RECOMMENDED PROCEDURES
Storage Conditions
APPLES

To minimize textural changes over several months of storage, a temperature of 31 to 32F is recommended (Rouse and Atkins, 1955). To accelerate changes in texture, storage at 45F is advised. During the period requried for analysis, further changes can be controlled by maintaining the samples at 31 to 32F.

Golden Delicious apples are best stored in polyethylene bags with holes. Red Delicious and Winesap apples can be stored in the cartons in which they are shipped. Prior to analysis, samples should be taken from cold storage, removed from the bags, and allowed to come to room temperature.

CARROTS
Carrots should be stored in plastic bags at 32F. Prior to analysis, samples should be taken from cold storage, removed from the bags, and allowed to come to room temperature.

MELONS
Melsons should be stored at 60 to 65F for not more than three days, or at 32F for not more than seven days. They may be stored in open boxes. Prior to use they should be removed from storage and kept at room temperature overnight.

Sampling
GENERAL
The sample selected for analysis should be as representative as possible of the entire lot of food. the variability in fruits and vegetables is due to many factors, including genetic constitution, soil and climatic conditions during plant growth, maturity at harvest, and storage conditions prior to use. In addition, different parts of the same plant differ in composition.

It is customary to reduce variability in the population to be sampled by limiting the genetic constitution to one variety and one strain. It is also customary to use plant material from a common source, since this reduces the variability due to climate and soil conditions and imposes some control on the maturity. If samples must be shipped to the point of analysis, shipments should be made under refrigerated conditions to arrive on a work day so that facilities will be available for immediate care.

In sampling foods sufficient material must be taken to compensate for the variability involved. Replicate samples should be analyzed in order to provide a measure of variability. This measure is used in statistical analysis to determine whether differences are significant among varieties, storage conditions, or other imposed variables.

APPLES
The exact number of apples used by a laboratory is dictated by the number of tests to be performed and by the reproducibility of results between replications. For tests in which replications prove to be very much alike, a few replications will yield resutls having statistical significance. When the variability due to materail or method is unknown, it is advisable to begin with a large number of replications.

To illustrate, the planning of one laboratory for the first season's work is described here. Eight apples of each variety and size were needed for each series of tests, and 10 replications were planned. The eight apples for each repliacation were divided as follows:

• Two apples for the Succulometer
• Two apples for the Texture press
• Two apples for testing moisture, alchol-insoluble solids, and soluble solids.
• One apple for the Magness Probe
• One apple for sensory evaluation by the panel

Following statistical analysis of this season's work, which demonstrated reproducibility within each method, the number of replications was reduced to five.

CARROTS
Variation from carrot to carrot may be high. Therefore it is recommended that each carrot be tested individually. Use a portion of each sliced carrot for judging by a sensory panel, and the remainder for one or more of the following: Texturepress, turgor pressure, lignin content, or other chemical tests. Whole carrots may be judged for flexibility and compressibility by the panel and then be submitted to further chemical or physical analyses.

MELONS
At least 10 melons should be used, each melon comprising one replication. Some tests require more replications than others. For example, melon-to-melon variation will be greater for pectic substances than for moisture or sugars. Each melonmay be judged by a sensory panel and other analyses may be made on the reaminder of the melon. Prepare representative portions by cutting the melons into quarters and using alternate sections for the tests. Cut each melon in half from the stem to the blossom end, and quarter these halves.

Use the shaded portions for sensory analyses and the unshaded portions for objective tests. As can be seen, each group (shaded and unshaded) of eights comprises portions of the top, bottom, and both ends of the melon. Remove and discard the rind with approximately 1 cm thickness of flesh.

Updated: Thursday, September 6, 2007.