144 MISC. PUBLICATION 5 4 0, TJ. S. DEPT. OF AGRICULTURE 



Before the tenderometer reading is taken it is desirable to bring the peas 

 to a temperature of about 60° F. by immersion in water for 3 to 5 minutes. At 

 least three readings should be taken, and the average used to represent the tender- 

 ness of the load. For first-grade peas the tenderometer value should probably 

 not exceed 105; for second-grade, 115; and for third-grade, 125. It may be 

 expected that third-grade peas will yield a very poor quality of dehydrated 

 product. 



COLOR TEST (GREEN LIMA BEANS) 



The maturity of green lima beans is generally estimated by deter- 

 mining the percentage of white beans in a well-mixed, representative 

 sample of the raw material. 



Procedure: The sample should be obtained by subsampling various parts of 

 each load. Usually each packer sets up his own percentage limits of white 

 beans for different grades ; however, it is generally required that first-grade green 

 lima beans contain less than 10 percent of white beans. 



PRESSURE TEST ( SWEET CORN ) 



The maturity of sweet corn is usually determined by the thumbnail 

 test and observation of the character of the expressed juice. 



Procedure : The pressure required to break the hull of several kernels on 

 several cobs selected from a representative sample is noted. At the stage of 

 maturity desirable for dehydration the expressed juice is milk white in color and 

 has a creamy consistency. If the juice is slightly cloudy the corn is too immature, 

 and if it is thick and sticky the corn is overmature. Obviously this method is 

 subject to considerable variation due to the personal factor. 



MOISTURE CONTENT ( SWEET CORN ) 



The maturity of sweet corn is sometimes estimated on the basis of 

 moisture content in a representative sample. For dehydration, first- 

 grade corn should have a moisture content of between 70 and 75 percent. 

 Corn with a moisture content greater than this range will probably 

 be too immature, and with a lower moisture content it may be too 

 mature. 



"Procedure: Use the rapid distillation method (p. 146) on a carefully chosen 

 sample obtained by careful removal of several kernels from several cobs selected 

 from a representative sample. 



Moisture Determination 



Moisture content is probably the most important criterion of keep- 

 ing quality of dehydrated products. A great deal of work has been 

 done to develop accurate and reproducible methods, but the present 

 status of the problem is far from satisfactory. Accurate determina- 

 tion of moisture requires painstaking and time-consuming procedures 

 that are not practicable in control laboratories. It is therefore neces- 

 sary to use methods which, though not measuring the absolute amount 

 of moisture, give close approximations that are readily reproducible. 

 The amount of moisture ordinarily determined is therefore an em- 

 pirical quantity which will suffice for the purpose but must not be con- 

 sidered absolute. 



Two general methods are used for the determination of moisture 

 in vegetables. With the direct method the water is removed from the 

 sample and determined from the loss in weight of the sample or by 

 collecting and measuring its volume. This method is exemplified by 

 the vacuum- and air-oven methods and by the so-called distillation 

 (toluene) methods. The indirect methods do not require that water 



