EFFECT OF PREMATURE FREEZING ON COMPOSITION 



OF WHEAT 



By M. J. Bush ' 



Assistant Chemist, Montana Agricultural Experiment Station 



INTRODUCTION 



A consideration of the effects of freezing temperatures upon the 

 chemical composition of the immature wheat kernel is of general interest 

 from a biochemical standpoint and of special interest to those engaged 

 in the study and handling of wheat and its milling products, particularly 

 in the spring-wheat sections. It is of economic importance, especially 

 during the present high prices of wheat and its products, that a large 

 amount of what is popularly called "frosted wheat" is annually classed 

 as fit for nothing better than chicken feed. 



This paper presents results of an investigation of the efifect of pre- 

 mature freezing on the more important chemical constituents of the 

 wheat kernel, paying special attention to the nitrogen compounds, from 

 which the gluten is formed. Consideration of some of the effects of 

 freezing on the milling and bread-making value of wheat will be taken 

 up in later publications. 



Harper (4)' made some analyses of "rusted and frosted" Minnesota 

 wheats in 1889. He reported that the average protein content for 

 rusted and frosted wheats was more than 2 per cent greater than that 

 for the graded wheats, while the ratio of total nitrogen to albuminoid 

 nitrogen was about the same in the damaged and undamaged w^heats. 

 The damaged wheat was higher in ash, fat, and fiber but lower in water 

 and carbohydrates than the sound wheat. Different results of analyses 

 of frozen wheat are reported by Foster and Merrill (5, p. LXVI) in con- 

 nection with some Utah samples. Their figures show the total protein 

 to be about 3 per cent lower in frozen than in sound wheat. The frozen 

 wheat samples contained more fiber, fat, and water than the sound 

 wheat. Shutt (5, p. 117), in a report of the analyses of Canadian sam- 

 ples of frozen and sound wheats in 1892, found the frozen samples higher 

 in water, fat, fiber, and ash than the sound samples. The percentages 

 of total nitrogen were very nearly the same in both the sound and frozen 

 wheats. In 1907 Shutt (<5) determined the albuminoid and nonalbu- 

 minoid nitrogen in samples of sound, frosted, and badly frosted wheat 



• The writer is indebted to Mr. W. F. Day, of the Montana State Grain Laboratory, for milling the wheat 

 samples dealt with in these experiments, and esf)ecially to ^Ir. Edmund Burke, chemist of the Experiment 

 Station, for helpful criticism and advice. 



' Reference is made by number (italic) to '' Literature cited." p. iS8. 



Journal of Agricultural Research. Vol. XIX, No. 4 



Washington, D. C. May 15. 19J0 



ye Key No. Mont.-6 



(181) 



