Culinary uses of Rhubarb

Rhubarb or "pie plant" is prized for use in pies, tarts, and sauces. Only the petioles are eaten, although herbal remedies use the leaves and roots. The high levels of oxalic acid and other compounds within the leaves are toxic to humans. The petioles contain lower levels of oxalic acid and, primarily, malic acid.

Harvesting and Preparation  

Rhubarb is sold by the "bunch" which is usually 2 to 2-1/2 lbs., 1 lb. cooked yields 3/4 cup. When buying Rhubarb choose fresh crisp stalks, and peel off any stringy covering before use. Stand the stalks in cold water for an hour or so to refresh them before cooking. The stalks can be stored for 2-4 weeks at 32­ F. A 1 pound bunch contains 3-5 stalks. Before use, discard any leaves and trim the ends. Completely peeling rhubarb is unnecessary. Rhubarb requires sweetening to minimize the extreme tartness. It can be served as a sauce over ice cream, combined with fresh strawberries, or made into pies, tarts, puddings, breads, jam, jellies, and refreshing beverages.

The time of harvest is dependent upon the variety as well as on the location and temperature. With varieties that produce many seed stalks, harvesting should begin before the seeds start to turn color. Home gardeners should remove the seed stalks when they first appear. Generally, harvesting begins in late May or early June, with an option of a second harvest made in late August. A commercially available mechanical Rhubarb harvester can recover 60 to 70% of the crop in a once-over harvest. Approximately 25% of Michigan's Rhubarb is harvested twice. The stalks should be firm at harvest. If they are harvested too late they become pithy and tough. In Maryland I can continuously harvest from 3 plants starting in early May and continuing through to the end of the summer if I water regularly. I pick 2-4 stalks at a time from each plant and can do this almost weekly. I leave most of the plant intact to keep it actively growing. Lack of water and the more intense heat in the hotter parts of the summer seems to be what ends my harvest.

Harvesting should be delayed until the second year following planting to permit accumulation of root reserve. During the second year, a light harvest may be taken and normal harvests may begin in the third year. Stalks may be clean cut, taking the entire plant at the soil line or harvesting sequentially by pulling the stalks at the prime size over a period of 4-6 weeks. Do not remove more than 2/3 of the fully developed petiole from any plant at harvest. As stalks are cut, leaves are removed and left in the field or they can be composed.

Select petioles that are bright pink, crisp and free of disease or insect damage. Young, dark pink, smaller diameter petioles are sweeter and more tender than thick, long green ones, but this also depends and the particular variety of Rhubarb. Don't cut the Rhubarb stalks from the plant, but instead snap them off. They will come away quite easily and this is much better for the plant. I grab a stalk right down where it emerges from the ground, and use a sort of rocking, twisting motion. Visualize snapping away a single celery stalk from the bunch. If the stalk is grasped too high it snaps in two. At any given time, harvest less than 1/3 of the stalks from any one plant. Rhubarb may be harvested later but very few stalks should be taken from any one plant.

Storing Rhubarb

Rhubarb, if not used immediately, can be stored by refrigeration, caning, freezing or drying. Here are some very basic procedures for each of these methods.

Refrigeration

Cut all of the leaf away from the Rhubarb petiole and the petioles will keep well in the refrigerator for two to three weeks in sealed plastic bags.

Caning

• An average of 10-1/2 pounds is needed per canner load of 7 quarts; an average of 7 pounds is needed per canner load of 9 pints. A lug weighs 28 pounds and yields 14 to 28 quarts--an average of 1-1/2 pounds per quart.
• Select young, tender, well-colored stalks from the spring or late fall crop.
• Trim off leaves. Wash stalks and cut into 1/2-inch to 1-inch pieces. In a large saucepan add 1/2 cup sugar for each quart of fruit. Let stand until juice appears. Heat gently to boiling. Fill jars without delay, leaving 1/2-inch headspace. Adjust lids and process.
• Process directions for canning Rhubarb in a boiling-water, a dial, or a weighted-gauge canner are given in Table 1, Table 2, and Table 3.

Recommended process time for Rhubarb, stewed in a boiling-water caner

		Process Time at Altitudes of
Style of Pack	Jar Size	0 - 1,000 ft	1,001 - 6,000 ft	Above 6,000 ft
Hot	Pints or Quarts	15 min	20	25

Process Times for Rhubarb in a Dial-Gauge Pressure Caner

			Caner Pressure (PSI) at Altitudes of
Style of Pack	Jar Size	Process Time (Min)	0 - 2,000 ft	2,001 - 4,000 ft	4,001 - 6,000 ft	6,001 - 8,000 ft
Hot	Pints or Quarts	8	6	7	8	9

  Process Times for Some Acid Foods in Weighted-Gauge Pressure Caner

			Canner Pressure (PSI) at Altitudes of
Style of Pack	Jar Size	Process Time (Min)	0 - 1,000 ft	Above 1,000 ft
Hot	Pints or Quarts	8	5	10

Freezing

Choose firm, tender, well-colored stalks with good flavor and few fibers. Wash, trim and cut into lengths to fit the package. Heating Rhubarb in boiling water for 1 minute and cooling promptly in cold water helps retain color and flavor.

Dry Pack Method: Pack either raw or preheated Rhubarb tightly into containers without sugar. Leave head space (see table below). Seal and freeze.

Syrup Pack Method: Pack either raw or preheated Rhubarb tightly into containers, cover with cold 40 percent syrup (see table below). Leave head space (see table below). Seal and freeze.

Head space to allow between packed food and closure

Type of Pack		Container with wide top opening		Container with narrow top opening
	Pint	Quart	Pint	Quart
Liquid pack*	1/2 inch	1 inch	3/4 inch***	1 1/2 inch
Dry pack**	1/2 inch	1/2 inch	1/2 inch	1/2 inch
* Fruit packed in juice, sugar, syrup, or water; crushed or pureed fruit, or fruit juice. ** Fruit or vegetable packed without added sugar or liquid. *** Head space for juice should be 1.5 inches.

Syrups for Use in Freezing Fruits

Type of Syrup	Percent Syrup *	Cups of Sugar **	Cups of Water	Yield of Syrup in Cups
Very Light	10%	?	4	4? cups
Light	20%	1	4	4? cups
Medium	30%	1?	4	5 cups
Heavy	40%	2?	4	5 1/3 cups
Very Heavy	50%	4	4	6 cups
* Approximate. ** In general, up to one-fourth of the sugar may be replaced by corn syrup or mild-flavored honey. A larger proportion of corn syrup may be used if a very bland, light-colored type is selected.

Drying

Wash and remove any blemished areas. Cut off the pulpy ends. Cut into 1/2-inch strips or 1/2-inch cubes. To decrease some of the acidity in the Rhubarb (and reduce the amount of sugar needed to sweeten), pour boiling water over the pieces and let sit for 3 to 5 minutes. Drain. A characteristic of the dried product will be brittle.