Legumes PDF

Legumes 1. Overview of legumes l Member of Fabaceae plant family, the third largest family of flowering plants. l Similar flower and fruit structures è 5-petaled irregular flower in bilateral symmetry (butterfly shaped) è The fruit is a pod, with one row of seeds Pod l Carry multiple and...

Legumes 1. Overview of legumes l Member of Fabaceae plant family, the third largest family of flowering plants. l Similar flower and fruit structures è 5-petaled irregular flower in bilateral symmetry (butterfly shaped) è The fruit is a pod, with one row of seeds Pod l Carry multiple and edible seeds, the pod will naturally open and release its seeds when ripe (Dehiscent) l The seed contains two prominent food-storing cotyledons (dicot) Composition of legume seeds l Seed coat l Micropyle l Cotyledon x2 l Embryo Nuts (Different from legume) l Usually a hard outer shell protecting a single seed l Indehiscent: The shell does not open on its own when ripe Drupes(Stone fruits) l Pulp on the outside, hard shell on the inside that contains a single seed Pulses l An edible seed that grows in a pod, it includes all beans, peas and lentils. E.g. Baked beans, chickpeas, garden peas, runner beans l Dried seeds of the legume plants Relationship between among legumes, pulses and beans 2. Importance of legumes Nutritional values l Inexpensive source of protein, vitamins, minerals, complex carbohydrate and fiber l Low in fat and sodium l No cholesterol l Low glycemic index l Source of prebiotics that feed gut flora to help prevent digestive disease è Individuals can count beans and peas as either a vegetable or a protein food è Green peas, green lima beans and green beans are vegetable groups (Since nutritional value similar to vegetable) l 1 ounce-equivalent of protein è 1/4 cup cooked beans è 1 tablespoon of peanut butter Root Nodules l Contain nitrogen-fixing bacteria, converting free atmospheric nitrogen (N2) into ammonium (NH4+) l Nitrifying bacteria in the soil quickly convert ammonium to nitrite (NO2-) then to nitrate (NO3-) l Nitrate is usually absorbed and used by plants Legumes in agriculture l Tolerant to most types of soils, drought l Self-pollinating l Legumes enrich the soil, farmers often rotate legumes with crops that deplete soil nitrogen l The “three sisters”, easy to grow and harvest, can tolerate most types of souls l Long storage time when dry 3. Preparing dried legumes (pulses) l Pulses are bought either tinned or dried l Dried kidney beans and soya beans contain toxins. è May cause diarrhea and vomiting è Soaked overnight and cooked properly before eating Preparing dried legumes 1. Remove foreign particles and rinse well, put the beans in a cooking pot 3 times the volume of cold water. 2. Soak overnight (get the toxins out) for ~10 hours, no soaking for split peas and lentils. 3. Drain the beans, place them in a pot and add fresh cold water to cover by 1-2 inches. 4. Bring to a boil, reduce heat and simmer, covered, until tender. Do not boil. Different simmering time is required for different beans. 5. Check texture for doneness, they should remain intact unless soup or puree. Cooked beans should be soft and creamy not hard or grainy. Purpose of soaking l Minimize the gases produced by intestinal bacteria when they ferment the indigestible carbohydrates in beans l Will not interfere with its nutritive value Storage of pulses l Dried beans will keep up to a year stored in a airtight containers in a cool dry place l High temperature, high humidity and too long the storage time will lead to difficulty in cooking 4. Highlights of specific legume Peanuts l Origin: South America l Spanish explorers brought them to Europe. Trading introduced peanut to Africa. Slave trade returned peanuts to North America. l Staple crop of the South America, best grow in light sandy soils l The whole growing cycle is about 5 months l Develop underground è After pollination, the flower stalk elongates downward, pushing the developing fruits into the soil, then the fruit matures into a pod. Different uses of peanut Soybean l Oil: 13%-25% l Complete protein with amount of 30%-50%, higher than lean beef l Grow best in warm temperate climate with moderate rainfall l Sacred crops of the ancient China, domesticated in northern China at least 3000 years ago “Cinderella” crops - Prior to WWII soybeans are relatively obscure - Suddenly become the second most important income earner among all cash crops, outranked only by corns Edamame - Immature soybean, cannot be consumed raw because of its toxin Soy milk l Non-dairy substitute for lactose intolerant people, no saturated fat l Need boiling è Lipoxygenase: convert soy fatty acids to odorous compound (grassy smell) è Trypsin inhibitor: interfere the digestive process Tofu l Protein in soy milk is precipitated out through the use of coagulants. e.g. CaCl2, MgCl2 and pressed into blocks Fermented products l E.g. Miso, Natto l Deactivates the trypsin inhibitors, phytic acid, hemagglutinin and etc in raw soybean, the nutrients thus are more available and digestible E.g. Vitamin K and C, iron, Magnesium and fiber Why soybean good for your health? l Phytoestrogen è Protect against hormonal cancers like breast and prostate cancer è Lower the risk of heart disease è Reduce menopausal symptoms and bone loss (osteoporosis) in older women è Some also fear that it causes breast cancer, thyroid problem and dementia l Still controversial è Type of study è Ethnicity è Hormone responses (Pre- and post- menopausal women / Hormone +ve/-ve cancer) è Type of soy A variety of applications of soybean l Animal feeds l Soy flour (increase the protein content) e.g. breads, pastsa, baked goods, Japanese sticky rice pastes’ coating l Vietnamese pancake (soya milk + honey) l Thickening sauces l Protein supplement Texture Vegetable Protein (TVP) l Spinning the soy protein into long slender porous fibers l Rehydrate rapidly, it can pick up flavors easily from other substances Meat extenders and imitation meats l Lower costs l Reduce fat content and cholesterol-free l Maintain moisture, and add texture by maintaining cohesiveness l USDA limits the use of TVP to no more than 30% in any products