452 



COOKERY 



The hydrate once formed may be dried by -eva- 

 poration, and still retains some water and the 

 same degree of solubility. Many farinaceous pre- 

 parations, such as corn-flour, &c., consist chiefly of 

 starch in this condition. This, however, is not the 

 limit of starch cookery. If it is heated to about 

 400, it is converted into dextrin, which is com- 

 pletely soluble in water at all temperatures, the 

 solution being mucilaginous but not pasty. Dex- 

 trin differs from starch in other properties (see 

 DEXTRIN), but is composed of the same elements 

 in the same proportions, C 6 H 10 O 5 i.e. six equiva- 

 lents of carbon to five of water, or its elements. 

 This change of starch into dextrin is of great prac- 

 tical importance as an operation of cookery, inas- 

 much as it anticipates the first stage of the digestion 

 of starch. 



The saliva, the pancreatic juice, and one of the 

 intestinal secretions contain a peculiar principle 

 which has received the name or animal diastase, 

 from its resemblance to the diastase of malt. This 

 converts the starch of food into the completely 

 soluble dextrin, a change absolutely necessary for 

 its assimilation as nutriment. In some animals 

 the supply of this is so small that starch is almost 

 worthless to them as food. It passes through the 

 body unaltered. Such is the case with the carni- 

 vora. Human infants, when suddenly deprived of 

 their mother's milk, have not sufficiently developed 

 the power of salivary, pancreatic, and intestinal 

 secretion of diastase to digest starch, and there- 

 fore demand assistance. Such assistance may be 

 afforded by carrying the cookery of starch to what we 

 venture to call the second stage viz. its complete 

 or partial conversion into dextrin. Thus, ordinary 

 flour or oatmeal, simply heated in boiling water or 

 milk, is merely subjected to the first stage viz. 

 hydration of the starch ; but if the flour or oatmeal 

 be well baked, a considerable proportion of its 

 starch is converted into dextrin. A knowledge of 

 this is of great importance to mothers, and also to 

 nurses preparing food for dyspeptics, as adults vary 

 greatly in their powers of diastatic secretion. 



The reader will now understand why bread is 

 rendered more digestible by toasting, and why 

 crust of bread is more digestible than the crumb, 

 in spite of greater hardness. In the ordinary 

 baking of bread a variable amount of the starcn 

 is converted into dextrin. Well-baked bread is 

 more digestible than under-baked. In the cookery 

 of oatcakes, bannocks, scones, and all kinds of 

 biscuits, this should be understood. The writer 

 enjoys the luxury of hot rolls without their in- 

 digestibility, by simply moistening stale crusts of 

 bread and reheating them in a kitchen oven. They 

 thus become softened like new bread, and more 

 digestible than before on account of the dextrinisa- 

 tion of a larger proportion of the starch. Baked 

 and fried potatoes have a similar advantage. 



The diastase of malt (see MALT) may be used 

 for the dextrinisation of farinaceous food by add- 

 ing malt flour or extract of malt to it ; or the 

 grain itself may be malted. The temperature at 

 which malt diastase acts most vigorously is about 

 140. At lower temperatures it acts more slowly ; 

 at much higher, its curious property is destroyed. 

 To illustrate its action, make some oatmeal por- 

 ridge very thick, then add about tyth part of dry 

 malt flour at about 140, and stir. In a few 

 minutes the thick pudding becomes quite sloppy 

 owing to the greater solubility of the dextrin into 

 which the starch has thus been converted. 



The cellulose i.e. the stalks and the cell walls, 

 such as the fleshy part of leaves, &c. are more or 

 less digestible, according to their looseness of struc- 

 ture and their interfluidity or succulent character. 

 Thus we may digest a raw lettuce more easily than 

 H raw cabbage, or the inner leaves of either more 



readily than the outer leaves or stalks. The 

 action of cookery on cellulose appears to consist in 

 the loosening of its fibres, and rendering them 

 more soluble. It is therefore advantageous that the 

 water in which green vegetables, such as cabbages, 

 are cooked should boil vigorously, the agitation of 

 the steam bubbles assisting in the loosening of the 

 fibres. Cellulose, like starch, may be converted 

 into dextrin and sugar by the combined action of 

 moderate heat with moisture and an acid. This 

 change is aided by a little diastase. Sawdust and 

 old rags may thus be converted into digestible and 

 nutritious food, but not with commercial profit at 

 present. An example of such conversion in 

 Nature's laboratory is afforded by the ripening of 

 a pear. Many varieties which are hard, woody, 

 and sour when full grown in autumn, become 

 gradually softer and sweeter, and finally delicious 

 by simple storage. The action of ensilage (see 

 ENSILAGE) of cattle food probably includes some 

 degree of such conversion of cellulose. 



The nitrogenous constituent of grain, the gluten, 

 is not so greatly altered by cookery. The writer's 

 investigations of this neglected subject lead him 

 to the conclusion that the alteration which does 

 occur is that of a partial hydration rendering the 

 gluten more soluble, but this hydration is not so 

 decided and definite as in the case of starch. 

 There is one constituent of vegetable food which 

 demands no cookery. This is pecten (otherwise 

 pectose and pectin) i.e. vegetable jelly. It exists 

 most abundantly in fruits, and is familiar to all 

 in the form of currant jelly, apple jelly, &c., which 

 are pecten plus sugar. The cookery of vegetable 

 casein will be discussed with that of the casein of 

 milk. 



Of the proximate elements of animal food the 

 most abundant is gelatin ; it constitutes about half 

 the weight of the body of most animals. It exists 

 in two forms soluble and insoluble. Its cookery 

 consists in the hydration of the insoluble form and 

 rendering it soluble, as in the stewing of bones, 

 tendons, skin, &c. in a stock-pot until their 

 gelatin becomes soluble jelly. The muscular fibre 

 itself, which with its enveloping membranes form 

 lean meat, is subjected to a similar change, but less 

 completely, in the course of cookery. 



The cookery of albumen differs materially from 

 any of the preceding. Albumen exists in raw flesh 

 meat as one of its juices, being a glairy liquid 

 which is distributed between the muscular fibres 

 and the joints, and around the bones, forming a 

 lubricant, and probably conveying material of 

 growth and renewal. It is typically seen in the 

 white of eggs. When heated to about 134, white 

 fibres begin to appear within it. If the heat is 

 continued, and gradually increased, they increase, 

 until at about 160 the whole mass becomes white 

 and nearly opaque. It is now coagulated into a 

 tender, delicate, jelly-like substance, easily digest- 

 ible and highly nutritious. If the heat is further 

 raised, it becomes harder and harder, up to 212. 

 If this heat is continued, it shrinks, and becomes 

 tough and horny, losing some of its water of com- 

 position, and its easy digestibility. 



Ignorance of these particulars, and further ignor- 

 ance of the fact that water has the same tempera- 

 ture, whether ' simmering ' or boiling violently, 

 causes the spoiling of vast quantities of food and 

 wasting of much fuel in this country. The cooking 

 temperature for all animal food is from 160 to 

 180. When maintained for any length of time 

 at the temperature of boiling or 'simmering' 

 water, it is spoiled. To prove this, take a beefsteak 

 and cut it in half. Place one half in water in a 

 common saucepan, and boil or ' simmer ' it for half 

 an hour or more. Place the other half in water in 

 an open-mouthed jar (such as a gallipot), and 



