocolate, brussel sprouts, all the best things in life,” he said.

Astringency is perceived when polyphenols meet the protein molecules in saliva. It creates a physical perception in the mouth that imparts a texture to the cider.

“It makes the cider feel ‘rough’ or ‘fuzzy.’ It gives ‘grip’ to a cider. It’s like the difference between drinking tea versus drinking water,” he said.

Bittersweet cider flavors imparted by tannins include spice, clover, leather, woody, slightly heavy, less fruity, even medicinal. Bittersharps have similar, though somewhat more intense, flavors, accompanied by elevated acidity.

“Most cider makers do some blending, when working with bittersweet apples,” Winzeler said. “With Dabinett, for example, in most years you would need a sharper apple to lower the pH so as to reduce the potential for microbial spoilage and to increase the acidity.”

Ethrel trial

One of the challenges of growing cider varieties is the need for labor efficiency with small-fruited varieties. One potential solution is a shake-and-catch system augmented with Ethrel (ethephon), which is sprayed at harvest to promote development of the abscission layer in the tree. (Ethrel is not registered for use in Vermont, Rhode Island, Louisiana, Missouri, Nebraska, South Dakota, North Dakota, Montana, Wyoming and Alaska.)

Abscission is a term used to describe how plants shed leaves, fruit, flowers and seed. The abscission layer forms at the base of the pedicel. Its top layer has cells with weak walls and a bottom layer that expands at harvest, causing the top layer to break.

On fruit trees, the abscission layer occurs between the stem of the apple and the tree spur. “We applied it to some crab apple varieties. Some were responsive and some were not,” Winzeler said.

Two of the three varieties they tested, Manchurian crab apples and Hughes’ Virginia, dropped significantly more fruit when shaken and sprayed with Ethrel than when shaken or sprayed alone.

Ethrel is currently labeled for use in sugarcane, pineapples and large-fruited greenhouse tomatoes in Texas, Colorado, California and Pennsylvania. It is also labeled for apples to promote stem loosening.

-by Dave Weinstock