Weight for weight tomatoes, raw or canned, rank with lettuce and green string beans as sources of vitamins A and B, and with oranges and lemons as sources of vitamin C.

Seed Vegetables

The plants whose seeds are commonly classed as vegetables belong chiefly to the Leguminosa, or pulse family. Such seeds. include the various kinds of beans, peas, and lentils and are known collectively as legumes or pulses. Seeds of the Graminaceæ, or grass family, which includes the common cereals, and which have been studied under the general name of "grains in the preceding chapter, are sometimes grouped with the vegetables. Thus sweet corn is commonly classed as a vegetable, and rice, though handled as a grain crop commercially, is sometimes given the place of a vegetable on the table.

Beans and peas are commonly marketed as food both in the green condition (fresh or canned) and in the dry state, the dry legumes being sometimes classed as "grains." The Census Bureau reports the production of dry edible beans, but fresh legumes do not appear separately in the census reports. Hence we have no statistical data as to the extent to which the green and dry legumes together enter into the food supply of the country as a whole. From the data of about 400 studies of families and other groups of people, Langworthy estimated that they supply 3.3 per cent of the protein, 0.2 per cent of the fat, and 2.0 per cent of the carbohydrate in the average American dietary.

On account of the recent growth of the pea-canning industry, it seems likely that the legumes may now be playing a larger part in the food supply than at the time of the observations upon which Langworthy's estimates are based.

The present methods of canning peas were fully described by Bitting in Bulletin 125, of the Bureau of Chemistry, United States Department of Agriculture, from which the following paragraphs are taken. (Note that this description, quoted

from a bulletin published several years ago, takes no account of the vitamins. The student may find it a useful exercise to annotate the description and discussion from the point of view of the probable variations in vitamin content among peas and the influence of each step in the canning process upon each of the vitamins which the green peas may be presumed to contain.)

Pea Canning as Described by Bitting

Pea canning is one of the most important lines of the canning industry, being third in order of output, tomatoes and corn being, respectively, first and second, although peas are second in point of value. The pea pack for 1907 is estimated at 6,505,961 cases, valued at $14,650,000.

The first labor-saving device of importance in pea canning was the podding machine invented by Madame Faure in France in 1883. The invention was practically duplicated in this country in 1889. The American podding machine was improved, and in 1893 it was patented as a vining machine. The whole pea-canning industry was changed by this invention. Practically all of the peas canned in this country are passed through these vining machines, so that their use has virtually changed the growing of peas in small patches-market-garden fashion, with hundreds of persons going over the vines and picking the pods — to the cultivating of large fields which are cut by a machine. The viner occupies the same relation to hand picking in the pea-canning industry that the thrashing machine does to the flail in the thrashing of wheat.

The first operation through which the peas pass after leaving the viner is that of washing. This is accomplished in what is known as the squirrel cage, which is a wire cylinder about 3 feet in diameter and 12 feet long. The cylinder is set on a slight incline so that when the peas are admitted at one end they will tend to roll to the other as the cylinder revolves. On the inside is a perforated pipe that sprays a stream of water upon the peas, which insures their being well washed provided the spray has some force. When the weather is very warm and the peas accumulate more rapidly than they can be passed through the filler, it may be necessary to wash the shelled peas in cold water every few hours in order to prevent fermentation.

After the peas pass through the washer, they should be graded according to the degree of maturity or hardness. This is accomplished by passing them through tanks containing salt solutions of different densities. It has been found that the young tender peas will float in a salt solution somewhat heavier than water and those more mature will sink, while the very mature

peas will sink in a heavy salt solution. Peas, therefore, may be sorted very readily into different grades according to their density by using different strengths of salt water. In practice three grades have been made. The first grade consists of all peas which will float in a solution having a specific gravity of 1.040. The second grade consists of those peas which will sink in a solution of this density but which will float in a solution having a specific gravity of 1.070. The third grade consists of the peas which will sink in the latter solution.

Grading. The grading of peas for quality is as sharp and clear as that for size. The lightest weight peas are the finest, being even in quality, succulent, and tender. The heaviest peas are the poorest, being uneven in quality, hard, overripe, and of bad color. The middle-weight peas are good, but harder than the first grade, of darker color, and not so uniform. These differences are most apparent before the canning is done, though they are readily distinguishable in the can, and also show on chemical examination. A chemical examination of peas graded for quality as well as for size gave results as shown in the table on page 363.

The table shows more total solids and higher protein and starch content in the third-grade goods. This might be expected, as the third grade represents the more mature product. If canned peas were purchased for their nutritive properties only, then the third grade would be the preferable one to buy, but they are usually selected for their delicacy and flavor, which are found in the highest degree in the youngest and tenderest peas, or the first grade.

The grading for size is a very simple matter. The peas are passed over sieves, or into a revolving cylinder having four sections with perforations of different sizes. The perforations in the first sieve or section measure nine thirty-seconds of an inch in diameter. The peas which pass through this size opening are known as No. 1, or " petits pois." The next size of perforation is ten thirty-seconds of an inch in diameter, and the peas passing through are known as No. 2, extra sifted," or extra fins." The third size of perforation is eleven thirty-seconds of an inch, and the peas which pass through are known as No. 3, "sifted," or fins." The last size is twelve thirtyseconds of an inch, and the peas which pass through are known as No. 4, or early June" peas. The peas which are too large to pass through this sieve go over the end and are known as No. 5, or marrowfats." Some packers add one more sieve for late peas, with perforations thirteen thirtyseconds of an inch in diameter for the No. 5, and those which pass over this sieve are called No. 6, or " telephone peas." The sizes of these perforations are standard and in general use. Some packers have attempted to make sizes of their own by reaming out the holes, while others do not use all four sieves, but group two sizes together; and some peas are ungraded.

TABLE 47.

GRADE

CHEMICAL EXAMINATION OF PEAS GRADED FOR SIZE AND
QUALITY

[Analyses made in the Division of Foods, Bureau of Chemistry.]

TOTAL
SOLIDS

HSV

REDUCING

SUGAR

UNDETER

MINED

Per cent Per cent Per cent Per cent Per cent Per cent Per cent Per cent Per cent

After the peas have been graded into sizes they are usually run in thin layers over slowly moving belts, so that pieces of foreign material, broken, fully matured, and defective peas may be seen easily and removed. Lowgrade peas are not so carefully picked over.

Blanching. There are two objects in blanching peas: (1) To remove the mucous substance from the outside and a part of the green coloring matter, so as to have a clear liquor in the can; and (2) to drive water into the peas, so that all will be tender.

In the young, juicy pea, the water content is at its maximum, so that the cleaning of the surface is all that is necessary. The time required for blanching is from one-half to one minute for No. 1 and No. 2, or "petits pois" and "extra sifted "; one and a half minutes for No. 3, or "sifted "; two minutes for No. 4, or "early June"; and two and one half minutes for No. 5, or marrowfat peas. To get the best results, peas which are very old and hard will need a blanch approximately five times as long as young peas of the corresponding grade, while those in the intermediate stages will require a blanch proportional to their development.

It is evident, therefore, that among peas that are good, but ungraded as to quality, there will be a greater or less number which will be hard because of