Commodities / Strawberries

Flavor | Texture | Color | Size | Shape | Defects and Disease | Shelf Life | Nutritive Value
MW Commercial Small Fruit and Grape Spray Guide | MW Small Fruit Pest Management Handbook | Postharvest Information (UC Davis) | USDA Grade Standards

Strawberry quality is a combination of appearance and flavor. According to grade standards, the berries should be of one variety or similar varietal characteristics with the cap (calyx) attached, which are firm, not overripe or undeveloped, and which are free from mold or decay and free from damage caused by dirt, moisture, foreign matter, disease, insects, or mechanical or other means.
Fruit should be free from: (1) Attached stems (2) Mold (3) Decay; (4) Insects or when there is visible evidence of the presence of insects; (5) Mummified berries; and, (6) Clusters, and free from damage caused by (1) Shriveling; (2) Broken skins; 3) Scars; and (4) Green berries.
Quality characteristics of interest to the grower include plant vigor, yield potential, ease of harvest and disease resistance.

Flavor top

Strawberry flavor is related to degree of ripeness. Fruit that is harvested at full ripeness will have the highest sugar content and flavor. However, fruit is often harvested prior to full ripeness so that it is firm enough to be shipped. New varieties have improved firmness for shipping. Additionally, improvements in post harvest handling and shipping conditions have allowed growers to ship fruit that is more ripe.

Texture top

Strawberry fruit should be firm but not crunchy. Excessively ripe fruit can be too soft.

Color top

Strawberry varieties vary in color from deep red to red-orange. For a given variety, fruit should be fully colored, without white or green tips. Calyx color is also important. The calyx should remain green and healthy.

Strawberries are bright colored at harvest with healthy green calyxes. Water loss will cause the fruit to become wilted and dull.

Size top

Strawberry fruit range is size by variety and as the season progresses. Many new varieties produce very large fruit that are over 2 inches long and more than an inch in diameter. There are grade standards for strawberries related to diameter. U.S. No. 1 fruit must be at least 3/4 inch in diameter and U.S. No. 2 fruit must be at least 5/8 inch in diameter.

Shape top

Strawberry fruit should be well developed and normally shaped. Varieties vary slightly in shape, but most are conical. Occasionally fruit is misshapen due to lack of seed development, which results in differential growth of fruit flesh. Grade standards state that “undeveloped” means that the berry has not attained a normal shape and development due to frost injury, lack of pollination, insect injury, or other causes. "Button'' berries are the most common type of this condition.

Strawberries grown under normal conditions will have fully developed fruit. Frost injury is a common cause of undeveloped fruit. Frost injury is avoided through site selection and overhead irrigation during frost events. Undeveloped fruit can also be caused by tarnished plant bug feeding on developing fruit and flowers. Damage can be avoided by scouting for insect pests and well-timed insecticide applications. Control recommendations can be found in the Midwest Small Fruit Pest Management Handbook and Midwest Small Fruit and Grape Spray Guide for Commercial Growers, or through your local Cooperative Extension Service. Lack of pollination can also lead to undeveloped fruit but it is a less common cause. Installation of beehives can improve pollination.

Defects and Disease top

Defects

Soft fruit, wet stem scars, attached stems, and green berries are common defects of blueberries. These must be graded out during packing.

Disease

The most common diseases affecting fruit is gray mold (Botrytis). Control recommendations can be found in the Midwest Small Fruit Pest Management Handbook and Midwest Small Fruit and Grape Spray Guide for Commercial Growers, or through your local Cooperative Extension Service.

Gray Mold (Botrytis cinerea) 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. Infection occurs primarily during bloom, so control measures are timed accordingly.

Insects

Tarnished plant bug is the most common pest that affects fruit quality. This pest feeds on developing flowers and fruit causing seed abortion and subsequent lack of fruit development. Other insect pests such as spittle bug and root worms affect plant vigor.

Shelf Life top

Decreased quality during postharvest handling is most often associated with water loss and decay.

It is important to remove field heat as soon as possible to prevent water loss. Most shippers will use forced air cooling to achieve temperatures of 32-34˚F. Berries freeze at 31˚F. A shelf life of 5-7 days can be expected if these temperatures are maintained at 90% to 95% humidity.

Nutritive Value top

Serving Size: 8 medium strawberries (147g)
Amount Per Serving

% Daily Value*

Calories 45 Calories from Fat 0
Total Fat 0g 1%
___Saturated Fat 0g 0%
___Cholesterol 0mg 0%
Sodium 0mg 0%
Total Carbohydrate 12g 4%
___Dietary Fiber 4g 18%
___Sugars 8g  
Protein 1g  
Vitamin A 0%
Vitamin C 15%
Calcium 0%
Iron 2%
*Percent Daily Values are based on a 2,000 calorie diet.
(Source: Produce Marketing Association and the Produce for Better Health Foundation. 2002-2003.)
Strawberries, Raw 1 cup
Weight of Household Measure % Water Food Energy
K cal
 Protein Fat Saturated Fatty Acid Mono - unsaturated Fatty Acid Poly - unsaturated Fatty Acid
149g 92 45 1g  1g 0g 0.1g 0.3g
Cholesterol Carbohydrate Calcium Phosphorus Iron Potassium Sodium Vitamin A (IU)
 0mg 10g 21mg 28mg 0.6mg 247mg 1mg 40
Vitamin A (RE) Thiamin Riboflavin Niacin Ascorbic Acid      
4 0.03mg 0.1mg 0.3mg 84mg
(Source: USDA. Nutritive Value of Foods (HG-72), Release 3.2. 1990.)


top

Content author: B. Bordelon, 2003. Links updated: January 2012.