PROXIMATE COMPOSITION OF FRESH FRUITS 6 



AVERAGES AND VARIATIONS 



Averages are arithmetical means of individual values as given in 

 percentage of the edible portion except in a few stated cases. In 

 these few instances averages were taken on a water-free basis and 

 calculated back to the fresh, at the average water content. Probable 

 error, indicated as P. E., has been given to indicate variation in 

 individual determinations and is the standard deviation X 0.6745. 

 In cases where part of the source material was given only as averages, 

 estimates have been made by allowing for variation within the group 

 averaged. 



WATER 



Water content refers to the loss in weight from drying or the differ- 

 ence between the weight of the total solids and the fresh substance. 

 In some cases the material was air dried at 100° C. and in others it 

 was dried in vacuum at lower temperatures. Probably the errors 

 due to method are greater in the determination of this constituent 

 than in any of the others. 



PROTEIN, FAT, AND ASH 



Protein was calculated as NX6.25, the nitrogen being determined 

 by the Kjeldahl method or one of its modifications. Fat was deter- 

 mined as ether extract, and it includes therefore other ether-soluble 

 substances such as plant pigments. Ash is the residue from burning 

 the dry substance until it is free from carbon. When determinations 

 of fat content were lacking, a figure was sometimes assumed to 

 admit of calculations of fuel value. In a single case, also, such an 

 assumption was made for protein. All assumptions were made on 

 the basis of analyses of similar substances and may be in error by 

 several tenths of a per cent, but these errors would hardly be sig- 

 nificant in dietary calculations. 



TOTAL CARBOHYDRATES 



The term "total by difference including fiber " under carbohydrates 

 refers to solids other than protein, fat, and ash. Like nitrogen-free 

 extract it includes organic acids and undetermined solids as well as 

 the substances properly classed as carbohydrates. It is numerically 

 equal to the sum of nitrogen-free extract and fiber. It is apparent 

 that any errors in the determination of water, protein, fat, or ash 

 will be reflected in this quantity and that it is therefore less reliable 

 than a direct determination. No indication of the variation in this 

 quantity is given since individual calculations of it were not recorded, 

 but it can be assumed that the variation in this group of substances 

 would be of about the same order as that of the water content. 



FIBER 



Fiber is the loss in weight from incinerating the residue obtained 

 by successive treatments of the fat-free dry substance with dilute 

 sulphuric acid and dilute sodium hydroxide. 



SUGARS 



The term " sugars as invert" refers to total sugars, and the quantity 

 is given as in the other constituents, in percentage of the fresh edible 

 substance. They were determined in the majority of cases on the 



