STATES RELATIONS SERVICE. 455 



In the experimental kitchen household methods of preparing pectin 

 extracts from apples and the peel of oranges and lemons have been 

 worked out and these extracts have been successfully used in the 

 making of lemon, orange, strawberry, rhubarb, cherrj^ pineapple, 

 mint, and spiced vinegar jellies and in jellied preserves of straw- 

 berry, peach, nectarine, pineapple, cherry, and raspberry. Quanti- 

 tative tests on these pectin extracts show that jelly-making power 

 does not run parallel with pectin yield as determined by present 

 methods. 



The determinations of the internal temperatures of cooked food 

 by the use of electric thermo-couples were continued. The relations 

 between the length of the cooking period and the temperature at- 

 tained in the food when baked, boiled, and fried in deep fat were 

 studied in the case of several foods of high protein content and of a 

 few foods rich in starch or other carbohydrate. The results show 

 that in the case of potatoes of nearly uniform size and weight the 

 rate of heat penetration is faster in boiling than in baking. The 

 ijiaximuni temperature attained at the center of l)oiled potatoes is 

 lower for ver}' large potatoes than for medium-sized or small ones, 

 but so far no evidence has been obtained to show that this is the case 

 with baked potatoes. The final temperature attained in peas, cab- 

 bage, carrots, and beets when boiled is 100° C, and the time required 

 for reaching this point depends chiefly on the size. Peas, separate 

 cabbage leaves, and sliced carrots attain the temperature of the bath 

 in a short time and remain at that temperature during most of the 

 cooking period. Heat penetrates much more slowly in the case of 

 whole potatoes and bee^s, and the cooking period is much longer. 

 The results with plain milk-ancl-egg custard, both boiled and baked, 

 shoAv that the coagulation temperature of a custard varies with the 

 temperature and kind of heating medium, the proportions of protein, 

 water, and acid in the mixture, and the amount and kind of sugar 

 used. Pum^jkin custard used for making pumpkin pie also showed 

 considerable variation in coagulation temperature. The maximum 

 temperature at the center, when coagulation was considered to be 

 complete, ranged from 87° to 102° C, depending on the thickness of 

 the filling and the temperature of the oven during baking. The 

 length of time during which the center of the pie registered a temper- 

 ature above 80° C. varied from 8 to 38 minutes. Thus it appears 

 that 8 minutes was the shortest time during which the coolest part of 

 these pumpkin custard pies remained above 80° C, even ignoring the 

 fact that the temperature at the center of the pie* sometimes goes 

 down very slowly after the pie is removed from the oven. 



Tliese experiments with pumpkin custards are of interest in view of 

 a recent suggestion that botulism may be caused by infected canned 

 pumpkin used in pie. This, of course, raises the question whether 

 puM'.pkin custard in pie is maintained at a sufficiently liigh tempera- 

 ture for a long enough period to insure the destruction of the toxin 

 of certain strains of botulinus. 



The studies on pastry making are now practically complete. It 

 has been shown that i:)hysical structure and condition of the fat are 

 much more important than chemical composition in making good 

 pastry and that almost any bland food fat or oil may be successfully 



25684— AGR 1923 30 



