Foods, their selection and preparation

Changes in Quality. The enzymes present change the form of carbohydrates in vege¬ tables held after gathering. The change from sugar to starch is especially noticeable in sweet corn and green peas. It takes place to a lesser degree in all succulent forms of vege¬ tables, however, and is an important factor in loss of flavor. There is also some breaking down of the chemical substances that give characteristic flavor and color to vegetables, and a toughening of the fiber, especially noticeable in asparagus. These are all brought about, at least in part, by enzymatic changes. More serious is the effect of enzymes on loss of vitamin content. The oxidative en¬ zymes present in all plant tissues are specially destructive to vitamin C. A gradual loss of this vitamin occurs when vegetables are held after gathering. This loss increases rapidly when the cell contents are exposed by bruis¬ ing or cutting. The pro-vitamin A, or carotin content, of the leafy vegetables is lowered as they wilt and the cells collapse. The B vitamins are more stable but there is some storage loss of these too. All this adds up to the original statement. The succulent vegetables are highest in quality when first gathered. The develop¬ ment of rapid transportation and refrigera¬ tion, and of methods of controlling or re¬ tarding undesirable changes has made it possible to ship vegetables long distances with minimum changes in quality. Impor¬ tant factors in controlling these changes are low temperatures, moist air to prevent wilting, and avoidance of bruising. The seed of fresh legumes lose quality after shelling. They should be purchased in Iced Vegetables • Crushed ice provides the low temperature and moisture required to maintain quality fresh vegetables National Association of Ice Industries the pod unless wanted for immediate use. Since cold retards changes in pod vegetables, they should be held at low temperatures. The roots, tubers, and bulbs are more stable than the other groups. Some changes take place after gathering, but these vege¬ tables lose less in vitamin content than do the more succulent vegetables. Losses can be held to a minimum by suitable storage conditions. The carbohydrate content of all root vegetables changes form with the tem¬ perature of storage. (See page 74.) Buying Guides. The above discussion sug¬ gests the things to look for in selecting vege¬ tables. Quality comes first: fresh, firm, but tender vegetables, free from bruises or other imperfections, are best. Those of uniform sizes and regular shapes are most easily pre¬ pared and have the least waste. Head vege¬ tables should be solid with few waste leaves, and leafy ones should not be wilted. There are many varieties of the differ¬ ent vegetables. Some of these are better adapted to certain uses than others. Many varieties are especially adapted to growing conditions in certain sections of the country. It is well to know the varieties in the local market at different seasons, and the uses for which each serves best.