ANNUAL REPORT, 1933 45 



ways. As a sole source of protein for rats, fish meal from which the glue has been 

 extracted is superior to unextracted fish meal. Similarly, the vacuum-dried 

 meals gave better weight gains with rats than flame-dried. In cooperation with 

 the Poultry Department, work is being conducted with both chicks and laying 

 hens. 



Effect of Fertilization on the Vitamin A and C Content of Asparagus. (C. R. 



Fellers, R. E. Young, and J. A. Clague.) Two crops of asparagus grown at the 

 Waltham Field Station have now been assayed for vitamins A and C. While it 

 is evident that fertilization has no major effect on the vitamin C content of 

 asparagus, the results show a slight depressing effect due to high potassium and a 

 moderate increase due to high nitrogen fertilization. No significant effect on 

 vitamin A was found. 



Canned asparagus retained fully the original vitamin A content, but lost from 

 60 to 80 per cent of the vitamin C. On the other hand, quick-frozen asparagus 

 showed no vitamin losses after storage for several months. The results are now 

 being prepared for publication. 



Oven Canning. (W. W. Chenoweth, C. R. Fellers, and Pearl Haddock.) 

 The use of electric and gas ovens for canning fruits, vegetables, and meats has 

 been extensively advocated by range manufacturers and public utility represen- 

 tatives. Experimental results on a variety of foods, including a careful study 

 of heat transfer in ovens and in jars of foods in the ovens, showed that a tempera- 

 ture of 212° to 213° F. is never exceeded. Oven canning is considered less likely 

 to prevent spoilage in canned non-acid vegetables, meats, and marine products 

 than the pressure-cooker or water-bath methods. Loss of liquid in the jars 

 and scorching at the top and sides are two undesirable factors. The work is 

 being continued. 



Maple Products. (C. R. Fellers.) Molds may cause maple sugar to become 

 soft and semi-liquid. The action was traced to the liberation of invertase by the 

 mold mycelium. The invertase acts on the maple sugar (sucrose) and causes in- 

 version. Losses due to this type of spoilage are very large, and no previous 

 explanation was found in the literature. The degree of mold infection may be 

 readily determined by making a direct microscopic Howard count of the maple 

 sugar. This should be of great assistance to buyers of maple sugar in determining 

 keeping quality of sugar and its suitability for syrup manufacture. 



Two seasons' work have been completed on vitamin A and C determinations 

 on maple sap, syrup, and sugar. Neither vitamin was present in significant 

 amounts. 



DEPARTMENT OF OLERICULTURE 



Ralph A. Van Meter in Charge 



Asparagus Investigations. (Robert E. Young, Waltham.) 

 Fertilizers. The yields of the asparagus fertilizer plots show an average 

 increase of about 45 per cent over the yields of last year, with a much greater 

 increase at Waltham and Concord than at Eastham. The quality of asparagus 

 on all plots was higher than last year. In general the results obtained were about 

 the same as last year. 



In Waltham the most outstanding result was the increase in \ield due to 



