Commodities / Snap Beans
Snap bean quality is a combination of appearance and physical condition. The beans should be well formed, uniform, straight, crisp, have good color and no defects. Except for color and length there is little distinction among varieties. Some varieties have a larger diameter than others or may appear smoother in texture. Quality characteristics of interest to the grower include plant vigor, resistance to lodging, uniformity of set, yield potential, ease of harvest and disease resistance.Flavor top
Fresh snap beans have a relatively uniform flavor. There are differences among varieties but they are difficult to quantify. There is a noticeable difference between snap beans and romano beans, pole beans and White Half Runner beans. Snap beans that have become wilted, have chilling injury or disease may have a poor flavor.
Snap beans increase in fiber as they mature. There are also significant differences in fiber content among varieties. Fresh market snap beans generally have a higher fiber content than processing varieties. Higher fiber content results in less breakage during harvest and handling. Fiber development parallels seed development in those varieties having fiber. When seed development is noticeable in the pod by the swelling each seed causes in the pod, the beans are near the limit of suitability for marketing. Seeds are of different sizes. Small seeded varieties may have a longer harvest window than large seeded varieties.
Snap beans are green or yellow. Horticultural beans and other specialty beans may be purple or variegated. Green snap beans are light, medium or dark green. Dark colored beans tend to mask some russeting and other minor defects that are more evident on light colored beans. Yellow beans, sometimes called wax beans, may be light yellow to an intense, almost gold color. Seeds are either white or dark; dark seeded varieties are often early.
Snap beans are bright colored at harvest when the pods are turgid. Water loss will cause the pods to become wilted and dull. Chilling injury will cause loss of color intensity.
Fresh market snap bean length is 5 to 7 inches with most being 5 to 6.5 inches. Diameter in fresh market sales is not related to any grade standard. There are grade standards for processing snap beans related to sieve size (diameter). Sieve sizes range from 14.5- to 18.5-64ths of an inch (sieve 1) to 27- to 30-64ths of an inch (sieve 6). Typically harvest for processing begins when 50% of the beans are sieve size 4 (21- to 24- 64ths). There are "petite" size snap beans that are mature at 4 inches long. They are used for whole pack beans by processors.
Curved pods and pods with missing seeds are the most common defects in shape. Slightly curved pods are not a quality problem, however the more the pods are curved the less uniform they appear. Straight pods provide a better appearance. The percentage of curved pods increases in plants with pods set low in the plants or plants that lodge allowing pods to touch the soil. The pod cross-section may be nearly round or slightly oval. The pods are more likely to have missing seeds if the plant is under stress at the time of pod set.
Snap beans that grow under optimum soil, temperature and moisture conditions will have fewer curved pods and missing seeds. Many varieties are subject to lodging if the plant grows too luxuriantly and has a large crop. Lodging increases the number of pods touching the soil and results in a higher percentage of curved pods. For this reason plants that are upright and have a high set are desirable. Pod set is concentrated in most bush beans, however bloom takes place over several days. High temperature during bloom (over 85˚F) can result in poor set or a "split set". There are differences among varieties in susceptibility to split set.
The most common diseases affecting the pods are white mold and gray mold. Control recommendations can be found in the Midwest Vegetable Production Guide for Commercial Growers, or through your local Cooperative Extension Service.
White Mold (Sclerotinia sclerotiorum) usually develops after there is a full canopy of leaves with moist soil and temperatures 50˚ to 80˚ F (55˚ to 60˚F optimum). The infection takes place in the field but can be controlled with sprays at bloom.
Gray Mold (Botrytis cinerarea) can occur in the field or in storage. Gray mold is most likely to develop when there is a full canopy of leaves creating a micro-climate with high humidity.
European Corn Borer can infest the pods of snap bean. Monitoring and spray programs are effective in preventing the problem.
Decreased quality during postharvest handling is most often associated with water loss, chilling injury, and decay.
It is important to remove field heat as soon as possible to prevent water loss. Most shippers will use hydro cooling to achieve temperatures of 41˚ to 45˚F; a shelf life of 8-12 days can be expected if these temperatures are maintained at 95% to 100% humidity. Limpness and shrivel are noticeable if more than a 5% water loss occurs.
Chilling injury will occur at storage temperatures below 41˚F. Exposure to ethylene at usual storage temperatures causes loss of green pigment and increased browning.
|Snap Bean, Raw 1 cup|
|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.