The Vitamine Manual Part 4

_Pages 50 and 61 of the British Medical Research Committee's report_ __________________________________________________________________________ CLa.s.sES OF FOODSTUFFS VITAMINE "A" VITAMINE "B" VITAMINE "C"

___________________________________ ____________ ____________ ____________ _Fats and oils:_ b.u.t.ter . . . . . . . . . . . . +++ 0 Cream . . . . . . . . . . . . . ++ 0 Cod-liver oil . . . . . . . . . +++ 0 Mutton and beef fat or suet . . ++ Lard . . . . . . . . . . . . . 0 Olive oil . . . . . . . . . . . 0 Cotton seed oil . . . . . . . . 0 Cocoanut oil . . . . . . . . . 0 Cocoa-b.u.t.ter . . . . . . . . . 0 Linseed oil . . . . . . . . . . 0 Fish oil, whale oil, herring oil, etc. . . . . . . . . . . ++ Hardened fats (hydrogenated) of animal or vegetable origin 0 Margarine from animal fat . . . In propor- tion to animal fat used Margarine from vegetable fat or lard . . . . . . . . . . . 0 Nut b.u.t.ters . . . . . . . . . . + _Meat, fish, etc.:_ Lean meat (beef, mutton, etc.) + + + Liver . . . . . . . . . . . . . ++ ++ + Kidneys . . . . . . . . . . . . ++ + Heart . . . . . . . . . . . . . ++ + Brain . . . . . . . . . . . . . + ++ Sweetbreads . . . . . . . . . . + ++ Fish, white . . . . . . . . . . 0 Very slight if any Fish fat (salmon, herring, etc.) ++ Very slight if any Fish roe . . . . . . . . . . . + ++ Tinned meats . . . . . . . . . ? Very slight 0 _Milk, cheese, etc.:_ Milk, cow's whole raw . . . . . ++ + + Milk, cow's skim . . . . . . . 0 + + Milk, cow's dried whole . . . . Less than + Less than ++ + Milk, cow's boiled whole . . . ? + Less than + Milk, cow's condensed sweetened + + Cheese, whole milk . . . . . . + Less than + Cheese, skim milk . . . . . . . 0 Eggs, fresh . . . . . . . . . . ++ +++ 0?

Eggs, dried . . . . . . . . . . ++ +++ 0?

_Cereals, pulses, etc.:_ Wheat, maize, rice (whole germ) + + 0 Wheat, maize, rice germ . . . . ++ +++ 0 Wheat, maize, rice bran . . . . 0 ++ 0 White wheat flour, pure corn flour, polished rice, etc. . 0 0 0 Custard powders, egg substi- tutes prepared from cereal products . . . . . . . . . . 0 0 0 Linseed, millet . . . . . . . . ++ ++ 0 Dried peas, lentils, etc. . . . ++ Pea-flour, kilned . . . . . . . 0 0 Soy beans, haricot beans . . . + ++ 0 Germinated pulses or cereals . + ++ ++ _Vegetables and fruits:_ Cabbage, fresh, raw . . . . . . ++ + +++ Cabbage, fresh, cooked . . . . + + Cabbage, dried . . . . . . . . + + Very slight Cabbage, canned . . . . . . . . Very slight Swedes, raw expressed juice . . +++ Lettuce . . . . . . . . . . . . ++ + Spinach, dried . . . . . . . . ++ + Carrots, fresh, raw . . . . . . + + + Carrots, dried . . . . . . . . Very slight Less than + Beetroot, raw, expressed juice + + Potatoes, raw . . . . . . . . . + Potatoes, cooked . . . . . . . ++ Beans, fresh scarlet runners raw Lemon juice, fresh . . . . . . +++ Lemon juice, preserved . . . . Lime juice, fresh . . . . . . . ++ Lime juice, preserved . . . . . Very slight Orange juice, fresh . . . . . . +++ Raspberries . . . . . . . . . . ++ Apples . . . . . . . . . . . . + Bananas . . . . . . . . . . . . + + Very slight Tomatoes, canned . . . . . . . ++ Nuts . . . . . . . . . . . . . + ++ _Miscellaneous:_ Yeast dried . . . . . . . . . . ? +++ Yeast extract and autolysed . . ? +++ 0 Meat extract . . . . . . . . . 0 0 0 Malt extract . . . . . . . . . + in some specimens Beer . . . . . . . . . . . . . 0 0 Honey . . . . . . . . . . . . . + ___________________________________ ____________ ____________ ____________

+++ indicates abundant; ++ relatively large; + present in small amount; 0 absent.

The following table (2) has been compiled from a review of both British and American data and represents a rather more complete cla.s.sification than the British report. The four plus system has also been used to permit more complete comparisons.

TABLE 2

_________________________________________________________________________ FOODSTUFF "A" "B" "C"

____________________________________ ___________ ___________ ____________ _Meats_: Beef heart . . . . . . . . . . . + + ?

Brains . . . . . . . . . . . . . ++ +++ +?

Codfish . . . . . . . . . . . . + + ?

Cod testes . . . . . . . . . . . + Fish roe . . . . . . . . . . . . + ++ ?

Herring . . . . . . . . . . . . ++ ++ ?

Horse meat . . . . . . . . . . . ++ ++ Kidney . . . . . . . . . . . . . ++ ++ Lean muscle . . . . . . . . . . 0 0 +?

Liver . . . . . . . . . . . . . + + +?

Pancreas . . . . . . . . . . . . 0 +++ Pig heart . . . . . . . . . . . + + ?

Placenta . . . . . . . . . . . . + Thymus (sweetbreads) . . . . . . 0 0 0 _Vegetables:_ Beet root . . . . . . . . . . . + + ++ Beet root juice . . . . . . . . ? Little +++ Cabbage, dried . . . . . . . . . +++ +++ + Cabbage, fresh . . . . . . . . . +++ +++ ++++ Carrots . . . . . . . . . . . . +++ +++ ++ Cauliflower . . . . . . . . . . ++ +++ ++ Celery . . . . . . . . . . . . . ? +++ ?

Chard . . . . . . . . . . . . . +++ ++ ?

Dasheens . . . . . . . . . . . . + ++ ?

Lettuce . . . . . . . . . . . . ++ ++ ++++ Mangels . . . . . . . . . . . . ++ ++ ?

Onions . . . . . . . . . . . . . ? +++ +++ Parsnips . . . . . . . . . . . . ++ +++ Peas (fresh) . . . . . . . . . . + ++ +++ Potatoes . . . . . . . . . . . . 0 +++ ++ Potatoes (sweet) . . . . . . . . +++ ++ ?

Rutabaga . . . . . . . . . . . . +++ Spinach . . . . . . . . . . . . +++ +++ +++ _Cereals:_ Barley . . . . . . . . . . . . . + +++ ?

Bread (white) . . . . . . . . . + +? Bread (whole meal) . . . . . . . + +++ ?

Maize (yellow) . . . . . . . . . + +++ ?

Maize (white) . . . . . . . . . 0 +++ ?

Oats . . . . . . . . . . . . . . + +++ 0 Rice polished . . . . . . . . . 0 0 0 Rice (whole grain) . . . . . . . + +++ 0 Rye . . . . . . . . . . . . . . + +++ 0 Corn embryo . . . . . . . . . . +++ Corn (kaffir) . . . . . . . . . +++ Corn (see maize) . . . . . . . . Corn pollen . . . . . . . . . . ++ Malt extract . . . . . . . . . . 0 0 0 Wheat bran . . . . . . . . . . . 0 + 0 Wheat embryo . . . . . . . . . . ++ +++ 0 Wheat endosperm . . . . . . . . 0 0 0 Wheat kernel . . . . . . . . . . + +++ 0 _Other seeds:_ Beans, kidney . . . . . . . . . +++ Beans, navy . . . . . . . . . . +++ 0 Beans, soy . . . . . . . . . . . + +++ 0 Cotton seed . . . . . . . . . . ++ +++ Flaxseed . . . . . . . . . . . . ++ +++ Hemp seed . . . . . . . . . . . ++ +++ Millet seed . . . . . . . . . . ++ +++ Peanuts . . . . . . . . . . . . + ++ Peas (dry) . . . . . . . . . . . +? ++ 0 Sun flower seeds . . . . . . . . + _Fruits:_ Apples . . . . . . . . . . . . . ++ ++ Bananas . . . . . . . . . . . . ? ++ ++ Grapefruit . . . . . . . . . . . +++ +++ Grape juice . . . . . . . . . . + + Grapes . . . . . . . . . . . . . 0 + + Lemons . . . . . . . . . . . . . +++ ++++ Limes . . . . . . . . . . . . . ++ ++ Oranges . . . . . . . . . . . . +++ ++++ Pears . . . . . . . . . . . . . ++ ++ Raisins . . . . . . . . . . . . + + Tomatoes . . . . . . . . . . . . ++ +++ ++++ _Oils and fats:_ Almond oil . . . . . . . . . . . 0 0 Beef fat . . . . . . . . . . . . + 0 0 b.u.t.ter . . . . . . . . . . . . . ++++ 0 0 Cocoanut oil . . . . . . . . . . 0 0 0 Cod liver oil . . . . . . . . . ++++ 0 0 Corn oil . . . . . . . . . . . . 0 0 0 Cotton seed oil . . . . . . . . 0? 0 0 Egg yolk fat . . . . . . . . . . ++++ 0 0 Fish oils . . . . . . . . . . . ++ 0 0 Lard . . . . . . . . . . . . . . 0 0 0 Oleo, animal . . . . . . . . . . + 0 0 Oleo, vegetable. . . . . . . . . 0 0 0 Olive oil . . . . . . . . . . . 0 0 0 Pork fat . . . . . . . . . . . . 0? 0 Tallow . . . . . . . . . . . . . 0 0 0 Vegetable oils . . . . . . . . . 0? 0 0 _Nuts:_ Almonds . . . . . . . . . . . . + +++ Brazil nut . . . . . . . . . . . +++ Chestnut . . . . . . . . . . . . +++ Cocoanut . . . . . . . . . . . . ++ +++ English walnuts . . . . . . . . +++ Filbert . . . . . . . . . . . . +++ Hickory . . . . . . . . . . . . + + + Pine . . . . . . . . . . . . . . + + + _Dairy products:_ b.u.t.ter . . . . . . . . . . . . . ++++ 0 0 Cheese . . . . . . . . . . . . . ++ + ?

Condensed milk . . . . . . . . . ++ + 0 Cream . . . . . . . . . . . . . +++ + ?

Eggs . . . . . . . . . . . . . . ++++ ++ 0 Milk powder (skim) . . . . . . . + +++ +?

Milk powder (whole) . . . . . . +++ +++ +?

Milk whole . . . . . . . . . . . +++ +++ ++ Whey . . . . . . . . . . . . . . + +++ + _Miscellaneous:_ Alfalfa . . . . . . . . . . . . +++ +++ ?

Blood . . . . . . . . . . . . . Varies with source Clover . . . . . . . . . . . . . +++ ++++ ?

Honey . . . . . . . . . . . . . ++ 0 Malt extract . . . . . . . . . . 0 0 0 Nectar . . . . . . . . . . . . . 0 0 0 Timothy . . . . . . . . . . . . ++ +++ Yeast, brewers . . . . . . . . . 0 ++++ 0 Yeast cakes . . . . . . . . . . 0 ++ 0 Yeast extract . . . . . . . . . 0 +++ 0 ____________________________________ ___________ ___________ ____________

CHAPTER VI

THE CHEMICAL AND PHYSIOLOGICAL PROPERTIES OF THE VITAMINE

While the chemists have not yet been able to isolate and identify the various vitamines they have succeeded in demonstrating many of the properties of these substances and it is the knowledge of these properties that has enabled us to produce concentrates and conduct tests. Another practical consideration involved in this matter of properties lies in the effect of cooking and commercial methods of food preparation, for not only must we learn where the vitamine resides but how to prevent injury or destruction in our utilization of the source.

The properties of the vitamines may therefore be grouped under two heads: first chemical properties and second physiological properties.

I. CHEMICAL PROPERTIES OF VITAMINE "A"

_a_. This dietary factor's presence in b.u.t.ter fat and egg yolk fat indicates its solubility in the fat and it would naturally follow that the fat solvents would suffice to remove it with the fats when food sources are treated with such a reagent. Experience has shown however that while ether extraction applied to b.u.t.ter or egg yolk removes the vitamine with the fat this process fails when it is applied to vegetable sources such as cotton seed, corn germ, spinach, lettuce, etc. Neither does the cold or hot press method of oil extraction liberate the vitamine with the oil.

Recent experiments by Osborne and Mendel, to which we have previously referred, have shown that preliminary treatment of vegetable sources with alcohol seems to loosen the bond between the source and the vitamine and that when this binding is once loosened subsequent ether extraction will take the vitamine out. That the binding is not difficult to break is shown by the fact that when vegetables are eaten as a source of vitamine the body is able to separate the complex. It is further evident that the body does separate this complex and stores it in animal fat from the experiments with cow feeds and feeding. Milk for example is rich or poor in vitamine according to the supply of the latter in the food given to the cow. The only logical conclusion to be drawn from this observation is that the cow does not synthesize this factor but splits it off from the food source and then, since it is fat soluble, is able to mobilize it in the b.u.t.ter fat of the milk or to a more limited extent in the body fat. This observation as to the dependence of milk content upon food has been confirmed in the case of nursing mothers and suggests the need of especial attention to the diet of the mother during the lactating period.

_b_. It has been generally a.s.sumed that the "A" vitamine is comparatively stable to heat. Sherman, MacLeod and Kramer state that "dry heating at a temperature of 100C. with free access of air, only very slowly destroyed fat soluble vitamine." Osborne and Mendel reported that b.u.t.ter fat treated with steam for two hours and a half did not appear to have lost its value as a source of this vitamine. Drummond's earlier work with fish oils and whale oils seemed to confirm this conclusion. Sherman and his co-workers cited above put it this way: "The results thus far obtained emphasize the importance of taking full account of the time as well as the temperature of heating, and of the initial concentration of the vitamine in the food, as well as of the opportunity for previous storage of the vitamine by the test animal." More recent work by Steenbock and his co-workers in America shows that these earlier results are incorrect in the case of b.u.t.ter fat and that twelve hours exposure of b.u.t.ter fat to 100C. may, under certain conditions, destroy the efficiency of that substance as a source of the vitamine. Drummond and other English workers have confirmed Steenbock in later experiments. Their work has shown that the presence or absence of oxygen is a factor, which may determine the extent of destruction of the vitamine. Heat alone is of very limited effect but when sources are heated in the presence of oxygen destruction of the A vitamine may be very rapid. Drummond attributes the absence of the A vitamine in lard to the oxidation that takes place in the commercial rendering of this product. We must conclude therefore that while the vitamine may be destroyed by continuous exposure to a temperature of 100C. the effect is largely determined by the nature of the process and the way the vitamine is held in the source. Cooking of vegetables therefore will not as a rule result in appreciable destruction of this factor.

_c_. The process of hydrogenation used in hardening fats appears to completely destroy the vitamine, hence the many lard subst.i.tutes now in use must in general be considered "A" vitamine-free regardless of the content of "A" in the fats from which they are derived unless they have been made by blending instead of hydrogenation.

_d_. Acids and alkalies have apparently little effect on this particular vitamine.

It may be well to state here however that owing to variability in behavior with variation in conditions it is dangerous to draw too general conclusions and until a given source has actually been investigated under specific cooking conditions one should not rely too strongly on a.n.a.logies based on comparative experiments. This statement applies to all vitamines and presents one of the live subjects of investigation for the cooking schools and the food factories.

_e_. Little has been learned further about the chemistry of this substance. [Footnote: Since the above was put in type Steenbock has shown that the A vitamine resists saponification and that by saponifying fats which contain the A it may be possible to secure a fraction rich in the vitamine and free of fat.] b.u.t.ter fat, nitrogen free and phosphorus free is shown to carry the vitamine and it is therefore a.s.sumed that the vitamine lacks these elements. It has been claimed that it may be removed from b.u.t.ter fat by prolonged extraction with water but this has not been confirmed by more recent experimenters. Steenbock was the first to call attention to the a.s.sociation of the A vitamine with yellow pigment in plant and animal sources. b.u.t.ter, egg yolk, carrots, yellow corn contain it while white corn and white roots are less rich in this vitamine. This observation suggested the chemical relation between the vitamine and carotin. It has however been shown by Palmer and others that carotin is not vitamine A. This a.s.sociation of the pigment with the vitamine is therefore apparently a coincidence and this clue has failed as yet to throw light on the chemical nature of vitamine A.

II. THE CHEMICAL PROPERTIES OF VITAMINE "B"

When Funk first studied this substance he conducted all his evaporations in vacuo from fear that higher temperatures would prove destructive.

Subsequent investigation however has shown that 100 has very little if any destructive effect if the vitamine is held in acid or neutral solution. Temperatures between 100 and 120 maintained in an autoclave at 15 pounds above normal pressure do tend to slowly destroy the factor. The extent of this destruction also varies with the character of the crude extract. In general, then, there is little fear of injuring this vitamine in ordinary cooking temperatures if the use of alkali is avoided.

The effect of alkali depends upon the temperature to a very marked degree.

Osborne has recently reinvestigated this matter and finds that in the presence of a 0.1N solution of alkali at 20C. there is very little destruction but that raising the temperature to 90C. brings about a marked destruction. Seidell has shown that if the vitamine is absorbed by Lloyd's reagent and this reagent be then extracted with dilute alkali the vitamine pa.s.ses into the alkaline solution. If the latter is neutralized quickly it is possible to recover most of the vitamine by this method. The effect of alkali becomes of practical importance to the housewife because of certain cooking habits. I refer to the well known practice of adding soda to the water in which vegetables are cooked to soften the vegetable and accelerate the cooking. Daniels and Loughlin in this country investigated this matter and came to the conclusion that this procedure did not produce enough destruction to be dangerous. Later the matter was studied by Chick and Hume in England and these investigators brought out a feature that had perhaps been overlooked in the previous work. Their point was that in ordinary feeding tests the results merely tell whether there is enough vitamine present to produce normal growth. Hence if the substance tested has much vitamine, a large part of it might be destroyed and this fact not appear in the test because enough might still be left to induce normal growth. By reducing the amount tested so that it was just adequate for normal growth and then applying the soda-cooking experimentation they showed that this method of cookery does do serious harm to the vitamine. From the practical point of view it is of course sufficient to show that enough is left after a cooking process to suffice for normal growth when the substance is taken in the portion sizes ordinarily eaten. The effect of alkali deserves more attention on the part of cooks and food preparateurs and we need more data concerning the minimal dose necessary to protect the human animal.

In neutral and acid solution it is perfectly safe to a.s.sume little destruction of this vitamin through heat and it is now common practice to boil sources with the extracting reagent and to use the steam bath freely to concentrate and evaporate these extracts. We have recently investigated the effect upon cabbage of cooking in a pressure cooker at eight pounds pressure. The cabbage so cooked, when dried and mixed so as to form 10 per cent of a basal vitamine free diet, yielded all the "B" vitamine necessary to produce normal growth in rats.

The very name of this vitamine indicates its ready solubility in water. It is also soluble in 95 per cent alcohol and either of these extractants may be used to obtain the vitamine. It is not readily soluble in absolute alcohol and 95 per cent is not as good an extractant as water. Substances rich in the vitamine apparently yield the latter more readily if they have first been subjected to autolysis or if the extracting fluid is acidified.

Funk was the first to show that yeast produced a greater yield if it was allowed to autolyse before extraction with alcohol. However, Osborne and Wakeman have produced a method of treating fresh yeast by boiling it with slightly acidified water which seem as efficient as autolysis in the yield produced.

The various methods of extraction now in vogue have already been discussed in Chapter II and need not be repeated here. In general it is apparent that to obtain concentrates of high potency it is permissible to employ temperatures of 100C. if we will maintain an acid or neutral reaction but that alkali should be avoided wherever possible and when its use is imperative the temperature must be kept below 20C. or destruction will result. In applying this rule to cooking operations the results should be determined by direct tests rather than by a.s.sumptions based on these generalizations. It should also be noted that the alkalinity of a solution should be determined on the basis of hydrogen ion concentration and not on amount of alkali added since many substances have a marked buffer reaction.

The water-soluble "B" is not only soluble in water but can be dissolved in other reagents. Thus McCollum has shown that while benzene is of little value as an extractant of this vitamine, if we will first extract the vitamine with alcohol or water and deposit this on dextrin by evaporation it is then possible by shaking the activated dextrin with benzene to cause the vitamine to pa.s.s into solution in benzene. Voegtlin and Meyers have recently shown that it is soluble in olive oil and in oleic acid and their data suggest a new means of concentrating the substance which may be of value in tracing its character.

The "B" vitamine is relatively easily absorbed by finely divided precipitates. We have already referred to the use of fuller's earth for this purpose by Seidell. This adsorptive power sometimes manifests itself in the treatment of plant extracts. A watery extract of alfalfa can be made to throw down its protein complex by diluting it to 40 per cent with alcohol. Osborne reports however that this process frequently removes the vitamine also which appears to be thrown down with the precipitated material. This adsorptive power therefore often appears as a difficulty in the handling of the substance as well as a means of extraction. We have used Osborne's method with alfalfa extracts and find the above result is not by any means invariable, for in some of our extracts we retained the greater part of the vitamine. Kaolin and ordinary charcoal are not very good adsorbents but the latter can be activated to serve this purpose.

The elementary nature of the "B" vitamine remains a mystery. Extracts which contain it show the presence of nitrogen. Funk's earlier researches on yeast and rice polis.h.i.+ngs both yielded crystalline complexes which he a.n.a.lysed. His data on this subject follow:

_A. The yeast complex_

Crystals melting at 233C. consisting of:

I. A complex melting at 229C. and forming needles and prisms nearly insoluble in water and with the apparent formula of C_24H_19O_2N_5.

II. A complex melting at 222C. and soluble in water. Formula C_29H_23O_2N_5.

III. Nicotinic acid melting at 235C. C_6H_5O_2N.

_B. The rice complex_

Crystals melting at 233C. consisting of:

I. A complex melting at 233C. and with a formula of C_26H_20O_9N_4.