Commodities / Cucumbers
There is genetic diversity in the appearance of cucumbers in the market place. The components of quality are different for fresh market and processed cucumbers (pickles). The long English or Dutch cucumbers grown in greenhouses will not be discussed here, nor will the smooth skinned Beit Alpha types that are grown in the Middle East and North Africa.
Cucumber fruit quality consists primarily of color, shape, diameter and length that meet market demands. Processors have unique requirements for quality of brine stock, including firmness and lack of carpel separation and specific length to diameter ratios (L/D) for different products. Fresh market cucumbers or "slicers" should have uniform dark green color, small (yellow) ground spot, be straight and have relatively blocky ends.Flavor top
Flavor is a relatively stable characteristic in cucumber fruit. Bitterness is sometimes a problem and is thought to be associated with adverse growing conditions. Plant stress and temperatures above 92˚F or below 60˚F have been cited as contributing to bitterness.
In recent years most commercial varieties of slicing cucumbers have a uniform dark green color. This characteristic has become a standard for the U.S. market. Previously, cucumbers were lighter in color with stippling. Cucumbers for pickling continue to have the lighter color with stippling.
Although the expression of a uniform dark green color is primarily a genetic trait, lack of nitrogen can result in less color intensity. The United States Standards for Grades specify that fruit be "well colored", meaning that not less than three-fourths of the surface of the cucumber is a medium green or darker color, and that at least a light green color extends to the blossom end on one side of the cucumber. Buyers will object to large yellow ground spots where the fruit have lain on the ground. This is more of a problem on bare ground than on black plastic mulch. They are called "yellow bellies" in the trade.
Virus infection can cause a mottling effect in the fruit. Most fresh market varieties have resistance to cucumber mosaic virus (cmv) but few have resistance to watermelon mosaic virus or zucchini yellow mosaic.
Cucumbers are picked by size. If cucumbers are harvested when they are over mature there will be loss of color intensity. In old varieties with black spines the fruit would begin to turn yellow. Cucumbers released in the last ten years have white spines and may lose color intensity, but they do not turn yellow. Overmature fruit are not marketable.
Cucumbers are harvested by size. The United States Standards for Grades specify that U.S. Fancy fruit must not be greater than 2-3/8 inches in diameter or less than 6 inches long. Most slicers are 7 to 8-1/2 inches long. U.S. Large must have a diameter of at least 2-1/4 inches and a length of 6 inches. There is no maximum for either dimension for large. Overmature or "over grown" fruit yield to slight pressure of the thumb. The seeds may be tough and fibrous, and the pulp in the seed cavity is usually watery or jelly-like.
Shape and color are the two main criteria determining quality in the market. Genetics establish the typical shape for a variety. The market demands a uniform and well-formed product. U.S. Standards for "well formed" means that the cucumber is practically straight and not more than very slightly constricted or more than moderately tapered or pointed. The standards include silhouettes of minimum shapes allowed for each grade.
Misshapen fruit usually result from stress or lack of pollination. Stress from lack of moisture during fruit development can result in nubs and curved fruit. Poor pollination or a nitrogen deficiency can cause fruit to be pointed at the blossom end. A deficiency of potassium may cause a distinct tapering of the stem end of the fruit. Any combination of factors that reduce the vigor of the crop could contribute to the development of misshapen fruit and the resulting loss of marketable yield.
Weeds will compete for moisture and may contribute to misshapen fruit. Herbicide injury can reduce vigor of the vines and contribute to poor quality. Foliar diseases will also reduce vine vigor.
Diseases affecting cucumber fruit include angular leaf spot (Pseudomonas lachrymans), scab (Cladosporium cucumerinum), belly rot (Rhizoctonia solani), anthracnose (Colletotrichum lagenarium), phytophthora fruit rot (Phytophthora capsici), cottony leak (Pythium aphanidermatum) and several viruses. Most varieties have resistance to scab and cucumber mosaic virus (cmv). There is no or only intermediate resistance to the rest of the diseases in most varieties of slicers and pickles. Review the claimed resistance for each variety. Recommendations for control are available in the Midwest Vegetable Production Guide or from your local Cooperative Extension Service.Humid, warm and rainy weather presents the best conditions for disease development. Angular leaf spot and phytophthora fruit rot often begin in low or poorly drained areas of the field. Early fruit infections of these diseases are difficult to see in the packing shed.
Fields with phytophthora infections may have to be abandoned.
The skin of the cucumber is very tender and abrasions will leave scars that will reduce the visual quality. Harvest crews must be careful in handling the vines. Care must be taken when harvesting to snap the stem off cleanly and not pull the fruit which can cause some of the flesh to come out of the fruit.
Storage of cucumber is 10 to 14 days at 50˚F to 55˚F with 95% humidity. Cucumbers are subject to chilling injury if stored at lower temperatures. Cucumbers do not produce much ethylene themselves but they are sensitive to it. Cucumbers should not be stored or shipped with produce that generates ethylene.
|Cucumber w/peel 6 slices|
|Weight of Household Measure||% Water||Food Energy
|Protein||Fat||Saturated Fatty Acid||Mono - unsaturated Fatty Acid||Poly - unsaturated Fatty Acid|
|Cholesterol||Carbohydrate||Calcium||Phosphorus||Iron||Potassium||Sodium||Vitamin A (IU)|
|Vitamin A (RE)||Thiamin||Riboflavin||Niacin||Ascorbic Acid|
|(Source: USDA. Nutritive Value of Foods (HG-72), Release 3.2. 1990.)|
Content authors: J. Neibauer and E. Maynard, 2002. Links updated January 2012.