vegetables and vegetable preparation chapter 20. introductory foods, 13 th ed. bennion and scheule...

Vegetables and Vegetable Preparation

Chapter 20

Introductory Foods, 13th ed.Bennion and Scheule

© 2010 Pearson Higher Education,Upper Saddle River, NJ 07458. • All Rights Reserved.2

Vegetables

Plants or parts of plants used for foods

Plants or parts of plants served raw of cooked as part of main course of meal



Consumption Trends

Vegetable consumption has increased since 1970

Americans consume less than the recommended servings of vegetables per day Need to increase consumption of dark green and orange

vegetables and legumes See www.mypyramid.gov

Americans favor starchy vegetables such as potatoes



Nutrition

Vegetable consumption is associated with reduce risk of Certain cancers Type 2 diabetes Stroke Potentially cardiovascular disease and hypertension

2 ½ cups of vegetables is recommended for reference 2000 Kcal diet



Nutrition

Should consume Dark green Orange Legumes Starchy vegetables Other vegetables

Vegetables are rich in Fiber Folate Potassium Vitamin A Vitamin C Phytochemicals



Kinds of Vegetables

Leaf vegetables Lettuce

Vegetable-fruits Tomatoes

Flowers Broccoli

Stems and shoots Asparagus

Roots Carrots

Bulbs Garlic and onion

Tubers Potatoes

Seeds Peas



Mushrooms

Not technically a vegetable

Are fungi

Often served “like” vegetables



Purchasing Vegetables

Seek firm, crisp, bright in color

Consider size, shape, gloss, color, absence of defects, and freshness

Consider point of origin – local?



Grades

Fresh, frozen, and canned vegetables may be graded

USDA has established grades Grading is NOT required by law May be “Packed under continuous inspection of USDA”

Manufacturers may have their own grading standards.



Economic Considerations

Cost per serving

Cost per nutrients

Consider When in season usually better priced Compare fresh, frozen, canned



Organic

National standards for organic foods established by USDA in 2002

“Natural” and “Organic” are not the same



Biotechnology

Traditional biotechnology Plant and animal breeding

Genetic engineering

Regulated by USDA FDA EPA



“Convenience” Vegetables

Partially processed Value added Fresh cuts Packaging

Modified atmosphere Hermetic



Vegetable Storage

Short shelf life

Terminology to know Respiration Senescing



Vegetable Storage

General conditions High humidity conditions often best

Loss of turgor

Avoid storage by other vegetables that Are strongly flavored vegetables Produce ethylene gas



Vegetable Storage

Temperature Best temperature varies with vegetable Roots and tubers usually not refrigerated Tomatoes – best flavor when stored at room

temperature Many other vegetables – best stored under

refrigeration



Methods to Extend Storage

Coatings Vegetable-oil emulsion on some vegetables Edible wax

Storage Controlled atmosphere Oxygen levels reduced to extend storage



Preliminary Preparation

Most vegetables grow near or in ground

Food safety and preparation Select vegetables with minimum decay Thoroughly wash Avoid cross-contamination



Edible Portion and Yield

EP – edible portion AP – as purchased

Yield – the percent of the vegetable remaining after cleaning and peeling



Preparation and Quality

Why cook? Plant pigments Enzymatic oxidative browning Discoloration of potatoes Flavor Texture Prevention of nutrient losses



Why Cook?

Improved palatability Consider raw vs. cooked green beans or potatoes

More digestible i.e. dried legumes

Gelatinization of starch

Destroy microorganisms



Plant Pigments

Chlorophyll Green Green beans, broccoli, others Excess heat and acid = olive green color Alkaline - i.e. baking soda

Negative impact on nutrients and texture Promotes bright green color

Carotenoids Orange and red Carrots, watermelon, tomatoes Includes lycopene



Plant Pigments

Anthocyanins Red cabbage, radishes, black raspberries Water soluble Acid medium = red Alkaline medium = blue and purple Reacts with tin and iron



Plant Pigments

Betalains Red (red beets) Yellow (Yellow cactus pear) Very soluble in water

Anthoxanthins White Potatoes May combine with metals (aluminum or iron) Stable to heat but if prolonged may darken



Enzymatic Oxidative Browning

Darkening of cut vegetables and fruits upon exposure to air Vegetables – potatoes and sweet potatoes Fruits – bananas, apples, and peaches

Prevention Acid solutions such as lemon juice Vitamin C Sulfur dioxide may be used for dehydrated fruits Submerge in water



Discoloration of Potatoes

Some potatoes may be especially prone to darken after cooking Cooking in acidic liquid is preventative Cream of tartar in water



Flavor

Compounds responsible for flavor Aldehydes Alcohols Ketones Organic acids Esters Sulfur-containing compounds

Factors affecting flavor Overcooking Amount of water used Method of cooking



Cabbage Flavors

Cabbage, cauliflower, broccoli, Brussels sprouts, kale, kohlrabi, mustard, rutabaga, and turnips

Mild when raw

Develop strong flavors when overcooked

Best to cook without lid or tipped lid to vent volatile compounds



Onion Flavors

Onions, leeks, garlic, and chives

Strong flavored when raw

More mild after cooking



Texture

Cooking to tender-crisp recommended

Fiber components Cellulose Hemicellulose Pectins Betaglucans Lignin

A noncarbohydrate molecule Gums and mucilages



Fiber - Influence of Cooking

Fiber not lost Cellulose softened Hemicellulose disintegrate in alkaline water Acid prevents softening Calcium salts make vegetable tissues firmer



Prevention of Nutrient Losses

Higher nutrient levels when vegetables prepared and used close to time of harvest

Lost during storage Vitamin C and B vitamins

Lost in cooking Dissolving action of water Chemical decomposition (acid or alkaline) Oxidation Loss of solids into cooking water Volatilization



Cooking Methods

Broiling and grilling

Roasting and baking

Pan-frying and deep-frying

Sautéing

Boiling Blanching Parboiling

Steaming

Pressure cooking

Microwave cooking



Cooking of Frozen and Canned

Frozen vegetables

Canned vegetables



Vegetarian Diets

Semi-vegetarian Pesco-vegetarian Lacto-ovo-vegetarian Lacto-vegetarian Ovo-vegetarian Vegan



Dried Legumes

Dried beans, peas, and lentils

Inexpensive protein source

Rich in Complex carbohydrate Dietary fiber Protein

Low in fat



Preparation of Legumes

Must be cooked before eating

Soaking of Beans Soft water is preferable

Use of alkali not recommended May make beans too soft Destructive to thiamin

Canned beans offer convenience

Raffinose and Sachyose



Soybeans

Good source of protein

Soy products Texturized soy proteins Whole soybeans Soy milk Tofu Fermented soy products

vegetables and vegetable preparation chapter 20. introductory foods, 13 th ed. bennion and scheule...

Documents