382 



KN()\vLi:i)r.i:. 



OCTOIItR, 1012. 



it is clear that a high percentage of water will result 

 in a bulky food. During the process of cooking, 

 ineat and fish dccrcasi- in weight ; in almost everv 

 case vegetables increase, and cereals alwavs do so. 



Unfortunately, details were not kept as to the 

 weight of the lisli before cooking, but as will be 

 shown, the percentage amount of water is lower in 

 the cooked than in the uncooked sam|)les. 



With regard to meat it is stated that however 

 cooked it loses from one-fifth to one-third of its 

 weight. 



Johnston found : — 



Professor Grindle\- observed that on boiling lean 

 beef it lost forty-four and two-thirds per cent, of its 

 original weight: at a temperature of 85 C, a similar 

 sample boiled in boiling water lost forty-five per cent. 

 He found, further, that beside losing water, some of 

 the fat, mineral matters and protein are dissolved 

 out at the same time, and on examining the extracts 

 be found as the average of ninety-one samples that 

 the loss of mineral matter was fort\'-four and a half 

 per cent, of the total amount present in the meat, of 

 fat twelve per cent., and of protein seven and a 

 quarter per cent. In the process of stewing, highly 

 riavoured soluble matters are removed from the 

 meat and transferred to the bouillon. 



At the same time comparing the nutrients in cooked 

 and uncooked meats, we find a higher percentage of 

 nutrients in the cooked condition and a lower 

 percentage of water. 



One great difficultv that confronts the food chemist 

 is the material he works with: individually one sheep 

 is not exactly like another, one may be fatter, 

 another leaner: so with fish, vegetables and cereals. 

 It is stated by Professor Snyder that in the case of 

 flour containing twelve i)er cent, of moisture, if one 

 hundred pounds be kejit in a dry place a reduction 

 of three pounds in weight may be observed, whereas 

 in a damp place a corresponding increase may take 

 place. Therefore, in this class of analysis only 

 approximations can be made, and it is important to 

 obtain as much information as possible, repeating 

 the examination of articles of food, and taking the 

 mean of a large number of analyses. 



Thus, with three samples of uncooked American 

 halibut it was found : — 



When first the work with vegetables was started 

 it was impossible to judge how much vegetable was 

 reijuired : in three cases the supply fell short, and 

 fresh samples had to be prepared the following year, 

 giving verydifferent resultson the dry basis for protein. 



Six samples of mackerel were also analysed :- 



These data confirm the fact long known, that the 

 nitrogenous compounds vary (a) with the maturitv of 

 the plant (b) variety of the plant (c) soil and cultivation 

 ((/) the season. In our present state of know ledge we 

 assume all the nitrogen of our foods exists in the 

 form of protein, but research is showing that some 

 is present as non-proteid : further, that proteids differ 

 considerably from each other : one form is found 

 chiefly in nuts, another in meat. Often a mixture of 

 various kinds is present, and the important question 

 of the replacement of one form by another is being 

 in\estigated by Dr. II. I", .\rmstrong and others. 

 One important point recpiiring investigation is the 

 qui'stion of loss in the cooking of vegetaliles. When- 

 e\er possible they should not be cooked in an excess 

 of water, which it is necessary to drain off afterwards. 

 Professor Snyder, at the University of Minnesota, 

 made a study of the loss of nutrients in potatoes, 

 cabbages and carrots : he states that one hundred 

 pounds of uncooked cabbage only contain seven and 

 a lialf pounds of solid matter, and of this two and a 

 half to three pounds are lost in cooking, the loss con- 

 sisting of protein, mineral matter, and carbohydrates. 

 With carrots cooked in small pieces twentv per cent, 

 to thirty per cent, of the total food material is 

 extracted : the average of seventeen American analvses 

 shows only 11 • j of solid matter, while the average of 

 thirty-five European analyses shows 13-2, and of this 

 from two and a half to four pounds (mainly consisting 

 of sugar, mineral matter and protein) is lost. 



With potatoes it was found that the loss suffered 

 on boiling was inconsiderable, provided thev were 

 unpeeled. With spinach we have only ten pounds 

 of solid matter in one hundred pounds ; w hen drained 

 after cooking the loss is two and a quarter pounds. 

 Celeriac nine and a-half pounds solid in one hundred 

 pounds, and the average of three samples shows that 

 four and a half pounds are lost. Borecole, or curlv 

 greens, one hundred pounds contain ten and one-third 

 solid, and of this five and a quarter pounds are lost. 

 Turning to a still more common article of food, rice, 

 it is freipiently boiled in an excess of water, which is 

 then drained off. In tliis i)rocess protein, fat and 



